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cardio-vascular system > Local regulation of blood flow > Flashcards

Local regulation of blood flow Flashcards

1
Q
  1. When is adrenaline released?
A

released in response to lowered BP

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2
Q
  1. What two things does adrenaline do?
A
  1. Speeds heart rate and force of ventricular contraction
  2. Dilates skeletal muscle vascular beds and constricts the splanchnic (mesenteric) vascular beds
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3
Q
  1. What does the things that adrenaline does result in
A

results in increased cardiac output and systolic BP

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4
Q

What is the main role of ADH

A

Main role is formation of concentrated urine by retaining water to control plasma osmolarity

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5
Q
  1. What are 2 other names for anti-diuretic hormone
A

Arginine vasopressin or vasopressin

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6
Q
  1. What can slow down the release of ADH
A

alcohol

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7
Q
  1. What is the function of the ventricles
A

pumping chamber

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8
Q
  1. What is the function of arterioles
A

resistance vessels

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9
Q
  1. What is the function of capillaries
A

Exchange vessels

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10
Q
  1. What is the function of venules/veins
A

Capacitance vessels

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11
Q
  1. What is the function of the atrium
A

Receiving chamber

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12
Q
  1. What is a metarteriole continuous with
A

A metarteriole is continuous with the thoroughfare channel passing between terminal arteriole and postcapillary venule

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13
Q
  1. What do capillaries enable?
A

enable the exchange of water, O2, CO2 and many other nutrient and waste chemical substances between blood and surrounding tissues

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14
Q
  1. What does metarterioles being continuous cause?
A

This causes blood to be shunted between the two vessels when precapillary sphincters are closed, bypassing the capillary bed

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15
Q
  1. What does basal flow vary by?
A

flow varies by tissue

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16
Q
  1. Where is are examples of basal flow being high and it being low
A

High: Kidneys
Low: skeletal muscle

17
Q
  1. What happens when cells become more active
A

When cells become more active this increases circulation to the region, at the expense of other tissues.

18
Q
  1. what 3 things mediate the regulation of blood flow
A

The regulation of local flow is mediated by:

  1. Neural factors (sympathetic nervous system)
  2. Endocrine factors (hormones)
  3. Local factors (bi-products signaling metabolic demand)
19
Q
  1. what are 2 factors that affect blood flow
A
  1. Pressure (driving force) of the flow (Cardiac Output)
  2. Total peripheral resistance
20
Q
  1. what is Total Peripheral resistance (TPR)?
A

the sum of the resistance of all peripheral vasculature in the systemic circulation

21
Q
  1. what are 4 factors that affect TPR
A

Affected by:
- Mean arterial pressure
- Viscosity/ volume of the blood
- Turbulence
- Length/volume of the conduction system

22
Q
  1. what 2 things is varying the resistance of the arterioles used to control?
A
  1. flow to a particular organ/organs
  2. whole-body perfusion pressure
23
Q
  1. where does neural input come from
A

comes via the sympathetic nervous system

24
Q
  1. what does sympathetic nervous system release to cause vascoconstriction
A

releases noradrenaline

25
Q
  1. what does noradrenaline bind to on vascular smooth muscle
A

binds to α1 adrenoreceptors

26
Q
  1. where are the effects of neural input the strongest
A

effects are strongest in the skin, kidney, skeletal muscle and digestive tract vessels

27
Q
  1. which 2 instances is blood flow regulation most important
A

Flow regulation is most important:
1. in organs that require constant perfusion

  1. where local metabolic conditions may change rapidly and markedly
28
Q
  1. what are the 2 primary functions of local mechanism
A
  1. autoregulation
  2. Metabolic vasodilation
29
Q
  1. what is autoregulation
A

adjustment of local resistance over a large range of arterial pressures to provide constant local flow

30
Q
  1. what is metabolic vasodilation
A

upregulation of flow when local metabolic demands increase achieved by dilating muscular vessels to decrease resistance

31
Q
  1. outline the mechanism of autoregulation
A
  1. Stretch receptors (mechanically gated ion channels) open, leading to constriction in vessels

2.This allows influx of Na+ ions and Ca2+ ions

  1. Vasodilating metabolites (adenosine, K+ ions) act on smooth muscle cells to cause relaxation
  2. As flow increases these substances are washed out of the tissue and muscle tone increases again
32
Q
  1. what type of vasodilator is nitric oxide?
A

A potent vasodilator

33
Q
  1. What produces nitric oxide
A

vascular endothelium

34
Q
  1. What are the 2 forms of NOS
A
  1. endothelial NOS (eNOS)

2.inducible NOS (iNOS)

35
Q
  1. How is NO synthesised
A

NO is synthesised from L-arginine and oxygen by the nitric oxide synthase (NOS) enzyme in response to increased intracellular Ca2+

36
Q
  1. outline the mechanism for NO signalling
A
  1. NO quickly diffuses out of the endothelium and into vascular smooth muscle
  2. in vascular smooth muscle, it activates guanylyl cyclase
  3. This increases cyclic GMP levels, leading to relaxation
37
Q
  1. what does sildenafil citrate AKA Viagra cause when it acts on the NO signalling pathway?
A

it causes the enhancement of the NO signalling pathway

cardio-vascular system (7 decks)

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