The Cardiovascular System 3

Question 1

is systole contraction or relaxation

Answer 1

contraction

Question 2

is diastole contraction or relaxation

Answer 2

relaxation

Question 3

is pressure higher during systole or diastole

Answer 3

systole (contraction)

Question 4

what is happening during diastole

Answer 4

all four chambers are relaxed
blood is flowing into the atria then ventricles

Question 5

what is happening during atrial diastole

Answer 5

atria relax, their pressure is low
AV valves start off closed
as atria fill, ventricle pressure becomes lower than atrial pressure
AV valves open allowing blood to flow passively into ventricles (80% of what’s in the ventricles)

Question 6

what is happening during atrial systole

Answer 6

atria depolarize because of SA node
atria contract, their pressure gets higher
blood is forced from atria into ventricles (20-30% of what’s in the ventricles)

Question 7

what is happening during ventricular diastole

Answer 7

ventricles are relaxed, their pressure is low
ventricles being filled passively
AV valves open once ventricular pressure is below atrial pressure

Question 8

what is happening during ventricular systole

Answer 8

ventricles contract, their pressure rises
AV valves close
semilunar valves open when ventricular pressure gets above arterial pressure
blood is ejected from ventricles into pulmonary and systemic circulation

Question 9

define end-diastolic volume (EDV)

Answer 9

volume of blood in each ventricle at end of ventricular diastole (relaxation)
aka: how much blood fills the ventricle before it contracts

Question 10

what is happening during the isovolumetric ventricular contraction phase

Answer 10

ventricles begin to contract after depolarization
AV valves close
ventricular pressure is still less than arterial pressure so semilunar valves are still closed
all valves are closed
blood volume doesn’t change

Question 11

what is happening during the ventricular ejection phase

Answer 11

semilunar valves open
ventricles continue to contract and push blood out the trunks

Question 12

define stroke volume (SV)

Answer 12

amount of blood ejected by ventricles

Question 13

define end systolic volume (ESV) and give its equation

Answer 13

amount of blood remaining in ventricle after contraction
ESV = EDV - SV

Question 14

what is happening during the isovolumetric ventricular relaxation phase

Answer 14

ventricles relax and their pressure drops
semi-lunar valves close
AV valves still closed
all valves closed, no movement of blood

Question 15

what happens if ejected blood volumes between both ventricles are not equal

Answer 15

edema or swelling

Question 16

define cardiac output (CO) and give its equation

Answer 16

amount of blood pumped by a single ventricle in one minute
liters/min
CO = HR x SV

Question 17

define cardiac reserve

Answer 17

difference between cardiac output during exercise and at rest
ex. athletes have higher cardiac reserves

Question 18

define chronotropic agents

Answer 18

substances that change heart rate by altering the activity of SA and/or AV nodal cells

Question 19

what does a positive chronotropic agent do

Answer 19

increase heart rate

Question 20

what does a negative chronotropic agent do

Answer 20

decrease heart rate

Question 21

explain how sympathetic nerve stimulation influences heart rate

Answer 21

sympathetic nerves release norepinephrine onto heart
at the time same, sympathetic simulation causes Arenal gland to release epinephrine and NE
epinephrine and norepinephrine bind to beta-one adrenergic receptors on the AV and SA node
bind activates G-coupled protein pathway ultimately causing phosphorylated calcium channels to enhance calcium influx so the cell fires sooner
increases heart rate

Question 22

how does thyroid hormone influence heart rate

Answer 22

increases amount of beta-one adrenergic receptors
more binding, more firing
increase in heart rate

Question 23

how does caffeine influence heart rate

Answer 23

inhibits breakdown of cAMP
more activated protein kinase, more phosphorylation
increase in heart rate

Question 24

how does nicotine influence heart rate

Answer 24

increases release of norepinephrine
more stimulus, more firing
increase in heart rate

Question 25

how does cocaine influence heart rate

Answer 25

inhibits reuptake of norepinephrine
more opportunities for it to bind
increase in heart rate

Question 26

how does increased parasympathetic activity influence heart rate

Answer 26

parasympathetic outflow is sent from cardiac inhibitory center to SA and AV node using vagus nerve
parasympathetic axons release acetylcholine onto muscarinic receptors on SA and AV node
ACh binds and opens the potassium channels
potassium flows out of cell making it more negative
takes conducting cell longer to reach threshold
lowers heart rate

Question 27

how do beta-blocker drugs influence heart rate

Answer 27

interfere with EPI and NE binding to beta receptors
used to treat high blood pressure

Question 28

how do autonomic reflexes influence heart rate

Answer 28

baroreceptors, chemoreceptors, and proprioceptors send signals to cardiovascular control center in medulla oblongata

Question 29

how does the atrial reflex influence heart rate

Answer 29

aka bainbridge reflex
stops heart from overfilling
increases heart rate if baroreceptors detect too much stretch

Question 30

what are the three factors that influence stroke volume

Answer 30

venous return, inotropic agents, and afterload

Question 31

how does venous return affect stroke volume

Answer 31

directly related to stroke volume
determines preload

Question 32

define venous return

Answer 32

volume of blood returned to the heart

Question 33

define preload

Answer 33

pressure stretching the heart wall before shortening

Question 34

what is the frank-sterling law

Answer 34

as EDV increase, SV increase
more blood in ventricle, more stretch, more overlap of thick and thin filaments, more forceful contraction, more SV

Question 35

what causes venous return rate to decrease

Answer 35

low blood volume
high heart rate

Question 36

how do inotropic agents influence stroke volume

Answer 36

alter contractility
positive: more calcium, higher contractility, increase in stroke volume
negative: less calcium, lower contractility, decrease in stroke volume

Question 37

how does afterload influence stroke volume

Answer 37

afterload and stroke volume are inversely related
can be caused by atherosclerosis

Question 38

define afterload

Answer 38

resistance in arteries to eject blood in ventricles