Regulation of arteriolar resistance

Question 1

what is poiseuilles law

Answer 1

a statement in physics

Question 2

describe poiseuilles law

Answer 2

the velocity of steady flow of a fluid through a narrow tube varies directly as the pressure and the fourth power of the radius of the tube and inversely as the length of the tube and the coefficient of viscosity

Question 3

what is active hyperaemia

Answer 3

it is the increase in organ blood flow that is associated with increased metabolic activity of an organ or tissue

Question 4

give an example of active hyperaemia

Answer 4

the increase in blood flow that accompanies muscle contraction, which is also called exercise or functional hyperaemia in skeletal muscle

Question 5

what is pressure auto regulation defined as

Answer 5

the intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure,

as resistance decreases, blood flow increases despite the presence of reduced perfusion pressure

Question 6

describe reactive hyperaemia

Answer 6

it is the transient increase in organ blood flow that occurs following a brief period os ischameia

Question 7

what does vascular tone refer to

Answer 7

the degree of constriction experienced by a blood vessel relative to its maximally dilated state

Question 8

what do all arterial and venous vessels under basal conditions exhibit

Answer 8

some degree of smooth muscle contraction that determines the diameter of the vessel

Question 9

what is meant my haemodynamics

Answer 9

literal meaning - blood movement

it is the study of blood flow or the circulations of blood, it is the dynamics of blood flow

Question 10

what is active hyperaemia

Answer 10

it is the increase in organ blood flow

Question 11

what is active hyperaemia associated with

Answer 11

increased metabolic activity of an organ or tissue

Question 12

give an example of active hyperaemia

Answer 12

increased blood flow that accompanies muscle contraction

Question 13

what is the result when blood flow falls?

Answer 13

arterial resistance falls as the resistance vessels dilate

Question 14

what is reactive hyperaemia

Answer 14

it is the transient increase in organ blood flow that occurs following a brief period of ischaemia

Question 15

basically describe reactive hyperaemia

Answer 15

it is an increase in organ blood flow when there is an inadequate blood supply to an organ

Question 16

what is marcy’s law

Answer 16

it is an equation that describe the flow of a fluid through a porous medium

Question 17

what is blood flow equal to

Answer 17

the change in pressure over the resistance

Question 18

what pressure equal to

Answer 18

blood flow multiplied by the resistance

Question 19

what is varying the radius of arterioles used to control

Answer 19

flow through individual vascular beds

Question 20

what does varying the radius of arterioles affect

Answer 20

the change in pressure

Question 21

what does the total peripheral resistance affect

Answer 21

the mean arterial pressure

Question 22

what is cerebral circulation

Answer 22

it is the movement of blood through the network of cerebral arteries and veins supplying the brain

Question 23

what is the rate of the cerebral blood flow in a typical adult

Answer 23

750ml per minute

Question 24

what percentage of cardiac output does cerebral blood flow represent

Answer 24

15%

Question 25

describe the extrinsic neural control of arteriolar resistance

Answer 25

sympathetic nerves cause arteriolar constriction, increasing total peripheral resistance parasympathetic nerves usually don't have an effect on arteriolar resistance

Question 26

describe how sympathetic nerves control arteriolar resistance

Answer 26

sympathetic nerves release norepinephrine this binds to alpha 1 receptors this causes arteriolar constriction this decreases flow through that tissue this increases total peripheral resistance

Question 27

describe how parasympathetic nerves control arteriolar resistance

Answer 27

usually have no effect on arteriolar resistance

Question 28

where is the hormone epinephrine/adrenaline released from

Answer 28

the adrenal medulla

Question 29

describe how the hormone epinephrine/adrenaline controls arteriolar resistance

Answer 29

this hormones binds to alpha 1 receptors causing arteriolar constriction decreasing flow through that tissue increasing the total peripheral resistance

Question 30

in skeletal and cardiac muscle what is the result of epinephrine/adrenaline activating beta 2 receptors

Answer 30

causes arteriolar dilation increasing flow through that tissue decreasing total peripheral resistance

Question 31

describe how the hormone angiotensin II controls arteriolar resistance

Answer 31

causes arteriolar constriction increases blood pressure stimulates the release of aldosterone increases the total peripheral resistance

Question 32

what is arteriolar resistance (vascular resistance)

Answer 32

it is the resistance that must be overcome to push blood through the circulatory system and create flow

Question 33

what is arteriolar resistance used in calculations of

Answer 33

blood pressure, blood flow and cardiac output

Question 34

what is systemic vascular resistance also known as

Answer 34

total peripheral resistance

Question 35

what is pulmonary vascular resistance

Answer 35

it is the resistance offered by the pulmonary circulation

Question 36

describe how the hormone vasopressin controls arteriolar resistance

Answer 36

``` it increases blood pressure promotes water retention released in response to low blood volume causes arteriolar constriction increases the total peripheral resistance ```

Question 37

describe how the atrial natriuretic peptide hormone controls arteriolar resistance

Answer 37

released in response to high blood volume increases renal sodium excretion reduces an expanded extracellular fluid volume causes arteriolar dilation decreases total peripheral resistance

Question 38

describe how the brain natriuretic peptide hormone controls arteriolar resistance

Answer 38

released in response to high blood volume secreted in response to stretching caused by increased ventricular blood volume causes arteriolar dilation decreases total peripheral resistance

Question 39

in terms of local (intrinsic) control of arteriolar resistance describe how active hyperaemia controls arteriolar resistance

Answer 39

``` increased organ blood flow associated with increased metabolic activity of an organ increased metabolic activity increased concentration of metabolites triggers release of EDRFs causing arteriolar dilation smooth muscle relaxation increasing flow to wash out metabolites ```

Question 40

what is the mean arterial pressure

Answer 40

the average pressure in a patient's arteries during one cardiac cycle

Question 41

describe how pressure auto regulation controls arteriolar resistance

Answer 41

``` decrease in mean arterial pressure causes decrease in flow metabolites accumulate triggering the release of EDRFs causing arteriolar dilations causing flow to be restored to normal ```

Question 42

describe how the injury response controls arteriolar resistance

Answer 42

arteriolar dilation increased blood flow increased permeability