Ch. 15

Front 1

distributed

Back 1

Blood does NOT flow equally to all organs but instead gets ____________ among the organs based on need.

Front 2

Extrinsic control mechanisms
local control.

Back 2

________ _________ _________ provide adequate arterial pressure for all organs in the systemic circuit, but only an individual organ or tissue can really "know" how much blood it needs at any given time, and it so it regulates its own blood flow thorugh _______ ________.

Front 3

vascular resistance

Back 3

Changes in the distribution of blood flow to organs - that is, changes in the percentage of cardiac output supplied to each organ - due to changes in _________ __________ of individual organs.

Front 4

vascular resistance

Back 4

The __________ __________ of an organ (or tissue) is altered by the contraction or relaxation of smooth muscle in arterioles (and small arteries).

Front 5

vasoconstrict
vasodilate

Back 5

Arterioles can _________ or _________ in response to intrinsic factors, thereby changing the resistance to blood flow.

Front 6

Intrinsic control mechanisms

Back 6

___________ _______ _________ regulate NOT only the distribution of blood flow among the organs, but also the distribution of blood flow w/in the organs.

Front 7

Intrinsic

Back 7

_________ mechanisms are responsible for the sharing of flow among cap beds.

Front 8

heart, brain and skeletal muscle

Back 8

Intrinsic control is especially important in regulating blood flow to the _______, _______, and ________ ________.

Front 9

1) Neural mechanisms play only a minor role in regulating blood flow to the heart & brain.
2) Metabolic activity in the heart & skeletal muscles can vary greatly, changing there demands for 02 and nutrients.

Back 9

What are the 2 reason why intrinsic mechanisms are important?

Front 10

metabolic activity

Back 10

________ ________ of the brain as a whole is relatively constant, activity varies from region to region w/in the brain.

Front 11

increase
decreasing

Back 11

Intrinsic mechanisms work on a continual basis to _________ blood flow to regions that are becoming more active while reducing flow to those whose activity is __________.

Front 12

relaxation
contraction

Back 12

Intrinsic control of organ flow is accomplished through __________ or __________ of smooth muscle in arterioles, which control the flow through individual cap beds w/in an organ or tissue.

Front 13

vascular smooth muscle

Back 13

What senses whether blood flow is adequate or not?

Front 14

1. changes in metabolic activity
2. changes in blood flow
3. stretch of arteriolar smooth muscle
4. local chemical messengers

Back 14

What are the 4 factors that vascular muscle responds to regulation?

Front 15

extracellular fluid
metabolic activity

Back 15

Vascular smooth muscle cells in arterioles are sensitive to condition in __________ ______ & respond to changes in the concentrations of a wide variety of chemical substances, including 02, CO2, K+ ions, H+ ions, and others. These change in concentrations occur as a result _________ ________.

Front 16

contracts
relaxes

Back 16

Arteriolar smooth muscle either ________ or _________ depending on whether concentrations of particular substances rises or falls.

Front 17

vasodilation
vasoconstriction

Back 17

Changes associated w/ increased metabolic activity generally cause __________, whereas changes associated with decreased metabolic activity induce ___________.

Front 18

ischemia

Back 18

blood flow is insufficient to keep up w/ metabolic demand

Front 19

02
c02

Back 19

The decrease in _________ & the increase in ________ ________ both act on arteriolar smooth muscle, causing it to relax.

Front 20

vascular resistance

Back 20

When the muscle relaxes, ________ _________ in tissue drops, and blood flow in that region increases.

Front 21

active hyperemia

Back 21

higher than normal rate of blood flow following metabolic activity.

Front 22

02
CO2

Back 22

________ delivery to the tissue & _______ _______ removal from the tissue increases & eventually a new steady state is acheived.

Front 23

active hyperemia
nerves or hormones

Back 23

______ _________ is an example of intrinsic control, because the change of blood flow has a direct affect of the reduced oxygen & elevated C02 on arterioles themselves, & that no ______ or _________ are involved.

Front 24

Tissue 02
metabolic concentration

Back 24

_______ _______ & __________ ____________ can also change as a result of changes in blood flow.

Front 25

vasodilation
vascular resistance

Back 25

If blood flow is blocked, the 02 concentration falls and the CO2 production exceed rates of delivery & removal. Both induce _________ & a reduction in _________ _________ tends to increase in blood flow.

Front 26

Reactive hyperemia

Back 26

an increase in blood flow in response to a previous reduction in blood flow.

Front 27

reactive hyperemia

Back 27

The basic mechanism underlying ________ _________ is the same as that for active hyperemia - decreases in tissue oxygen & increases in metabolic concentrations induce vasodilations & an increase in blood flow.

Front 28

concentration

Back 28

The only difference in reactive and active hyperemia in the CAUSE of the changes in _____________.

Front 29

reverse
intrinsic control mechanisms

Back 29

The sequence of events occuring in reactive hyperemia also works in _________ : if blood flow rise above what is required for metabolic needs, ________ ________ __________ will induce vasoconstriction & a reduction in blood flow.

Front 30

stretch - sensitive fibers

Back 30

They are responsive to stretch which occurs when pressure of blood w/in the arterioles increases

Front 31

myogenic response

Back 31

a change in vascular resistance that occurs in response to stretch of blood vessels, and that does NOT requirs the action of sympathetic nerves, bloodbourne, or other chemical agents.

Front 32

Perfussion pressure

Back 32

the pressure gradient that drives blood flow through a given organ or tissue

Front 33

Negative feedback loop

Back 33

Myogenic control of vascular resistance in response to change in perfusion pressure is similar to the other intrinsic control mechanisms involves a _________ _________ _____.

Front 34

flow autoregulation

Back 34

local regulation that tends to keep blood flow constant.

Front 35

vascular smooth muscle

Back 35

Contractile activity of __________ ______ _______ is also affected by a variety of chemical substances, most of which are secreted by blood vessels endothelial cells or by cells in surronding tissues.

Front 36

Nitric oxide

Back 36

released on a continual basis by endothelial cells in arterioles & act on smooth muscle to promote vasodilation.

Front 37

bradykinin
histamine

Back 37

substances produces by inflamed tissues, such as _________ & _________, stimulate nitric oxide synthesis. The resulting increase in blood flow accounts for redness of inflamed areas.

Front 38

Prostacyclin

Back 38

an eicosanoid that functions in preventing blood clots

vasodilator

Front 39

Adensine

Back 39

an important vasodilator in the coronary arteries.

Front 40

Endothelin -1

Back 40

substance that promote vasoconstriction