Today's Medical Assistant

Today's Medical Assistant
2th edition Chapter 12 Circulatory System

Lesson 12.1 The Heart Describe the size and location of the heart.
Identify the layers of the heart wall, and state the type of tissue in each layer. Label a diagram of the heart, including chambers, valves, and associated vessels.

Lesson 11.1 The Heart (cont’d)
Trace the pathway of blood flow through the heart. Describe the components and function of the conduction system of the heart. Summarize the events of a cardiac cycle, and correlated the heart sounds heard with these events.

Introduction to the Circulatory System
Made up of: Heart: central pump Blood vessels: moves blood through body Blood: transport medium William Harvey ( ) was the first Western physician to describe the fact that blood is pumped through a closed system by the heart.

Heart Muscular pump Provides the force necessary to circulate blood to all tissues in body Tissues need a continuous supply of oxygen and nutrients Metabolic waste products: must be removed Pumps 5 liters of blood every minute The heart is composed of muscle tissue that is designed to contract regularly. The contractions of the heart squeeze the blood out, and the force of continuous contractions keeps the blood flowing in one direction.

Form, Size, and Location of the Heart
Located in thoracic cavity between the lungs Posterior to sternum Anterior to vertebral column Two thirds of heart mass: to the left of body’s midline (one third is to the right) Apex: pointed end of heart Extends downward to level of fifth intercostal space The heart is about the size of a closed fist. The space between the lungs where the heart is located is called the mediastinum. What is the name of the pointed end of the heart? Apical is the adjectival form of apex.

Base: opposite end Larger and less pointed than apex Has several large vessels attached to it Size of heart: varies with size of individual Average: 9 cm wide and 12 cm long (size of a closed fist) Organs are named by shape, not position, so the base of the heart is superior to the apex. The vessels that extend from base of the heart are sometimes called the great vessels.

Where is the base of the heart? Where is the apex of the heart? What body structures protect the heart? (Vertebrae, sternum, ribs.)

Coverings of the Heart Pericardium: loose-fitting, double-layered sac that encloses the heart consisting of: Fibrous pericardium: outer layer of pericardium Consists of tough, white fibrous connective tissue Parietal pericardium: serous membrane that lines the fibrous pericardium Visceral pericardium: parietal pericardium reflects back onto the surface of the heart to form the visceral pericardium Also called epicardium What are the three layers of the pericardium? What type of tissue is the fibrous pericardium? Parietal pericardium? Visceral pericardium (epicardium)? In general, what does parietal mean when describing one of several layers of tissue? (The layer that lines a cavity wall.) In general, what does visceral mean when describing one of several layers of tissue? (The layer that adheres to an organ.) In the heart, the parietal layer adheres to the fibrous pericardium, which is not exactly a cavity wall, but which is superficial to the visceral pericardium and forms an outer covering to the heart.

Coverings of the Heart Pericardial cavity: small space between parietal and visceral layers of pericardium Contains a thin layer of serous fluid Reduces friction between the membranes as they rub against each other during heart contractions A small amount of fluid between two membranes reduces friction. What is pericardidits? (Inflammation of the pericardium.)

Coverings of the Heart What color is the myocardium (heart muscle tissue)? (Reddish.) What color is the visceral pericardium? (Yellow.) What is another name for the visceral pericardium? (Epicardium.) What color is the parietal pericardium? (Lavender.) What color is the fibrous pericardium? (Gray.) Where is the pericardial cavity? (Between the visceral and parietal layers.)

Layers of the Heart Wall
Epicardium (same as the visceral pericardium): consists of a serous membrane Thin protective layer: firmly anchored to underlying muscle Contains blood vessels: nourish heart wall Myocardium: forms bulk of heart wall Composed of cardiac muscle tissue When talking about the heart instead of the pericardium, the visceral pericardium is called the epicardium. My- means muscle. -Cardium is a noun form of cardi- meaning heart. What is the adjective form? (Cardiac and –cardial.)

Layers of the Heart Wall
Myocardium: forms bulk of heart wall Contraction of myocardium: Provides force that ejects blood from heart and moves it through vessels Endocardium: smooth inner lining of heart wall Permits blood to move easily through heart Also forms the valves of the heart Endo- means inside or within. It is often combined with a word root to designate the innermost layer of tissue. (Examples: endoplasmic reticulum, endothelial, endometrium)

Chambers of the Heart Four chambers: Right atrium Right ventricle
Left atrium Left ventricle An atrium was the central court of an ancient roman house. Ventricle means little belly. The term is used for belly-shaped hollow spaces formed by one or more organs. There is normally no direct condition between the chambers of the right heart and the left heart.

Chambers of the Heart Atria: thin-walled chambers
Receive blood from the veins Ventricles: thick-walled chambers Forcefully pump blood out of the heart From where do the atria receive blood? From where do the ventricles receive blood?

