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Home , Tricuspid valve

20. Anatomy of the

Answers to Pre- Lab Assignments Pre-Lab Activity 1: 1. a b. c. d. right e. tricuspid valve f. right g. pulmonary trunk h. left atrium i. j. mitral (bicuspid) valve k. left ventricle

2. a. 6 b. 1 c. 5 d. 7 e. 9 f. 2 g. 4 h. 8 i. 3

Pre-Lab Activity 2: 1. apex inferior to base; large vessels arise from base 2. epicardium (circled), myocardium, 3. coronal (frontal)

Pre-Lab Activity 3: 1. a – fibers b – striations c – intercalated disc d – nucleus 2. b

Pre-Lab Activity 4: 1. d 2. b 3. c Answers to Activity Questions Activity 1

Making Connections: Heart Anatomy

Structure Description (Structure and/or Function) Connections to Things I Have Already Learned

Epicardium Outer layer of heart wall Also called visceral , the innermost layer of the serous pericardium

Myocardium Middle layer of heart wall; predominantly cardiac “myo” = muscle muscle tissue myoglobin, myofilament

Endocardium Inner layer of the heart wall Other terms with “endo” prefix: endomysium, en- doneurium, endothelium

Right atrium Thin-walled receiving chamber that receives Contains SA node (pacemaker). from the superior vena cava, inferior vena cava, and coronary sinus

Right ventricle Pumps deoxygenated blood to lungs via the pulmo- Separated from left ventricle by interventricular nary trunk. septum.

Left atrium Receives oxygenated blood from the pulmonary An atrium is an entry chamber. veins.

Left ventricle Pumps oxygenated blood to the body via the aorta. Supplied by anterior and posterior interventricular arteries.

Tricuspid valve Prevents backflow of blood from the right ventricle Also called right atrioventricular valve. to the right atrium.

Mitral (bicuspid) Prevents backflow of blood from the left ventricle to Also called left atrioventricular valve. valve the left atrium.

Pulmonary trunk Transports deoxygenated blood from the right ven- A trunk is a blood vessel that gives rise to other tricle to the lungs. blood vessels.

Pulmonary valve Prevents backflow of blood from the pulmonary Opens when right ventricular pressure exceeds trunk to the right ventricle. pressure in pulmonary trunk.

Aorta Transports oxygenated blood from the left ventricle Descending aorta is divided into thoracic aorta • Ascending to the body. (above diaphragm) and abdominal aorta (below aorta diaphragm). • Aortic arch • Descending aorta

Aortic valve Prevents backflow of blood from the aorta to left Opens when left ventricular pressure exceeds pres- ventricle. sure in aorta.

Chordae tendineae Anchor atrioventricular valves to papillary muscles Literally means “heart strings.” of heart wall. Contracts to prevent AV valves from inverting. Three in the right ventricle and two in the left ven- tricle; attach to cusps of AV valves.

Coronary sinus Collects venous blood from cardiac veins and returns A sinus is an enlarged vein. Superior sagittal sinus it to the right atrium. collects venous blood in brain.

Inferior vena cava Large vein that receives deoxygenated blood from Right and left common iliac veins fuse to form it. the lower body and returns it to the right atrium

Superior vena cava Large vein that receives deoxygenated blood from Right and left brachiocephalic veins fuse to form it. the upper body and returns it to the right atrium

Pulmonary veins Return oxygenated blood from the lungs to the left Exception to the rule that veins carry deoxygenat- atrium. ed blood.

Fossa ovalis Depression in ; remnant of the fo- Fossa = depression; ovalis = oval shaped; foramen ramen ovale ovale shunts blood from right atrium to left atrium in fetus.

Ligamentum arte- Band of fibrous connective tissue between pulmo- Ductus arteriosus shunts blood from pulmonary riosum nary trunk and aorta; remnant of the ductus arterio- trunk to aorta in fetus. sus.

Activity 2 A. External Anatomy 3. a. Aorta carries oxygenated blood from the LV to all parts of the body. b. Pulmonary trunk carries deoxygenated blood from RV to lungs. c. Superior vena cava returns deoxygenated blood to RA. d. Inferior vena cava returns deoxygenated blood to RA. e. Pulmonary veins return oxygenated blood from the lungs to the LA. f. Ventricles are thick-walled pumping chambers. g. Atria are thin-walled receiving chambers. How do the locations of the superior and inferior in a sheep heart differ from those of the human heart? In the sheep, they project ante- riorly and posteriorly instead of superiorly and inferiorly. 4. Predict the function of the anterior interventricular ar- tery. Supplies the ventricles with blood Predict the function of the cardiac vein. Collects venous blood from ventricles. B. Internal Anatomy 2. a. Epicardium produces serous fluid. b. Myocardium contracts to pump blood. c. Endocardium provides smooth surface for blood flow. d. separates left and right ventricles. e. Tricuspid valve prevents backflow of blood from RV to RA. f. Bicuspid valve prevents backflow of blood from LV to LA. g. Pulmonary valve prevents backflow of blood from pulmonary trunk to RV. h. Aortic valve prevents backflow of blood from aorta to LV i. anchor valve to ventricular wall. j. Papillary muscles contract to prevent inversion of valve. Compare and contrast the structure of the tricuspid and bicuspid valves. Tricuspid contains three cusps (flaps), whereas bicuspid contains two cusps. Compare and contrast the structure of the right and left ventricles. Left ven- tricular wall is much thicker due to function of pumping blood to all parts of the body.

