Chapter 16

Question 1

what is the myogenic response? **

Answer 1

a reflex constriction of smooth muscle after an increase of vascular pressure

OR

a dilation of smooth muscle after a decrease of vascular pressure

Question 2

what is another name for the sinoatrial (SA) node?

Answer 2

heart’s pacemaker

Question 3

why is there a delay that occurs is sending impulses? *

Answer 3

a 0.10 s delay occurs to allow atria to contract and propel blood into ventricles

Question 4

is parasympathetic or sympathetic transmission faster at rest? what is the benefit of having faster transmission?

Answer 4

parasympathetic

has greater influence on variability because it can communicate faster

Question 5

what influences heart rate and variability between heart beats?

Answer 5

the parasympathetic nervous system since acetyl coline has faster transmission than epinephrine and norepinephrine

Question 6

what is the function of the AV bundle (bundle of His)?

Answer 6

transmits impulse to the purkinje system that penetrates the right and left ventricles

Question 7

how is the heart’s output of blood and the blood’s distribution regulated?

Answer 7

input from the brain (desire/anticipation) and the peripheral nervous system (meta/mechano-reflex) send signals to the control centre in the ventrolateral medulla

Question 8

what are baroreceptors? how do they function?

Answer 8

stretch receptors in the arteriole walls

when there is a large stretch, a lot of pressure, baroreceptors signal to delay the next heart beat to reduce the pressure

Question 9

what does the mechanic reflex control?

Answer 9

force and tension

Question 10

what are chronotropic effects? *

Answer 10

rate and rhythm of the heart

effects electrical conduction

Question 11

what are inotropic effects? *

Answer 11

force of contraction

Question 12

when the sympathetic cardioaccelerator nerves are stimulated, what hormones are released?

Answer 12

epinephrine and norepinephrine

Question 13

how does heart rate increase at start and during low/moderate intensity exercise? give an example *

Answer 13

inhibition of parasympathetic stimulation

example) anticipation

Question 14

how does heart rate increase during strenuous exercise? give an example *

Answer 14

additional parasympathetic inhibition

direct activation of sympathetic cardioaccelerator nerves

example) peripheral afferent feedback

Question 15

how does bradycardia happen?

Answer 15

stimulation of vagus nerve from medulla’s cardioinhibitory centre

Question 16

what is the function of acetylcholine?

Answer 16

delays the rate of sinus discharge to slow heart rate (depolarization)

Question 17

which nervous system do endurance runners want to be using?

Answer 17

their vagus/parasympathetic nervous system so they don’t get tired

Question 18

what has the greatest control over heart rate from rest to moderate exercise?

Answer 18

central command system

Question 19

does emotional state affect heart rate and blood pressure values? *

Answer 19

central command in cardiovascular regulation explains how emotional state can affect cardiovascular response making it difficult to obtain “true” resting values for heart rate and blood pressure

Question 20

what are 3 mechanisms that can assess the nature and intensity of exercise and muscle mass activated?

Answer 20

1. reflex neural input, size and strength of contraction
2. chemical stimulation (CO2 and acidity in muscled)
3. feed-forward outflow (DESIRE)

Question 21

where are baroreceptors located? why?

Answer 21

aortic arch to assess how the heart is doing because blood is going directly to there

carotid sinus because it leads blood to the brain

Question 22

what are 2 factors that relate to the volume of flow in a blood vessel?

Answer 22

1. directly to pressure gradient between two ends of the vessels
2. inversely to resistance encountered to fluid flow

Question 23

what is a stimulus for angiogenesis? *

Answer 23

friction between blood and internal vascular wall creating resistance that affects blood flow

Question 24

what are 3 factors that determine blood resistance? *

Answer 24

1. blood thickness
2. length of conducting tube
3. blood vessel radius

Question 25

what are 2 factors that contribute to reduced blood flow to non-active tissues?

Answer 25

1. increases sympathetic nervous system outflow (fight or flight)
2. local chemicals that stimulate vasoconstriction or enhance effects of vasoconstrictors

Question 26

what are 3 things that happen when dormant capillaries open during exercise?

Answer 26

1. increase in total muscle blood flow (increasing O2 and glucose)
2. large blood volume is delivered with minimal increase in blood flow velocity
3. increases effective surface for gas and nutrient exchange

Question 27

what is the function of nitric oxide?

Answer 27

dilates blood vessels and decreases vascular resistance

Question 28

what stimulates nitric oxide synthesis?

Answer 28

stimuli from chemicals, sheering stress and vessel stretch from increased blood flow through the vessel lumen

Question 29

what are limitations to exercise for cardiac transplant patients?

Answer 29

adaptations have no meaningful effect on sub maximal or peak VO2