Chambers of the Heart Right atrium: receives deoxygenated blood
From superior vena cava and inferior vena cava Superior vena cava: returns blood to heart Inferior vena cava: returns blood to heart What blood vessels supply blood to the right atrium? From where does the superior vena cava return blood? (Head, neck, and upper extremities.) From where does the inferior vena cava return blood? (Thorax, abdomen, pelvis, lower extremities.)

Chambers of the Heart Left atrium: receives oxygenated blood
From lungs through four pulmonary veins Interatrial septum: partition that separates right and left atria Fossa ovalis: thin region in the septum Represents an opening (foramen ovale) that is present between the atria in the fetal heart From where does the left atrium receive blood? What is the interatrial septum? During fetal development, there is normally an opening between the right and left atrium (foramen ovalis). This improves fetal circulation, because the fetus receives oxygenated blood through the umbilical cord, not from the lungs. This opening usually closes right after birth and forms the fossa ovalis.

Chambers of the Heart Right ventricle: receives blood from the right atrium Pumps it to lungs, where it picks up oxygen Left ventricle: receives blood from left atrium Pumps it to tissues of body Interventricular septum: thick, muscular partition between the right and left ventricles From where do the right and left ventricle receive blood? Which ventricle pumps blood to the lungs? Which ventricle pumps blood to the body? What structure separates the two ventricles?

Chambers of the Heart On which side of the illustration is the right side of the heart? Left side of the heart? What structures are shown in blue? (Superior vena cava and inferior vena cava.) Which is superior, the right atrium or right ventricle? (Right atrium.) Which structure is not visible: the intratrial septum or the intraventricular septum? (Intratrial septum.)

Valves of the Heart Atrioventricular (AV) valves
Permit the flow of blood from atria into corresponding ventricle Prevent backflow of blood from ventricles into atria Consist of a fibrous connective tissue ring and double folds of endocardium Form the cusps of the valve – attached to papillary muscles in the ventricles by chordae tendineae A valve controls the flow of liquids or gases. Preventing backflow of blood increases the efficiency of the heart’s pumping action. When the atria contract, the pressure forces the atrioventricular valves to open downward into the ventricles. When the atria relax, the valves move back to the closed position.

Valves of the Heart Atrioventricular (AV) valves
Tricuspid valve: between right atrium and right ventricle Has three cusps Bicuspid (mitral) valve: between left atrium and left ventricle Has two cusps A cusp is a point formed by intersecting arcs. The term is also used for teeth (bicuspid and tricuspid). Where is the tricuspid intra-atrial valve? Where is the bicuspid intra-atrial valve? What is another name for the bicuspid valve? (Mitral valve.)

Valves of the Heart Semilunar (SL) valves
Located at the bases of the large vessels that carry blood from the ventricles Each valve consists of three cuplike cusps Prevent the flow of blood back into the ventricles Pulmonary SL valve: located at the exit of the right ventricle In the base of the pulmonary trunk Aortic SL valve: located at the exit of the left ventricle In the base of the aorta Semilunar means half moon. What valve is located at the exit of the right ventricle? What valve is located at the exit of the left ventricle?

Pathway of Blood Through the Heart
Both atria contract at the same time Both ventricles contract at the same time Heart functions as two pumps: Pulmonary circulation: pump on the right side Pumps blood to lungs Systemic circulation: pump on the left side Pumps blood to rest of body Which side of the heart is responsible for the pulmonary circulation? Which side of the heart is responsible for the systemic circulation?

Blood flow through the heart Blood enters right atrium through superior vena cava and inferior vena cava Low in oxygen and high in carbon dioxide Flows through tricuspid valve into right ventricle Passes through pulmonary SL valve Flows into pulmonary trunk and into pulmonary arteries Blood carried to lungs Carbon dioxide is released and oxygen is picked up Is the blood entering the right atrium oxygen rich or oxygen depleted? Why? What is the path of blood from the right atrium to the lungs? (Right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary arteries [right and left], lungs.)

Blood flow through the heart Pulmonary veins carry blood to left atrium Blood flows through bicuspid valve into left ventricle Flows through aortic SL valve into aorta Distributed to all parts of the body through the systemic circulation Is the blood entering the right atrium oxygen rich or oxygen depleted? Why? What is the path of blood from the left atrium to the abdomen? (Left atrium, bicuspid valve, left ventricle, aortic semilunar valve, aorta, descending aorta, arteries in the abdomen.)

Blood Supply to the Myocardium
Myocardium: needs a continuous supply of oxygen and nutrients Has an extensive network of blood vessels Two coronary arteries: branch from aorta Right and left coronary arteries Have numerous branches The coronary arteries branch from the aorta almost immediately above the aortic valve. What arteries supply blood to the myocardium? Blood flow through the coronary arteries is greatest during diastole. During systole, the contraction of the heart reduces flow through the coronary arteries.

