L8

Question 1

what is a very broad way of describing the arterial network structure

Answer 1

a multilayered system of tubes

Question 2

compare and contrast arteries and arterioles

Answer 2

the most inner layer is the endothelial layer

arteries have lots of elastic tissue which is important for their function

arterioles have finger like smooth muscle that wraps around the lumen which gives it its function

Question 3

what is the function of aorta and large arteries

Answer 3

Distribute blood

Pressure reservoir
- Reduce fluctuations in pressure and flow = maintain flow throughout cardiac cycle

Question 4

what makes the arteries act as a pressure reservoir

Answer 4

The arteries and the aorta have lots of elastic tissue therefore it has the ability to change shape which is what helps it be a pressure reservoir

Some blood goes towards the periphery but some goes out which causes the arterial balloon (stretch)

Question 5

what is recoil

Answer 5

Recoil happens during diastole. it is when the arterial walls snap back which causes the elastic potential energy to be released causing blood flow away from heart as aortic valve shut!

Question 6

what happens in the aorta and large arteries during systole

Answer 6

Systole = stretching =

stores potential energy

Question 7

what happens in the aorta and large arteries during diastole

Answer 7

Diastole = recoil =

release stored energy

Question 8

what is compliance

Answer 8

the stretchiness

Question 9

what does compliance =

Answer 9

dV / dP

Question 10

what does stiffness =

Answer 10

1 / compliance

Question 11

what happens to our arteries as we age

Answer 11

Young arteries are compliant

When you age you get increased smooth muscle layers, collagen and fibrous which makes it less complaint

this is also what you see in cardiovascular disease

Question 12

what is the roles of the small arterioles

Answer 12

Main determinant of resistance (local and total peripheral resistance)

Important in controlling local flow

Question 13

what is vasoconstriction and vasodilation

Answer 13

vasoconstriction = contraction of smooth muscle

vasodilation = relaxation of smooth muscle

Question 14

how does vasoconstriction and vasodilation control the resistance of the arterioles

Answer 14

Smooth muscle cells wrap around the lumen.

Contraction squeezes lumen to reduce diameter

Question 15

what is the min pressure just before ventricular contraction

Answer 15

diastolic pressure (DP)

Question 16

what is the maximum arterial pressure reached during peak ventricular ejection

Answer 16

systolic pressure (SP)

Question 17

what is the normal blood pressure

Answer 17

120 / 80 mmHg

systolic / diastolic

Question 18

if you had hypertension what would you expect the blood pressure to be

Answer 18

> 140 / 90 mmHg

Question 19

if you had hypotension what would you expect the blood pressure to be

Answer 19

< 90 / 60 mmHg

Question 20

what is pulse pressure

Answer 20

systolic pressure - diastolic pressure

Question 21

what is the calculation of mean arterial blood pressure

Answer 21

mean ABP = DP + 1/3(SP-DP)

diastolic pressure + 1/3 of the pulse pressure

we calc like this because the heart spends longer in diastole

Question 22

what is the value for mean arterial blood pressure

Answer 22

90mmHg

Question 23

what is the dicrotic notch

Answer 23

when the aortic valve closes at the end of systole. This causes a slight transient increase in pressure

Question 24

why do we need to keep BP constant

Answer 24

for pufusion

Question 25

what is mean arterial blood pressure dependent on

Answer 25

CO and TPR MABP = CO x TPR

Question 26

how is TPR determined

Answer 26

it is the sum of global resistance from all the vascular beds

Question 27

how is blood pressure increase via TPR

Answer 27

when you had a drop in blood pressure you get vasoconstriction from SM in the arterioles

Question 28

how does CO increase blood pressure

Answer 28

the heart increases HR which increases CO which increases BP

Question 29

why is it important the BP is maintained at a homeostatic level

Answer 29

to maintain perfusion

Question 30

describe how arterioles determine how blood flow is distributed

Answer 30

when specific organs need more blood then you get vasodilation of arterioles at that organ and vasoconstriction to the organs that don't need as much blood at that time the increase in blood flow comes from decrease in blood flow from another vascular bed This is all designed to keep MAP at a stable level

Question 31

what is important to note from changing blood flow distributions

Answer 31

there is no change in pressure as resistance and flow change it is also important to know that the total volume of blood does NOT change as the increased volume of blood to one vascular bed has come from another therefore volume to that organ changes but total volume does not

Question 32

what are the control mechanisms for vascular resistance

Answer 32

neural controls, hormonal controls and local controls

Question 33

what are the 2 ways of neural control on vascular resistance

Answer 33

sympathetic nervous system (noradrenalin) postganglionic autonomic nerves

Question 34

how does the sympathetic nervous system have extrinsic control over vascular resistance

