1. Chapter 20 Blood Vessels and Circulation

2. STRUCTURE AND FUNCTION Heart  Arteries  Arterioles  Capillaries 
Blood vessels form a network in our body taking the blood from the heart to the tissues of the body and returning it back to the heart.
Classified by size and histological organization
The direction of the flow of the blood in different vessels of the body is:
Heart  Arteries  Arterioles  Capillaries 
Venules Veins  Heart

3. Anatomy of Blood Vessels
60,000 miles of blood vessels in the body!! ONLY 1 MILE of those is actually visible to the eye. To put that in perspective, the distance around the earth is about 25,000 miles, making the distance your blood vessels could travel if laid end to end more than 2x around the earth.
Arteries carry blood AWAY FROM heart
Heart, arteries, and capillaries contain approximately 30-35% of the blood at any given time.
Veins carry blood BACK TO heart
Veins contain 60-65% of the blood
About 1/3 of the blood in the veins is circulating in the liver, bone marrow and skin.
Capillaries connect smallest arteries to veins

4. BODY WORLDS

5. Pulse Pressure-Pulse
Difference between systolic and diastolic pressures is called the PULSE PRESSURE. (EX: pp = 40)
Measures maximum force generated on small arteries
Pulse pressure is felt as a throbbing pulsation in an artery (pulse) during systole as the elastic arteries are expanded by the blood being forced into them by ventricles. (Strongest in the arteries close to the heart, becomes weaker in arterioles and disappears in capillaries and veins.)
Pulse is routinely measured in the radial, common carotid, brachial, femoral, temporal arteries. Pulse rate is generally the same as heart rate between 70 and 80 beats/min.
Pulse is the temporary increase in arterial pressure that can be felt throughout the body. Pulse rate can be used to measure heart rate for a normal, healthy heart and can be an indicator of heart health. A very weak contraction may NOT register a pulse rate.
Heart rate is the rate at which the heart beats or contracts. Any contraction, even if weak, is part of the heart rate.
Rapid resting pulse rate is called tachycardia and a slow pulse rate is termed bradycardia.

6. Evaluating Circulation
BP is usually measured in the left brachial artery using an instrument known as Sphygmomanometer.
Systolic blood pressure is the force of blood recorded during ventricular contraction. Diastolic blood pressure is the force of blood recorded during ventricular relaxation.
The various sounds that are heard while taking blood pressure are called Korotkoff sounds.

7. Arteries Blood vessels that take the blood away from the heart.
The wall of an artery consists of 3 major layers
Tunica intima – innermost layer lines the blood vessel; exposed to blood
Endothelium (epithelium) overlies basement membrane and sparse layer of loose connective tissue
selectively permeable barrier
secrete chemicals that stimulate dilation or constriction of the vessel
normally repels blood cells and platelets that may adhere and form a clot (prostacyclin)
when tissue around vessel is inflamed, endothelial cells cause leukocytes to congregate in tissues where their defensive actions are needed
Arteries

8. Arteries –Vessel Layers
Tunica media – middle layer
smooth muscle, collagen, and elastic tissue (strengthens vessel prevents rupture).
Capable of vasoconstriction and vasodilation
Tunica externa – outermost layer
loose connective tissue
mainly composed of collagen
collagen anchors vessel to nearby organs, giving it stability.
vasa vasorum – (“vessels of vessels”)
small vessels that supply blood to the outer half of the wall of larger vessels- similar to the coronary arteries that provide blood to the wall of the heart. Inner half receive nutrition from diffusion of blood in the lumen.

10. Arteries “TYPES” – Elastic / Muscular arteries
Elastic (CONDUCTING) arteries
Found CLOSER TO THE HEART
Have more collagen and elastic fibers and LESS smooth muscle, are able to receive blood under HIGHER pressure
More ability to stretch in response to blood pressure
Transport large volumes of blood away from the heart to the muscular arteries
ELASTICITY EVENS OUT PULSE FORCE
(Ex: aorta, common carotid, subclavian, pulmonary trunk)
Muscular (DISTRIBUTING) arteries
Found CLOSER TO THE ORGANS AND TISSUES.
Distribute blood to the body's skeletal muscle and internal organs. Most of the arterial system vessels are muscular arteries.
Have MORE smooth muscle tissue making them capable of vasoconstriction and vasodilation, control flow of blood
Ex: external carotid, brachial, femoral, renal, and splenic