Blood Supply to the Myocardium
Function: Pump blood to the lungs through the pulmonary circulation Pump blood to the rest of the body through the systemic circulation Accomplished by contraction and relaxation of the cardiac muscle in the myocardium What is the function of the heart? Why is it necessary for blood to be pumped to the lungs? Why is it necessary for blood to be pumped through systemic circulation?

Components of the Conduction System
Sinoatrial node (SA node) Located in the right atrium: near entrance of superior vena cava Initiates impulses: without neural stimulation 70-80 times per minute Establishes basic rhythm of the heartbeat Called the pacemaker of the heart Impulses travel throughout atrial myocardium Cause atria to contract simultaneously Impulses reach AV node The myocardial cells in the SA node are more excitable than other cardiac cells. In addition, they contract rhythmically times per minute. If the SA node is not functioning or if impulses are blocked from reaching the ventricles, the myocardial cells of the ventricles will beat at approximately times per minute. When the cells of the SA node contract, the impulse spreads across both atria, and both atria contract.

Atrioventricular Node (AV node) Located in floor of right atrium: near interatrial septum Cells in the AV node: conduct impulses more slowly Causes brief delay as impulses travel through the node There is a brief delay in the spread of the impulse at the AV node. Why is the delay at the AV node helpful in terms of cardiac efficiency? (Allows the atria to finish contracting before the impulse spreads to the ventricles.)

Atrioventricular bundle, bundle branches, and conduction myofibers From AV node: Impulses travel through AV bundle (bundle of His) to right and left bundle branches Bundle branches Extend along the right and left sides of the interventricular septum Branch profusely to form conduction myofibers (Purkinje fibers) Conduction myofibers: transmit impulses to myocardium Cause ventricles to contract simultaneously – blood is forced out through SL valves into aorta The right and left bundle branches carry nerve impulses along the intraventricular septum. Because the impulses are carried rapidly to conduction fibers that penetrate all parts of the myocardium of the ventricles, the myocardial cells of the ventricles contract together. What happens to the blood when the ventricles contract?

Where is the sinoatrial node (SA node)? Where is the atrioventricular node (AV node)? Where is the atrioventricular bundle (bundle of His)? Where are the right and left bundle branches? Where are the conduction myofibers (Purkinje fibers)?

Cardiac Cycle Consists of one heartbeat
Two atria contract at same time Then relax while two ventricles contract What is the cardiac cycle?

Cardiac Cycle With a heart rate of 75 beats per minute, one cardiac cycle lasts 0.8 second Atrial systole: contraction of the atria (0.1 second) AV valves are open Ventricles are in diastole (relaxed) Blood is forced into ventricles What is the position of the AV valves when the atria contract? During atrial systole, what is the condition of the ventricles? What happens to blood during atrial systole?

Cardiac Cycle With a heart rate of 75 beats per minute, one cardiac cycle lasts 0.8 second Ventricular systole: contraction of ventricles (0.3 second) Atria are in diastole (relaxed) – are filling with blood returned through venae cavae All chambers are in simultaneous diastole (0.4 second) 70% of ventricular filling occurs during this period During ventricular systole, what is the position of the AV valves? (Closed.) During ventricular systole, what is the position of the semilunar valves? (Open.) What happens to the blood?

Heart Sounds First heart sound: lubb Second heart sound: dupp
Caused by closure of AV valves Second heart sound: dupp Caused by closure of SL valves Pause between dupp of the first beat and lubb of second beat Entire heart is resting Abnormal heart sounds: murmurs Caused by faulty valves What causes the first heart sound? What causes the second heart sound? Why is there a longer pause after the second heart sound than after the first heart sound? When abnormal swishing or hissing sounds are heard between the normal heart sounds, it is called a murmur. Some heart murmurs are benign. These are more common in children and often disappear as the child grows.

Blood and Blood Vessels
Lesson 12.2 Blood and Blood Vessels Describe the physical characteristics and functions of blood. Identify the composition of blood plasma. Identify the formed elements of the blood. State the function of each formed element in blood.

Blood and Blood Vessels (cont’d)
Lesson 12.2 Blood and Blood Vessels (cont’d) Describe the life cycle of an erythrocyte. List and describe the five types of leukocytes. Explain the blood clotting mechanism of the body.

Lesson 12.2 Blood and Blood Vessels (cont’d) Explain the basis of blood types. Describe the structure and function of arteries. Describe the structure and function of capillaries.

Lesson 12.2 Blood and Blood Vessels (cont’d) Describe the structure and function of veins. Describe ways in which the aging of an individual affects the circulatory system. Identify pathology related to the circulatory system.

