Integration of cardiovascular mechanisms Flashcards

1
Q

Factors which influence MAP?

A

Heart Rate
Stroke Volume
Systemic vascular resistance

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2
Q

Main site of systemic vascular resistance?

A

Arterioles

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3
Q

Components of cardiovascular system?

A

Heart - pump
Arteries - passageway of blood from heart to tissues
Arterioles - major resistance vessels
Capillaries - Site of gas exchange, nutrients and water between blood and tissues
Veins - Contains most of blood volume during rest - passageways of blood from tissues to heart

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4
Q

What must venous return provide?

A

The heart with sufficient blood to pump

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5
Q

Name for veins?

A

Capacitance vessels

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6
Q

How is HR mainly regulated?

A

Autonomic nervous system

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7
Q

How is SV mainly regulated?

A

Preload
Myocardial contactility
Afterload

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8
Q

CO equation=

A

CO= HR x SV

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9
Q

How can MAP be estimated?

A

DBP + 1/3 pulse pressure

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10
Q

How is systemic vascular resistance regulated?

A

By vascular smooth muscles

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11
Q

What does contraction of vascular smooth muscles cause?

A

Vasoconstriction and decreases SVR and MAP

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12
Q

What are vascular smooth muscles controlled by?

A

Intrinsic and extrinsic mechanisms

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13
Q

What is resistance to blood flow directly proportional tp?

A

Blood viscosity and length of blood vessel

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14
Q

What is resistance to blood flow inversely proportional to?

A

Radius of blood vessel to the power of 4

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15
Q

Resistance to flow equation?

A
R proportional to n.l/r^4
n=blood viscosity 
L= length of blood vessel
r= radius of blood vessel 
R= resistance to flow
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16
Q

What does extrinsic control of vascular smooth muscle involve?

A

Nerves and hormones

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17
Q

If we constrict muscle in arterioles what happens?

A

Increases resistance and decreases flow

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18
Q

What are vascular smooth muscles supplies by?

A

Sympathetic nerve fibers

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19
Q

Vascular smooth muscle neurotransmitter and receptor it works on?

A

Noradrenaline

acts on alpha receptors

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20
Q

Vasomotor tone?

A

Vascular smooth muscle partially constructed at rest

21
Q

Control of vascular smooth muscles via hormones?

A

Adrenaline
Organ specific
Depends on predominant type of receptor

22
Q

What does adrenaline acting on alpha receptors cause?

A

Vasoconstriction

23
Q

What causes vasodilation?

A

Adrenaline acting on beta 2 receptors

24
Q

Where are alpha receptors predominantly found?

A

Skin
Gut
Kidney arterioles

25
Q

What receptor is found on cardiac and skeletal muscle arterioles?

A

Beta2 receptors

26
Q

Other hormones which extrinsically affect vascular smooth muscle control?

A

Angiotensin 2- causes vasoconstriction

Antidiuretic hormone- causes vasoconstriction

27
Q

What do local metabolic changes within an organ influence?

A

Contraction of arteriolar smooth muscles

28
Q

What factors causes relaxation of arteriolar smooth muscles?

A

Vasodilation

Metabolic hyperaemia

29
Q

What do other local chemicals released within an organ influence? and when are they released

A

Contraction of arterial and arteriolar smooth muscles

Following a tissue injury or inflammation

30
Q

Examples of humoral agents which cause contraction of arteriolar smooth muscles resulting in vasoconstriction?

A

Serotonin
Thromboxane A2
Leukotrienes
Endothelin

31
Q

Endothelin?

A

Potent vasoconstrictor released from endothelial cells- production stimulated by various agents which cause vasoconstriction

32
Q

What s endothelium important for?

A

Maintenance of vascular health

33
Q

What can endothelial damage/dysfunction be caused by?

A

High BP
High cholesterol
Diabetes
Smoking

34
Q

What are endothelial produced vasodilators?

A

Anti-thrombotic
Anti-inflammatory
Anti-oxidants

35
Q

Endothelial produced vasoconstrictors are?

A

Pro-thrombatic
Pro-inflammatory
Pro-oxidants

36
Q

What does a cold temperature cause?

A

Vasoconstriction

37
Q

What does warmth cause?

A

Vasodilation

38
Q

What is vasomotor tone caused by?

A

Tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline

39
Q

What will increased sympathetic discharge cause in vascular smooth muscles?

A

Increase the vasomotor tone

Vasoconstriction

40
Q

What causes decreased vasomotor tone (vasodilation)?

A

Decreased sympathetic discharge to vascular smooth muscle

41
Q

There is no significant parasympathetic innervation of arterial smooth muscles. True or False?

A

There is no significant parasympathetic innervation in arterial smooth muscle EXCEPT in penis and clitoris.

42
Q

What hormone controls vascular smooth muscle?

A

Adrenaline from the adrenal medulla

43
Q

Explain the affect of adrenaline?

A

Largely organ specific - depends on predominant type of receptor

44
Q

What does adrenaline acting on alpha receptors cause?

A

Vasoconstriction

45
Q

What are important in immediate control of BP?

A

Angiotensin 2

ADH

46
Q

Intrinsic control of vascular smooth muscles can override extrinsic controls? True or False?

A

True

47
Q

What do intrinsic control of vascular smooth muscle include?

A

Chemical and physical factors

48
Q

Intrinsic control of vascular smooth muscles?

A

These match the blood flow of different tissues to their metabolic needs