12. Disorders = Aneurysm weak point in an artery or the heart wall
forms thin-walled, bulging sac where there is a weak spot in elastic fibers may rupture at any time causing hemorrhage also stroke, shock, pain (pressure on other structures) possible death
common sites: abdominal aorta, renal arteries, and arterial circle (Circle of Willis) at base of the brain
most common cause is atherosclerosis and hypertension
Also the result from congenital weakness of the blood vessels or result of trauma or bacterial infections such as syphilis
Other risk factors include diabetes, obesity, tobacco use, alcoholism, high cholesterol, and increasing age
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13. Arterioles small microscopic arteries delivering blood to capillaries.
Contain tunica interna, tunica media and very thin tunica externa.
through vasoconstriction and vasodilation regulate the amount of blood entering into the capillaries of an organ or tissue.
Blood pressure affected by changes in diameter of arterioles

14. Veins Medium veins named for area: radial, ulnar
Same three tunics
Contain less smooth muscle and elastic tissue; flexible
Thinner walled –Low BP- collapse when empty
Blood flow very steady and not pulsating
Contain VALVES to prevent the backflow of blood.
Lumen is larger than arteries.
Expand easily to accommodate increased blood flow
Operate as blood reservoirs
60% of blood volume at rest is in systemic veins / venules
Medium veins named for area: radial, ulnar
Large veins: pulmonary, vena cava, jugular
Veins’capacitance or ability to stretch is more than arteries
 Venoconstriction reduces blood flow in veins increasing the volume in arteries and capillaries in the event of serious hemorrhaging. Can maintain near normal volumes despite significant blood loss

15. Valves

16. Varicose veins Results in part from the failure of valves
Results in part from the failure of valves
Walls of some leg veins lose elasticity and stretch; valves weaken allowing blood to pool; veins enlarge, blood stagnates and forms a clot and edema
hemorrhoids are varicose veins of the anal canal

17. Deep Vein Thrombosis
Deep vein thrombosis (DVT) formation of blood clot (thrombus) in a DEEP VEIN predominantly in the legs.
Signs may include pain, swelling, redness, warmness, and engorged superficial veins.
Pulmonary embolism, a potentially life- threatening complication
Causes include venous stasis and hypercoagulation.
Risk factors: older age, autoimmune disease, obesity
Prevention/treatment: Walking and calf exercises reduce venous stasis - leg muscle contractions compress veins pump blood up towards the heart
Physical compression methods improve blood flow.
Anticoagulation medications increases the risk of bleeding in high-risk scenarios.

18. Venules Formed by joining of small capillaries.
Contain tunica interna and media; NO TUNICA EXTERNA
Collect blood from capillaries and drain it into veins.
Most WBC immerge from blood thru these

19. Comparison Arteries Veins Take blood away Brings blood back
Oxygenated blood
Deoxygenated blood
Thicker vessel wall -3 layers
Tunica intima-same
Tunica media- thicker
Tunica externa-thinner
Tunica media- thinner
Tunica externa-thicker
Small lumen
Large lumen
Strong wall – does not collapse
Thinner walls that collapse and flatten easily
Higher blood pressure
Lower to zero blood pressure
Comes out in spurts
Slow flow of blood if cut
Does not contain valves
Several one-way valves

21. Circulatory Routes Most common route
heart  arteries  arterioles  capillaries  venules  veins
Portal system
blood flows through two CONSECUTIVE capillary networks before returning to heart
Hypothalamic hypophyseal portal system - anterior pituitary
Hepatic portal system (intestines-liver)
Anastomoses - branches of two blood vessels merge; provide alternate routes for blood to reach a tissue or organ.
arteriovenous (shunt) - artery flows directly into vein bypasses capillaries
venous - one vein empties directly into another; Blockage of vein rarely life threatening
Arterial - two arteries merge; Common around joints where movement may temporarily compress vessel

22. Collateral Circulation

23. Systemic Circulation
The systemic circulation takes oxygenated blood from the left ventricle → aorta → the body, including some lung tissue (but does not supply the air sacs of the lungs) and returns the deoxygenated blood to the right atrium.
The Systemic Circuit
Contains 84% of blood volume
Supplies entire body
Except for pulmonary circuit
The aorta is divided into the ascending aorta, arch of the aorta, and the descending aorta (thoracic and abdominal aorta). Each section gives off arteries that branch to supply the whole body.
Blood returns to the heart through the systemic veins. All the veins of the systemic circulation flow into the superior or inferior vena cavae or the coronary sinus, which in turn empty into the right atrium.

