Regional Circulations I, II

Question 1

Purpose of Autoregulation of arteriolar resistance?

Answer 1

maintain constant flow during pressure ∆

Question 2

Hyperemia is?

Achieved how?

Answer 2

Increased blood flow to body part

altering arteriolar resistance

Question 3

Active Hyperemia is a response to what?

Answer 3

↑ metabolic activity in tissues

Question 4

Reactive Hyperemia is a response to what?

Answer 4

↓ O2 delivery

(U) 2º to ↓ flow from obstruction

Question 5

Myogenic Hypothesis of Pressure

Answer 5

↑ P ->
↑ stretch ->
opens stretch-activated Ca2+ ->
↑ Ca2+ ->
contracts vessels ->
↓ flow

Opposite occurs w/ ↓ P

Question 6

Myogenic hypothesis explains?

Answer 6

autoregulation

does not explain active or reactive hyperemia

Question 7

Metabolic Hypothesis says what happens when ↑ in Pressure?

Answer 7

↑ P ->
↑ flow -> 
↑ O2 delivery ->
removes metabolic byproducts ->
vasoconstriction ->
↓ flow

Question 8

Metabolic Hypothesis says what happens when ↓in Pressure?

Answer 8

↓ P ->
↓ flow ->
↓ O2 delivery ->
↑ metabolic byproducts ->
relaxes vessels ->
↑ flow

Question 9

Metabolic hypothesis explains?

Answer 9

active and reactive hyperemia and autoregulation

Question 10

Arteriolar Resistance in Skeletal mm at Rest

Answer 10

arteriolar resistance ↑ due to:
↓ in dilation mediators,
resting symp vasoconstriction of α1 receptors

Question 11

Effects of symp stim of skeletal mm

Answer 11

epinephrine activates β2 receptors ->
vasodilation ->
metabolic byproducts (adenosine, CO2, K)

Question 12

α1 adrenergic receptors:

location
chem mediator
result

Answer 12

all arteriolar smooth mm

Norepi (from symp fibers),
Epi (from adrenal medulla)

Vasoconstriction

Question 13

β2 adrenergic receptors:

location
chem mediator
result

Answer 13

arteriolar smooth mm heart, skeletal

Epi (from adrenal medulla)

Vasodialation

Question 14

Coronary Circulation:

Reactive Hyperemia in LV

Answer 14

↑ LV wall pressure during systole occludes coronary circulation ->

↓ L coronary vascular resistance ->
↑ L coronary flow during diastole

Question 15

Symp stim of cardiac mm

Answer 15

activates β1 rec ->
↑ chrono and inotropics ->
↑ metabolism/byproducts ->
↓ O2 -> 
vasodilation

Question 16

Symp stim of coronary vasculature

Answer 16

activates α1 receptors ->

vasoconstriction

Question 17

During exercise, which mediator dominates?

Answer 17

vasodilators

Question 18

Normal perfusion of blood in brain tissue?

Answer 18

50 ml/min/100g of tissue

Question 19

Normal cerebral perfusion pressure = ?

Answer 19

map - Intracranial Venous Pressure

(U) ~ 85 mmHg

Question 20

Cushing Reflex

Answer 20

Response to ↑ ICP:

symp NS causes widespread vasoconstriction ->
↑ systemic arterial pressure

Question 21

Primary method for ↑ flow in brain?

Answer 21

metabolic: ↑ CO2 and H+

Question 22

Symp innerv of brain vasculature:
receptors
action

Answer 22

α1 receptors

vasoconstriction

Question 23

Parasymp innerv of brain:
neurotransmitter
action

Answer 23

ACh

vasodilation

Question 24

Cerebral blood flow regulation highly dependent on?

Answer 24

mental activity,

is highly localized

Question 25

Range of mean arterial pressure in renal circulation

Answer 25

80 - 170 mmHg

Question 26

Renal circulation autoregulates how?

Answer 26

↑ renal artery P -> 1) myogenic vasoconstr of afferent (supply organ) arterioles 2) ↑ glomerular filtration rate -> ↑ water delivery -> ↑ release of vasoconstrictors

Question 27

Anterior hypothalamus' fxn in temp regulation?

Answer 27

coordinates mechanisms of heat generation/loss

Question 28

Anterior hypothalamus receives input from?

Answer 28

own thermoreceptors and | receptors in skin

Question 29

Anterior hypothalamus generates heat how?

Answer 29

↑ metabolic rate shivering vasoconstrict skin bv (↑ SNS tone)

Question 30

Anterior hypothalamus dissipates heat how?

Answer 30

↓ SNS tone to skin bv vasodial skin bv (↑ BF) shunt blood to skin surface

Question 31

Fear causes vaso?

Answer 31

constriction

Question 32

Embarrassment causes vaso?

Answer 32

dilation

Question 33

What causes hyperemic responses?

Answer 33

Deficiency in O2 in tissues

Question 34

% breakdown of blood distribution per organ/system: ``` Cerebral Coronary Renal GI Skeletal mm Skin ```

Answer 34

Cerebral 15% Coronary 5% Renal 25% GI 25% Skeletal mm 25% Skin 5%

Question 35

During exercise, what happens to distribution of CO to: Skin Heart Skeletal mm

Answer 35

skin: ↑ 370% heart: ↑ 367% skeletal mm: ↑ 1066%

Question 36

During exercise, what happens to distribution of CO to: Brain GI Bone, misc

Answer 36

brain: no change GI: ↓ 45-56% Bone: ↓ 30%

Question 37

R Coronary Artery supplies blood to?

Answer 37

R vent | R atrium

Question 38

L coronary Artery supplies blood to?

Answer 38

L vent | L atrium

Question 39

Skin densely innervated by?

Answer 39

Sympathetics | no parasymps

Question 40

Purpose of SNS innervation of skin?

Answer 40

body temp regulation

Question 41

Local metabolic control is most important for what circulations? (5)

Answer 41

1) coronary 2) cerebral 3) exercising skeletal mm 4) pulmonary 5) renal

Question 42

Sympathetic control is most important for what circulations?

Answer 42

1) resting skeletal mm | 2) skin

Question 43

Vasoactive metabolites in coronary circulation?

Answer 43

hypoxia | adenosine

Question 44

Vasoactive metabolites in cerebral circulation?

Answer 44

CO2 | H+

Question 45

Vasoactive metabolites in skeletal mm circulation?

Answer 45

lactate K+ adenosine

Question 46

Vasoactive metabolites in pulmonary circulation?

Answer 46

hypoxia

Question 47

Metabolic hypothesis states?

Answer 47

If O2 delivery to tissue cannot keep up with consumption, metabolic by-products accumulate. Metabolic by-products induce smooth muscle relaxation and enhance flow.