Answer 34

the SNS releases noradrenaline which binds to the a1 adrenergic receptor when NA is bound it causes venoconstriction when there is less NA bound there is vasodilation therefore there is a tonal activation of the SNS

Question 35

how do we regulate how much of an effect noradrenaline has

Answer 35

Innervation density varies depending on vascular bed this is because different vascular beds have different amount of the a1 adrenergic receptors eg the brain has low numbers of α1- adrenergic receptors = limited vasoconstriction which is important because brain needs constant flow where as skin and GI have lots of receptors because flow needs to be flexible

Question 36

how does parasympathetic have control over venous resistance

Answer 36

it doesn't

Question 37

how do postganglionic autonomic nerves have extrinsic control over vascular resistance

Answer 37

PGAN release nitric oxide which causes the relaxation of smooth muscle this is a specialised system which is only found in specific areas of the body (GI and penis)

Question 38

where does NO effect vascular resistance in the body

Answer 38

GI tract and penis

Question 39

how does viagra work

Answer 39

Viagra works because it is used in the postganglionic autonomic nerve pathway, it releases NO which causes dilation to get more blood flow to the penis

Question 40

what hormones cause vasoconstriction

Answer 40

adrenaline, angiotensin 2 and vasopressin

Question 41

what hormones cause vasodilation

Answer 41

adrenaline, atrial natriuretic peptide

Question 42

how does adrenaline cause both vasoconstriction and vasodilation

Answer 42

because there are 2 adrenaline receptors a 1 adrenergic receptors = constriction B2 = dilation this is controlled by how many receptors are expressed Eg skeletal muscle B2 > a1 whereas skin a1 > B2

Question 43

what do ADH and angiotensin 2 do what they usually do that effects blood and their effect in the vasculature

Answer 43

they increase blood volume ADH increases water reabsorption in the kidney which increases blood volume angiotensin 2 causes Na+ reabsorption in the kidneys. water follows salt therefore increasing blood volume when it acts on the vasculature it causes vasoconstriction

Question 44

what does atrial natriuretic peptide do

Answer 44

it decreases blood volume by decreasing water reabsorption in the kidney when it acts on the vasculature it causes vasodilation

Question 45

what are the local control mechanisms

Answer 45

active hyperemia (metabolic autoregulation) flow autoregulation (myogenic autoregulation) these are the intrinsic control factors

Question 46

describe what happens in active hyperemia

Answer 46

this happens when you are using that organ alot (eg skeletal muscles when exercising). you need more blood flow to take more O2 to make energy the products of metabolism cause vasodilation in the vascular bed this is a tissue specific response

Question 47

where is active hyperemia highly developed

Answer 47

skeletal and cardiac muscle because of their high metabolic demands

Question 48

what is flow autoregulation

Answer 48

it is the control of blood flow to maintain flow despite changes in perfusion pressure

Question 49

how does flow autoregulation work

Answer 49

When the pressure goes up then the smooth muscle cells stretch which stimulates them to contract Reduction in blood flow decreases the pressure reduction is stretch on the vessel stimulates them to contract

Question 50

Direct sympathetic stimulation of the systemic arterioles can cause: A: vasoconstriction mediated by α1 adrenergic receptors B: vasodilation mediated by α1 adrenergic receptors C: vasoconstriction mediated by β2 adrenergic receptors D: vasoconstriction mediated by β1 adrenergic receptors

Answer 50

A

Question 51

The aorta and large arteries maintain the flow of blood during diastole BECAUSE the strong elastic recoil of the arterial walls forces blood away from the heart as the aortic valve is shut.

Answer 51

Both statements are true and causal

Question 52

Mean arterial blood pressure is calculated by: A: adding diastolic and systolic pressure B: subtracting diastolic from systolic pressure C: adding the diastolic and systolic pressure and dividing by 2 D: adding one-third of the difference between the diastolic and systolic pressure to the diastolic pressure

Answer 52

D

Question 53

Which of these statements is INCORRECT? Vasopressin increases mean arterial blood pressure by: A: increasing water absorption in the kidneys B: decreasing stroke volume C: causing vasoconstriction D: increasing cardiac output

Answer 53

...

Question 54

The flow of blood away from the heart is maintained during diastole BECAUSE smooth muscle cells within the walls of the aorta constrict during diastole.

Answer 54

the first statement is true and the second is false

Question 55

Adrenaline will increase blood flow to skeletal muscles (assuming no change in perfusion pressure) BECAUSE adrenaline stimulates alpha-1 adrenergic receptors in the vascular smooth muscle of skeletal arterioles to provoke vasodilation.

Answer 55

a1 is constriction therefore first is true and second is false