Ch. 20 - Heart Physiology

Question 1

at what period in the cardiac cycle are all 4 valves closed?

Answer 1

isovolumetric ventricular contraction & isovolumetric ventricular relaxation

Question 2

what type of junction connects myocardiocytes?

Answer 2

intercalated discs, gap junctions

Question 3

what connects myocardiocytes to underlying connective tissue?

Answer 3

hemidesmisomes

Question 4

what does depolarization mean?

Answer 4

the cell gets more positive, increase permeability for Na+ (it comes in w + charge)

Question 5

how do cardiac muscles’ action potential differ from skeletal muscles?

Answer 5

cardiac muscles act slower than skeletal bc they must allow full contraction

Question 6

what is spontaneous depolarization? what causes it?

Answer 6

cells can reach threshold without help because of leaky Na+ channels

Question 7

what are the main conducting cells?

Answer 7

pacemaker cells

Question 8

purpose of conducting cells

Answer 8

spread action potential throughout the heart

Question 9

purpose of contractile cells

Answer 9

create force of contraction, respond to conducting cell signals

Question 10

describe impulse conduction pathway through the heart

Answer 10

SA Node 
AV node
atria
inter ventricular septum
purkinje fibers & papillary muscles
ventricular myocardium

Question 11

purpose of SA node, location?

Answer 11

create HR, natural pacemaker. in right atrium

Question 12

purpose and location of purkinje fibers

Answer 12

push blood out, help papillary muscles with contraction, in ventricles

Question 13

purpose and location of AV node

Answer 13

pacemaker activity, delay so atria can fully contract

Question 14

what is more serious, premature ventricular contractions (PVCs) or ventricular fibrillation?

Answer 14

ventricular fibrillation, bc the ventricles are quivering and aren’t pumping enough blood

Question 15

possible causes of premature ventricular contractions (PVCs)

Answer 15

early firing of ectopic focus

stress, lack of sleep, irritation of heart

Question 16

what is ectopic focus?

Answer 16

any part of heart thats doing its own thing

Question 17

which direction do you want impulse to flow?

Answer 17

apex —> base

Question 18

other names for semilunar valves

Answer 18

pulmonary & aortic

Question 19

phases of cardiac cycle

Answer 19

atrial systole
AV valve opens, blood —> ventricles
atrial diastole, AV valve closed
isovolumetric ventricular contraction
end of ventricular systole
semilunar valves closed (isovolumetric relaxation)
AV valve opens, passive atrial filling occurs

Question 20

formula for stroke volume

Answer 20

end diastolic volume - end systolic volume

Question 21

what happens to ventricular volume during passive filling?

Answer 21

increases (because ventricles are filling w blood)

Question 22

what make up walls of ventricles?

Answer 22

papillary muscles, trabeculae carnae, purkenje fibers

Question 23

what is the name of process of listening to the heart

Answer 23

auscultation

Question 24

formula for cardiac output

Answer 24

HR x SV

Question 25

what raises HR?

Answer 25

sympathetic autonomic nervous system, epinephrine (adrenaline)

Question 26

what is stroke volume?

Answer 26

amount of blood pumped out by heart in 1 min

Question 27

what makes the "lubb" "dubb" sound

Answer 27

``` lubb = AV valve closing & semilunars opening dubb = ejection of blood from heart, semilunars closing, AV opens ```

Question 28

what is a heart murmur? are they always pathological?

Answer 28

irregularity of blood flow, not always bad

Question 29

what is cardiac reserve?

Answer 29

resting output - maximal output

Question 30

which branch of autonomic nervous system increases HR?

Answer 30

sympathetic (fight or flight)

Question 31

medulla oblongata role in HR

Answer 31

location of autonomic reflex centers, manipulates HR as needed

Question 32

nerve used to transmit signal through sympathetic nervous system

Answer 32

cardiac nerve

Question 33

nerve used to transmit signal through parasympathetic nervous system

Answer 33

vagus

Question 34

hormone affects on heart

Answer 34

inc HR and contractility

Question 35

what are baroreceptors?

Answer 35

sensory inputs sensitive to pressure (barometer measures pressure)

Question 36

what are chemoreceptors?

Answer 36

sensory inputs sensitive to gases (CO2 & O2)

Question 37

what is barostatic reflex?

Answer 37

dec HR bc of inc BP in head and neck region

Question 38

what is atrial reflex?

Answer 38

inc HR bc of inc venous return (more blood returning to heart through veins)

Question 39

what is preload

Answer 39

tension in ventricular myocardium right before systole

Question 40

what is afterload

Answer 40

BP in aorta & pulmonary trunk, opposes opening of semilunar valves and limits stroke volume

Question 41

what is Frank-Starling Law of the Heart

Answer 41

ventricles will adapt to contract to push out the amount of blood it receives

Question 42

which cells can spontaneous depolarize

Answer 42

conducting cells, pacemaker cells