24. Capillaries
Microscopic network of vessels which connect arterioles and venules and permeate all active tissues
Forms extensive branching network to increase surface area for diffusion and filtration. The capillary bed is an interweaving network of capillaries supplying an organ.
Composed of TUNICA INTIMA ONLY!
Primary function - permit the EXCHANGE OF NUTRIENTS AND GASES between the blood and the tissues.
Distribution of capillaries in tissues of the body varies depending on the metabolic activity of the body.
Abundant in lungs, liver, kidney, muscles
Absent in avascular structures such as tendons, ligaments, epidermis, cartilage, cornea, lens

25. Capillary Bed Locations

26. Capillary Bed
Blood flow from arterioles feed into capillaries by ring of smooth muscle fibers called precapillary sphincters- 1) open sphincters- high blood perfusion 2) closed sphincters- blood moves through thoroughfare channel to a venule – little fluid exchange occur.
3/4th of capillaries are shut down at a given time
Vasomotion (vasoconstriction and flow)
Contraction / relaxation cycle of capillary sphincters
Causes blood flow in capillary beds to constantly change routes
Influenced by O2 and CO2 levels in tissue and blood

27. Types of Capillaries There are three main types of capillaries:
Continuous - They are continuous in the sense that the endothelial cells provide an uninterrupted lining, and only allow small molecules, like water, glucose and ions to diffuse
Fenestrated - (derived from "fenestra," Latin for "window") have pores in the endothelial cells that allow small molecules and limited amounts of protein to diffuse.
Sinusoid - special type of capillaries that have larger openings in the endothelium that allow red and white blood cells and various serum proteins to pass across membrane. Sinusoid blood vessels are primarily located in the bone marrow, lymph nodes, and adrenal gland.
Discontinuous sinusoidal capillaries are special sinusoids that do not have the tight junctions between cells; present in the LIVER AND SPLEEN where greater movement of cells and materials is necessary.

28. Continuous Type Capillaries
Most common- plasma membrane of endothelial cells forms continuous ring around the capillary with many tight junctions interlaced with intercellular clefts for movement of small molecules.
Have no pores -least permeable
skin, skeletal & smooth muscles, & lungs
the blood–brain barrier specialized continuous capillary

29. Fenestrated capillaries
plasma membranes have many holes – “FILTRATION”
e.g. in kidneys, small intestine, choroid plexuses,

30. Sinusoids Discontinuous
very large fenestrations (pores) permit the movement of water, solutes and large proteins (albumin, clotting factors) between the blood and interstitial fluid
e.g. liver, bone marrow, spleen. pituitary, and adrenal glands

31. 1. Capillary Exchange- Diffusion
REMEMBER primary function of capillaries is the exchange of substances between the blood and tissue cells. Capillary exchange plays a key role in homeostasis.
Three (3) processes move materials across capillary walls.
Diffusion (most important method)
Net movement of ions and molecules (solid substances) from an area of HIGHER concentration to an area of LOWER concentration. Diffuse down their concentration gradients (High  Low).
Water, ions, small organic molecules such as glucose, amino acids and urea move between adjacent endothelial cells or through the pores of fenestrated capillaries.
Many ions (Na+, K+, Ca+ Cl-) must use channels in the plasma membrane
O2, CO2, fatty acids and steroids area able to move directly across membrane

