cardiovascular system - regulatory mechanisms

Question 1

stroke volume

Answer 1

approx. 70ml

Question 2

cardiac output

Answer 2

approx. 4-7 l/min
(assuming human resting heart rate is 60-100bpm)

Question 3

effects of cardiac output affected by activity

Answer 3

can decrease by 10%
or
can increase by up to 500%

Question 4

inotropy

Answer 4

strength of contraction

Question 5

chronotropy

Answer 5

contraction frequency (tachycardia/bradycardia)

Question 6

tachycardia

Answer 6

increased heart rate

Question 7

braadycardia

Answer 7

decreased heart rate

Question 8

dromotropy

Answer 8

velocity of signal conduction by cardiomyocytes

Question 9

lusitropy

Answer 9

myocardial relaxation

Question 10

bathmotropy

Answer 10

myocardial excitability

Question 11

autonomic innervation

Answer 11

sympathetic: increases rate+force of contractions
parasympathetic: slows heart rate

Question 12

sympathetic regulation

Answer 12

-mostly mediated by b1-adrenergic receptors
-INcreases:
=inotropy
=chronotropy (tachycardia)
=dromotropy
=bathmotropy
=lusitropy

Question 13

parasympathetic regulation

Answer 13

-mediated by M2 muscarinic acetylcholine receptors
-DEcreases
=chronotropy (bradycardia)
=inotropy
=bathmotropy
=dromotropy

Question 14

how is sympathetic nervous activity increased ?

Answer 14

-exercise
-standing up
-stress
-haemorrhage

Question 15

effects of sympathetic stimulation

Answer 15

-ventricular pressure rises more rapidly to a HIGHER systolic pressure
-ejection fraction increased
-diastolic vol. falls
-stroke vol. increases
-duration of systole decreases

Question 16

effect of sympathetic stimulation on pacemaker

Answer 16

-increased slope of pre-potential
-increased size of action potential

Question 17

effects of parasympathetic stimulation on pacemaker

Answer 17

-decreased slope of pre-potential
-initial pacemaker potential becomes slightly more negative