Presentation is loading. Please wait.

Presentation is loading. Please wait.

Blood and Blood Vessels

Similar presentations


Presentation on theme: "Blood and Blood Vessels"— Presentation transcript:

1 Blood and Blood Vessels

2 Module 17.3: Red blood cell production and recycling
RBC production and recycling Events occurring in red bone marrow Blood cell formation (erythropoiesis) occurs only in red bone marrow (myeloid tissue) Located in vertebrae, ribs, sternum, skull, scapulae, pelvis, and proximal limb bones Fatty yellow bone marrow can convert to red bone marrow in cases of severe, sustained blood loss Developing RBCs absorb amino acids and iron from bloodstream and synthesize Hb

3 Module 17.3: Red blood cell production and recycling
Stages Proerythroblasts Erythroblasts Actively producing Hb After four days becomes normoblast Reticulocyte (80% of mature cell Hb) Ejects organelles including nucleus Enters bloodstream after two days After 24 hours in circulation, is mature RBC

4 Module 17.3: Red blood cell production and recycling
Events occurring at macrophages Engulf old RBCs before they rupture (hemolyze) Hemoglobin recycling Iron Stored in phagocyte Released into bloodstream attached to plasma protein (transferrin) Globular proteins disassembled into amino acids for other uses Heme  biliverdin  bilirubin  bloodstream Hemoglobin not phagocytized breaks down into protein chains and eliminated in urine (hemoglobinuria) Excess of bilirubin =jaundice

5 Module 17.3: Red blood cell production and recycling
Events occurring at liver Bilirubin excreted into bile Accumulating bile due to diseases or disorders can lead to yellowish discoloration of eyes and skin (jaundice) Events occurring at the large intestine Bacteria convert bilirubin to urobilins and stercobilins which become part of feces Give feces yellow-brown or brown coloration

6 Module 17.3: Red blood cell production and recycling
Events occurring at kidneys Excrete some hemoglobin and urobilins Give urine its yellow color Presence of intact RBCs in urine (hematuria) Only after urinary tract damage

7 Fe2+ transported in circulation
Events Occurring in the Red Bone Marrow Start Developing RBCs absorb amino acids and Fe2+ from the bloodstream and synthesize new Hb molecules. Cells destines to become RBCs first differentiate into proerythroblasts. Proerythroblasts then differentiate into various stages of cells called erythroblasts, which actively synthesize hemoglobin. Erythroblasts are named according to total size, amount of hemoglobin present, and size and appearance of the nucleus. Events in the life cycle of RBCs Events Occurring in Macrophages Macrophages in liver, spleen, and bone marrow Fe2+ Fe2+ transported in circulation by transferrin RBC formation Heme Amino acids Average life span of RBC is 120 days 90% Biliverdin After roughly four days of differentiation, the erythroblast, now called a normoblast, sheds its nucleus and becomes a reticulocyte (re-TIK-ū-lō-sīt), which contains 80 percent of the Hb of mature RBC. Old and damaged RBCs Bilirubin 10% In the bloodstream, the rupture of RBCs is called hemolysis. Ejection of nucleus After two days in the bone marrow, reticulocytes enter the bloodstream. After 24 hours in circulation, the reticulocytes complete their maturation and become indistinguishable from other mature RBCs. Figure 17.3 Red blood cells are continuously produced and recycled Bilirubin bound to albumin in bloodstream Hemoglobin that is not phagocytized breaks down, and the alpha and beta chains are eliminated in urine. When abnormally large numbers of RBCs break down in the bloodstream, urine may turn red or brown. This condition is called hemoglobobinuria. New RBCs released into circulation Liver Bilirubin Events Occurring in the Kidney Excreted in bile Absorbed into the circulation Hb Events Occurring in the Liver Urobilins Bilirubin Urobilins, sterconilins Eliminated in feces Eliminated in urine Events Occurring in the Large Intestine Figure 17.3 7

8 Module 17.3 Review a. Define hemolysis.
b. Identify the products formed during the breakdown of heme. c. In what way would a liver disease affect the level of bilirubin in the blood?

9 Module 17.4: Blood types Blood types
Determined by presence or absence of cell surface markers (antigens) Are genetically determined glycoproteins or glycolipids Can trigger a protective defense mechanism (immune response) Identify blood cells as “self” or “foreign” to immune system More than 50 blood cell surface antigens exist Three particularly important A, B, Rh (or D)

10 Module 17.4: Blood types Four blood types (AB antigens)
Type A (A surface antigens) Anti-B antibodies in plasma Type B (B surface antigens) Anti-A antibodies in plasma Type AB (Both A and B surface antigens) No anti-A or anti-B antibodies in plasma Type O (no A or B surface antigens) Both anti-A and anti-B antibodies in plasma

11 The characteristics of blood for each of the four blood types
Type A Type B Type AB Type O Type A blood has RBCs with surface antigen A only. Type B blood has RBCs with surface antigen B only. Type AB blood has RBCs with both A and B surface antigens. Type O blood has RBCs lacking both A and B surface antigens. Surface antigen A Surface antigen B Figure Blood type is determined by the presence or absence of specific surface antigens on RBCs If you have Type A blood, your plasma contains anti-B antibodies, which will attack Type B surface antigens. If you have Type B blood, your plasma contains anti-A antibodies. If you have Type AB blood, your plasma has neither anti-A nor anti-B antibodies. If you have Type O blood, your plasma contains both anti-A and anti-B antibodies. Figure 11

12 Module 17.4: Blood types Rh surface antigens
Separate antigen from A or B Presence or absence on RBC determines positive or negative blood type respectively Examples: AB+, O–

13 Figure Blood type is determined by the presence or absence of specific surface antigens on RBCs Figure 13

14 Module 17.4 Review a. What is the function of surface antigens on RBCs? b. Which blood type(s) can be safely transfused into a person with Type O blood?

15 CLINICAL MODULE 17.5: Newborn hemolytic disease
Genetically determined antigens mean that a child can have a blood type different from either parent During pregnancy, the placenta restricts direct transport between maternal and infant blood Anti-A and anti-B antibodies are too large to cross Anti-Rh antibodies can cross Can lead to mother’s antibodies attacking fetal RBCs

16 CLINICAL MODULE 17.5: Newborn hemolytic disease
First pregnancy with Rh– mother and Rh+ infant During pregnancy, few issues occur because no anti-Rh antibodies exist in maternal circulation During birth, hemorraging may expose maternal blood to fetal Rh+ cells Leads to sensitization or activation of mother’s immune system to produce anti-Rh antibodies

17 Rh– mother First Pregnancy of an Rh– Mother with an Rh+ infant Rh+ fetus The most common form of hemolytic disease of the newborn develops after an Rh– women has carried an Rh+ fetus. During First Pregnancy Problems seldom develop during a first pregnancy, because very few fetal cells enter the maternal circulation then, and thus the mother’s immune system is not stimulated to produce anti-Rh antibodies. Maternal blood supply and tissue Placenta Figure Hemolytic disease of the newborn is an RBC-related disorder caused by a cross-reaction between fetal and maternal blood types Fetal blood supply and tissue Exposure to fetal red blood cell antigens generally occurs during delivery, when bleeding takes place at the placenta and uterus. Such mixing of fetal and maternal blood can stimulate the mother’s immune system to produce anti-Rh antibodies, leading to sensitization. Hemorrhaging at Delivery Maternal blood supply and tissue Rh antigen on fetal red blood cells Fetal blood supply and tissue Roughly 20 percent of Rh– mothers who carried Rh+ children become sensitized within 6 months of delivery. Because the anti-Rh antibodies are not produced in significant amounts until after delivery, a woman’s first infant is not affected. Maternal Antibody Production Maternal blood supply and tissue Maternal antibodies to Rh antigen Figure 17.5 17

18 CLINICAL MODULE 17.5: Newborn hemolytic disease
Second pregnancy with Rh– mother and Rh+ infant Subsequent pregnancy with Rh+ infant can allow maternal anti-Rh antibodies to cross placental barrier Attack fetal RBCs and cause hemolysis and anemia = Erythroblastosis fetalis Full transfusion of fetal blood may be necessary to remove maternal anti-Rh antibodies Prevention RhoGAM antibodies can be administered to maternal circulation at 26–28 weeks and before/after birth Destroys any fetal RBCs that cross placenta Prevents maternal sensitization