33. Simple Diffusion

34. 2. Capillary Exchange- Filtration
FILTRATION is the movement of FLUID AND SOLUTES across a porous membrane using the driving force of hydrostatic pressure.
Capillary HYDROSTATIC pressure (CHP) = pressure FLUID exerts on walls of capillary blood vessel. The capillary hydrostatic pressure (CHP) occurs at both arterial and venous ends but is much higher at the arterial end as blood pressure is higher in arteries than veins.
Water and small solutes are forced through capillary wall.
Interstitial hydrostatic pressure (IHP) = pressure exerted by the fluid surrounding the vessel. The arterial CHP is greater than the interstitial hydrostatic pressure and overcomes any resistance it may produce fluid is forced “OUT” of the capillary.
Net Hydrostatic Pressure (NHP)
Capillary hydrostatic pressure (CHP) MINUS (-) Interstitial fluid hydrostatic pressure (IHP)
(CHP – IHP = NHP)

35. Components

37. 2. Capillary Exchange - Reabsorption
Osmolarity is the measure of solute concentration, the number of osmoles (Osm) of solute per litre (L) of solution
Osmosis- spontaneous net movement of solvent/fluid molecules thru a semi-permeable membrane into a region of higher solute concentration.
Osmotic pressure is the pressure applied to PREVENT osmotic (fluid) movement across a membrane. Higher the solute concentration of solution to fluid concentration the greater osmotic pressure results in less fluid movement. Osmotic pressure is created by solid substances such as plasma proteins (ex: albumin) that do not cross the membrane
Inside capillary - Blood COLLOID osmotic pressure (BCOP)
BCOP is the same on both the arterial and venous ends
Outside capillary- Interstitial fluid colloid osmotic pressure (ICOP)
Net Blood Colloid Osmotic Pressure (BCOP minus ICOP = NCP) Also referred to as oncotic pressure “opposes hydrostatic pressure”
At the VENOUS END of the capillary (not at the arterial end) the blood colloid osmotic pressures (BCOP) is GREATER than the Net Hydrostatic Pressure (NHP).
RESULT: FLUID IS “REABSORBED” BACK INTO THE CAPILLARY.

38. Components
NHP – NCP = NFP

39. Filtration/Reabsorption Process
Fluid and molecules filter out of the arterial end of the capillary and osmotically re-enter at the venous end delivering materials to cells and removing metabolic wastes
Two pressures promote movement:
Capillary hydrostatic pressure (CHP) forces H2O OUT
Blood Colloid Osmotic Pressure (BCOP) draws H2O BACK
Net Capillary Hydrostatic Pressure (NHP) minus Net Blood Colloid Osmotic Pressure (NCP) = Net filtration pressure (NFP) NHP – NCP = NFP
On average only 85% of the fluid that leaves at arterial end reenters the capillaries at the venous end.
Other 15% is returned to circulatory system via the lymphatic system.

40. REVIEW Dynamics of Capillary Exchange
Arterial End: FILTRATION
Filtration is the process where particles are driven through selectively permeable membrane by water.
Delivers materials and removes metabolic waste
Hydrostatic pressure higher =greater force between inside of the blood vessel and the interstitial fluid
BCOP pressure lower than hydrostatic pressure-fluid out
Venous End: REABSORPTION/Osmosis
Hydrostatic pressure lower = less force
BCOP pressure higher than hydrostatic pressure-fluid in
Higher number of venous capillaries–more surface area
Greater diameter (2x) that of arterial end
Absorb 85% of fluid filtered at arterial end
Animation:

41. Capillary Fluid Movement Functions
Ensures that plasma and interstitial fluid are in CONSTANT COMMUNICATION and mutual exchange
Accelerates DISTRIBUTION of nutrients, hormones, and dissolved gases throughout tissues
Assists in the TRANSPORT of insoluble lipids and tissue proteins that cannot enter bloodstream by crossing capillary walls using transcytosis, the process where macromolecules are transported across the interior of a cell via vesicles
Has a FLUSHING ACTION that carries bacterial toxins and other chemical stimuli to lymphatic tissues and organs responsible for providing immunity to disease. Substances released into interstitial fluid and picked up by the lymphatic vessels

42. Capillary Disorders Hemorrhaging= Decreases filtration
Reduces Capillary Hydrostatic Pressure (CHP) and Net Filtration Pressure (CHP-BCOP) = blood loss means less fluid in capillaries less pressure fluid can exert
Increases reabsorption of interstitial fluid (recall of fluids)
Dehydration = Decreases filtration
Increases BCOP (less fluid in ratio to solutes)
Accelerates reabsorption (higher BCOP greater reabsorption)
An increase in CHP = Increases filtration
Fluid moves out of blood and builds up in peripheral tissues
When the filtration exceeds the reabsorption, it results in an increase in the interstitial fluid tissue volume = edema.