Blood Primary transport medium
Provides cells with nutrients and oxygen Removes metabolic wastes Blood cells are formed in the red bone marrow. Where is the red bone marrow in adults? (Sternum, ribs, skull, clavicle, vertebrae, and pelvis.) The cells are suspended in liquid that is pumped by the heart throughout the circulatory system.

Functions and Characteristics of the Blood
Connective tissue Consists of cells and cell fragments (formed elements) suspended in an intercellular matrix (plasma) Blood is the only liquid tissue in the body Blood volume in an average adult: Female: 4-5 liters Male: 5-6 liters What is the liquid part of blood called? What type of tissue is blood?

Transportation Regulation Protection

Transportation Carries oxygen and nutrients to cells Transports carbon dioxide and nitrogenous wastes From the tissues to the lungs and kidneys Carries hormones from endocrine glands to target tissues Where does the blood gain oxygen? Where is oxygen removed from the blood? Where does the blood gain carbon dioxide? Where is carbon dioxide removed from the blood? What other substances are carried by blood?

Regulation Regulates body temperature Removes heat from skeletal muscles: Fluid and electrolyte balance Salts and plasma proteins contribute to the osmotic pressure pH regulation through the action of buffers in the blood What does the blood help regulate? When blood removes heat from skeletal muscles, it transports the heat to other regions (e.g., transports to skin, where it can be dissipated). An electrolyte is a substance containing ions with an electrical charge. Substances such as sodium chloride separate when dissolved into sodium and chloride. Because they no longer share an electron, they become positively (Na+) or negatively (Cl-) charged. The most abundant plasma protein, albumin, is produced in the liver. Acidity or alkalinity are measured by the pH scale, which is an inverse measure of the hydrogen ion concentration. Body processes require a relatively constant pH. A substance that neutralizes acids or bases is called a buffer.

Protection Clotting mechanisms: prevent fluid loss through hemorrhage When blood vessels are damaged Phagocytic white blood cells Help protect against microorganisms Antibodies in the plasma Help protect against disease How does the blood function to protect humans? Antibodies neutralize foreign antigens. (Remember: “Your body produces antibody.”)

Composition of the Blood
Plasma: 55% of blood volume Red blood cells: 45% of blood volume Buffy coat: consists of WBCs and platelets Forms a thin white layer between the plasma and RBCs The liquid part of blood is called plasma. After blood clots, the liquid part is called serum. When blood is centrifuged, the heaviest elements go to the outside, which is the bottom of the tube containing the blood. Between the plasma and the red blood cells is a whitish layer called the buffy coat.

What percent of body weight is blood? What percent of blood is plasma? What is contained in the buffy coat? What percent of blood consists of formed elements? What type of blood cells make up most of the formed elements?

Plasma Liquid portion of the blood 90% water Remaining portion: approximately 100 different organic and inorganic solutes Various chemicals are dissolved in blood plasma. A solute is a name for something that is dissolved in another substance. Plasma proteins remain in the blood and interstitial fluid. Help keep fluid in the blood (osmosis).

Plasmas Proteins Most abundant solute
Remain in blood and interstitial fluid Are not used for energy Many are synthesized in liver Types Albumins Globulins Fibrinogen

Plasmas Proteins Albumins 60% of plasma proteins Produced in liver
Contribute to osmotic pressure of blood Play role in maintaining fluid balance between blood and interstitial fluid Albumins are the smallest plasma proteins.

Plasmas Proteins Albumins
Play role in maintaining fluid balance between blood and interstitial fluid If the osmotic pressure of blood decreases, fluid moves from blood into interstitial spaces If blood osmotic pressure increases, fluid moves from interstitial spaces into blood Why are albumins important in the blood? What happens if the osmotic pressure of blood decreases and fluid moves from blood into interstitial spaces? (Results in edema; decreases blood volume; in severe cases, may reduce blood pressure.) What happens if the osmotic pressure of blood increases and fluid moves from interstitial spaces into blood? (Increases blood volume; increases blood pressure; decreases amount of water available to cells.)

Plasmas Proteins Globulins 36% of the plasma proteins Three types:
Alpha and beta globulins: produced in the liver Gamma globulins: produced in lymphoid tissue What is the function of alpha and beta globulins? (Transport lipids and fat-soluble vitamins in blood.) Where are gamma globulins produced? (In lymphoid tissue.) What is the function of gamma globulins? (Are antibodies that function in immunity.)

Plasmas Proteins Fibrinogen 4% of plasma proteins Produced in liver
Functions in blood clotting During clotting process: soluble fibrinogen is converted into insoluble fibrin When blood clots in a test tube, liquid that remains is called serum Fibrinogen is the largest of the plasma proteins. When soluble fibrinogen is converted into insoluble fibrin, it forms the foundation of a blood clot Serum is similar to plasma but it has no fibrinogen (fibrinogen is converted to fibrin). When is serum produced?

