Integrated cardiovascular function

Question 1

How is CO regulated?

Answer 1

Sympathetic activity to veins: increased venous compliance = increased CVP = increased venous return = increased CO; blood volume: increased CVP = increased venous return = increased CO; skeletal muscle pump: increased CVP = increased venous return = increased CO; inspiration movements: increased venous pressure = increased CO

Question 2

How is total peripheral resistance (TPR) regulated?

Answer 2

Hematocrit; local controls; neural controls; hormonal controls

Question 3

How does hematocrit affect TPR?

Answer 3

Increased hematocrit = increased blood viscosity = increased TPR; doesn’t normally change unless training in high altitude to increase oxygen carrying capacity

Question 4

How do local controls increase TPR?

Answer 4

Vasoconstrictors increase peripheral resistance: internal blood pressure from myogenic response; Endothelin-1

Question 5

How do local controls decrease TPR?

Answer 5

Vasodilators decrease peripheral resistance: decreased O2; increased K+; increased CO2; increased H+; increased osmolality; adenosine; eicosanoids; NO

Question 6

How do neural controls increase TPR?

Answer 6

Increased sympathetic stimulation = vasoconstriction

Question 7

How do neural controls decrease TPR?

Answer 7

Decreased sympathetic stimulation + neurons releasing NO = vasodilation

Question 8

How do hormonal controls increase TPR?

Answer 8

Epi (on alpha adrenergic on tissues not directly involved in exercise) + angiotensin II + vasopressin = vasoconstriction

Question 9

How do hormonal controls decrease TPR?

Answer 9

Epi (on beta-2 adrenergic on skeletal muscles) + atrial natriuretic peptide = vasodilation

Question 10

What detects changes in blood pressure?

Answer 10

Baroreceptors in the carotid bodies and aortic arch

Question 11

How do baroreceptors detect changes in blood pressure?

Answer 11

Are stretch-sensitive

Question 12

How do baroreceptors normalise blood pressure?

Answer 12

Affect HR directly, and SV indirectly, to affect CO ad thus MAP

Question 13

What is the control centre for CV?

Answer 13

Medulla oblongata; is connected to baroreceptors by vagus (to aortic) and glossopharangeal (to carotid) nerves

Question 14

How does the medulla oblongata interpret impulses from baroreceptors?

Answer 14

Rate of impulses in afferent nerves related to pressure (increased impulses = increased MAP)

Question 15

How does the medulla oblongata regulate MAP?

Answer 15

Increased MAP: decreased sympathetic to heart, arterioles, veins; increased parasympathetic to heart; = decreased HR + decreased SV = decreased CO = decrease MAP to normal

Question 16

How does the CV system compensate for increased blood volume/pressure?

Answer 16

Vasodilation and decreased CO

Question 17

How do the kidneys compensate for increased blood volume/pressure?

Answer 17

Excretion of fluid in urine to decrease blood volume

Question 18

How do the kidneys compensate for decreased blood volume/pressure?

Answer 18

Baroreceptors in kidneys detect; increase secretion of renin; angiotensin II is released: aldosterone released by adrenal cortex ( = increased water absorption at kidneys) + vasoconstricts vessels

Question 19

How does the CV system compensate for decreased blood volume/pressure?

Answer 19

Baroreceptors in carotid bodies and aortic arch detect; pituitary gland releases ADH: vasoconstriction + increased water absorption at kidneys; sympathetic output decreased: Epi released from adrenal medulla = vasoconstriction + increased HR

Question 20

What occurs during the orthostatic baroreceptor reflex?

Answer 20

In tilt position w/ no muscular contraction in legs: HR increases to maintain CO as blood pressure decreases transiently; SV decreases w/ influence of sympathetic as blood pools in legs from gravity; TPR increased due to increased sympathetic stimulation; blood pressure has transient drop

Question 21

What is the valsalva maneouvre?

Answer 21

Forced expiration with closed glottis

Question 22

What are examples of when the valsalva maneouvre might occur?

Answer 22

When coughing, lifting heavy weights, and playing brass

Question 23

What occurs during the valsalva maneouvre?

Answer 23

Intrathoracic pressure increases dramatically; heart mechanically squeezed; blood pressure increases; HR plummets to compensate for high blood pressure; blood pressure decreases again; HR peaks to increase CO. Release of pressure around heart mechanically releases heart; blood pressure decreases transiently

Question 24

During exercise, where does blood flow increase?

Answer 24

Skeletal muscle, skin, heart

Question 25

During exercise, where does blood flow decrease?

Answer 25

Kidneys, digestive tracts, all other parts of body not directly involved in exercise

Question 26

During exercise, where does blood flow remain constant?

Answer 26

Brain, due to autoregulation and the fixed volume of the cranial cavity being unable to accommodate large increases in blood flow

Question 27

During exercise, where does peripheral resistance decrease?

Answer 27

Muscle, heart, and skin

Question 28

During exercise, where does peripheral resistance increase?

Answer 28

Everywhere that isn’t directly involved in PA

Question 29

What is the net effect on TPR during exercise?

Answer 29

Decreased TPR (vasodilation > vasoconstriction)

Question 30

How does CO differ between trained and untrained individuals?

Answer 30

CO greater in trained

Question 31

How does HRmax differ between trained and untrained individuals?

Answer 31

Little difference - HRmax mainly determined by age; trained people have a lower HR for a given workload

Question 32

How does SV differ between trained and untrained individuals?

Answer 32

SV greater in trained