43. Cardiovascular Regulation
Blood supply to a tissue can be expressed in terms
blood flow – the AMOUNT of blood FLOWING THROUGH an organ, tissue, or blood vessel in a given time (ml/min)
perfusion – adequacy of blood sent TO THE TISSUES to meet nutrient and oxygen demands
Hemodynamics
physical principles of blood flow based on pressure and resistance
The heart generates pressure to overcome resistance
the greater the resistance the less the flow
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44. FACTORS AFFECTING BLOOD FLOW
Blood Flow, the volume of blood flowing
through any tissue, depends on:
Blood Pressure: hydrostatic pressure in the
arterial system that pushes blood through
capillary beds.
Arterial pressure (mm Hg) caused by contraction of the ventricles = highest in aorta
120 mm Hg during systole & 80 during diastole
Pressure falls the further from the heart
In capillaries BP is close to 30mm Hg with no systole and diastole difference. BP is lower in venules and in larger veins it is near to zero.
Factors that affect blood pressure include cardiac output, blood volume, resistance, such as viscosity, and elasticity of arteries.

45. HEMODYNAMICS: Flow factors
Resistance (Peripheral): is the friction (opposition) between the blood and the walls of the vessels which increases BP. Resistance depends on the following factors.
Size of the lumen: smaller the lumen, greater is the resistance to blood flow.
Blood Viscosity: Thickness of the blood is due to ratio of RBCs and to plasma and concentration of plasma proteins (in particular albumin).
Total blood vessel length: Resistance is directly proportional to the length of the blood vessel. The longer the greater the resistance
Surface Area: given volume of blood distributed over a greater area slower the flow.
Aorta 3-5 cm2; Capillaries cm2;
Want slower flow in capillaries to allow for filtration and reabsorption
Turbulence -Swirling action that disturbs smooth flow of liquid due to sudden changes in vessel diameter, irregular surfaces (ex: plaque buildup).

46. Hemodaynamics: Factors Affecting Blood Flow
Venous return: volume of blood back to heart from systemic veins, depends on pressure difference from venules to right atrium. Two mechanisms act to return venous blood.
Skeletal muscle pump: Skeletal muscles surrounding the veins -- contract --> this exerts pressure on the walls of the veins > forces the valves open --> blood is pumped up --> skeletal muscle relaxed > valve close preventing the backward flow of blood.
Respiratory pump : during inspiration diaphragm moves inferiorly (down). Causes decrease in pressure in thoracic cavity and an increase in the pressure of abdominopelvic cavity. Blood flows from the veins in abdominopelvic region to veins in thoracic region. During expiration, valves close preventing back flow.
Gravity drains blood from the head

47. Deep and Superficial Veins
Deep veins play a significant role in propelling blood toward the heart. One-way valves in deep veins prevent blood from flowing backward, and the muscles surrounding the deep veins compress them, helping force the blood toward the heart, just as squeezing a toothpaste tube ejects toothpaste. The powerful calf muscles are particularly important, forcefully compressing the deep veins in the legs with every step. Deep veins carry 90% or more of the blood from the legs toward the heart.
Superficial veins have the same type of valves as deep veins, but they are not surrounded by muscle. Thus, blood in the superficial veins is not forced toward the heart by the squeezing action of muscles, and it flows more slowly than blood in the deep veins. 