Other Solutes Urea and uric acid: waste products of protein and nucleic acid catabolism Transported to the kidneys for excretion Respiratory gases Oxygen and carbon dioxide Electrolytes Important in: Muscle contraction Nerve impulse conduction pH of body fluids Which type of molecules are products of protein metabolism? What are urea and uric acid? Where are urea and uric acid excreted? How are oxygen and carbon dioxide transported in the blood? What are common electrolytes in blood plasma?

Formed Elements Erythrocytes: red blood cells
Leukocytes: white blood cells Thrombocytes: platelets What are the three types of blood cells in the blood?

Formed Elements Hematopoiesis: production of blood cells
Before birth: occurs primarily in liver and spleen After birth: Red bone marrow in specific regions of body Some WBCs are produced in lymphoid tissue Hemocytoblast: a stem cell in the bone marrow from which blood cells develop Seven different cell lines develop from the hemocytoblast Hem- or hemat- are the word roots meaning blood. The suffix -poiesis means formation or production. The word root cyt- means cell. The suffix -blast means immature cell. Where is blood produced during fetal development? Where are blood cells produced after birth?

Formed Elements What seven types of cells develop from the hemocytoblast? How many stages are there in the development of erythrocytes? How many stages are there in the development of basophils, eosinophils, and neutrophils? How many stages are there in the development of lymphocytes and monocytes? How many stages are there in the development of thrombocytes (platelets)?

Erythrocytes Characteristics and functions of RBCs
Most numerous of formed elements RBC range for adult: Female: million RBCs/cubic millimeter (mm3) of blood Male: million RBCs/cubic millimeter (mm3) of blood Erythro- means red. Who normally has more erythrocytes? Males or females?

Biconcave disks: thin in middle and thicker around periphery Provide flexibility for moving through capillaries Provide maximum surface area for diffusion of gases Mature RBCs: do not have a nucleus (anucleate) During development: nucleus is lost from cell Gives cell more room for hemoglobin The nucleus is lost from RBCs during development. RBCs do not divide, they just carry oxygen.

Develop from stem cells in red bone marrow Move from bone marrow into blood while still immature Function of erythrocytes: Transport oxygen and, to a lesser extent, carbon dioxide What is the name for immature erythrocytes that may be found in circulating blood? (Reticulocytes.) What is the function of erythrocytes?

Erythrocytes Characteristics and functions of RBCs Hemoglobin
Makes up one third of each erythrocyte Heme: formed from a pigment that contains iron Globin: protein Heme combines with oxygen in the lungs: oxyhemoglobin (bright red) Oxygen is released to diffuse into tissue cells: deoxyhemoglobin (darker red in color) Hemoglobin is a protein with a heme molecule that contains iron. Iron causes the blood to be red. Some invertebrates have other minerals in their blood. The blood of the horseshoe crab and other crustaceans contains hemocyanin, which has copper as the metallic element. When combined with oxygen, blood is bright red. After oxygen has been released, the color of the blood is darker red.

Erythrocytes Production of erythrocytes Negative feedback mechanism
Erythropoietin: stimulates erythrocyte production Liver produces erythropoietin in inactive form Secretes it into blood Erythropoietin is a hormone produced by the liver in an inactive form.

Erythrocytes Production of erythrocytes
Renal erythropoietic factor (REF): activates erythropoietin When blood oxygen concentration is low: Kidneys release REF into blood – activates erythropoietin Stimulates red bone marrow to produce RBCs Additional RBCs: combine with oxygen Increases blood oxygen concentration As blood oxygen concentration increases: Levels of REF and active erythropoietin decrease – RBC production decreases When do the kidneys release erythropoietic factor (REF)? What happens when more RBCs are released by the liver?

Erythrocytes Production of erythrocytes Needed for RBC production:
Iron Vitamin B12 Folic acid What essential nutrients are necessary for erythrocyte production? Where are these nutrients obtained? (From food.)

Erythrocytes Production of erythrocytes Intrinsic factor:
Produced by stomach Needed for absorption of vitamin B12 in the intestines Without intrinsic factor: vitamin B12 cannot be absorbed Results in pernicious anemia Sometimes vitamin B12 is called the “extrinsic factor,” because it must be obtained outside the body. Which nutrient can only be absorbed if the stomach produces intrinsic factor? Pernicious anemia must be treated with injections of vitamin B12.

Erythrocytes Destruction of erythrocytes
Lifespan of an erythrocyte: 120 days As erythrocyte ages: Cell membrane becomes fragile Macrophages (phagocytic cells in spleen and liver) remove them from circulation Replaced by an equal number of new cells 2 million erythrocytes are destroyed and replaced every second In what organs are old erythrocytes destroyed? How are they replaced?

