Control of Blood Flow

Question 1

What are blood vessels used for?

Answer 1

• delivery of nutrients
• removal of waste

Question 2

How do blood vessels deliver nutrients?

Answer 2

microvascular exchange

Question 3

What is the total volume of capillaries?

Answer 3

4.8 liters

Question 4

What is the blood volume in capillaries?

Answer 4

1.8 liters

Question 5

What is the relationship between blood volume and total volume in capillaries?

Answer 5

blood volume in capillaries is less than total capillary volume

Question 6

Where is the blood velocity the lowest?

Answer 6

in capillaries

Question 7

What is the difference in speeds of blood velocity throughout the body?

Answer 7

fast in major arteries> slows down in capillaries> fast towards heart> slow in lungs

Question 8

Where is blood volume the most?

Answer 8

in veins

Question 9

Veins are known as what?

Answer 9

capacitance vessels

Question 10

Arterioles are known as what?

Answer 10

resistance vessels

Question 11

What is the function of arterioles?

Answer 11

regulate systemic vascular resistance

Question 12

What do arterioles respond to?

Answer 12

1. tissue demand
2. flow and pressure inside the vessel
3. neurogenic stimuli
4. hormones, drugs, other chemical stimuli

Question 13

What is the regulation of arteriolar tone?

Answer 13

Ca comes into smooth muscle muscle and causes contraction

Question 14

How does the sympathetic nervous system control arteiolar tone?

Answer 14

1. releases norepinephrine
2. alpha receptors on vascular smooth muscle cells cause constriction
3. IP3 causes Ca release from sarcoplasmic reticulum

Question 15

How does the parasympathetic nervous system control arteiolar tone?

Answer 15

1. Ach binds to muscarinic receptors on endothelial cells
2. activates eNOS: nitric oxide diffuses to VSMC> soluble GC> cGMP> dilation

Question 16

What is the process of preparation of autoregulation of blood flow?

Answer 16

1. endothelium NOT involved
2. myogenic response eliminated by treatment with nitrates
3. VSMC alone is required

Question 17

What is included in the autoregulation of blood flow?

Answer 17

1. pressuere is raised/lowered equally t both ends
2. vessel diameter can b edtermined precisely using microscopy
3. endothelial cells can be removed mechanically or chemically

Question 18

What is the myogenic hypothesis of autoregulation?

Answer 18

vascular smooth muscle contracts in repsonse to an increase in pressure

increased transmural pressure> increased stretch> constriction

Question 19

What is active hyperemia?

Answer 19

increased metabolic activity creates byproducts that induce and increase blood flow

example: doing multiple reps at gym

Question 20

What is reactive hyperemia?

Answer 20

buildup of waste products induce reactive hyperemia once blood flow is reestablished

example: having boulder fall on arm and taken off some time after

Question 21

What is the mtabolic hypothesis of autoregulation?

Answer 21

lack of O2> metabolic byproducts> vasodilation

Question 22

What is the flaw of the metabolic hypothesis?

Answer 22

flawed when attempting to explain what happens when blood flow increases

Question 23

What is the flaw of the metabolic hypothesis?

Answer 23

flawed when attempting to explain what happens when blood flow increases

Question 24

What is the flaw in the myogenic hypothesis?

Answer 24

does a poor job of explaining how metabolic activity or increased flow leads to dilation

Question 25

What occurs with pressure with flow-induced vasodilation?

Answer 25

pressure is increased on one side and lowered on the other equally ## Footnote increased flow without changing pressure

Question 26

What is the endothelial regulation of blood flow?

Answer 26

senses mechanical forces and stimulates vasodilation in response to an increase in flow by producing an "endothelial-derived relaxing factor" (nitric oxide)

Question 27

What is the summary local control of blood flow?

Answer 27

* metabolic autoregulation -> metabolism * myogenic autoregulation -> pressure * endothelial-dependent control of arteriolar tone -> flow * autonomic nervous system

Question 28

What are the 3 types of blood capillaries?

Answer 28

* continuous: cell-cell junctions (allows least amount of things through) * fenestrated: fenestrae (only fluid) * sinusoidal: caveolae

Question 29

Are blood capillaries permeable?

Answer 29

YES

Question 30

What is blood vessel permeability is required for?

Answer 30

1. bathing tissues in nutrients and removal of wastes 2. maintaining basal permeability to prevent edema 3. inflammatory responses: increased vascular permeability is the first step in inflammation 4. regulating the transmigration of immune cells to fight infection/resolve inflammation

Question 31

What are the 4 R's of inflammation?

Answer 31

* tumor: swelling * rubor: redness * calor: hot * dolor: pain

Question 32

How does material leave the capillaries?

Answer 32

by convection (filtration) or diffusion (osmosis)

Question 33

What is Ernest Starlings hypothesis on the law of filtration?

Answer 33

fluid is filtered from the arterial side of the capillary bed and 90% is reabsorbed on the venous side

Question 34

What is the formula for Ernest Starling's hypothesis?

Answer 34

Jv/s = Lp [(Pc-Pi) - sigma (pi c - pi i)]

Question 35

Why was Ernest's theory incorrect?

Answer 35

becuase vessels cannot both filter and reabsorb fluid

Question 36

If Jv/s is negative then...

Answer 36

more fluid flows in

Question 37

If Jv/s is positive then...

Answer 37

mroe fluid flows out, high hydrostatic, low oncotic

Question 38

What the formula of Fick's first law of diffusion?

Answer 38

Js = PS change in C= PS (Cc - Ci)

Question 39

What is Fick's first law of diffusion?

Answer 39

molecules move from the higher conc. to the lower conc.

Question 40

What is the process of lymphatic vasculature?

Answer 40

1. lymphatic vessels begin in tissues as bilnd ended sacs that absorb big cells 2. large/immune cells merge into collecting lymphatic vessels 3. lymphatic vesslels take immune cells to lymph nodes -> immune reactions 4. lymph nodes -> thoracic duct -> left subclavian vein

Question 41

What is tissue fluid homeostasis?

Answer 41

removal of excess fluid from tissue

Question 42

What is the role of lymphatic vessels during tissue fluid homeostasis?

Answer 42

* actively pump * regulate endothelial permeability

Question 43

How do lymphatic vessle prevent edmea?

Answer 43

* increased tissue pressure drives lymph flow, which clears excess fluid * being permeable ## Footnote must have hydrostatic pressure

Question 44

What is the largest lymphatic and empties all lymph into left subclavian vein?

Answer 44

thoracic duct

Question 45

What is responsible for 85% of osmotic pressure gradient and is removed from tissues by lymphatic vasculature?

Answer 45

albumin

Question 46

What is lymphedema?

Answer 46

occurs when lymphatic vessels fail to remove fluid and interstitial fluid builds up

Question 47

What does increased lymphatic vessel permeability lead to?

Answer 47

adipose deposition and obesity

Question 48

Cholesterol removal from atherosclerotic plaques depend on what?

Answer 48

lymphatic vessels