Download Lab. No 12

Lab. No 12
The circulatory system: heart.
I. Fill in the blanks.
1. When the left ventricle contracts, blood enters the ____________________ .
2. The right side of the heart pumps blood to the ________________________ .
3. The _______________ node is known as the pacemaker.
4. Arteries are blood vessels that take blood ________________ the heart.
5. The blood vessels that serve the heart are the ________________ arteries and veins.
6. The valve between the left atrium and left ventricle is the __________________, or mitral, valve.
7. The chamber of the heart with the thickest myocardium is the ____________________.
8. The phase of heart contraction is called _________________; the phase of relaxation is called
______________.
9. Adjacent cardiac muscle cells are joined end to end at specialized structures known as
___________________,which contain two types of membrane junctions: _______________ and
________________.
10. The circulatory route from aorta to the venae cavae is the _______________ circuit.
11. The pacemaker potential of the SA node cells results from the slow inflow of __________________ .
12. Electrical signals pass quickly from one cardiac myocyte to another through the ________________ of the
intercalated discs.
13. Repolarization of the ventricles produces the __________________ of the electrocardiogram.
14. The ________________ nerves innervate the heart and tend to reduce the heart rate.
15. Blood in the heart chambers is separated from the myocardium by a thin membrane called the
____________________ .
II. Match the following:
(a) indicates ventricular repolarization
(b) represents the time from the beginning of ventricular depolarization to the end of ventricular repolarization
(c) represents atrial depolarization
(d) represents the time when the ventricular contractile fibers are fully depolarized; occurs during the plateau
phase of the action potential
(e) represents the onset of ventricular depolarization
(f ) represents the conduction time from the beginning of atrial excitation to the beginning of ventricular excitation
(1) P wave
(2) QRS complex
(3) T wave
(4) P–Q interval
(5) S–T segment
(6) Q–T interval
III. Match the following:
(a) amount of blood contained in the ventricles at the end of ventricular relaxation
(b) period of time when cardiac muscle fibers are contracting and exerting force but not shortening
(c) amount of blood ejected per beat by each ventricle
(d) amount of blood remaining in the ventricles following ventricular contraction
(e) difference between a person’s maximum cardiac output and cardiac output at rest
(f) period of time when semilunar valves are open and blood flows out of the ventricles
(g) period when all four valves are closed and ventricular blood volume does not change
(1) cardiac reserve
(2) stroke volume
(3) end-diastolic volume (EDV)
(4) isovolumetric relaxation
(5) end-systolic volume (ESV)
(6) ventricular ejection
(7) isovolumetric contraction
IV. Match the following:
(a) collects oxygenated blood from the pulmonary circulation
(b) pumps deoxygenated blood to the lungs for oxygenation
(c) their contraction pulls on and tightens the chordae tendineae, preventing the valve cusps from everting
(d) cardiac muscle tissue
(e) increase blood-holding capacity of the atria
(f ) tendonlike cords connected to the atrioventricular valve cusps which, along with the papillary muscles,
prevent valve eversion
(g) the superficial dense irregular connective tissue covering of the heart
(h) outer layer of the serous pericardium; is fused to the fibrous pericardium
(i) endothelial cells lining the interior of the heart; are continuous with the endothelium of the blood vessels
( j) pumps oxygenated blood to all body cells, except the air sacs of the lungs
(k) prevents backflow of blood from the right ventricle into the right atrium
(l) collects deoxygenated blood from the systemic circulation
(m) left atrioventricular valve
(n) the remnant of the foramen ovale, an opening in the interatrial septum of the fetal heart
(o) blood vessels that pierce the heart muscle and supply blood to the cardiac muscle fibers
(p) grooves on the surface of the heart which delineate the external boundaries between the chambers
(q) prevent backflow of blood from the arteries into the ventricles
(r) the gap junction and desmosome connections between individual cardiac muscle fibers
(s) internal wall dividing the chambers of the heart
(t) separate the upper and lower heart chambers, preventing backflow of blood from the ventricles back into the
atria
(u) inner visceral layer of the pericardium;adheres tightly to the surface of the heart
(v) ridges formed by raised bundles of cardiac muscle fibers
(1) right atrium
(2) right ventricle
(3) left atrium
(4) left ventricle
(5) tricuspid valve
(6) bicuspid (mitral) valve
(7) chordae tendineae
(8) auricles
(9) papillary muscles
(10) trabeculae carneae
(11) fibrous pericardium
(12) parietal pericardium
(13) epicardium
(14) myocardium
(15) endocardium
(16) atrioventricular valves
(17) semilunar valves
(18) intercalated discs
(19) sulci
(20) septum
(21) fossa ovalis
(22) coronary circulation
V. True or false
1. The left ventricle is a stronger pump than the right ventricle because more blood is needed to supply the body
tissues than to supply the lungs.(True or false?)
2. The heart lies in the left half of the thoracic cavity. (True or false?)
3. The only point of electrical contact between the atria and ventricles is the fibrous tissue that surrounds and
supports the heart valves.(True or false?)
4. The atria and ventricles each act as a functional syncytium. (True or false?)
VI. Determine which five of the following statements are false, and briefly explain why.
1. The blood supply to the myocardium is the coronary circulation; everything else is called the systemic circuit.
2. There are no valves at the point where venous blood flows into the atria.
3. No blood can enter the ventricles until the atria contract.
4. The vagus nerves reduce the heart rate but have little effect on the strength of ventricular contraction.
5. A high blood CO2 level and low blood pH stimulate an increase in heart rate.
6. The first heart sound occurs at the time of the P wave of the electrocardiogram.
7. If all nerves to the heart were severed, the heart would instantly stop beating.
8. If the two pulmonary arteries were clamped shut, systemic edema would follow.
9. Ventricular cardiocytes have a stable resting membrane potential but myocytes of the SA node do not.
10. An electrocardiogram is a tracing of the action potential of a cardiocyte.
VII. Circle the correct choice in each instance to complete the statements:
1. During ventricular filling, ventricular pressure must be (greater than/less than) atrial pressure, whereas during
ventricular ejection ventricular pressure must be (greater than/less than) aortic pressure.
2. During isovolumetric ventricular contraction and relaxation,ventricular pressure is (greater than/less than)
atrial pressure and (greater than/less than) aortic pressure.
3. The first heart sound is associated with closing of the(AV/semilunar) valves and signals the onset of
(systole/diastole), whereas the second heart sound is associated with closing of the (AV/semilunar) valves and
signals the onset of (systole/diastole).