Vascular Mechanics and regulation

Question 1

Change in Pressure =

Answer 1

CO x R

Question 2

Driving Pressure

Answer 2

The pressure gradient between two points
e.g. for the systemic circulation ∆P = Pa-Pv.
The driving pressure governs blood flow.

Question 3

Transmural Pressure

Answer 3

The pressure across the vessel wall

(inside minus outside)

Question 4

• Hydrostatic Pressure

Answer 4

Dependent on gravity

Question 5

LaPlace Equation

For a thick walled cylinder:

Answer 5

T= (P*r ) /Wall thickness

Question 6

The larger the vessel radius the ____the wall tension required to withstand an
internal pressure

Answer 6

larger

Question 7

Aneurysm

Answer 7

Thinning of vessel wall
 Radius increases
 Wall tension increases
viscous circle!!

Question 8

Hydrostatic pressure: P = ρgh

What is ρgh and units?

Answer 8

ρ = density of the fluid (kg m-3)
g = acceleration due to gravity (9.81 m s-2)
h = distance below the surface (m)
Units – usually mmHg (or kPa), (1 mmHg = 13
mm H2O)

Question 9

Total pressure at a specific point =

Answer 9

hydrostatic pressure + vascular pressure
generated by heart
Thus in large arteries in foot when standing:

Question 10

Intrinsic mechanisms
(autoregulation)
 Distribute blood flow to ?

Answer 10

individual

organs and tissues as needed

Question 11

Extrinsic mechanisms
• Maintain?
• Redistribute blood during ?

Answer 11

mean arterial pressure (MAP)

exercise and
thermoregulation

Question 12

Neural regulation of vascular tone

(resistance) is primarily via ?

Answer 12

the

sympathetic nerves

Question 13

In most cases increased sympathetic

activity increases vascular ?

Answer 13

tone (via

vascular smooth muscle contraction).

Question 14

• NE released from sympathetic

terminals in vasculature binds to the?

Answer 14

α1-adrenoceptors leading to

vasoconstriction

Question 15

A decrease in sympathetic nerve

firing leads to vaso?

Answer 15

dilation

Question 16

Vasoconstriction is in response to ___________release of norepinephrine
acting on _________receptors on
vascular smooth muscle

Answer 16

postganglionic

α1-adrenergic

Question 17

Vasodilation may occur in response to
activation of \_\_\_\_\_\_\_receptors,
e.g. in vasculature in skeletal muscle.
Primarily in response to epinephrine
released from the adrenal \_\_\_\_\_\_\_

Answer 17

β2- adrenergic

medulla

Question 18

The __________are the predominant α-receptor located on

vascular smooth muscle.

Answer 18

α1-adrenoceptors

Question 19

__ released from sympathetic terminals
in vasculature binds to the α1- adrenoceptors
These receptors are linked to _________ receptors that activate ______________
contraction through the IP3 signal transduction pathway and ultimately
vasoconstriction

Answer 19

NE
G-protein

smooth muscle

Question 20

β2-adrenoceptors are mostly found in ???? (also airway smooth
muscle)

Answer 20

skeletal

muscle vasculature

Question 21

β2 -adrenoceptors are More sensitive to ______vs ______

Answer 21

adrenaline

noradrenaline

Question 22

Stimulation of β2-receptors results in?

Answer 22

vasodilation.

Question 23

β2 -adrenoceptors Act via cAMP to inhibit _____light chain kinase, and thus inhibit contraction
Contributes to increase in blood flow during
exercise in response to circulating _______

Answer 23

myosin

adrenaline

Question 24

β2-agonists (activators) e.g.

Answer 24

salbutamol, are useful in

the treatment of asthma (bronchial dilators)

Question 25

Alpha1-adrenoreceptors | Antagonists, e.g.

Answer 25

prazosin (treat high blood pressure) can be useful | in the treatment of severe hypertension

Question 26

Progressive increase in ______ _______ ______with mean arterial pressure

Answer 26

muscle sympathetic | nerve

Question 27

Blood Flow within tissues primarily responds to changes in ______needs, often at the level of the precapillary ______

Answer 27

metabolic | sphincters

Question 28

Factors that promote dilation are:

Answer 28

Decreased tissue oxygen levels  Increased levels of CO2 and H+ (brain) The generation of lactic acid or other acids by tissue cells. The release of adenosine, prostaglandins and nitric oxide (NO) from endothelial cells. Rising concentrations of potassium ions or hydrogen ions in the interstitial fluid. Chemicals released during local inflammation, including histamine and NO. Elevated local temperatures (skin)

Question 29

Reactive hyperaemia Driven by _______

Answer 29

When blood flow is restored after a brief occlusion, blood flow rises above pre-occlusion level for a period proportional to the duration of the occlusion. metabolites

Question 30

Vascular Autoregulation:

Answer 30

Intrinsic capacity to maintain constant blood flow despite changes in perfusion (circulatory) pressure.

Question 31

In many tissues (e.g. brain, kidney) blood flow is _______ over a wide range of pressures Less important in other vascular beds e.g. cutaneous circulation (skin) and________

Answer 31

near constant | skeletal muscle.

Question 32

Myogenic mechanisms are intrinsic (built-in) to the ______ blood vessels, particularly in small arteries and _______

Answer 32

smooth muscle | arterioles

Question 33

Autoregulation ensuring flow is constant. Likely due to ______sensitive ion channels (___) opening, leading to depolarization.

Answer 33

stretch | Ca2+

Question 34

If the pressure within a myogenic vessel is suddenly increased, the vessel responds by _______, normalizing flow

Answer 34

constricting | FLOW

Question 35

Three unique mechanisms mediate | the CV adjustments:

Answer 35

the arterial baroreflex, central command, and the skeletal muscle exercise pressor reflex.

Question 36

The net effect of BP control is an exercise-induced increase in sympathetic nerve activity and decrease in parasympathetic nerve activity that is actively modulated by the?

Answer 36

arterial | baroreflex.

Question 37

Blood pressure control in exercise downstream effects

Answer 37

``` Increases in heart rate (HR), cardiac output (CO), cardiac contractility, and blood pressure along with elevations in arterial resistance and reductions in venous capacitance ```