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Second Year - Biomedical Sciences BS22001 > Lecture 19 - Peripheral Vascular Resistance > Flashcards

Lecture 19 - Peripheral Vascular Resistance Flashcards

1
Q

How is blood pressure measured

A

A sphygmomanometer

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2
Q

What are the Kortkoff sounds produced by

A

Intermittent and turbulent flow through the artery

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3
Q

How are the Kortkoff audible

A

Through a stethoscope

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4
Q

When do Kortkoff sounds begin

A

When the cuff pressure is just below systolic pressure

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5
Q

When do the Kortkoff sounds begin to fade

A

When the cuff pressure is close to diastolic pressure

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6
Q

What is the normal systolic pressure at rest for a 20 year old

A

100-140 mmHg

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7
Q

What is the normal diastolic pressure for a 20 year old at rest

A

50-90 mmHg

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8
Q

How is mean arterial blood pressure calculated

A

By the cardiac output multiplied by the total peripheral resistance

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9
Q

What mainly affects systolic pressure

A

The stroke volume and particularly the ejection velocity

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10
Q

What is diastolic pressure mainly affected by

A

Total peripheral resistance and the time allowed for blood to flow out of the arteries

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11
Q

What are the functions of the peripheral vascular system

A

To convey blood from the heart to the capillaries and then back to the heart, the regulation of arterial tone and peripheral vascular resistance, the regulation of blood flow to muscles and other tissues, to respond to traumatic injury with vasoconstriction and haemostasis, and the response to sustained increase in intraluminal pressure which occurs through growth and hypertrophy

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12
Q

What vessels are the main site of resistance

A

Arterioles

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13
Q

Where is the biggest drop in pressure

A

Between the conduit arteries and the arterial end of the capillaries

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14
Q

What controls local blood flow

A

Local arteriole radius

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15
Q

What does doubling the radius of a blood vessel cause

A

A 16-fold increase in the flow

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16
Q

What controls TPR and therefore MABP

A

The arteriole radius

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17
Q

What causes hypertension

A

The narrowing of the resistance vessels

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18
Q

What is the internal radius of arteries

A

2.5cm to 1mm

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19
Q

What is the internal radius of arterioles

A

0.01-0.2 mm

20
Q

What size of effect does small changes in the radius of the resistance vessels locally cause on blood flow

A

A relatively large effect

21
Q

What is Raynauld’s disease

A

Vasoconstriction of the resistance vessels in the hand causing the reduction of blood flow to the point of damage

22
Q

What is causes if all the blood vessels become a little narrower

A

Hypertension

23
Q

What type of control alters arteriolar radius

A

Intrinsic or extrinsic

24
Q

What are the intrinsic (local) control mechanisms to alter arteriolar radius

A

Stretching, production of metabolites and local release of chemicals

25
Q

What are the extrinsic control mechanisms to alter arteriolar radius

A

Hormones and the autonomic nervous system (mainly sympathetic)

26
Q

What do many organs and tissues have which is caused by sympathetic activity

A

A resting vasomotor tone

27
Q

What does increased sympathetic activity to arterioles cause

A

Vasoconstriction

28
Q

What does decreased sympathetic activity to arterioles cause

A

Vasodilation

29
Q

What is the sympathetic nervous system neurotransmitter

A

Noradrenaline

30
Q

What receptors does the sympathetic neurotransmitter act on

A

Alpha 1-adrenoceptors of vascular smooth muscle

31
Q

What are veins stimulated by

A

Sympathetic venoconstrictor nerves

32
Q

What do the sympathetic venoconstrictor nerves cause

A

They shift the blood centrally which supports the central venous pressure

33
Q

What causes the sigmoidal shape of the pressure-volume curve in veins

A

The thin-walled nature of veins

34
Q

If there is less blood on the central veins what happens

A

The central venous pressure drops causing the stroke volume to decrease

35
Q

What do peripheral veins have in the tunic media

A

Smooth muscle

36
Q

What do veins serve as

A

Blood reservoirs

37
Q

Within vascular smooth muscle vasoconstriction occurs through the release of

A

Adrenaline

38
Q

What activates the alpha 1 vascular receptors

A

Angiotensin II and endothelin

39
Q

What does the release of angiotensin II and endothelin cause

A

Vasoconstriction within the endothelium and the opening of calcium channels through depolarisation

40
Q

Within vascular smooth muscle how does vasodilation occur

A

Through the release of cholinergic and adrenergic molecules

41
Q

What activates the beta 2 vascular receptors

A

Adenosine and prostacyclin

42
Q

What happens in response to the release of adenosine

A

The opening of ATP-dependent K+ channels

43
Q

What is the endothelium derived releasing factor

A

Nitric oxide

44
Q

Why is nitric oxide usually relased

A

Due to shear stress

45
Q

What does the release of nitric oxide cause

A

Increased blood velocity and vessel dilation

Second Year - Biomedical Sciences BS22001 (28 decks)

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