Blood Flow (5) Flashcards Preview

Physiology and Neuroscience > Blood Flow (5) > Flashcards

Flashcards in Blood Flow (5) Deck (44):
1

What is blood flow?

Continuous movement of blood through the circulatory system

2

What is the average overall blood flow in an adult (CO)?

5000mL/min

3

What are the main functions of circulatory system?

Deliver blood to organs
Delivery of O2 and nutrients
Removal of CO2
Maintenance of ion concentrations
Delivery of hormones around the body

4

What makes up the circulatory system?

A pump
A series of collecting tubes
Extensive system thin vessels, exchange of nutrients, fluids across walls

5

What are the 3 components of the vasculature?

1. Arterial system
2. Venous system
3. Microcircualtion (nutrients/exchange waste)

6

What makes up hemodynamics?

Velocity
Pressure
Flow
Resistance
Dimensions of components of systemic circulation

7

What is the role of arterial blood pressure?

Development and maintenance adequate to perfuse tissues

8

How do you determine blood pressure?

MABP (Mean arterial blood pressure)= CO (cardiac output)x TPR (total peripheral resistance)
CO=HR (heart rate) x SV (stroke volume)

9

What other factors will affect blood pressure?

Change flow and change in resistance

10

What is flow?

A measure of volume per unit of time

11

What is a measure of flow?

Q (flow)= V (velocity)A (cross-sectional area)

12

What is pressure differential?

Difference in blood pressure at the beginning and end of a tube at any one time

13

What happens in terms of areas as vessels get smaller?

Cross-sectional areas get larger

14

Where is resistance greatest in the body?

Small vessels

15

Where is velocity at it's lowest and why?

In the capillaries to promote exchange

16

What is velocity?

Measurement of the movement of an objected divided by the time it took to travel to a location (speed)

17

What is sheer stress?

As blood flows through a blood vessel it exerts a force on the vessel wall parallel to the wall

18

What is sheer stress dependent on?

Area and location of vessels

19

What is sheer stress directly proportional to?

Flow rate and viscosity

20

What is Poiseuille's Law?

Q= (pie x Pr4)/ 8nl
Q- flow rate
P-pressure
R- radius
n- fluid viscosity
l- length of tubing

21

What is resistance to blood flow directly proportional to?

Length of the vessels and viscosity of blood

22

What is the equation for resistance?

alpha Ln/r4
L- length of vessel
N- viscosity of blood
R-radius of vessel

23

What is total peripheral resistance (TPR)?

Sum of all vascular resistance within systemic circulation

24

What alters resistance?

Contraction of the smooth muscle in the vessel wall-
Local tissue factors
Innervation
Hormones
Local wall stress

25

What is functional hyperaemia?

Increase in organ blood flow (hyperaemia) associated with increased metabolic activity of an organ or tissue

26

What are the by-products vasodilators of metabolism?

CO2, H+, K+, lactate, adenosine

27

What is reactive hyperaemia?

Occurs after cessation of blood flow e.g. after myocardial infarction or stroke

28

Why does reactive hyperaemia occur?

Due to tissue hypoxia and a build up of vasodilator metabolites to dilate arterioles and decrease vascular resistance

29

What is sympathetic innervation?

Vasoconstriction (alpha-adrenergic stimulation) of vascular smooth muscle

30

What happens when skeletal muscle (sympathetic) vasodilates?

beta-adrenergic and cholinergic sympathetic stimulation releasing acetylcholine

31

What increases Mean Arterial Pressure (MAP) in sympathetic innervation?

TPR and CO

32

What is involved in parasympathetic innervation?

Vasodilation of vascular smooth muscle (few organs)
Slows heart rate (deceleration of SA node, decreased atrial contractility- muscarinic receptors

33

What can signal innervation?

Baroreceptors or chemoreceptors

34

What is innervation?

Supplying nerves

35

Where are baroreceptors found?

Carotid sinus and aortic arch

36

What do baroreceptors do?

Respond to vascular stretch

37

How do you lower blood pressure?

Decrease in sympathetic innervation and increase in parasympathetic innervation

38

What happens when parasympathetic stimulation increases?

Decrease in heart rate and stroke volume which decreases cardiac output

39

What happens when sympathetic stimulation increases?

Increase in heart rate and stroke volume which increases cardiac output

40

What hormones are involved in vasoconstriction?

Adrenalin, angiotensin II, vasopressin

41

What hormones are involved in vasodilation?

Atrial natriuetic factor, kallikrein-kinin system

42

What are paracrine agents?

chemical messengers involved in cell-cell communication

43

What does Nitric Oxide do as a paracrine agent?

Released from endothelium, vasodilator which is also anti-proliferative and anti-thrombotic

44

What does Endothelin-1 (ET-1) do as a paracrine agent?

Released from endothelium, most potent vasoconstrictor ever isolated
Release stimulated by Ang II, hypoxia, sheer stress and catecholamines