19 Second Pregnancy of an Rh– Mother with an Rh+ Infant
fetus If a subsequent pregnancy involves an Rh+ fetus, maternal anti-Rh antibodies produced after the first delivery cross the placenta and enter the fetal bloodstream. These antibodies destroy fetal RBCs, producing a dangerous anemia. The fetal demand for blood cells increases, and they begin leaving the bone marrow and entering the bloodstream before completing their development. Because these immature RBCs are erythroblasts, HDN is also known as erythroblastosis fetalis. Fortunately, the mother’s anti-Rh antibody production can be prevented if such antibodies (available under the name RhoGAM) are administered to the mother in weeks 26–28 of pregnancy and during and after delivery. These antibodies destroy any fetal RBCs that cross the placenta before they can stimulate a maternal immune response. Because maternal sensitization does not occur, no anti-Rh antibodies are produced. Figure Hemolytic disease of the newborn is an RBC-related disorder caused by a cross-reaction between fetal and maternal blood types During Second Pregnancy Maternal blood supply and tissue Maternal anti-Rh antibodies Fetal blood supply and tissue Hemolysis of fetal RBCs Figure 17.5 19

20 CLINICAL MODULE 17.5 Review
a. Define hemolytic disease of the newborn (HDN). b. Why is RhoGAM administered to Rh– mothers?

21 Module 17.6: White blood cells
White blood cells (leukocytes) Spend only a short time in circulation Mostly located in loose and dense connective tissues where infections often occur Can migrate out of bloodstream Contact and adhere to vessel walls near infection site Squeeze between adjacent endothelial cells = Emigration Are attracted to chemicals from pathogens, damaged tissues, or other WBCs = Positive chemotaxis

22 Module 17.6: White blood cells
White blood cell types Granular leukocytes (have cytoplasmic granules) Neutrophil Eosinophil Basophil Agranular leukocytes (lacking cytoplasmic granules) Monocyte Lymphocyte Changing populations of different WBC types associated with different conditions can be seen in a differential WBC count

23 Module 17.6: White blood cells
Granular leukocytes Neutrophils Multilobed nucleus Phagocytic cells that engulf pathogens and debris Eosinophils Granules generally stain bright red Phagocytic cells that engulf antibody-labeled materials Increase abundance with allergies and parasitic infections Basophils Granules generally stain blue Release histamine and other chemicals promoting inflammation

24 The structure and function of white
blood cells (leukocytes) GRANULAR LEUKOCYTES Neutrophil Eosinophil Basophil WBCs can be divided into two classes Figure White blood cells defend the body against pathogens, toxins, cellular debris, and abnormal or damaged cells Shared Properties of WBCs AGRANULAR LEUKOCYTES • WBCs circulate for only a short portion of their life span, using the bloodstream primarily to travel between organs and to rapidly reach areas of infection or injury. White blood cells spend most of their time migrating through loose and dense connective tissues throughout the body. Monocyte Lymphocyte • All WBCs can migrate out of the bloodstream. When circulating white blood cells in the bloodstream become activated, they contact and adhere to the vessel walls and squeeze between adjacent endothelial cells to enter the surrounding tissue. This process is called emigration, or diapedesis (dia, through; pedesis, a leaping). • All WBCs are attracted to specific chemical stimuli. This characteristic, called postive chemotaxis (kē-mō-TAK-sis), guides WBCs to invading pathogens, damaged tissues, and other active WBCs. • Neutrophils, eosinophils, and monocytes are capable of phagocytosis. These phagocytes can engulf pathogens, cell debris, or other materials. Macrophages are monocytes that have moved out of the bloodstream and have become actively phagocytic. Figure 17.6 24

25 Module 17.6: White blood cells
Agranular leukocytes Monocytes Large cells with bean-shaped nucleus Enter tissues and become macrophages (phagocytes) Lymphocytes Slightly larger than RBC with large round nucleus Provide defense against specific pathogens or toxins

26 Module 17.6 Review a. Identify the five types of white blood cells.
b. How do basophils respond during inflammation?

27 Module 17.7: Formed element production
Formed elements Appropriate term since platelets are cell fragments Platelets Structure: flattened discs that appear round when viewed from top but spindle-shaped in blood smear Function: clump together and stick to damaged vessel walls where they release clotting chemicals Immediate precursor cell is megakaryocyte (mega-, big + karyon, nucleus + -cyte, cell) Platelets average 350,000 ul; continuously replaced every 9-12 days. Stick together at damaged

28 Module 17.8: Hemostasis Hemostasis (haima, blood + stasis, halt)
Stops blood loss from damaged blood vessel walls Establishes framework for tissue repairs

29 Monocyte Small lymphocyte Neutrophil Platelets Eosinophil Small
Fig. 18.1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Monocyte Small lymphocyte Neutrophil Platelets Eosinophil Small lymphocyte Erythrocyte Young (band) neutrophil Neutrophil Monocyte Large lymphocyte Neutrophil Basophil

30 Section 2: Functional Anatomy of Blood Vessels
Blood vessels conduct blood between heart and peripheral tissues Two circuits Pulmonary circuit (to and from lungs) Systemic circuit (to and from rest of body) Each circuit begins and ends with heart Occur in sequence

31 Section 2: Functional Anatomy of Blood Vessels
Specific vessels Arteries (transport blood away from heart) Veins (transport blood to the heart) Capillaries (exchange substances between blood and tissues) Interconnect smallest arteries and smallest veins

32 Section 2: Functional Anatomy of Blood Vessels
General circulation pathway through circuits Right atrium (entry chamber) from systemic circuit to right ventricle, to pulmonary circuit Pulmonary circuit Pulmonary arteries to pulmonary capillaries to pulmonary veins Left atrium from pulmonary circuit to left ventricle, to systemic circuit Systemic circuit Systemic arteries to systemic capillaries to systemic veins

33 Figure 17 Section 2 The Functional Anatomy of Blood Vessels
33

34 Module 17.10: Arteries and veins
Both arteries and veins have three layers Tunica intima (tunica interna) Innermost layer Endothelial cells with connective tissue with elastic fibers In arteries, outer margin has layer of elastic fibers (internal elastic membrane) Tunica media Middle layer Contains concentric sheets of smooth muscle Capable of vasoconstriction or vasodilation Collagen fibers connect tunica media to other layers

35 Module 17.10: Arteries and veins
Both arteries and veins have three layers (continued) Tunica externa Outermost layer Connective tissue sheath with collagen and elastic fibers Generally thicker in veins Anchor vessel to surrounding tissues

36 A photomicrograph of an artery and an adjacent vein
Figure Arteries and veins differ in the structure and thickness of their walls LM x 60 Figure 36

37 The structure of the wall of an artery Artery
Tunica intima Smooth muscle Internal elastic membrane Figure Arteries and veins differ in the structure and thickness of their walls External elastic membrane Tunica media Endothelium Elastic fiber Tunica externa Figure 37

38 The structure of the wall of a vein Vein Endothelium Smooth muscle
Figure Arteries and veins differ in the structure and thickness of their walls Smooth muscle Tunica intima Tunica media Tunica externa Figure 38

39 Module 17.10: Arteries and veins
Five general blood vessel classes Arteries Elastic arteries (large vessels close to the heart that stretch and recoil when heart beats) Muscular arteries (medium-sized arteries, distribute blood to skeletal muscles and internal organs) Arterioles Poorly defined tunica externa and tunica media only 1–2 smooth muscle cells thick Capillaries Thin, exchange vessels

40 Module 17.10: Arteries and veins
Five general blood vessel classes (continued) Venules (small veins lacking tunica media, collect blood from capillaries) Veins Medium-sized veins (tunica media is thin but tunica externa is thick with longitudinal collagen and elastic fibers) Large veins (superior and inferior venae cavae and tributaries having thin tunica media)

