Q2-Physiology-Exam3-Definitions

Front 1

Regulation

Back 1

maintenance of a CONSTANT level

Front 2

Control

Back 2

CHANGING the activity level

Front 3

reflex arc

Back 3

a feedback loop resulting in an involuntary response to a stimulus that travels through afferent pathway to CNS then through efferent pathway to effector organ

Front 4

baroreceptor

Back 4

pressure sensitive mechanoreceptor in carotid sinus (and aortic arch and other large thoracic arteries) that provide short-term regulation of mean arterial blood pressure

Front 5

afferent pathway

Back 5

from receptor to CNS

Front 6

efferent pathway

Back 6

from CNS to effector organ

Front 7

effector organ

Back 7

final destination of efferent stimulus. for BP, effector organs are heart, resistance vessels, capacitance vessels, and adrenal medulla

Front 8

adaptation

Back 8

afferent output of baroreceptors resets in the face of CHRONIC change in pressure

Front 9

tonic activity

Back 9

static (always firing); dependent on MAGNITUDE of mean arterial pressure

Front 10

phasic activity

Back 10

dynamic; reflects the RATE OF CHANGE of pressure

Front 11

Pressor / Depressor

Back 11

vasomotor centers that control peripheral vascular resistance;
Pressor - controls sympathetic outflow to peripheral vasculature;
Depressor - inhibits pressor center activity

Front 12

Orthostatic hypotension

Back 12

baroreceptor reflex arc fails to compensate for effects of gravity

Front 13

extrinsic control

Back 13

mediated by ANS and circulating hormonal factors, and is systemic (outside of tissue)

Front 14

intrinsic control

Back 14

local control based on needs of tissue (inside of tissue)

Front 15

vasomotion

Back 15

normal pattern of rhythmic changes in flow within a capillary bed

Front 16

autoregulation

Back 16

intrinsic ability of an organ or tissue to alter local vascular resistance to maintain a constant blood flow despite changes in perfusion pressure

Front 17

metabolic vasoregulation

Back 17

ability of a tissue to control blood flow to meet the metabolic needs

Front 18

autocoids

Back 18

locally produced vasoactive substances (generally potent vasodilators)

Front 19

myogenic

Back 19

rapid stretch of vascular smooth muscle causes it to contract, resulting in increased resistance

Front 20

endogenic

Back 20

endothelial cells produce two relaxation factors (i.e. NO), a contracting factor, and a hyperpolarizing factor which affect resistance

Front 21

reactive hyperemia

Back 21

when flow to ischemic tissue is restored, flow increases exceed the pre-ischemic levels

Front 22

active hyperemia

Back 22

increase in metabolic activity results in increase in local flow

Front 23

shear stress

Back 23

increased friction causes endothelial cells to produce and release NO

Front 24

Nitric oxide

Back 24

an endothelium-derived relaxation factor (EDRF)

Front 25

endothelin

Back 25

a 21 aa peptide; most potent vasoconstrictor identified

Front 26

terminal arteriole

Back 26

a.k.a. metarterioles; last arterioles before capillaries

Front 27

exchange vessels

Back 27

capillaries and small venules

Front 28

diffusive flux

Back 28

the magnitude and net direction of diffusion

Front 29

bulk flow

Back 29

the movement of small solutes WITH WATER out of capillaries

Front 30

gel matrix

Back 30

an entangled meshwork consisting primarily of hyaluronic acid

Front 31

fluid trapping

Back 31

a function of the gel matrix; prevents the free flow of interstitial fluids, especially in response to gravity

Front 32

capillary hydrostatic pressure

Back 32

pushes water out of capillaries

Front 33

interstitial hydrostatic pressure

Back 33

pulls water out of capillaries (negative interstitial pressure)

Front 34

plasma oncotic pressure

Back 34

due primarily to plasma proteins and the cations they attract; results in net movement of water INTO exchange vessels

Front 35

interstitial oncotic pressure

Back 35

is less than plasma oncotic pressure; net movement of water into exchange vessels

Front 36

terminal lymphatic vessels

Back 36

small blind-ended tubes composed of a single layer of endothelial cells surrounded by little or no basement membrane

Front 37

lymph

Back 37

the fluid filtered by the exchange vessels, but not reabsorbed

Front 38

myogenic contraction

Back 38

contraction of pre-capillary arterioles to reduce capillary pressure

Front 39

capillary filtration coefficient

Back 39

describes the conductance of an exchange vessel wall to water

Front 40

reflection coefficient

Back 40

describes the permeability of a microvascular bed to plasma proteins

Front 41

net driving force

Back 41

the direction of flow taking all forces into account

Front 42

net fluid flux

Back 42

?

Front 43

lymphatic pump

Back 43

increase in interstitial pressure forces water into lymphatic vessels and along one-way channels toward the heart

Front 44

edema

Back 44

the presence of excess fluid in the tissues