Integrated cardiovascular function Flashcards Preview

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Flashcards in Integrated cardiovascular function Deck (32)
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1
Q

How is CO regulated?

A

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

2
Q

How is total peripheral resistance (TPR) regulated?

A

Hematocrit; local controls; neural controls; hormonal controls

3
Q

How does hematocrit affect TPR?

A

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

4
Q

How do local controls increase TPR?

A

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

5
Q

How do local controls decrease TPR?

A

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

6
Q

How do neural controls increase TPR?

A

Increased sympathetic stimulation = vasoconstriction

7
Q

How do neural controls decrease TPR?

A

Decreased sympathetic stimulation + neurons releasing NO = vasodilation

8
Q

How do hormonal controls increase TPR?

A

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

9
Q

How do hormonal controls decrease TPR?

A

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

10
Q

What detects changes in blood pressure?

A

Baroreceptors in the carotid bodies and aortic arch

11
Q

How do baroreceptors detect changes in blood pressure?

A

Are stretch-sensitive

12
Q

How do baroreceptors normalise blood pressure?

A

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

13
Q

What is the control centre for CV?

A

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

14
Q

How does the medulla oblongata interpret impulses from baroreceptors?

A

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

15
Q

How does the medulla oblongata regulate MAP?

A

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

16
Q

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

A

Vasodilation and decreased CO

17
Q

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

A

Excretion of fluid in urine to decrease blood volume

18
Q

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

A

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

19
Q

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

A

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

20
Q

What occurs during the orthostatic baroreceptor reflex?

A

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

21
Q

What is the valsalva maneouvre?

A

Forced expiration with closed glottis

22
Q

What are examples of when the valsalva maneouvre might occur?

A

When coughing, lifting heavy weights, and playing brass

23
Q

What occurs during the valsalva maneouvre?

A

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

24
Q

During exercise, where does blood flow increase?

A

Skeletal muscle, skin, heart

25
Q

During exercise, where does blood flow decrease?

A

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

26
Q

During exercise, where does blood flow remain constant?

A

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

27
Q

During exercise, where does peripheral resistance decrease?

A

Muscle, heart, and skin

28
Q

During exercise, where does peripheral resistance increase?

A

Everywhere that isn’t directly involved in PA

29
Q

What is the net effect on TPR during exercise?

A

Decreased TPR (vasodilation > vasoconstriction)

30
Q

How does CO differ between trained and untrained individuals?

A

CO greater in trained

31
Q

How does HRmax differ between trained and untrained individuals?

A

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

32
Q

How does SV differ between trained and untrained individuals?

A

SV greater in trained