41 The five general classes of blood vessels:
arteries, arterioles, capillaries, venules, and veins Large Veins Elastic Arteries Include the superior and inferior venae cavae and their tributaries; contain all three vessel wall layers; have a slender tunica media composed of a mixture of elastic and collagen fibers Large vessels that transport blood away from the heart; include the pulmonary trunk and the aorta and its major branches; are resilent, elastic vessels capable of stretching and recoiling as the heart beats and arterial pressures change Tunica externa Internal elastic layer Tunica media Tunica intima Tunica intima Tunica media Tunica externa Medium-sized Veins Muscular Arteries Range from 2 to 9 mm in internal diameter; the tunica media is thin and contains relatively few smooth muscle cells; the thickest layer is the tunica externa, which contains longitudinal bundles of elastic and collagen fibers Medium-sized arteries that distribute blood to the body’s skeletal muscles and internal organs Figure Arteries and veins differ in the structure and thickness of their walls Tunica externa Tunica externa Tunica media Tunica media Tunica intima Tunica intima Venules Arterioles Collect blood from capillary beds and are the smallest venous vessels; those smaller than 50 μm lack a tunica media and resemble expanded capillaries Have a poorly defined tunica externa, and the tunica media consists of only one or two layers of smooth muscle cells Tunica externa Smooth muscle cells Endothelium Endothelium Capillaries The only blood vessels whose walls permit exchange between the blood and the surrounding interstitial fluids due to thin walls and short diffusion distances Pores Endothelial cells Endothelial cells Basal lamina Basal lamina Figure 41

42 Module 17.10 Review a. List the five general classes of blood vessels.
b. Describe a capillary. c. A cross section of tissue shows several small, thin-walled vessels with very little smooth muscle tissue in the tunica media. Which type of vessels are these?

43 Module 17.11: Capillaries Typical capillary consists of tube of endothelial cells with delicate basal lamina Neither tunica intima nor externa are present Average diameter = 8 µm About the same as an RBC Two major categories Continuous capillaries Fenestrated capillaries

44 Module 17.11: Capillaries Continuous capillaries
Endothelium is a complete lining Located throughout body in all tissues except epithelium and cartilage Permit diffusion of water, small solutes, and lipid-soluble materials Prevent loss of blood cells and plasma proteins Some selective vesicular transport Some capillaries have endothelial tight junctions Restricted and regulated permeability

45 Module 17.11: Capillaries Fenestrated capillaries
Contain windows or pores penetrating endothelium Permit rapid exchange of water and larger solutes Examples: capillaries in brain and endocrine organs, absorptive areas of GI tract, kidney filtration sites

46 materials transported across the endothelial cell
The two major types of capillaries: continuous capillaries and fenestrated capillaries Basal lamina Endothelial cell Nucleus Figure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluid A continuous capillary A fenestrated capillary Fenestrations, or pores Vesicles containing materials transported across the endothelial cell Boundary between endothelial cells Boundary between endothelial cells Basal lamina Basal lamina Figure – 2 46

47 Module 17.11: Capillaries Sinusoids
Resemble fenestrated capillaries that are flattened and irregularly shaped Commonly have gaps between endothelial cells Basal lamina is thin or absent Permit more water and solute (plasma proteins) exchange Occur in liver, bone marrow, spleen, and many endocrine organs

48 A sinusoid Gap between adjacent cells
Figure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluid Figure 48

49 Module 17.11: Capillaries Capillary bed
Network of capillaries with several connections between arterioles and venules Can have collateral arteries (functionally redundant) fusing to one arteriole (forming an arterial anastomosis) leading to capillary bed Can be bypassed by arteriovenous anastomosis that directly connects arteriole to venule

50 Module 17.11: Capillaries Capillary bed (continued)
Thoroughfare channels (direct passages through capillary bed) Begin with metarteriole segment that can constrict or dilate to control flow Has multiple capillaries connecting to venules Have bands of smooth muscle (precapillary sphincters) to control flow into capillary bed Vasomotion (cycling contraction and relaxing changing capillary bed flow)

51 A capillary bed Collateral arteries Vein Venule Arteriole Metarteriole
Thoroughfare channel Smooth muscle cells Capillaries Figure Capillary structure and capillary blood flow affect the rates of exchange between the blood and interstitial fluid Precapillary sphincter Small venules Arteriovenous anastomosis KEY Precapillary sphincters Continuous blood flow Variable blood flow Figure 51

52 Module 17.11 Review a. Identify the two types of capillaries.
b. At what sites in the body are fenestrated capillaries located? c. Why do capillaries permit the diffusion of materials, whereas arteries and veins do not?

53 Module 17.12: Venous functional anatomy
Venous functional anatomy and pressure Blood pressure in venules and medium veins is <10% of that in ascending aorta (largest artery) These vessels contain valves (folds of tunica intima) that ensure one-way flow of blood toward heart Malfunctioning valves can lead to varicose veins (enlarged superifical thigh and leg veins) or distortion of adjacent tissues (hemorrhoids)

54 Figure Figure The venous system has low pressures and contains almost two-thirds of the body's blood volume 54

55 Module 17.12: Venous functional anatomy
Increasing venous blood flow Skeletal muscle contractions squeezing veins with valves Sympathetically controlled constriction of veins (venoconstriction) Venoconstriction can maintain arterial blood volume despite hemorrhaging

56 Total blood volume distribution
Figure Total blood volume distribution Unevenly distributed between arteries, veins, and capillaries Systemic venous system contains nearly 2/3 of total blood volume (~3.5 L) Of that , ~1 L is in venous networks of liver, bone marrow, and skin Systemic venous system Pulmonary circuit Heart arterial capillaries The distribution of blood volume within the body venous Figure The venous system has low pressures and contains almost two-thirds of the body's blood volume 56

57 Module 17.12 Review a. Define varicose veins.
b. Why are valves located in veins, but not in arteries? c. How is blood pressure maintained in veins to counter the force of gravity?

58 Module 17.13: Pulmonary circuit
Arteries of pulmonary circuit differ from those in systemic circuit Pulmonary arteries carry deoxygenated blood Right ventricle  pulmonary trunk (large artery)  pulmonary arteries  pulmonary arterioles  pulmonary capillaries (surrounded by alveoli, where gas exchange occurs)  pulmonary venules  pulmonary veins  left atrium

59 Fig. 19.1 CO2 O2 Pulmonary circuit O2-poor, CO2-rich blood O2-rich,
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CO2 O2 Pulmonary circuit O2-poor, CO2-rich blood O2-rich, CO2-poor blood Systemic circuit CO2 O2

60 The path of blood flow through the pulmonary circuit
Aortic arch Ascending aorta Pulmonary trunk Superior vena cava Left lung Left pulmonary arteries Right lung Right pulmonary arteries Left pulmonary veins Figure The pulmonary circuit, which is relatively short, carries deoxygenate blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium Right pulmonary veins Alveolus Capillary Inferior vena cava Descending aorta Figure 60

61 Module 17.13: Pulmonary circuit
Major patterns of blood vessel organization Peripheral arteries and veins are generally identical between left and right sides except near heart Vessels change names as they branch or move into new areas Tissues and organs are usually served by many arteries and veins Anastomoses reduce impact of potential blockages (occlusions)

62 Module Review a. Identify the two circulatory circuits of the cardiovascular system. b. Briefly describe the three major patterns of blood vessel organization. c. Trace a drop of blood through the lungs, beginning at the right ventricle and ending at the left atrium.

63 Module 17.14: Systemic vessels
Arterial system Originates from aorta (largest elastic vessel exiting left ventricle) Venous system All drain into: Superior vena cava (upper limbs, head, and neck) Inferior vena cava (trunk and lower limbs)

64 An overview of the systemic arterial system
Vertebral Common carotid Subclavian Brachiocephalic trunk Axillary Aortic arch Ascending aorta Descending aorta Brachial Diaphragm Celiac trunk Renal Gonadal Lumbar Radial Common iliac Internal iliac Ulnar External iliac Figure The systemic arterial and venous systems operate in parallel, and the major vessels often have similar names Palmar arches Digital arteries Deep femoral Femoral Popliteal Posterior tibial Anterior tibial Fibular Dorsalis pedis Plantar arch Figure 64

65 An overview of the systemic venous system
Vertebral External jugular Internal jugular Subclavian Brachiocephalic Axillary Superior vena cava Brachial Cephalic Diaphragm Basilic Inferior vena cava Renal Gonadal Radial Lumbar Median antebrachial Common iliac Ulnar Internal iliac Figure The systemic arterial and venous systems operate in parallel, and the major vessels often have similar names Palmar venous arches External iliac Digital veins Deep femoral Femoral Great saphenous Popliteal Small saphenous Posterior tibial Fibular Anterior tibial KEY Plantar venous arch Superficial veins Dorsal venous arch Deep veins Figure 65

66 Module 17.14: Systemic vessels
Arteries and veins are usually similar on both sides of body One significant difference between arteries and veins is distribution in the neck and limbs Arteries: deep in skin, protected by bones and soft tissues Veins: generally two sets, one deep and one superficial Important in controlling body temperature Venous blood flows superficially in hot weather to radiate heat Venous blood flows deep in cold weather to conserve heat

67 Module Review a. Name the two large veins that collect blood from the systemic circuit. b. Identify the largest artery in the body. c. Besides containing valves, cite another major difference between the arterial and venous systems.