48. Blood Circulation Dynamics
Circulation time – The time necessary for blood from right
atrium to lungs, back to heart, to body and back to right atrium.
In a resting person, takes approximately 1 min.
FROM AORTA TO CAPILLARIES, blood velocity (speed) decreases for three (3) reasons:
greater distance, more friction to reduce speed
smaller radii of arterioles and capillaries offers more resistance
farther from heart, the number of vessels and their total cross-sectional area becomes greater and greater
FROM CAPILLARIES TO VENA CAVA, flow increases again
decreased resistance going from capillaries to veins
large amount of blood forced into smaller channels
never regains velocity of large arteries
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49. Cardiovascular Regulation
Tissue Perfusion
Blood flow through the tissue carrying O2 and nutrients to tissues and organs
Carries CO2 and wastes away
Is affected by:
Cardiac output- amount of blood leaving the heart
Peripheral resistance
Flow interrupted or slowed
Blood pressure

50. Control of Blood Pressure and Flow
NEURAL Cardiovascular center in the MEDULLA of the brain
Control of vasoconstriction by adrenergic nerves (neurotransmitters: norepinephrine/epinephrine)
Stimulates smooth muscle contraction in arteriole walls
Control of vasodilation by cholinergic nerves (neurotransmitter: acetylcholine)
Relaxes smooth muscle
SENSORY STRUCTURES monitor blood pressure and chemistry within vessel
Baroreceptors -pressure sensors) in the walls of internal carotid artery monitors blood pressure – signal to brainstem
Chemoreceptors
In carotid artery - carotid bodies monitor blood chemistry. Detects composition of arterial blood adjust respiratory rate to stabilize pH, CO2, and O2, temperature
In aortic arch - aortic bodies similar to carotid bodies
Central chemoreceptors BELOW medulla oblongata of the brain: monitor cerebrospinal fluid; control respiratory function- dissolved gases; control blood flow to brain

52. Control of Blood Pressure Blood Flow
HORMONAL regulation of Blood Pressure
Renin-angiotensin-aldosterone system -vasoconstriction
Epinephrine & norepinephrine - increases heart rate/ force of contraction
VASOCONSTRICTION
ADH causes vasoconstriction and increased water reabsorption resulting in increase in BP and blood volume.
Erythropoietin (EPO)
VASODILATION
ANP (atrial natriuretic peptide) secreted by muscle cells in the upper atria acts to lower BP and blood volume; increases loss of salt and water in the urine
LOCAL (“neighborhood”) regulation of Blood Pressure
Vasodilators – NO- released in cases of low pH, Low O2 or high CO2 levels
Vasoconstrictors- prostaglandins -released by damaged tissues- regulate smooth muscle
Constrict pre-capillary sphincters

53. SHOCK AND HOMEOSTASIS
Shock is the failure of the cardiovascular system to DELIVER ADEQUATE AMOUNTS OF OXYGEN AND NUTRIENTS to meet the metabolic needs of body cells.
As a result, cellular membranes dysfunction, cellular metabolism is abnormal, and cellular death may eventually occur without proper treatment.
Types of Shock
Hypovolemic shock is due to decreased blood volume.
Cardiogenic shock is due to poor heart function.
Vascular shock is due to inappropriate vasodilation. often related to a loss of vasomotor tone, resulting in poor circulation and a rapid drop in blood pressure.
Obstructive shock is due to obstruction of blood flow.

54. Cardiovascular Adaptation to Exercise
Light Exercise
Extensive vasodilation occurs increasing circulation
Venous return increases with muscle contractions
Cardiac output rises – more blood ejected from the heart
Heavy Exercise
Activates sympathetic nervous system
Cardiac output increases to maximum (4x)
Restricts blood flow to “nonessential” organs (e.g., digestive system)
Redirects blood flow to skeletal muscles, lungs, and heart
Blood supply to brain is unaffected

55. Blood Vessel Disorders
Hypertension: persistently high blood pressure, with systolic pressure greater than 140mm Hg; diastolic pressure being greater than 90 mm Hg.
Primary hypertension (idiopathic) is persistently elevated high blood pressure which cannot be attributed to any causes. Factors responsible for primary tension include obesity, diet, lack of exercise, metabolic defects, nicotine, stress, and heredity – 95% of hypertension cases are of this type
Secondary hypertension: due to
Aldosteronism (mineralocorticoid) : hypersecretion causes excess reabsorption of salt and water by the kidneys.
Kidney disease : damage to renal tissue causes the kidney to release rennin, which in turn leads to vasoconstriction.
Atherosclerosis, hyperthyrodism..

