Lecture Quiz 6

Question 1

Where is the heart located?

Answer 1

in the mediastinum
superior to the diaphragm
anterior to the vertebral column
posterior to the sternum
left to the midline

Question 2

What is the pericardium?

Answer 2

a double walled sac around the heart

composed of a superficial fibrous pericardium and deep two-layer serous pericardium

Question 3

What is the parietal layer?

Answer 3

pericardium

lines the internal surface of the fibrous pericardium

Question 4

What is the visceral layer of the pericardium?

Answer 4

epicardium

lines the surface of the heart

Question 5

How are the layers of the pericardium separated?

Answer 5

a fluid-filled pericardial cavity

Question 6

What does the pericardium do?

Answer 6

protects and anchors the heart
prevents overfilling of the heart with blood
allows the heart to work in a friction-free environment

Question 7

What are the layers of the heart wall?

Answer 7

epicardium
myocardium
endocardium

Question 8

What is the epicardium?

Answer 8

visceral layer of the serous pericardium

Question 9

What is the myocardium?

Answer 9

cardiac muscle layer forming the bulk of the heart

Question 10

What is the endocardium?

Answer 10

endothelial layer of the inner myocardial surface

Question 11

What are the atria?

Answer 11

the receiving chambers of the heart

each atrium has a protruding auricle

Question 12

What are the pectinate muscles?

Answer 12

mark atrial walls

help atria contract more efficiently

Question 13

What are the ventricles?

Answer 13

the discharging chambers of the heart

Question 14

What are the papillary muscles?

Answer 14

line ventricular walls

prevent blood flowing back into atria

Question 15

What are the trabeculae carnae muscles?

Answer 15

mark ventricular walls

make contraction more efficient

Question 16

What difference do you find between the right and left ventricle?

Answer 16

both hold the same volume of blood, but the left ventricular wall is thicker

Question 17

Of the four chambers, how do they relate in chamber size?

Answer 17

atria are smaller than the ventricles

right side = left side

Question 18

Of the four chambers, how do they differ in wall thickness?

Answer 18

atria < ventricles

right ventricle < left ventricle

Question 19

What percentage do the atria account for blood pumped?

Answer 19

at rest, 5%

exercise, 40%

Question 20

What are the atrioventricular valves of the heart (general)?

Answer 20

valves between the atria and ventricles

prevent backflow into the atria when the ventricles contract

Question 21

What are the chordae tendineae?

Answer 21

anchor atriventricular valves to papillary muscles

Question 22

What is the mitral (bicuspid) valve?

Answer 22

AV valve between left atrium and left ventricle

Question 23

What is the tricuspid valve?

Answer 23

AV valve found between the right atrium and right ventricle

Question 24

What are the semilunar valves?

Answer 24

lie between the ventricle and the aorta

prevent the backflow of blood into the ventricles

Question 25

What is the aortic valve?

Answer 25

semilunar valve leading from the left ventricle into the aorta

Question 26

What is the pulmonary valve?

Answer 26

lies between the right ventricle and the pulmonary trunk

Question 27

What are arteries?

Answer 27

vessels that take blood away from the heart

Question 28

What are veins?

Answer 28

vessels that return vlood to the heart

Question 29

Where does oxygenation of blood occur?

Answer 29

varies in arteries and veins

Question 30

What does pulmonary circulation do?

Answer 30

enriches the blood with oxygen and removes excessive carbon dioxide

Question 31

Describe the pathway of the pulmonary circulation

Answer 31

blood enters right ventricle through tricuspid valve passes through pulmonary valve to pulmonary trunk splits into left and right pulmonary arteries travels through capillaries of the lungs for gas exchange right and left pulmonary veins return blood to left atrium

Question 32

What does systemic circulation do?

Answer 32

carries oxygenated blood to the entire body

Question 33

Describe the pathway of systemic circulation

Answer 33

blood passes through mitral valve into left ventricle travels through aortic valve into aorta and its branches capillaries in peripheral tissues allow gas exchange blood is returned to the right atrium through the superior and inferior venae cavae and the coronary sinus

Question 34

What are cardiomyocytes?

Answer 34

large, branched cells single central nucleus striated heavily vascularized

Question 35

What do intercalated discs of cardiac cells do?

Answer 35

connect cardiomyocytes allow free passage of ions between the cells allows heart muscle to contract simultaneously as a functional system

Question 36

How is the heart stimulated and what is that known as?

Answer 36

by nerves also self-excitable this is known as automaticity

Question 37

What are the two types of cardiomyocytes?

Answer 37

contractile cells | pacemaker cells

Question 38

What happens during phase 0 of action potential in contractile cardiomyocytes?

Answer 38

slow sodium channels leak until the muscle reaches the threshold of the fast sodium channels sodium ions rush in until the membrane polarity is reversed

Question 39

What happens during phase 1 of action potential in contractile cardiomyocytes?

Answer 39

polarity reversal causes the fast sodium channels to snap shut and the potassium channels to open this causes the membrane potential to start to become more negative

Question 40

What happens during phase 2 of action potential in contractile cardiomyocytes?

Answer 40

plateau potassium ions continue leaking out calcium channels open and positively charged calcium ions leak in, cancelling the effect of potassium ions leaking out no net change for 100 milliseconds calcium ions are used to form cross bridges excitation-contraction coupling: calcium ions cause the plateau phase and bind to troponin and initiate cross bridge formation

Question 41

What happens during phase 3 of action potential in contractile cardiomyocytes?

Answer 41

repolarization calcium ions quit leaking in passage of potassium ions out of the cell causes a return to the resting membrane potential

Question 42

What happens during phase 4 of action potential in contractile cardiomyocytes?

Answer 42

resting potential | the only activity during this phase is the constant leakage of the slow sodium channels

Question 43

What is unique about the refractory period in cardiomyocytes?

Answer 43

it is very long ~250 msec | premature stimulation does not cause tetanus for this reason