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BMS242 CVS Phys > L14 - Control of Circulation > Flashcards

L14 - Control of Circulation Flashcards

1
Q

What are the two key targets for control

How many layers?

A

Ateriole resitance and the stored blood in veins as well as the vascular smooth muscle
Multiple layers of control

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2
Q

What are two key differences between and artery and a vein

A

In the artery there is more elastic tissue and more smooth muscle

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3
Q

What does resting tension mean

What vessels possess it

A

The balance between the contraction of the smooth muscle and the elastic recoil
All vessels

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4
Q

What is myogenic regulation

A

When an artery is stretched it evokes a contraction of the smooth muscle causing the artery to return to its original shape

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5
Q

What is meant my metaboite regulation

A

Several metabolites are able to cause dilation/constriciton of the vessesl

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6
Q

What is this low level of designed to give, what can this be called

A

Constant level of flow

Also known as autoregulation

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7
Q

What are most vessels tonicallt innervated by

A

Sympathetic adrenoreceptor input (alpha receptors)

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8
Q

What is the effect of sympathetic stimulation of blood vessels supplying skeletal muscle, heart, lung and kidney
What NT is involved in this

A

Vasodilation

ACh involved

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9
Q

What is the effect of parasympathetic stimulation of blood vessels supplying erectile tissue / glands
What NT is involved in this

A

Vasodialtion

Ach involved

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10
Q

What can be said about the innervation density of sympathetic constrictors
Give examples

A

It varies
E.g. high in cutaneous tissue
low in cerebral tissue

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11
Q

What is the adrenal medullary hormone most involved in the control of circulation

A

Adrenaline

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12
Q

What is the effect of adrenaline at the skin and other viscera

A

Vasoconstriction

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13
Q

What is the effect of adrenaline at the skeltal muscle and liver

A

Vasodilation

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14
Q

Why would adrenaline cause vasodilation at the liver

A

Because liver stores glycogen ==> increased blood supply to increase glycogenolysis in the liveer to provide the skeltal muscle cells with glucose

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15
Q

What reaction is adrenaline responsible for;

Summarise

A

Defence reaction

Blood diverted to heart, skeletal muscle and the liver

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16
Q

Give an example of a kinin

A

Bradykinin

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17
Q

What is the effect of bradykinin

A

It is a vasodilatory peptide

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18
Q

What is the effect of angiotensin 2 on the blood vessels

A

Vasoconstriction leading to an increase in blood pressure

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19
Q

How is angiotensin II formed

A

Formed by enzymes e.g. renin acting on precurrsors when the blood pressure falls

20
Q

What is the effect of ACE inhibitors

A

Reduce the ammount of angiotensin II in the blood so reduced blood pressure

21
Q

What are ACE inhibitors used to treat

A

Hypertension

22
Q

What are extrinsic humoural controls of circulation

A

1) Adrenal medullary hormones
2) Kinins
3) Angiotensin II

23
Q

What are the local agents which are involved in the extrinsic control

A 
Prostaglandins 
Serotonin 
Histamine 
Endothellium derived relaxing factors 
Endothellium derived hyperpolarising factors
24
Q

What is the effect of prostaglandins

A

Act as vasodilators

25
Q

What is the effect of serotonin release

When is it released

A

Platelets release 5-Ht causing vasoconstriction to aid in the formation of clots

26
Q

What is the effect of histamine

When is it released

A

Released by mast cells in response to an allergen

Causes vasodilation

27
Q

What is the effect of endothelium derived relaxing factors

A

Released after stimulation - by Ach
NO from endothelial cells
Stimulated cGMP in muscles
Causes relaxation

28
Q

Describe how nitroglycerin can be used clinically

A

Is converted to NO (increased NO)
Vasodilation
Increased flow
Increased oxygen supply

29
Q

Describe how slidenafil citrate works - what is its trade name

A

Inhibits the cGMP breakdown

Causes dilation of the blood vessels

30
Q

Describe a endothellium derived hyperpolarising factors

A

Release after stimulations (again by Ach)

Complex pathways

31
Q

Describe the central control of the control of circulation

A

Interlinked CNS centres in the brainstem
CNS centres recieve diversive inputs
Emotional responses

32
Q

Describe how meduallary centres control circulation

A

Cardioexcitation / inhibition and vasomotor output

33
Q

What metabolites do medullary centres respond to

A

pH, CO2 (increase), O2 (decrease)

34
Q

Describe what else medullary centres may respond to (NOT metabolites)

A

Raised intercranial pressure, due to swelling, overcome by a fall in blood flow to the brain

35
Q

What stretch receptors are responsible for the detection of high pressure

A

Ones in the carotid sinus and the aortic arch

36
Q

What strech receptors are reponsible for the detection of low pressure

A

Atria, left ventricle and pulmonary veins

37
Q

What are the two buffer nerves to the strech receptors

A

Vagus and the glossopharyngeal

38
Q

Describe the effect of increased pressure on a stretch receptor

A

Increased rate of firing
Leads to decrease in vasoconstriction and increase in cardio inhibition
Vasodilation and bradycardia

39
Q

What are some long term regulatory mechanisms of circulation

A

Regulation of blood volume by the kidney

40
Q

What is the valsalva manouveur an example of

How is it performed

A

Peripheral propriception

Forced expiration against a close glottis

41
Q

What is another form of proprioception

A

Chemoreceptors

Normally effect respiration but can also have effects of the heart and vasculature

42
Q

What is the main higher brain centre involved in the control of circulation - what is it linked to

A

Hypothalamus linked to the cortex and the limbic system

43
Q

What does stimulation of the hypothalamic defence area cause

A

Sympathetic dilation of skeltal muscle

44
Q

What does stimulation of the hypothalamic thermoregulatory centres causes

A

If hot –> vasodilation and sweating

If cold –> vasoconstriction and shivering

45
Q

What does stimulation of the hypomedial preoptic area cause

A

Sexual responses

46
Q

What does stimualtion of the anterior cingulate gyrus cause

A

Bradycardia hypertension and playing dead

BMS242 CVS Phys (12 decks)

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