cardiovascular physiology

Question 1

where does 50% of the blood go at rest?

Answer 1

kidneys and liver

Question 2

what happens if cardiac demand goes up

Answer 2

cardiac output increases, blood to skeletal muscle (~60%)

Question 3

what’s pericarditis

Answer 3

inflammation of the pericardium - fluid accumulation in pericardial cavity

may restrict heart movement and filling

Question 4

when does coronary flow occur?

Answer 4

primarily in diastole

Question 5

what’s the purpose of the heart valves

Answer 5

prevent back flow of blood

Question 6

what makes the valves open?

Answer 6

pressure changes

Question 7

where are papillary muscles found?

Answer 7

only in the ventricles

Question 8

when are the pulmonary and aortic valves open?

Answer 8

open in systole

Question 9

when are AV valves open?

Answer 9

open in diastolic

Question 10

when are AV valves open and when are they closed?

Answer 10

diastole; systole

Question 11

when are the pulmonary and aortic valves open and when are they closed?

Answer 11

systole; diastole

Question 12

aspects of cardiac muscles - intercalated disks

Answer 12

desmosomes - to withstand stress
gap junction - ion movement, electrical impulses

Question 13

what are the two types of myocardial cells?

Answer 13

• autorhythmic cells
• contractile cells

Question 14

describe the Autorhythmic Cells

Answer 14

Generates and spreads action potentials
Pacemaker cells
Conducting cells
- initiate impulses if given enough time

Question 15

describe the contractile cells

Answer 15

99% of cardiac cells
Mechanical work of
contraction

Question 16

heart muscle electrical excitation

Answer 16

pacemaker cells
- Na+ influx
- Ca++ influx
- K+ efflux

Question 17

what’s slow depolarization

Answer 17

Na+ leaks into cell, K+ leaks in the second half as well

Question 18

what does K+ do?

Answer 18

it always leaves and repolarizes

Question 19

what are extrasystoles?

Answer 19

extra beats by purkinje fibres

Question 20

what’s the pacemaker potential?

Answer 20

the electrical change/rise in membrane potential that leads to an AP in SA node

Question 21

key aspect about myocardial contractile cells?

Answer 21

they have long refractory periods in cardiac muscle (lasts almost as long as the entire muscle twitch)

Question 22

what are some benefits of long refractory periods?

Answer 22

prevents tetanus, helps maintain regular heart beat, allows for relaxation and diastolic filling

Question 23

how does the NS regulate heart rate?

Answer 23

if pacemaker cells are more depolarized –> can reach threshold faster = faster HR

if pacemaker cells are hyperpolarized it takes longer to reach threshold = slow HR

Question 24

heart’s conduction sysem

Answer 24

SA node, internodal pathway, AV node, right and left branch of bundle of HIS, purkinje fibres

Question 25

what are the three major waves of an ECG?

Answer 25

P wave, QRS complex, T wave

Question 26

what happens in the P wave and what does it normally look like?

Answer 26

represents atrial depolarization, initiates atrial contraction, is usually smooth and rounded

Question 27

what happens in the QRS complex and what does it normally look like?

Answer 27

represents ventricular depolarization and atrial repolarization, initiates ventricular contraction Q- first downward deflection R- upward deflection S- downward deflection

Question 28

what happens in the T wave and what does it normally look like?

Answer 28

ventricular repolarization, initiates ventricular relaxation, usually rounded and upright

Question 29

what are the segments and intervals?

Answer 29

PR interval, QT interval, PR segment, ST segment