56. Pulmonary Circulation
The pulmonary circulation takes deoxygenated blood from the right ventricle to the air sacs of the lungs and returns oxygenated blood from the lungs to the left atrium. Pulmonary and systemic circulation are different in several ways :
Distance traveled by the blood is smaller
Pulmonary arteries are larger in diameter, thinner walls and hence resistance to blood flow is low.
Hydrostatic pressure in pulmonary capillary is low, tends to prevent pulmonary edema. (low CHP less fluid released from vessel)
Circulation:
Pulmonary Trunk → left and right pulmonary arteries → small basket-like capillaries in the lungs → venules → 2 right and 2 left pulmonary veins → left atria

57. Pulmonary Capillaries Near Alveoli
Basketlike capillary beds surround alveoli
Exchange of gases with air and blood at alveoli

58. Fetal Circulation
Fetus derives its O2 and nutrients and eliminates CO2 and wastes through the placenta via the maternal blood.
Deoxygentated blood flows TO the placenta from fetus through a pair of TWO umbilical ARTERIES that arise from internal iliac arteries and enters umbilical cord.
Oxygenated blood is brought via a SINGLE umbilical vein.
Structures of fetal circulation alter following birth to accommodate pulmonary, digestive, and liver functions.

59. Fetal Circulation
Oxygenated blood from the placenta carried to the fetus by the ONE umbilical vein. Placenta is the LUNGS of the fetus.
Oxygenated blood from umbilical vein moves to the liver %** of the blood bypasses hepatic circulation via the ductus venosus (DV) and enters the inferior vena cava (IVC). In the IVC, the oxygen rich blood from the DV mixes with deoxygenated systemic venous blood, returning from the lower fetal body producing a blood mixture.
60-65% of the umbilical vein blood enters the liver moving thru the portal vein into the right atria bypasses the lungs going directly to the left atria through an opening called the foramen ovale.
Blood entering right ventricle is pumped into the pulmonary artery
The ductus arteriosus, a special connection between the pulmonary artery and the aorta, directs most of this blood away from the lungs (which aren't functioning as the fetus is suspended in amniotic fluid).
The blood flowing from the left atria continues into the left ventricle, and is pumped through the aorta into the fetal body.
Deoxygenated blood leaving fetal circulation moves from the aorta through the internal iliac arteries to the TWO umbilical arteries, and re-enters the placenta, where CO2 and other waste products are taken up and enter the maternal circulation.
**Correction

60. Oxygen poor blood from fetal body
MIXTURE of oxygen rich and oxygen poor blood returning to the placenta via the umbilical arteries from the aorta
Oxygen poor blood from fetal body
Oxygen rich blood from the placenta

61. Pulmonary artery

62. Major arteries of the body

63. Aorta Branches Brachiocephalic trunk 1 artery - right side only.
Branches into
R. subclavian
Blood to right side
R. common carotid
Supplies blood to the head, neck,
L. common carotid
Blood source to the head
L. subclavian
Left side of the body

64. Common Carotid Arteries
Each common carotid divides
External carotid artery - supplies blood to most external head structures of the neck, lower jaw, and face
Facial
Occipital
Internal carotid artery - enters skull delivers blood to brain
Divides into three branches
Ophthalmic artery
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery

66. The Vertebral Arteries
Supplies brain with blood
Supplies meninges and spinal cord
Supplies cervical vertebrae and deep neck muscles
Left /right VERTEBRAL arteries
Branch from SUBCLAVIAN arteries
Enter cranium through foramen magnum
The Vertebral Arteries
Branches fuse to form basilar artery
Which branches to form posterior cerebral arteries
Become posterior communicating arteries

68. Anastomoses- Arterial Supply of Brain
Paired vertebral arteries combine to form basilar artery on pons
Cerebral arterial Circle of Willis on base of brain formed from anastomosis of basilar and internal carotid arteries
Circle of Willis - brain, internal ear and orbital structures
Basilar artery supplies cerebellum, pons, inner ear
Circle of Willis

69. Pulmonary Trunk branches into the left and right pulmonary arteries

70. Flow of Blood through the Lungs

71. Coronary Circulation
Left (LCA) and right (RCA) coronary arteries

72. Vessel changes names as they pass to different regions
Subclavian- supplies breast, pericardium gives rise to axillary
Axillary - scapular, pectoral regions, triceps, deltoid, latissiumus dorsi to brachial
Brachial used for BP and radial artery for pulse
Brachial to Radial and Ulnar
Palmar arches to hand