Erythrocytes Destruction of erythrocytes
Hemoglobin separates into heme and globulin: Heme broken down into: iron compound used to make new hemoglobin, bilirubin (yellow bile pigment) Globin (protein) broken down into amino acids: added to supply of amino acids available in body Why is it important to conserve the iron from hemoglobin? What is bilirubin? (Yellow bile pigment, becomes part of bile.) How is most bilirubin excreted from the body? What happens to the amino acids when hemoglobin from old erythrocytes is broken down?

Erythrocytes Where are red blood cells produced?
Where are they broken down? What happens to the iron and amino acids? What happens to the bilirubin from the heme?

Leukocytes Characteristics and functions of WBCs
Larger than erythrocytes Fewer in number Normal WBC count: 4,500-11,000 cells/mm3 Derived from hemocytoblast stem cells Do not lose their nuclei Are there more red blood cells or white blood cells in the blood? Do white blood cells also lose their nuclei?

Leukocytes Characteristics and functions of WBCs
Leukocytes do most of their work in the tissues Use blood as transport medium Move through capillary walls into tissue spaces: diapedesis Provide a defense against organisms that cause disease Where do leukocytes do most of their work? How do they get there? What is the function of white blood cells?

Leukocytes Granular leukocytes (granulocytes): granules in the cytoplasm Neutrophils Eosinophils Basophils Nongranular leukocytes (agranulocytes): no granules in the cytoplasm Lymphocytes Monocytes

Leukocytes Neutrophils Normal range: 50%-70% of WBCs
Purple, multilobed nucleus (3-5 lobes) Many fine granules in cytoplasm Stain violet-pink Neutrophils have many names. In addition to neutrophils, they may be called polymorphonuclear leukocytes (polys), or segmented leukocytes (segs). Neutr- means neutral, and, in contrast to the two other kinds of granulocytes, they take up only a small amount of Wright’s stain. The suffix -phil means attraction to.

Leukocytes Neutrophils Band: immature neutrophil
Curved, nonsegmented nuclei 0%-5% of neutrophils: normally present in band form First leukocytes to respond to tissue damage Engulf bacteria by phagocytosis Neutrophils and bands: increase during acute infections Immature neutrophils are called bands. When do neutrophils and bands increase in number?

Leukocytes Eosinophils Normal range: 1%-4% of WBCs
Segmented nucleus (no more than two lobes) Large granules in the cytoplasm: stain bright reddish orange Function: Neutralize histamine – number increases during allergic reactions Destroy parasitic worms Eosin- comes from the Greek word for dawn, characterized by a rosy glow on the horizon. How do eosinophils stain? What is the function of eosinophils?

Leukocytes Basophils Normal range: 0%-1% of WBCs S-shaped nucleus
Large, coarse granules in cytoplasms Stain dark bluish-black Almost completely obscure details of nucleus Secrete histamine and heparin Histamine: dilates blood vessels Heparin: inhibits blood clot formation How do basophils stain? What is the function of basophils? Histamine dilates blood vessels in allergic reactions, which increases blood flow to damaged tissues.

Leukocytes Lymphocytes Normal range: 20%-35% of WBCs
Large round or slightly indented nucleus Stains a deep purplish blue Small rim of sky-blue cytoplasm around nucleus Produces antibodies Increase in lymphocytes: occurs with certain viral diseases Infectious mononucleosis, mumps, chicken pox, rubella, viral hepatitis Lymphocytes are the second most numerous WBCs. What is the function of lympohcytes? When does the number of lymphocytes increase?

Leukocytes Monocytes Largest WBC Normal range: 3%-8% of WBCs
U-shaped or kidney-shaped nucleus Surrounded by abundant cytoplasm: stains grayish-blue Macrophages: monocytes that leave the blood and enter the tissues Engulf bacteria and cellular debris Finishes the cleanup process started by neutrophils What is the largest WBC? What is the function of monocytes?

Thrombocytes Also known as platelets
Consist of small fragments of large cells: megakaryocytes Develop from hemocytoblasts in red bone marrow Normal range: 150,000 to 500,000 platelets/mm3 of blood Function: Close breaks in blood vessels Become sticky and clump together to form platelet plugs Initiate the formation of blood clots Thromb- means blood clot. Thrombocytes are called cell fragments because they form from the breakdown of megakaryocytes. They are much smaller than other blood cells. What is the function of thrombocytes? What happens if an individual does not form enough platelets?

Hemostasis Blood vessels that are torn or cut: permit blood to escape
Into surrounding tissues or to outside of the body Excessive blood loss: may result in death Injured blood vessels: trigger reactions to minimize blood loss and tissue damage Hemostasis: the stoppage of bleeding Consists of three processes: Vascular constriction Platelet plug formation Coagulation What are the three processes of hemostasis?