Activity 3 1. Cardiac muscle tissue makes up the bulk of which heart wall layer? myocardium Describe the appearance of cardiac muscle fibers. short, branched cells; uninucleate; striated; intercalated discs 2. a. Gap junctions—allow communication among cardiac muscle fibers; ions able to move from one cell to another. b. Desmosomes—anchor cells together so that they do not tear apart during contraction. 3. Both are striated, both are packed with actin and myosin. 4. Skeletal muscle is under voluntary control; cardiac muscle is under involuntary control. Skeletal muscle fibers are long, cylindrical, and mul- tinucleate; cardiac muscle fibers are short, branched, and uninucleate.

Activity 4 No questions

Answers to POST- Lab ASSIGNMENTS

PART I. Check Your Understanding Activity 1: Examining the Functional Anatomy of the Heart 1. Identify the components of the heart. a. superior vena cava b. right atrium c. tricuspid valve d. right ventricle e. interventricular septum f. aorta g. pulmonary trunk h. pulmonary valve i. pulmonary veins j. aortic arch k. bicuspid valve l. left ventricle

2. Which heart structure(s): chordae tendineae a. anchor atrioventricular valves to the heart wall? pulmonary veins b. receive oxygenated blood from the lungs? interventricular septum c. separates the right and left ventricles? right ventricle d. pumps blood to the lungs? right atrium e. receives blood from the coronary sinus? bicuspid valve f. prevents backflow of blood into the left ventri- cle? g. is a remnant of the foramen ovale? tricuspid valve h. prevents backflow of blood into the right atri- um?

Activity 2: Dissecting a Mammalian Heart 1. Identify the components of the sheep heart. a. aorta b. right atrium c. tricuspid valve d. right ventricle e. left atrium f. bicuspid valve g. left ventricle h. interventricular septum i. epicardium j. myocardium k. endocardium

Activity 3: Reviewing the Microscopic Structure of Cardiac Muscle Tissue 1. Describe the appearance of a cardiac muscle fi- ber. uninucleate, striated, short, branched ______2. What causes the striations in these cells? arrangement of ac- tin and myosin______3. What are two functions of an intercalated disc? anchor cells (desmosomes) and allow •communication between cells (gap junc- tions) ______

Activity 4: Tracing Circulatory Pathways 1. Trace the pathway of blood from the heart (left ventricle) to the right adrenal gland and back to the left ventricle → ascending aorta → aortic arch → thoracic aorta → abdominal aorta → right suprarenal artery → right adrenal gland → right su- prarenal vein → inferior vena cava → right atrium»heart (right atrium). ______2. List the structures of the coronary pathway serving the anteri- or ventricular wall in order, beginning in the left ventricle and ending in the right atrium. left ventricle → ascending aorta → left coronary artery → ante- rior interventricular artery → anterior interventricular wall → great cardiac vein → coronary sinus → right atrium ______3. Identify the events of the pulmonary and systemic circulations in the accompanying illustration. Color blood vessels containing oxygenated blood red, color blood vessels containing deoxygenated blood blue, and color capillary beds purple. a. Materials are exchanged at •capillary beds. ______b. Deoxygenated blood enters right atrium. ______c. Deoxygenated blood flows through tricuspid valve to RV. ______d. RV pumps blood through pulmonary valve to pulmonary trunk. ______e. Gas exchange occurs in the lungs. ______f. Oxygenated blood enters LA via the pulmonary veins. ______g. Oxygenated blood flows through •bicuspid valve to LV. ______h. LV pumps oxygenated blood through aortic valve into aorta. ______i. Aorta delivers blood to the body.

PART II. Putting It All Together A. Review Questions Answer the following questions using your lecture notes, your textbook, and your lab notes. 1. Complete the following table.

Valve Location When Does the Valve Open?

Aortic aorta when ventricular pressure exceeds pres- valve sure in the aorta

Bicuspid between left when atrial pressure exceeds ventricular valve atrium and left pressure ventricle Pulmonary pulmonary when ventricular pressure exceeds pres- valve trunk sure in the pulmonary trunk

2. The fetal structure foramen ovale shunts blood from the right atrium to the left atrium. Its adult remnant is the fossa ovalis _. 3. The fetal structure ductus arteriosus shunts blood from the pulmonary trunk to the aorta. Its adult remnant is the ligament arterio- sum______. 4. Are all cardiac muscle fibers contractile? Explain. No, 1% are part of the intrinsic conduction system and do not con- tract.______5. What is a ? Why is the anterior interven- tricular artery called the “widow- maker”? blockage of a coronary artery (heart attack); blockage in this major artery often results in death______