74. Thoracic aorta supplies
viscera and body wall
Bronchial
Esophageal
Mediastinal branches
Phrenic arteries

75. Abdominal Aorta and Its Branches

76. Celiac trunk supplies:
Celiac Trunk Branches
Celiac trunk supplies:
Upper abdominal viscera:
Stomach
Left gastric
Spleen
splenic
Liver
Common hepatic
Right gastric
Indirectly the Pancreas
Pancreatic branches off splenic

77. Descending Aorta- Abdominal Aorta
Divides at terminal segment of the aorta into:
Left common iliac artery
Right common iliac artery
Unpaired branches
Major branches to visceral organs
Paired branches
To body wall
Kidneys
Urinary bladder
Structures outside abdominopelvic cavity

79. Mesenteric Arteries
Supply the intestines

80. Arteries of the Lower Extremity
branch to the lower limb arise from externsal iliac branch of the common iliac artery

81. Back of Knee

82. Veins of the Systemic Circulation
Drain blood from entire body & return it to right side of heart

83. The Systemic Circuit Veins of the Foot Capillaries of the sole
Drain into a network of plantar veins
Plantar venous arch
Drain into deep veins of leg:
Anterior tibial vein
Posterior tibial vein
Fibular vein
All three join to become popliteal vein
Dorsal Venous Arch
Collects blood from: Superior surface of foot/Digital veins
Drains into two superficial veins
Great saphenous vein (drains into femoral vein)
Small saphenous vein (drains into popliteal vein)

84. The Systemic Circuit Popliteal Vein Becomes the femoral vein
Before entering abdominal wall, receives blood from:
Great saphenous vein
Deep femoral vein
Femoral circumflex vein
Inside the pelvic cavity
Becomes the external iliac vein
External Iliac Veins
Are joined by internal iliac veins
To form right and left common iliac veins
The right and left common iliac veins
Merge to form the inferior vena cava

86. Hepatic portal system
A portal vein connects two organs without the involvement of heart in between. The portal veins begin and end with capillaries.
HPP detours venous blood from GI tract to liver on its way to the heart.
Connects capillaries of intestines and other digestive organs to modified capillaries of the liver (hepatic sinusoids) causes blood to pass thru 2 capillary beds before returning to the heart.
HPP give liver 1st contact with nutrients before the blood distributes to the body. Liver monitors blood content
Allows blood to be cleaned of bacteria and other toxins picked up in GI tract
Blood enters general circulation through the inferior vena cava via the hepatic vein.
The system extends from about the lower portion of the esophagus to the upper part of the anal canal as well as venous drainage from the gallbladder, stomach, spleen and pancreas.

89. Hepatic portal system

90. Tributaries of the Hepatic Portal Vein
Inferior mesenteric vein
Drains part of large intestine
Splenic vein
Drains spleen, part of stomach, and pancreas
Superior mesenteric vein
Drains part of stomach, small intestine, and part of large intestine
Left and right gastric veins
Drain part of stomach
Cystic vein
Drains gallbladder

91. Veins of Shoulder and Upper Limb
Cephalic superficial empties into the axillary vein;
communicates with the basilic
Basilic superficial visible with the naked eye
Brachial Vein deep drains Radial and Ulnar veins into the axillary
Axillary –deep brings blood from thorax, axilla (armpit), and upper arm
Blood will often be shunted from superficial to deep vessels or vice versa to maintain stable body temperature

92. Veins of the Thoracic Cavity
TWO BRACHIOCEPHALIC VEINS receives blood from: Subclavian veins
The LEFT AND RIGHT BRACHIOCEPHALIC VEINS merge to form the SUPERIOR VENA CAVA (SVC)
Superior Vena Cava receives blood from azygos vein and hemiazygos vein which receive blood from:
Intercostal veins
Esophageal veins
Veins of other mediastinal structures

93. Veins of the Head and Neck
INTERNAL JUGULAR vein receives most of the blood from the brain.
Drains: Facial vein; Superficial temporal
EXTERNAL JUGULAR vein drain the external structures of the head
Drains: Occipital
Jugulars and upper limb are drained into the SUBCLAVIAN vein