68 Module 17.15: Upper limb vessels
Arteries Branches of aortic arch Brachiocephalic trunk Right subclavian (right arm) Right common carotid artery (right side head & neck) Left common carotid artery (left side head & neck) Left subclavian artery (left arm)

69 Module 17.15: Upper limb vessels
Arteries (continued) Right subclavian artery branches Internal thoracic artery (pericardium, anterior chest wall) Vertebral artery (brain, spinal cord) Arteries of the arm Axillary artery (through axilla) Brachial artery (upper limb)

70 Module 17.15: Upper limb vessels
Arteries (continued) Arteries of the forearm Radial artery (follows radius) Ulnar artery (follows ulna) Palmar arches (hand) Digital arteries (thumb and fingers)

71 The branches of the aortic arch and the
arteries they give rise to Branches of the Aortic Arch Start Brachiocephalic trunk Left common carotid artery Left subclavian artery The Right Subclavian Artery Vertebral Major branches of the subclavian artery Internal thoracic Aortic arch Axillary Ascending aorta Deep brachial Arteries of the Arm Heart Brachial Ulnar collateral arteries Descending aorta Figure The branches of the aortic arch supply structures that are drained by the superior vena cava Radial Arteries of the Forearm Ulnar Deep palmar arch Superficial palmar arch Digital arteries Figure 17.15 71

72 Veins of the Neck The veins that drain into the superior vena cava External jugular vein Internal jugular vein Vertebral vein Brachiocephalic vein The Right Subclavian Vein Veins of the Arm Axillary vein Cephalic vein Superior vena cava Veins of the Forearm Brachial Median cubital vein Basilic Figure The branches of the aortic arch supply structures that are drained by the superior vena cava Median antebrachial vein Superior vena cava KEY Cephalic Superficial veins Deep veins Radial Basilic Ulnar Digital veins Deep palmar arch Start Superficial palmar arch Figure 17.15 72

73 Module 17.15: Upper limb vessels
Veins Digital veins (empty from thumb and fingers) Veins of the forearm Superficial palmar arch (hand) Median antebrachial vein (anterior forearm) Cephalic vein Basilic vein Median cubital vein (interconnects cephalic and basilic veins) Venous samples usually collected here

74 Module 17.15: Upper limb vessels
Veins (continued) Veins of the arm Cephalic vein (lateral side of arm) Basilic vein (median side of arm) Brachial vein (median area of arm) Right subclavian vein Merging of axillary vein and cephalic vein

75 Module 17.15: Upper limb vessels
Veins (continued) Veins of the neck External jugular vein (drains superficial head & neck) Internal jugular vein (drains deep head & neck) Vertebral vein (cervical spinal cord and posterior skull) Veins draining into superior vena cava (SVC) Internal thoracic vein (intercostal veins) Brachiocephalic vein (jugular, axillary, vertebral, and internal thoracic veins)

76 Module Review a. Name the two arteries formed by the division of the brachiocephalic trunk. b. A blockage of which branch from the aortic arch would interfere with blood flow to the left arm? c. Whenever Thor gets angry, a large vein bulges in the lateral region of his neck. Which vein is this?

77 Module 17.16: Head and neck vessels
Arteries Common carotid artery (head and neck) Palpated alongside trachea (windpipe) Contains carotid sinus (with baroreceptors monitoring blood pressure) Branches of common carotid artery External carotid artery (neck, esophagus, pharynx, larynx, lower jaw, cranium, and face on that side) Internal carotid artery (brain and eyes) Vertebral artery (enters cranium and fuses with basilar artery along ventral medulla oblongata)

78 Areas supplies by the external carotid, internal carotid, and vertebral arteries
Carotid canal Basilar Superficial temporal Maxillary Branches of the External Carotid Occipital Facial Internal carotid artery Lingual Figure The external carotid arteries supply the neck, lower jaw, and face, and the internal carotid and vertebral arteries supply the brain, while the external jugular veins drain the regions supplied by the external carotids, and the internal jugular veins drain the brain External carotid Vertebral artery Carotid sinus Common carotid artery Clavicle First rib Axillary Subclavian Brachiocephalic trunk Figure 78

79 Module 17.16: Head and neck vessels
Veins External jugular vein (cranium, face, lower jaw, and neck on that side) Internal jugular vein (various cranial venous sinuses) Vertebral vein (cervical spinal cord and posterior skull)

80 Areas drained by the external and internal jugular veins
Dural sinuses draining the brain Temporal Maxillary Jugular foramen Branches of the External Jugular Facial Occipital Figure The external carotid arteries supply the neck, lower jaw, and face, and the internal carotid and vertebral arteries supply the brain, while the external jugular veins drain the regions supplied by the external carotids, and the internal jugular veins drain the brain External jugular Vertebral vein Internal jugular vein Clavicle Right brachiocephalic Left brachiocephalic Axillary Right subclavian Superior vena cava Figure 80

81 Module Review a. Name the arterial structure that contains baroreceptors. b. Identify branches of the external carotid artery. c. Identify the veins that combine to form the brachiocephalic vein.

82 Module 17.18: Vessels of the trunk
Arteries Somatic branches of thoracic aorta Intercostal arteries (chest muscles and vertebral column) Superior phrenic artery (superior diaphragm) Visceral branches of thoracic aorta Bronchial arteries (lung tissues not involved in gas exchange) Esophageal arteries (esophagus) Mediastinal arteries (tissues of mediastinum) Pericardial arteries (pericardium)

83 Module 17.18: Vessels of the trunk
Arteries (continued) Major paired abdominal aorta branches Inferior phrenic arteries (inferior diaphragm and esophagus) Adrenal arteries (adrenal glands) Renal arteries (kidneys) Gonadal arteries (gonads) Lumbar arteries (vertebrae, spinal cord, abdominal wall)

84 Module 17.18: Vessels of the trunk
Arteries (continued) Major unpaired branches of abdominal aorta Celiac trunk (three branches) Left gastric artery (stomach and inferior esophagus) Splenic artery (spleen and stomach arteries) Common hepatic artery (arteries to liver, stomach, gallbladder, and proximal small intestine) Superior mesenteric artery (pancreas, duodenum, most of large intestine) Inferior mesenteric artery (colon and rectum)

85 The branches of the thoracic aorta and the abdominal aorta
Aortic arch Internal thoracic Thoracic aorta Visceral Branches of the Thoracic Aorta Somatic Branches of the Thoracic Aorta Bronchial arteries Esophageal arteries Intercostal arteries Mediastinal artery Superior phrenic artery Pericardial artery Figure The regions supplied by the descending aorta are drained by the superior and inferior vena cava Diaphragm Inferior phrenic Celiac trunk Adrenal Left gastric Renal Branches of the celiac trunk Splenic Gonadal Common hepatic Lumbar Common iliac Superior mesenteric Abdomial aorta Inferior mesenteric Figure 85

86 Module 17.18: Vessels of the trunk
Veins Azygos and hemiazygos veins (most of thorax) Intercostal veins (chest muscles) Esophageal veins (inferior esophagus) Bronchial veins (passageways of lungs) Mediastinal veins (mediastinal structures)

87 Module 17.18: Vessels of the trunk
Veins (continued) Major tributaries of inferior vena cava Lumbar veins (lumbar portion of abdomen) Gonadal veins (gonads) Hepatic veins (liver) Renal veins (kidneys) Adrenal veins (adrenal glands) Phrenic veins (diaphragm)

88 The major tributaries of the superior and inferior venae cavae
Brachiocephalic The Azygos and Hemiazygos Veins Superior vena cava Azygos vein Hemiazygos vein Internal thoracic Tributaries: Esophageal, bronchial, and mediastinal veins Inferior vena cava Hepatics Intercostal veins Phrenic Adrenal Renal Gonadal Lumbar Figure The regions supplied by the descending aorta are drained by the superior and inferior vena cava Common iliac Major Tributaries of the Inferior Vena Cava • Lumbar veins drain the lumbar portion of the abdomen, including the spinal cord and muscles of the body wall. • Gonadal (ovarian or testicular) veins drain the ovaries of testes. The right gonadal vein empties into the inferior vena cava; the left gonadal vein generally drains into the left renal vein. • Hepatic veins drain the sinusoids of the liver. • Renal veins, the largest tributaries of the inferior vena cava, collect blood from the kidneys. • Adrenal veins drain the adrenal glands. In most individuals, only the right adrenal vein drains into the inferior vena cava; the left adrenal vein drains into the left renal vein. • Phrenic veins drain the diaphragm. Only the right phrenic vein drains into the inferior vena cava; the left drains into the left renal vein. Figure 88

89 Module Review a. Which vessel collects most of the venous blood inferior to the diaphragm? b. Identify the major tributaries of the inferior vena cava. c. Grace is in an automobile accident, and her celiac trunk is ruptured. Which organs will be affected most directly by this injury?