Vascular Constriction
First response to blood vessel injury Contraction of smooth muscle in vessel walls (constriction) Restricts flow of blood through opening in the vessel Lasts only a few minutes Allows enough time for other aspects of hemostasis to begin Platelets secrete a chemical: serotonin Stimulates smooth muscle contraction in vessel wall Prolongs the vascular constriction What is the first response to blood vessel injury? What chemical prolongs vascular constriction?

Platelet Plug Formation
Normally platelets do not: Stick to each other Stick to blood vessel walls When blood vessel breaks: Underlying connective tissue is exposed Attracts platelets Accumulate in damaged region Adhere to connective tissue and each other Creates a platelet plug Obstructs tear in the vessel What causes platelets to clump together? How does the accumulation of platelets in an area of tissue damage help hemostasis?

Coagulation Formation of a blood clot
Procoagulants: factors in the blood that promote clotting Anticoagulants: factors in the blood that inhibit clotting Normally anticoagulants override procoagulants Blood remains fluid and does not clot When vessels damaged: procoagulants increase activity Results in the formation of a clot What are procoagulants? What are anticoagulants? Patients often refer to anticoagulants as blood thinners. It is important to note that anticoagulants inhibit blood clotting, but they do not dilute the blood.

Coagulation Involves a series of chemical reactions
Platelets and damaged tissues release chemicals Initiate a series of reactions: result in formation of prothrombin activator In the presence of calcium ions and prothrombin activator: Prothrombin (inactive) is converted thrombin (active) Thrombin converts fibrinogen (inactive) fibrin (active) Fibrin threads: form a mesh What chemicals in the blood are involved in blood clotting? (Prothrombin, fibrinogen, and calcium ions.) What blood cell fragments initiate blood clotting? What is the active form of thrombin? What is the active form of fibrinogen? Fibrin adheres to damaged tissue, traps blood cells and platelets to form the clot.

Coagulation After a clot has formed:
Fibrin strands contract: clot retraction Causes clot to shrink Fibroblasts migrate into clot Form fibrous connective tissue – repairs damaged area Clot is eventually dissolved: fibrinolysis How does a clot shrink? (Pulls edges of damaged tissue closer together; reduced blood flow to area; reduced probability of infection; enhanced healing.)

ABO Blood Groups Based on the presence or absence of certain antigens
On the surface of RBC membrane Blood types are inherited Blood types: Type A: A antigen Type B: B antigen Type AB: A and B antigens Type O: neither A nor B antigens The antigens of the blood type are present on the red blood cells at birth. What antibodies are found on the blood cells if an individual has blood type A? Type B? Type AB? Type O?

ABO Blood Groups Certain blood antibodies: develop in plasma shortly after birth Type A blood B antibodies Type B blood A antibodies Type AB blood Neither A nor B antibodies Type O blood A and B antibodies An individual has antibodies to all antigens that are NOT found on his or her blood cells. In the ABO blood groups, the antibodies develop shortly after birth.

Rh Blood Groups First studied in rhesus monkey
Rh positive (Rh+): Rh antigen 85% of population Rh negative (Rh-): do not have Rh antigen 15% of population The Rh antigen is another antigen on the red blood cells. Most individuals (85%) have the Rh antigen.

Rh Blood Groups Inherited trait
Normally: neither Rh+ nor Rh- individuals have Rh antibodies If Rh- person is exposed to Rh+ blood (through blood transfusion or transfer of blood between a mother and fetus) Individual develops Rh antibodies If exposed to Rh+ blood a second time: Transfusion reaction results Normally individuals do not have Rh antibodies. A person who is Rh+ will not develop Rh antibodies, but a person who is Rh- can develop antibodies if exposed to blood with the Rh antigen. For transfusions, both the ABO and Rh blood groups must be matched. If a transfusion reaction occurs, blood cells are destroyed by the AB and Rh antibodies. This causes clumping of the blood proteins and results in kidney damage due to the large amount of destroyed blood cells. Rhogam is given during pregnancy and right after birth to mothers who are Rh negative if the fetus is Rh positive. It consists of Rh antibodies which neutralize any Rh positive blood that might enter the mother’s circulation. This is done so that the mother will not be stimulated to produce antibodies herself. Before Rhogam, the first child was usually normal, but subsequent children were often at risk if the mother had produced antibodies during a previous pregnancy.

Blood Vessels Channels through which blood is distributed to body tissues Pulmonary vessels: transport blood from right ventricle to lungs and back to left atrium Systemic vessels: carry blood from left ventricle to all parts of the body and then return it to right atrium Where do the pulmonary vessels transport blood from and to? Where do the systemic vessels transport blood from and to?

Blood Vessels Is the blood in the pulmonary artery oxygenated or unoxygenated? Is the blood in the aorta oxygenated or unoxygenated?

