3.4.1. Regional Circulation

Question 1

Distribution of BF to tissues is:

Determined by ______________.

Influenced by _______________________.

Answer 1

Distribution of BF to tissues is:

Determined by local metabolic factors

Influenced by different intrinsic properties of each vascular bed

Question 2

What predominates cardiac output?

Answer 2

GI (25%)

Question 3

What is the system that requires the least blood?

Answer 3

The heart only needs 5% of the CO. Which is three times less than the brain.

Question 4

Blood flow is determined by local matabolic needs but is little affected by what?

Answer 4

Primarily determined by local metabolic NEEDS

However, there is little effect of local metabolites on BF

Question 5

Sympathetic stimulation _____ BF through skeletal muscle, but not cerebral circulation

Answer 5

Sympathetic stimulation increases BF through skeletal muscle

Question 6

Neural vs. local influence

Answer 6

Skeletal muscle Control
At rest - Regulated primarily by the neural influence

During exercise - Regulated predominantly by the local influence

Remember, BF is directly related to contractile state

Question 7

What is Maximal oxygen consumption (VO2 max)?

Answer 7

Maximum amount of oxygen your body can utilize in one minute

Question 8

Formula for aerobic endurance

Answer 8

VO2 = CO x (a- vO2)

[Fick equation]

Question 9

Factors affecting VO2 max

Answer 9

Heredity, sex, age, body composition, training (5-20%), others (e.g., EPO, blood doping)

Question 10

Arteriovenous anastomosis is controlled by what

Answer 10

SNS

Question 11

In the arteriovenous anastamosis, we constrict and divert blood into the superficial capillary during what?

Answer 11

Constrict and divert blood into the superficial capillary during low ambient temperature

Question 12

Oxygen requirements to maintain anastamoses

Answer 12

Very little

Question 13

BF through the skin is adjusted to maintain deep body temperatures by what mechanism?

Answer 13

BF through the skin is adjusted to maintain deep body temperatures by regulating ordinary arterioles and arteriovenous anastomosis

Question 14

Sweat glands secrete ______ which increases BF to skin and sweat glands

Answer 14

Sweat glands secrete bradykinin which increases BF to skin and sweat glands

Question 15

Unlike humans, mice maintain temperature by regulating BF to tail and do not sweat (result = what?)

Answer 15

Unlike humans, mice maintain temperature by regulating BF to tail and do not sweat (result = ↑↑↑temp, ↑↑↑HR, and ↑↑↑BP)

Question 16

More Fit = ____ BF and _____ in temp

Answer 16

More Fit = better BF and slower increase in temp

Question 17

What two things happen when transitioning from rest to exercise?

Answer 17

Increased demand for BF in the Heart, respiratory muscles, and active skeletal muscles

Increased demand for BF to dissipate heat via cutaneous vasodilation

Question 18

How does the CV system adjust to meet the demands of exercise?

Answer 18

↑ vascular resistance and ↓ BF to non-vital organs

↓ vascular resistance and ↑ BF to active muscles

↑ cardiac output

Question 19

Adenosine causes what?

Answer 19

Adenosine causes transient heart block in the atrioventricular (AV) node

It also causes endothelial-dependent relaxation of smooth muscle

Question 20

Mechanism of action for Adenosine

Answer 20

Via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell hyperpolarization by increasing outward K+ flux

Question 21

Why do surgeons use Adenosine to test fro blockages in coronary arteries?

Answer 21

One of Adenosine’s actions is to cause endothelial-dependent relaxation of smooth muscle

This causes dilation of the “normal” segments of arteries, i.e. where the endothelium is not separated from the tunica media by atherosclerotic plaque

This feature allows physicians to use adenosine to test for blockages in the coronary arteries, by exaggerating the difference between the normal and abnormal segments

Question 22

What cells release L-Lactate?

Answer 22

Optogenetically activated astrocytes release L-lactate,

Question 23

Functino of L Lactate

Answer 23

Optogenetically activated astrocytes release L-lactate, which excites locus coeruleus (LC) neurons and triggers release of norepinephrine

Question 24

LDH is responsible for what?

Answer 24

LDH is responsible for the conversion of NADH to NAD+ and back

Question 25

The near-equilibrium between free cytosolic NADH/NAD+ and lactate/pyruvate ratios established by LDH predicts that what?

Answer 25

predicts that transfer of additional electrons and protons from injected lactate to NAD+ will augment the elevated blood flows in stimulated retina and cortex, whereas transfer of electrons and protons from NADH to injected pyruvate will attenuate the elevated flows.

Question 26

What is one important function of NADH?

Answer 26

Fuels a signal cascade that increases NO radical production

Question 27

NO does what?

Answer 27

augments blood flow in photostimulated retina and visual cortex

Question 28

EDRF (endothelium-derived relaxing factor)

Answer 28

Promote smooth muscle relaxation

Analagous to NO

Question 29

EDHF (endothelial derived hyperpolarizing factor)

Answer 29

Hyperpolarizes vascular smooth muscle cells, causing the cells to relax, thus allowing the blood vessel to expand in diameter

Question 30

EDCF (endothelial derived contracting factor)

Answer 30

Endoperoxides (PGH2) and prostacyclin, which activate thromboxane-prostanoid (TP) receptors of the vascular smooth muscle cells

Question 31

PGs

Answer 31

Prostacyclins are synthesized in the walls of blood vessels and serves the physiological function of preventing needless clot formation