90 Module 17.19: Vessels of the viscera
Arteries Branches of common hepatic artery Hepatic artery proper (liver) Cystic (gallbladder) Gastroduodenal (stomach and duodenum) Right gastric (stomach) Right gastroepiploic (stomach and duodenum) Superior pancreaticoduodenal (duodenum)

91 Module 17.19: Vessels of the viscera
Arteries (continued) Superior mesenteric artery Inferior pancreaticoduodenal (pancreas and duodenum) Right colic (large intestine) Ileocolic (large intestine) Middle colic (large intestine) Intestinal arteries (small intestine)

92 Module 17.19: Vessels of the viscera
Arteries (continued) Inferior mesenteric artery Left colic (colon) Sigmoid (colon) Rectal (colon) Branches of the splenic artery Left gastroepiploic (stomach) Pancreatic (pancreas)

93 The locations of the celiac trunk, the superior and inferior mesenteric arteries, and their branches
Common hepatic artery Left gastric artery Splenic artery The celiac trunk Branches of the Common Hepatic Artery Hepatic artery proper (liver) Cystic (gallbladder) Liver Branches of the Splenic Artery Gastroduodenal (stomach and duodenum) Left gastroepiploic (stomach) Right gastric (stomach) Stomach Right gastroepiploic (stomach and duodenum) Pancreatic (pancreas) Superior pancreatico- duodenal (duodenum) Spleen Figure The viscera supplied by the celiac trunk and mesenteric arteries are drained by the tributaries of the hepatic portal vein Ascending colon Panceas Inferior Mesenteric Artery Superior Mesenteric Artery Left colic (colon) Inferior pancreaticoduodenal (pancreas and duodenum) Sigmoid (colon) Rectal (rectum) Right colic (large intestine) Small intestine Ileocolic (large intestine) Sigmoid colon Middle colic (cut) (large intestine) Rectum Intestinal arteries (small intestine) Figure 93

94 Module 17.19: Vessels of the viscera
Veins Hepatic portal vein tributaries Superior mesenteric vein and tributaries Pancreaticoduodenal Middle colic (transverse colon) Right colic (ascending colon) Ileocolic (Ileum and ascending colon) Intestinal (small intestine)

95 Module 17.19: Vessels of the viscera
Veins (continued) Hepatic portal vein tributaries (continued) Splenic vein and tributaries Left gastroepiploic (stomach) Right gastroepiploic (stomach) Pancreatic Inferior mesenteric vein and tributaries Left colic (descending colon) Sigmoid (sigmoid colon) Superior rectal (rectum)

96 The veins (and their tributaries) that form the hepatic portal vein
Inferior vena cava Left gastric Hepatic Right gastric Liver Stomach Splenic Vein and Its Tributaries Cystic Hepatic portal Left gastroepiploic (stomach) Spleen Right gastroepiploic (stomach) Superior Mesenteric Vein and Its Tributaries Pancreatic Pancreas Pancreaticoduodenal Descending colon Middle colic (from transverse colon) Inferior Mesenteric Vein and Its Tributaries Right colic (ascending colon) Ileocolic (ileum and ascending colon) Left colic (descending colon) Sigmoid (sigmoid colon) Figure The viscera supplied by the celiac trunk and mesenteric arteries are drained by the tributaries of the hepatic portal vein Intestinal (small intestine) Superior rectal (rectum) Tributaries of the Hepatic Portal Vein • The inferior mesenteric vein collects blood from capillaries along the inferior portion of the large intestine. It drains the left colic vein and the superior rectal veins, which collect venous blood from the descending colon, sigmoid colon, and rectum. • The splenic vein is formed by the union of the inferior mesenteric vein and veins from the spleen, the lateral border of the stomach (left gastroepiploic vein), and the pancreas (pancreatic veins). • The superior mesenteric vein collects blood from veins draining the stomach (right gastroepiploic vein), the small intestine (intestinal and pancreaticoduodenal veins), and two-thirds of the large intestine (ileocolic, right colic, and middle colic veins). Figure 96

97 Module Review a. List the unpaired branches of the abdominal aorta that supply blood to the visceral organs. b. Identify the three veins that merge to form the hepatic portal vein. c. Identify two veins that carry blood away from the stomach.

98 Module 17.20: Lower limb vessels
Arteries Common iliac artery Internal iliac artery (bladder, pelvic walls, external genitalia, medial side of thigh, in females, uterus and vagina) Lateral sacral artery Internal pudendal artery Obturator artery Superior gluteal artery

99 Module 17.20: Lower limb vessels
Arteries (continued) Common iliac artery (continued) External iliac artery Femoral artery Deep femoral artery Femoral circumflex arteries (ventral and lateral skin and deep muscles of thigh) Popliteal artery (posterior knee) Posterior and anterior tibial arteries (leg) Fibular artery (lateral leg)

100 Module 17.20: Lower limb vessels
Arteries (continued) Arteries of the foot Dorsalis pedis Dorsal arch Plantar arch Medial plantar Lateral plantar

101 The arteries that supply the pelvis and lower limb
Anterior View Internal Iliac and Its Branches Posterior View Internal iliac Common iliac External iliac Femoral Right external iliac Lateral sacral Deep femoral Deep femoral Internal pudendal Femoral circumflex Obturator Femoral circumflex Superior gluteal Femoral Figure The pelvis and lower limb are supplied by branches of the common iliac artery and drained by tributaries of the common iliac vein Descending genicular artery Popliteal Popliteal Anterior tibial Posterior tibial Anterior tibial Posterior tibial Fibular Arteries of the Foot Fibular (peroneal) Dorsalis pedis Medial plantar Lateral plantar Dorsal arch Plantar arch Figure 101

102 Module 17.20: Lower limb vessels
Veins External iliac veins (lower limbs, pelvis, and lower abdomen) Internal iliac veins (pelvic organs) External and internal iliac fuse to form common iliac veins

103 The veins that drain the pelvis and lower limb
Anterior View Posterior View Common iliac External iliac Internal iliac Gluteal Internal pudendal Lateral sacral Obturator Femoral Convergence of the great saphenous, the deep femoral, and the femoral circumflex veins Femoral circumflex Deep femoral Femoral Figure The pelvis and lower limb are supplied by branches of the common iliac artery and drained by tributaries of the common iliac vein Great saphenous Femoral Popliteal Small saphenous Anterior tibial Posterior tibial Fibular Dorsal venous arch Plantar venous arch Digital Figure 103

104 Module Review a. Name the first two divisions of the common iliac artery. b. The plantar venous arch carries blood to which three veins? c. A blood clot that blocks the popliteal vein would interfere with blood flow in which other veins?

