Microcirculation

Question 1

Blood volume (%CO) increases blood flow to what 4 places?

Answer 1

brain. kidneys, liver, and muscle

Question 2

Blood volume/tissue weight increases relative blood flow for what 6 places?

Answer 2

brain, kidneys, liver, heart, thyroid gland, and adrenal gland

Question 3

When precapillary sphincters are open, blood flows to _____.

Answer 3

capillaries

Question 4

When precapillary sphincters are closed, blood flows to ____.

Answer 4

metarterioles

Question 5

When arteriovenous anastomosis (AVA) is open, blood passes through ______.

Answer 5

AVA

Question 6

When arteriovenous anastomosis (AVA) is closed, blood passes through ______.

Answer 6

capillary bed

Question 7

_____ is the intermittent blood flow through the capillaries, turning on/off every few seconds or minutes.

Answer 7

Vasomotion

Question 8

_____ originated from altering periods of vasoconstriction and vasodilation of metarterioles and precapillary sphincters.

Answer 8

Vasomotion

Question 9

What types of endothelial junctions do capillaries have?

Answer 9

only a few tight junctions

Question 10

Capillary exchange is mediated by what three thing?

Answer 10

intercellular clefts
fenestrations
caveolae (plasmalemmal vesicles)

Question 11

____ are curving channels between endothelial cells.

Answer 11

intercellular clefts

Question 12

____ are pores within the plasma membrane.

Answer 12

fenestrations

Question 13

True or False? Fenestrations have larger diameter than intercellular clefts

Answer 13

True

Question 14

____ are invaginations of the plasma membrane that may coalesce to form vesicular channels all the way through the endothelial cell.

Answer 14

Caveolae

Question 15

______ and _____ has a role in diffusion of water-soluble ions and small solutes.

Answer 15

Intercellular clefts and Fenestrations

Question 16

_____ has a role in transcytosis of macromolecules, mainly plasma proteins, through the endothelium.

Answer 16

Caveolae

Question 17

What can’t pass through the blood-brain barrier (BBB)?

Answer 17

most neurotransmitters and toxins and bacteria

Question 18

Width of pores and fenestrations are smaller than albumin. Any molecule/cell larger than albumin will only pass through _____ capillaries.

Answer 18

sinusoid

Question 19

Continuous capillaries contain _____.

Answer 19

intercellular clefts

Question 20

Fenestrated capillaries contain _____.

Answer 20

fenestrations

Question 21

The _____ are the Hydrostatic and Colloid Osmotic Forces that Determine whether fluid will move out of the blood into he IF or in the opposite direction.

Answer 21

four Starling forces

Question 22

Name the 4 Starling forces.

Answer 22

Hydrostatic:
- capillary pressure
- interstitial fluid pressure
Osmotic:
- plasma colloid osmotic pressure
- interstitial fluid colloid osmotic pressure

Question 23

____ states that the fluid movement across the wall of a capillary is dependent on the balance between the hydrostatic pressure gradient and the oncotic pressure gradient across the capillary.

Answer 23

Starling’s hypothesis

Question 24

The change in _____ is the major factor responsible for the filtration-absorption along the capillary

Answer 24

hydrostatic pressure

Question 25

True or False? The change in hydrostatic pressure helps in the blood flow along the capillary.

Answer 25

True

Question 26

Filtration on the arterial side is slightly ____ than the absorption on the venous side.

Answer 26

larger

Question 27

______: the amount of fluid filtering from the arterial ends equals almost exactly the fluid by absorption.

Answer 27

Starling equilibrium

Question 28

Excess of filtration (Net fluid filtration) is the fluid that must be returned through the ______.

Answer 28

lymphatics

Question 29

What is the normal rate of net filtration in the entire body, not including the kidneys?

Answer 29

about 2 ml/min (2 L/day)

Question 30

True or False? Blood flow is regulated at the minimal level that will supply each tissue's requirements --- heart workload is kept at a minimum.

Answer 30

True

Question 31

What is the most important of the endothelial-derived relaxing factors?

Answer 31

Nitric Oxide

Question 32

____ is a lipophilic gas continually released from endothelial cells in response to a variety of chemical, physical, and mechanical stimuli (shear forces).

Answer 32

Nitric Oxide

Question 33

Endothelial-derived nitric oxide synthase (eNOS) enzymes synthesize NO from ____ and _____ (in the presence of Ca2+), in endothelial cells.

Answer 33

arginine and oxygen

Question 34

____ acts locally in tissues around due to 6 second half life.

Answer 34

NO

Question 35

NO diffuses into the vascular smooth muscle cells where it activates _____.

Answer 35

soluble guanylate cyclases

Question 36

What are the five actions of NO?

Answer 36

- direct vasodilation - indirect vasodilation by inhibiting vasoconstriction - anti-thrombotic effect (inhibits platelet activation and vasospasm) - anti-inflammatory effect (inhibits leukocyte adhesion to endothelium) - anti-proliferative effect (inhibits smooth muscle hyperplasia)

Question 37

What happens when NO reacts with the iron-containing heme groups of oxyhemoglobin in the erythrocytes?

Answer 37

NO is rapidly destroyed

Question 38

___ plays a role in the control of blood flow in the heart, blood vessels, brain and muscle.

Answer 38

Adenosine

Question 39

How does adenosine regulate cardiac blood flow and function?

Answer 39

- it regulates coronary blood flow (binding to AR2): vasodilation of coronary arterioles - it regulates heart rate, contractility (binding to AR1): action through SA and AV nodes

Question 40

____ has a role in vasodilation and capillary leakage of fluids during inflammation.

Answer 40

Bradykinin

Question 41

____ causes both powerful arteriolar dilation and increased capillary permeability.

Answer 41

Bradykinin

Question 42

____ has a powerful role in vasodilation and leakage of fluids in capillaries and arterioles.

Answer 42

Histamine

Question 43

____ is released upon tissue damage, inflammation, or an allergic reaction.

Answer 43

Histamine

Question 44

_____ is derived from mast cells in the damaged tissues and from basophils in the blood.

Answer 44

Histamine

Question 45

___ is an important vasodilator during hemostasis.

Answer 45

Prostacyclin

Question 46

___ is produced by endothelial cells.

Answer 46

Prostacycin

Question 47

_____ is a powerful vasoconstrictor, present in endothelial cells, but greatly released upon damage to the endothelium.

Answer 47

Endothelin

Question 48

_____ has an important role in hemostasis: helps prevent extensive bleeding from arteries as large as 5 mm in diameter.

Answer 48

Endothelin

Question 49

___ has a role in damage to the endothelium by hypertension.

Answer 49

Endothelin

Question 50

As little as one millionth of a gram of ___ can increase the arterial pressure of a human being 50 mm Hg or more.

Answer 50

Angiotensin II

Question 51

____ normally acts on many of the arterioles of the body at the same time to increase the total peripheral resistance and to decrease sodium and water excretion by the kidneys, thereby increasing the arterial pressure.

Answer 51

Angiotensin II

Question 52

_____ is the intrinsic ability of tissue to maintain a relatively constant blood flow despite large fluctuations in blood pressure.

Answer 52

Autoregulation