Blood Flow (5)

Question 1

What is blood flow?

Answer 1

Continuous movement of blood through the circulatory system

Question 2

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

Answer 2

5000mL/min

Question 3

What are the main functions of circulatory system?

Answer 3

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

Question 4

What makes up the circulatory system?

Answer 4

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

Question 5

What are the 3 components of the vasculature?

Answer 5

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

Question 6

What makes up hemodynamics?

Answer 6

Velocity
Pressure
Flow
Resistance
Dimensions of components of systemic circulation

Question 7

What is the role of arterial blood pressure?

Answer 7

Development and maintenance adequate to perfuse tissues

Question 8

How do you determine blood pressure?

Answer 8

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

Question 9

What other factors will affect blood pressure?

Answer 9

Change flow and change in resistance

Question 10

What is flow?

Answer 10

A measure of volume per unit of time

Question 11

What is a measure of flow?

Answer 11

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

Question 12

What is pressure differential?

Answer 12

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

Question 13

What happens in terms of areas as vessels get smaller?

Answer 13

Cross-sectional areas get larger

Question 14

Where is resistance greatest in the body?

Answer 14

Small vessels

Question 15

Where is velocity at it’s lowest and why?

Answer 15

In the capillaries to promote exchange

Question 16

What is velocity?

Answer 16

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

Question 17

What is sheer stress?

Answer 17

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

Question 18

What is sheer stress dependent on?

Answer 18

Area and location of vessels

Question 19

What is sheer stress directly proportional to?

Answer 19

Flow rate and viscosity

Question 20

What is Poiseuille’s Law?

Answer 20

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

Question 21

What is resistance to blood flow directly proportional to?

Answer 21

Length of the vessels and viscosity of blood

Question 22

What is the equation for resistance?

Answer 22

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

Question 23

What is total peripheral resistance (TPR)?

Answer 23

Sum of all vascular resistance within systemic circulation

Question 24

What alters resistance?

Answer 24

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

Question 25

What is functional hyperaemia?

Answer 25

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

Question 26

What are the by-products vasodilators of metabolism?

Answer 26

CO2, H+, K+, lactate, adenosine

Question 27

What is reactive hyperaemia?

Answer 27

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

Question 28

Why does reactive hyperaemia occur?

Answer 28

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

Question 29

What is sympathetic innervation?

Answer 29

Vasoconstriction (alpha-adrenergic stimulation) of vascular smooth muscle

Question 30

What happens when skeletal muscle (sympathetic) vasodilates?

Answer 30

beta-adrenergic and cholinergic sympathetic stimulation releasing acetylcholine

Question 31

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

Answer 31

TPR and CO

Question 32

What is involved in parasympathetic innervation?

Answer 32

Vasodilation of vascular smooth muscle (few organs)

Slows heart rate (deceleration of SA node, decreased atrial contractility- muscarinic receptors

Question 33

What can signal innervation?

Answer 33

Baroreceptors or chemoreceptors

Question 34

What is innervation?

Answer 34

Supplying nerves

Question 35

Where are baroreceptors found?

Answer 35

Carotid sinus and aortic arch

Question 36

What do baroreceptors do?

Answer 36

Respond to vascular stretch

Question 37

How do you lower blood pressure?

Answer 37

Decrease in sympathetic innervation and increase in parasympathetic innervation

Question 38

What happens when parasympathetic stimulation increases?

Answer 38

Decrease in heart rate and stroke volume which decreases cardiac output

Question 39

What happens when sympathetic stimulation increases?

Answer 39

Increase in heart rate and stroke volume which increases cardiac output

Question 40

What hormones are involved in vasoconstriction?

Answer 40

Adrenalin, angiotensin II, vasopressin

Question 41

What hormones are involved in vasodilation?

Answer 41

Atrial natriuetic factor, kallikrein-kinin system

Question 42

What are paracrine agents?

Answer 42

chemical messengers involved in cell-cell communication

Question 43

What does Nitric Oxide do as a paracrine agent?

Answer 43

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

Question 44

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

Answer 44

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