105 CLINICAL MODULE 17.21: Fetal circulation and defects
Unique fetal circulation structures Umbilical arteries (internal iliac arteries to placenta) Umbilical vein (placenta to ductus venosus) Ductus venosus (drains liver and umbilical vein into inferior vena cava) Ductus arteriosus (pulmonary trunk to aorta) Sends blood from right ventricle to systemic circuit Foramen ovale (right to left atrium) Has one-way valve to prevent backflow

106 The path of blood flow in a full-term fetus before birth
Foramen ovale Ductus arteriosus Aorta Placenta Pulmonary trunk Figure The pattern of blood flow through the fetal heart and the systemic circuit must change at birth Liver Inferior vena cava Umbilical vein Ductus venosus Umbilical cord Umbilical arteries Figure 106

107 CLINICAL MODULE 17.21: Fetal circulation and defects
At birth, fetal circulation changes due to activated pulmonary circulation Resulting pressure closes foramen ovale Fossa ovalis (shallow depression, adult remnant) Rising oxygen levels cause ductus arteriosus to constrict and close Ligamentum arteriosum (fibrous adult remnant)

108 The flow of blood through the heart upon the closing
of the ductus arteriosus and foramen ovale at birth Ductus arteriosus (closed) Pulmonary trunk Left atrium Figure The pattern of blood flow through the fetal heart and the systemic circuit must change at birth Foramen ovale (closed) Right atrium Left ventricle Right ventricle Inferior vena cava Figure 108

109 CLINICAL MODULE 17.21: Fetal circulation and defects
Congenital cardiac defects Ventricular septal defects Openings in interventricular septum Patent foramen ovale Passageway remains open Left ventricle must work harder to provide adequate systemic flow Patent ductus arteriosus Blood is not adequately oxygenated and skin bluish

110 CLINICAL MODULE 17.21 Review
a. Describe the pattern of fetal blood flow to and from the placenta. b. Identify the six structures that are necessary in the fetal circulation but cease to function at birth, and describe what becomes of these structures.

111 Module 18.4: Coronary circulation
Provides cardiac muscle cells with reliable supplies of oxygen and nutrients During maximum exertion, myocardial blood flow may increase to 9× resting levels Blood flow is continuous but not steady With left ventricular relaxation, aorta walls recoil (elastic rebound), which pushes blood into coronary arteries

112 Module 18.4: Coronary circulation
Coronary arteries Right coronary artery (right atrium, portions of both ventricles and conduction system of heart) Marginal arteries (right ventricle surface) Posterior interventricular artery (interventricular septum and adjacent ventricular portions) Left coronary artery (left ventricle, left atrium, and interventricular septum) Circumflex artery (from left coronary artery, follows coronary sulcus to meet right coronary artery branches) Anterior interventricular artery (interventricular sulcus)

113 Figure 18.4.1-2 The heart has an extensive blood supply
The locations of the arterial supply to the heart Pulmonary trunk Aortic arch An anterior view of the coronary arteries Left atrium Left Coronary Artery Left coronary artery Circumflex artery Right atrium Anterior interventricular artery Right Coronary Artery Right ventricle Left ventricle Right coronary artery in the coronary sulcus Marginal arteries Anterior view Figure The heart has an extensive blood supply Arterial anastomoses between the anterior and posterior interventricular arteries The branches of the coronary arteries on the posterior surface of the heart Circumflex artery Left atrium Marginal artery Right atrium Left ventricle Posterior interventricular artery Right ventricle Right coronary artery Posterior view Figure – 2 113

114 Module 18.4: Coronary circulation
Coronary veins Great cardiac vein (drains area supplied by anterior interventricular artery, empties into coronary sinus on posterior) Anterior cardiac veins (drains anterior surface of right ventricle, empties into right atrium)

115 vessels on the anterior surface of the heart
The major collecting vessels on the anterior surface of the heart Aortic arch Left atrium Right atrium Great cardiac vein Figure The heart has an extensive blood supply Anterior cardiac veins Right ventricle Left ventricle Anterior view Figure 115

116 Module 18.4: Coronary circulation
Coronary veins (continued) Coronary sinus (expanded vein, empties into right atrium) Posterior cardiac vein (drains area supplied by circumflex artery) Small cardiac vein (drains posterior right atrium and ventricle, empties into coronary sinus) Middle cardiac vein (drains area supplied by posterior interventricular artery, drains into coronary sinus)

117 The major collecting vessels on the posterior surface of the heart
Great cardiac vein Left atrium Coronary sinus Figure The heart has an extensive blood supply Right atrium Left ventricle Small cardiac vein Posterior cardiac vein Right ventricle Middle cardiac vein Posterior view Figure 117

118 Module 18.4 Review a. List the arteries and veins of the heart.
b. Describe what happens to blood flow during elastic rebound. c. Identify the main vessel that drains blood from the myocardial capillaries.

119 Module 18.5: Internal heart anatomy
Four chambers Two atria (left and right separated by interatrial septum) Two ventricles (left and right separated by interventricular septum) Left atrium flows into left ventricle Right atrium flows into right ventricle

120 Module 18.5: Internal heart anatomy
Right atrium Receives blood from superior and inferior venae cavae and coronary sinus Fossa ovalis (remnant of fetal foramen ovale) Pectinate (pectin, comb) muscles (muscular ridges on anterior atrial and auricle walls) Left atrium Receives blood from pulmonary veins

121 Module 18.5: Internal heart anatomy
Right ventricle Receives blood from right atrium through right atrioventricular (AV) valve Also known as tricuspid (tri, three) Has three flaps or cusps attached to tendinous connective fibers Fibers connect to papillary muscles Innervated to contract through moderator band which keeps “slamming” of AV cusps Prevents backflow of blood to atrium during ventricular contraction

122 Module 18.5: Internal heart anatomy
Left ventricle Receives blood from left atrium through right atrioventricular valve Also known as bicuspid and mitral (mitre, bishop’s hat) valve Prevents backflow of blood to atrium during ventricular contraction Has paired flaps or cusps Trabeculae carneae (carneus, fleshy) Muscular ridges on ventricular walls Aortic valve Allows blood to exit left ventricle and enter aorta

123 The internal anatomy of the heart and
the direction of blood flow between the chambers Ascending aorta Pulmonary trunk Superior vena cava Left Atrium Right Atrium Aortic arch Receives blood from the pulmonary veins Receives blood from the superior and inferior venae cavae and from the cardiac veins through the coronary sinus Left pulmonary veins Fossa ovalis Pectinate muscles on the inner surface of the auricle Figure Internal valves control the direction of blood flow between the heart chambers Opening of the coronary sinus Left Ventricle Right Ventricle Thick wall of left ventricle Right atrioventricular (AV) valve (tricuspid valve) Left atrioventricular (AV) valve (bicuspid valve) Chordae tendineae Inferior vena cava Trabeculae carneae Papillary muscle Interventricular septum Pulmonary valve (pulmonary semilunar valve) Aortic valve Moderator band Figure 123

124 Module 18.5: Internal heart anatomy
Ventricular comparisons Right ventricle has relatively thin wall Ventricle only pushes blood to nearby pulmonary circuit When it contracts, it squeezes against left ventricle wall forcing blood out pulmonary trunk Left ventricle has extremely thick wall and is round in cross section Ventricle must develop 4–6× as much pressure as right to push blood around systemic circuit When it contracts Diameter of chamber decreases Distance between base and apex decreases

125 interventricular sulcus
A sectional view of the heart showing the thicknesses of the ventricle walls and the shapes of the ventricular chambers Posterior interventricular sulcus The left ventricle has an extremely thick muscular wall and is round in cross section. Figure Internal valves control the direction of blood flow between the heart chambers The relatively thin wall of the right ventricle resembles a pouch attached to the massive wall of the left ventricle Fat in anterior interventricular sulcus Figure 125

126 Dilated (relaxed) Contracted The changes in ventricle
shape during ventricular contraction Left ventricle Right ventricle Dilated (relaxed) Figure Internal valves control the direction of blood flow between the heart chambers Contraction of left ventricle decreases the diameter of the ventricular chamber and reduces the distance between the base and apex Contraction of right ventricle squeezes blood against the thick wall of the left ventricle. Contracted Figure 126

127 Module 18.5 Review a. Damage to the semilunar valves on the right side of the heart would affect blood flow to which vessel? b. What prevents the AV valves from swinging into the atria? c. Why is the left ventricle more muscular than the right ventricle?