Arteries Carry blood away from heart
Pulmonary arteries: transport blood that has a low oxygen content From right ventricle to lungs Systemic arteries: transport oxygenated blood from left ventricle to body tissues Blood is pumped from ventricles into large elastic arteries Branch repeatedly into smaller arteries Branching results in microscopic arteries: arterioles The structure of arteries is different from veins. Arteries branch into smaller and smaller arteries.

Arteries Artery wall Tunica externa: outermost layer
Tunica intima: innermost layer Tunica media: middle layer Consists of smooth muscle Usually the thickest layer Provides support for the vessel Changes vessel diameter – to regulate blood flow and blood pressure Tunica externa: outermost layer What is the innermost layer of the artery wall? What is the middle layer of the artery wall? What is the outer layer of the artery wall? The muscle wall of the tunica media allows arteries and arterioles to dilate and constrict. This helps control blood pressure and blood supply to certain organs.

Capillaries Smallest and most numerous of the blood vessels
Form connection between: Vessels that carry blood away from the heart (arteries) Vessels that return blood to heart (veins) What is the function of capillaries?

Capillaries Capillary wall: consists of a thin endothelium (one cell layer) Permits exchange of materials between: Blood in the capillary Adjacent tissue cells Capillary is so small: erythrocytes must pass through them in single file Slows blood flow Allows time for transport of substances across capillary endothelium What type of tissue forms the capillary wall? Why does the capillary wall consist of only one layer? What substances pass across the capillary endothelium? (Oxygen, carbon dioxide, proteins, glucose, hormones, other chemical substances.)

Veins Carry blood toward heart After blood passes through capillaries:
Enters the smallest veins: venules Flows into progressively larger veins until reaches the heart Blood passes from the capillaries through venules to veins of increasing size.

Veins Vein walls: same three layers as the arteries
Less smooth muscle and connective tissue Makes walls of veins thinner and less rigid than those of arteries Blood in the veins has less pressure than blood in the arteries Veins can hold more blood: holds 70% of the total blood volume Venous valves: located in medium and large veins Keep blood flowing toward heart Are the walls of veins thinner or thicker than arteries? What is the purpose of valves in the large veins?

Circulatory Pathways The blood vessels of the body are functionally divided into two distinct circuits: Pulmonary circuit Systemic circuit What are the two functional circuits of the blood vessels?

Pulmonary Circuit Transports blood from right side of the heart to lungs Then returns it to left side of heart Contains oxygen-poor blood (increased levels of carbon dioxide) Where does blood enter the pulmonary circuit?

Pulmonary Circuit Pathway for pulmonary circuit
Blood is returned to right atrium from the tissue cells of the body Blood passes through tricuspid valve into right ventricle During ventricular systole: blood is ejected through pulmonary SL valve Into pulmonary trunk: divides into right and left pulmonary arteries Each pulmonary artery enters a lung Divides into smaller vessels until they become capillaries Capillaries of the lungs: form networks Surround the air sacs: alveoli What is the pathway for the pulmonary circuit? Where does gas exchange take place?

Pulmonary Circuit Pathway for pulmonary circuit In pulmonary circuit:
CO2 diffuses from capillary blood into alveoli O2 diffuses from alveoli into blood Oxygenated blood enters pulmonary venules Form progressively larger veins until two pulmonary veins emerge from each lung Blood is carried to left atrium In pulmonary circuit: Arteries carry deoxygenated blood away from heart Veins carry oxygenated blood to heart By what process does carbon dioxide move from the capillary blood into the alveoli? By what process does oxygen move from the alveoli into the capillary blood? Where does the oxygenated blood go? What type of blood vessel carries oxygenated blood in the pulmonary circuit? Deoxygenated blood?

Systemic Circuit Provides blood supply to all body tissues
Carries oxygen and nutrients to cells Picks up carbon dioxide and waste products Carries oxygenated blood from left ventricle through the arteries to the capillaries in the tissues From tissue capillaries: deoxygenated blood returns through a system of veins to right atrium What cells are supplied by the systemic circuit? Does the blood in the systemic circuit start out as oxygenated or deoxygenated?

Aging of the Circulatory System
Some cardiac changes can be prevented Closely related to: Diet Exercise Disease process In absence of disease: Heart tends to become smaller Left ventricle Decrease in number and size of cardiac muscles Reduced demand – decreased physical activity Conversely, with cardiovascular disease, the heart is often enlarged.

Thickening of endocardium and valves Valves become more rigid and incompetent Heart murmurs detected Myofibers replaced with fibrous tissue Greater heart rate in response to activity Dysrhythmias are more frequent

Disease processes Arteriosclerosis Hardening of arteries Additional stress Aggravate normal age-related changes Can be prevented with proper diet, regular exercise, and not smoking Lifestyle probably has more effect on the cardiovascular system than aging.

Highlight on Conditions and Procedures Affecting the Circulatory System

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