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CARDIO > Integration of Cardiovascular Mechanism > Flashcards

Integration of Cardiovascular Mechanism Flashcards

1
Q

what is the function of capillaries

A

Site of gas, nutrient and water between blood and tissues

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2
Q

what is the function of veins

A

capacitance vessels containing most blood volume at rest

venous return must supply heart with sufficient blood to pump

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3
Q

what is the main regulator of HR

A

autonomic nervous system

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4
Q

what us the main regulator of Systemic vascular resistance

A

arterioles (vascular smooth muscle)

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5
Q

what effect does vasoconstriction have on SVR and MAP

A

increases SVR and MAP

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6
Q

what effect does vasodilation have on SVR and MAP

A

decreases SVR and MAP

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7
Q

what is resistance to blood flow directionally proportional to

A

blood viscosity and length of blood vessel

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8
Q

what is resistance to blood flow inversely proportional to

A

radius of the blood vessels

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9
Q

what is the most important faction in influencing resistnace/controlling vascular smooth muscle

A

changes in radius of arterioles

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10
Q

when there is a small decrease in the radius what effect is there on resistane

A

huge increase in resistance

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11
Q

what 2 extrinsic mechanisms control vascular smooth muscle

A

nerves and hormones

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12
Q

what nerves supply vascular smooth muscle

A

sympathetic nerve fibres ONLY (except brain)

baroreceptor reflex

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13
Q

what is the neurotransmitter of the sympathetic nerve fibres acting on vascular smooth muscle

A

noradrenaline

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14
Q

what is vasomotor tone and how does it affect SVR

A

blood vessels are always partially contracted at rest because of tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline

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15
Q

what effect on vasomotor done does increasing sympathetic discharge have

A

increased vasomotor tone

VASOCONSTRICTION

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16
Q

what effect on vasomotor done does decreasing sympathetic discharge have

A

decreased vasomotor tone

VASODILATION

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17
Q

is there any parasympathetic activity of arterial smooth muscle

A

no only in penis and clitoris

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18
Q

what is the main hormone responsible for control of vascular smooth muscle control

A

Adrenaline

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19
Q

what receptors does adrenaline act on in vascular smooth muscle

A

A receptors in skin, gut and kidneys

B2 receptors in cardiac muscle and skeletal muscle

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20
Q

what effect does adrenaline have on a receptors

A

induces vasoconstriction of skin, gut, kidneys

21
Q

what effect does adrenenline have on B2 receptors

A

vasodilation of cardiac and skeletal muscle

22
Q

what hormone is resposnive for strategic redistribution of blood in exercise

A

Adrenaline

23
Q

what other hormones are responsive for the intermediate control of blood pressure and induce vasoconstriction of arterioles

A

Angiotensin II

ADH (vasopressin)

24
Q

how does the intrinsic mechanism control systemic vascular resistance and therefore MAP

A

Local Metabolites can OVER-RIDE extrinsic control

Local control aims to satisfy immediate demands of specific tissue eg. skeletal muscle and heart in exercise

25
Q

give 2 examples of local controls that are responsible for the intrinsic control of SVR

A

chemical factors and physical factors

26
Q

under what circumstances would local metabolites induce vasodilation and metabolic hyperaemia

A 
Decreased local PO2
Increased PCO2
Increased  local [H+] decreasesd pH
Increased extracellular [K+]
Increases osmolarity of ECF
Adenosine release from ATP
27
Q

what are released in response to tissue injury and inflammation to induce vasodilation to increase blood flow and oxygen to an area

A

local humoral agents eg. Histamine, Bradykinin, Nitric Oxide

28
Q

where is nitric oxide released from

A

continuous release by endothelial cells of arteries and arterioles

29
Q

how is nitric oxide formed

A

from amino acid L-argenine by Nitric Oxide from Synthase (NOS) - an enzyme when FLOW DEPENDANT FORMATION: (increased flow - sheer stress on vascular endothelium causing release of Ca in endothelial cells
RECEPTOR STIMULATED FORMATION: activation of NOS or by chemical stimuli

30
Q

what triggers NO to diffuse from vascular endothelium into adjacent smooth muscle to induce vasodilation

A

when cGMP is activated. signalling for smooth muscle relaxation

31
Q

why is the endothelium so important

A

maintains vascular health

32
Q

what happens when there is damage to the endothelium

A

high BP
high cholesterol
diabetes

33
Q

name 3 endothelial produced vasodilators

A

o Anti-thrombactic
o Anti-inflammatory
o Anti-oxidants

34
Q

name 3 endothelial produced vasoconstrictors

A

o Pro-thrombatic
o Pro-inflammatory
o Pro-oxidants

35
Q

name 3 physical factors affecting systemic vascular resistance

A

temperature
myogenic response to stretch in Brain and kidneys
sheer stress

36
Q

where does the myogenic response only occur

A

in brain and kindeys

37
Q

how does the myogenic response correct a rise in MAP

A

resistance vessels either in brain or kidneys constrict to limit the flow to prevent too much blood going to that area and causing swelling

38
Q

how does the myogenic response correct a fall in MAP

A

resistance vessels either in brain or kidneys dilate to increase blood flow to that area to ensure adequate perfusion

39
Q

how does sheer stress increase blood flow to metabolically active tissue

A

Dilation of arterioles causes sheer stress in arteries upstream causing dilation

40
Q

give 5 factors that increase venous return

A 
increased venomotor tone
increased skeletal pump
increased respiratory pump
increased atrial pressure
increased blood volume
41
Q

how does increased venomotor tone increase venous return

A

venous smooth muscle supplied with sympathetic fibres and stimulation causes venous constricition increasing blood to the RA
therefore increasing venomotor tone increases venous return, SV and MAP

42
Q

what contains most of the blood at rest

A

veins

43
Q

how does increasing the skeletal pump increase venous return

A

contraction of muscles aids venous return as blood is pushed towards the heart
valves ensure unidirectional
muscle activity increases venous return

44
Q

how does increasing the respiratory pump increase venous return

A

inspiration, intra-thoracic pressure decreases and intra-abdominal pressure increases pressure gradient for venous return and creates suction moving blood from veins to heart
increasing rate and depth increases venous return to heart

45
Q

how does increasing atrial pressure increase venous return

A

it increases EDV so increased SV (Starling Curve)

46
Q

how does the cardiovascular system respond acutely to exercise

A

Increased CO increases systolic BP
sympathetic vasomotor nerves reduce flow to kidneys and gut by vasoconstriction
skeletal and cardiac muscle hyperaemia overcomes vasomotor drive causing vasodilation
blood flow to skeletal and cardiac muscle increases in proportion to metabolic activity to increase blood flow and oxygen to tissue
Metabolic hyperaemia decreases SVR and DBP so pulse pressure increases

47
Q

what response occurs post exercise

A

hypotensive response - blood pools in veins

48
Q

what effect on BP does regular exercise ahve

A

reduces BP

49
Q

what is the chronic CVS response to regular exercise

A

reduction in sympathetic tone and noradrenaline levels
increase parasympathetic tone to heart
cardiac remodelling
reducing in plasma renin
improved endothelial function (increased vasodilators , decreased vasoconstrictors)
decreased arterial stiffening

CARDIO (14 decks)

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