128 Module 18.6: Heart valves Semilunar (half-moon shaped) valves
Aortic and pulmonary semilunar valves Allow blood to exit ventricles and enter aorta or pulmonary trunk Do not require muscular braces because cusps are stable All three symmetrical cusps support each other

129 Module 18.6: Heart valves Valve action during atrial contraction and ventricular relaxation AV valves Open Blood pressure from contracting atria pushes cusps apart Chordae tendineae are loose, offering no resistance Semilunar valves (aortic and pulmonary) Closed Little pressure from ventricles Blood pressure from aorta and pulmonary arteries keep closed

130 The positions of the valves and associated
structures when the ventricles are relaxed Pulmonary veins Left atrium Right ventricle Aortic valve (closed) Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves open Left AV (bicuspid) valve (open) Chordae tendineae (loose) Left ventricle (dilated) Papillary muscles (relaxed) Right AV (tricuspid) valve (open) KEY Oxygenated blood Aortic valve (closed) Superior view of cardiac valves Pulmonary valve (closed) Deoxygenated blood Figure 130

131 Module 18.6: Heart valves Valve action during atrial relaxation and ventricular contraction AV valves Closed Blood pressure from contracting ventricles pushes cusps together Papillary muscles tensing prevent cusps from swinging into atria (would allow backflow or regurgitation) Semilunar valves (aortic and pulmonary) Open High blood pressure from ventricles overcome blood pressures from aorta and pulmonary arteries Animation: The Heart: Valves

132 KEY Aortic sinus Oxygenated blood The positions of the valves and associated structures when the ventricles contract Deoxygenated blood Aorta Left atrium Aortic valve (open) Chordae tendineae (tense) Left AV (bicuspid) valve (closed) Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves open Left ventricle (contracted) Papillary muscles (contracted) Right AV (tricuspid) valve (closed) Ventricular contraction Aortic valve (open) Superior view of cardiac valves Pulmonary valve (open) Frontal section through left atrium and ventricle Figure 132

133 Module 18.6: Heart valves Cardiac skeleton
Flexible connective tissues in which all valves are encircled and supported Also surrounds aorta and pulmonary trunk Separates atrial and ventricular myocardium Contains dense bands of tough elastic tissue

134 A superior view of the heart showing the cardiac skeleton
Figure When the heart beats, the AV valves close before the semilunar valves open, and the semilunar valves close before the AV valves open Figure 134

135 Module 18.6 Review a. Define cardiac regurgitation.
b. Compare the structure of the tricuspid valve with that of the pulmonary valve. c. What do semilunar valves prevent?

136 Section 2: The Cardiac Cycle
Period from one heartbeat to the beginning of next Alternating periods of contraction (systole) and relaxation (diastole) Atria contract as a pair first As ventricles are relaxed and filling Ventricles contract as a pair next As atria are relaxed and filling Cardiac pacemaker system coordinates Typical cardiac cycle lasts 800 msec

137 A cardiac cycle: a heartbeat (contraction)
followed by a brief period of relaxation Figure 18 Section 2 The Cardiac Cycle Relaxation Contraction Figure 18 Section 137

138 The sequence of events during a single heartbeat
Figure 18 Section 2 The Cardiac Cycle Relaxation Atria contract Ventricles contract Relaxation Figure 18 Section 138

139 Cardiac cycle The two phases of the cardiac cycle for a
given chamber in the heart: systole (contraction) and diastole (relaxation) Start msec 800 msec 100 msec Atrial systole diastole systole Cardiac cycle Figure 18 Section 2 The Cardiac Cycle Ventricular Ventricular Atrial diastole 370 msec Figure 18 Section 139

140 Module 18.8: Cardiac cycle phases
Steps of cardiac cycle (for 75 bpm heart rate) When cycle begins, all four chambers are relaxed Atrial systole (100 msec) Contracting atria fill relaxed ventricles with blood Atrial diastole (270 msec) Concurrent with ventricular systole (2 phases) Ventricular systole – first phase Contracting ventricles push AV valves open but not enough pressure to open semilunar valves = Isovolumetric contraction

141 Module 18.8: Cardiac cycle phases
Steps of cardiac cycle (continued) Ventricular systole – second phase As ventricular pressure rises, semilunar valves open and blood leaves ventricle (= ventricular ejection) Ventricular diastole – early Ventricles relax and blood pressure in them drops allowing closure of semilunar valves Isovolumetric relaxation occurs with AV valves still closed Ventricular diastole – late All chambers relaxed Ventricles fill passively to roughly 70% Animation: The Heart: Cardiac Cycle

142 The phases of the cardiac cycle for a heart rate of 75 beats per minute
Start When the cardiac cycle begins, all four chambers are relaxed, and the ventricles are partially filled with blood. During atrial systole, the atria contract, completely filling the relaxed ventricles with blood. Atrial systole lasts 100 msec. Ventricular diastole lasts 530 msec (the 430 msec remaining in this cardiac cycle, plus the first 100 msec of the next). Throughout the rest of this cardiac cycle, filling occurs passively, and both the atria and the ventricles are relaxed. The next cardiac cycle begins with atrial systole and the completion of ventricular filling. Atrial systole ends and atrial diastole begins and continues until the start of the next cardiac cycle. As atrial systole ends, ventricular systole begins. This period, which lasts 270 msec, can be divided into two phases. msec 800 msec 100 msec Atrial systole Ventricular systole— first phase: Ventricular contraction pushes the AV valves closed but does not create enough pressure to open the semilunar valves. This is known as the period of isovolumetric contraction. Figure The cardiac cycle creates pressure gradients that maintain blood flow diastole Cardiac cycle systole Ventricular diastole —late: All chambers are relaxed. The ventricles fill passively to roughly 70% of their final volume. Ventricular Ventricular Atrial diastole Ventricular systole— second phase: As ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is forced out of the ventricle. This is known as the period of ventricular ejection. 370 msec Blood flows into the relaxed atria but the AV valves remain closed. This is known as the period of isovolumetric relaxation. Ventricular diastole— early: As the ventricles relax, the pressure in them drops; blood flows back against the cusps of the semilunar valves and forces them closed. Figure 142

143 The pressure changes within the aorta, left atrium, and left ventricle during the cardiac cycle
ATRIAL DIASTOLE ATRIAL SYSTOLE ATRIAL SYSTOLE ATRIAL DIASTOLE VENTRICULAR DIASTOLE VENTRICULAR SYSTOLE VENTRICULAR DIASTOLE 120 Aortic valve closes. Aortic valve opens. 90 Aorta Dicrotic notch KEY Atrial contraction begins. Pressure (mm Hg) Atria eject blood into ventricles. 60 Atrial systole ends; AV valves close. Left ventricle Isovolumetric contraction. Figure The cardiac cycle creates pressure gradients that maintain blood flow Ventricular ejection occurs. Semilunar valves close. 30 Left atrium Left AV valve closes. Isovolumetric relaxation occurs. Left AV valve opens. AV valves open; passive ventricular filling occurs. 100 200 300 400 500 600 700 800 Time (msec) The correspondence of the heart sounds with events during the cardiac cycle S1 S2 S4 S3 S4 Heart sounds “Lubb” “Dubb” Figure 143

144 Module 18.8: Cardiac cycle phases
Heart sounds S1 (known as “lubb”) Start of ventricular contraction and closure of AV valves S2 (known as “dupp”) Closure of semilunar valves S3 and S4 Very faint and rarely heard in adults S3 (blood flowing into ventricles) S4 (atrial contraction)

145 Module 18.8 Review a. Provide the alternate terms for heart contraction and heart relaxation. b. List the phases of the cardiac cycle. c. Is the heart always pumping blood when pressure in the left ventricle is rising? Explain.

146 Module 18.9: Cardiac output and conduction system
Network of specialized cardiac muscle cells Responsible for initiating and distributing stimulus to contract Can do so on their own (= automaticity) Components Sinoatrial (SA) node Embedded in posterior wall of right atrium Impulse generated by this pacemaker is distributed through other components Internodal pathways Distribute signal to atria on way to ventricles

147 Module 18.9: Cardiac output and conduction system
Conduction system (continued) Atrioventricular (AV) node Located at junction of atria and ventricles Also contains pacemaker cells If SA node damaged, can maintain heart rate at 40–60 bpm Can conduct impulses at maximum rate of 230/min = Maximum heart rate AV bundle and branches Located in interventricular septum Normally only electrical connection between atria and ventricles Branches relay signal to ventricles toward heart apex

148 Module 18.9: Cardiac output and conduction system
Conduction system (continued) Purkinje fibers Large-diameter conducting cells As fast as small myelinated axons Final part of conduction system that triggers ventricular systole Animation: The Heart: Conduction System

149 The components of the conducting system and their specific functions
Each heartbeat begins with an action potential generated at the sinoatrial (sī-nō-Ā-trē-al) node, or simply the SA node. The SA node is embedded in the posterior wall of the right atrium, near the entrance of the superior vena cava. The electrical impulse generated by this cardiac pacemaker is then distributed by other cells of the conducting system. Purkinje fibers are large-diameter conducting cells that propagate action potentials very rapidly—as fast as small myelinated axons. Purkinje cells are the final link in the distribution network, and they are responsible for the depolarization of the ventricular myocardial cells that triggers ventricular systole. In the atria, conducting cells are found in internodal pathways, which distribute the contractile stimulus to atrial muscle cells as the impulse travels toward the ventricles. Figure The heart rate, a key factor in cardiac output, is established by the SA node and distributed by the conducting system The AV node delivers the stimulus to the AV bundle, located within the interventricular septum. The AV bundle is normally the only electrical connection between the atria and the ventricles. Moderator band The AV bundle leads to the right and left bundle branches. The left bundle branch, which supplies the massive left ventricle, is much larger than the right bundle branch. Both branches extend toward the apex of the heart, turn, and fan out deep to the endocardial surface. The atrioventricular (AV) node is located at the junction between the atria and ventricles. The AV node also contains pacemaker cells, but they do not ordinarily affect the heart rate. However, if the SA node or internodal pathways are damaged, the heart will continue to beat because in the absence of commands from the SA node, the AV node will generate impulses at a rate of 40–60 beats per minute. Figure 149

150 The distribution of the
contractile stimulus, and how the conducting system coordinates the contractions of the cardiac cycle An action potential is generated at the SA node, and atrial activation begins. SA node Time = 0 The stimulus spreads across the atrial surfaces by cell-to-cell contact within the internodal pathways and soon reaches the AV node. AV node Elapsed time = 50 msec A 100-msec delay occurs at the AV node. During this delay, atrial contraction begins. Figure The heart rate, a key factor in cardiac output, is established by the SA node and distributed by the conducting system AV bundle Bundle branches Elapsed time = 150 msec As atrial contraction continues, the impulse travels along the interventricular septum within the AV bundle and the bundle branches to the Purkinje fibers and, via the moderator band, to the papillary muscles of the right ventricle. Moderator band Elapsed time = 175 msec The impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed, and ventricular contraction begins. Purkinje fibers Elapsed time = 225 msec Figure 150

151 Module 18.9 Review a. Define automaticity.
b. If the cells of the SA node failed to function, how would the heart rate be affected? c. Why is it important for impulses from the atria to be delayed at the AV node before they pass into the ventricles?

152 Module 18.11: Autonomic control of heart function
Pacemaker cells in the SA and AV nodes cannot maintain a stable resting potential Always gradual depolarization leading to threshold (= prepotential or pacemaker potential) Fastest rate at SA node (80–100 bpm) Brings other conduction system components to threshold

153 Heart rate under three conditions: at rest, under parasympathetic
stimulation, and under sympathetic stimulation A prepotential or pacemaker potential in a heart at rest Figure The intrinsic heart rate can be altered by autonomic activity Normal (resting) Prepotential (spontaneous depolarization) +20 Membrane potential (mV) –30 Threshold –60 Heart rate: 75 bpm 0.8 1.6 2.4 Time (sec) Figure 153

154 Module 18.11: Autonomic control of heart function
Autonomic changes to intrinsic heart rate Factors that change rate of depolarization and repolarization will change time to threshold Leads to change in heart rate Bradycardia (heart rate slower than normal, <60 bpm) Tachycardia (heart rate faster than normal, >100 bpm) Parasympathetic stimulation Binding of ACh from parasympathetic neurons opens K+ channels, slows heart rate Slows rate of depolarization Extends duration in repolarization

155 Module 18.11: Autonomic control of heart function
Autonomic changes to intrinsic heart rate (continued) Sympathetic stimulation Binding of noepinephrine to beta-1 receptors leads to opening of ion channels, and increases heart rate Increases rate of depolarization Shortens duration in repolarization

156 Parasympathetic stimulation
Heart rate under three conditions: at rest, under parasympathetic stimulation, and under sympathetic stimulation A prepotential or pacemaker potential in a heart at rest Increased heart rate resulting when ACh released by parasympathetic neurons opens chemically gated K+ channels, thereby slowing the rate of spontaneous depolarization Figure The intrinsic heart rate can be altered by autonomic activity Parasympathetic stimulation +20 Membrane potential (mV) –30 Threshold Hyperpolarization –60 Heart rate: 40 bpm Slower depolarization 0.8 1.6 2.4 Time (sec) Figure 156

157 CLINICAL MODULE 18.14: Electrocardiograms (ECG)
Electrocardiograms record electrical activities of heart from body surface through time Can be used to assess performance of: Nodes Conduction system Contractile components Appearance varies with placement and number of electrodes or leads

158 An electrocardiogram: a standard placement of
leads and the tracing that results One of the standard configurations for the placement of leads for an ECG 800 msec Figure Normal and abnormal cardiac activity can be detected in an electrocardiogram The features of a typical electrocardiogram P wave QRS complex T wave +1 R +0.5 P T Millivolts Q S –0.5 P–R interval Q–T interval Figure 158

159 CLINICAL MODULE 18.14: Electrocardiograms (ECG)
Typical ECG features P wave (atrial depolarization) Atria begin contracting ~25 msec after P wave start QRS complex (atrial repolarization and ventricular depolarization) Larger wave due to larger ventricles added to atrial activity Ventricles begin contracting shortly after R wave peak T wave (ventricular repolarization)

160 CLINICAL MODULE 18.14: Electrocardiograms (ECG)
Typical ECG features (continued) P-R interval (start of atrial depolarization to start of ventricular depolarization) >200 msec may indicate damage to conducting pathways or AV node Q-T interval (time for ventricles to undergo a single cycle) Starts at end of P-R interval to end of T wave

161 Module 18.16: Blood pressure and flow
Blood flow (F) is directly proportional to blood pressure Increased pressure = increased flow The pressure gradient (difference from one end of vessel to other) is more important Large gradient from aorta to capillaries Smaller, more numerous vessels produce more resistance, reducing pressure and flow At aorta: 2.5 cm diameter and 100 mm Hg pressure At capillaries: 8 µm diameter and 25 mm Hg pressure

162 Module 18.16: Blood pressure and flow
Arterial pressure is variable Rising during ventricular systole (systolic pressure) Declining during ventricular diastole (diastolic pressure) Commonly written with a “/” between pressures Example: 120/90 Pulse pressure (difference between systolic and diastolic) Example: 120 – 90 = 30 mm Hg Mean arterial pressure (MAP) Adding 1/3 of pulse pressure to diastolic pressure Example: 90 + (120 – 90)/3 = 100 mm Hg

163 The calculation of mean arterial pressure
Systolic Pulse pressure, the difference between systolic and diastolic pressures 120 Mean arterial pressure (MAP), the sum of the diastolic pressure and one-third of the pulse pressure 100 80 Here, MAP is Figure Blood flow is determined by the interplay between arterial pressure and peripheral resistance Diastolic 90 + (120 – 90 )/3 60 or = 100 mm Hg mm Hg 40 20 Aorta Elastic arteries Muscular arteries Arterioles Capillaries Venules Medium- sized veins Large veins Venae cavae Figure 163

164 Module 18.16: Blood pressure and flow
Capillary exchange Involves: Filtration Capillary hydrostatic pressure (CHP) provides driving force Water and small solutes leave capillaries Larger molecules (like plasma proteins) remain in blood Diffusion Osmosis

165 The effect of capillary hydrostatic pressure on
water and small solutes Capillary hydrostatic pressure (CHP) Amino acid Blood protein Glucose Ions Interstitial fluid Figure Blood flow is determined by the interplay between arterial pressure and peripheral resistance Small solutes Hydrogen bond Water molecule Endothelial cell 1 Endothelial cell 2 Figure 165

166 Module Review a. Define blood flow, and describe its relationship to blood pressure and peripheral resistance. b. In a healthy individual, where is blood pressure greater: in the aorta or in the inferior vena cava? Explain. c. For an individual with a blood pressure of 125/70, calculate the mean arterial pressure (MAP).


Download ppt "Blood and Blood Vessels"

Similar presentations


Ads by Google