Control of Tissue Blood Flow

Question 1

Most tissues have the ability to control their own blood flow in proportion to

Answer 1

their own specific metabolic needs

Question 2

What are the specific needs of tissues? (6)

1. Delivery of ____ to tissues
2. Delivery of ____ to tissues (such as?)
3. Removal of ___ from tissues
4. Removal of ___ from tissues
5. Maintaining proper what?
6. Transportation of what?

Answer 2

1. Delivery of O2 to tissues
2. Delivery of nutrients (glucose, amino acids, fatty acids)
3. Removal of CO2 from tissues
4. Removal of H+ ions from tissues
5. Maintaining proper concentrations of ions in tissues
6. Transport hormones and other substances to different tissues

Question 3

Acute control of blood flow occurs within (time frame)

Answer 3

seconds to minutes

Question 4

Long term control of blood flow occurs within

Answer 4

days, weeks or even months

Question 5

Acute control includes rapid changes in local vasodilation or vasoconstriction of _____, meta-_____ and pre-capillary _____

Answer 5

arterioles, meta-arterioles, pre-capillary sphincters

Question 6

Angiogenesis

Answer 6

new vessel formation

Question 7

Long term control includes ____ controlled changes that result from an increase or decrease in physical ____ and numbers of blood vessels supplying the ____

Answer 7

slow
size
tissues

Question 8

Effect of Oxygen availability examples (3)

Answer 8

1. High Altitude
2. Pneumonia
3. Carbon Monoxide Poisoning

Question 9

Vasodilator Theory includes either

Answer 9

less available o2 OR greater rate of metabolism, which leads to the greater rate of formation of vasodilator substances in tissue cells

Question 10

What intense vasodilator is important for the body?

Answer 10

Adenosine

Question 11

Substances will diffuse through the tissues to cause

Answer 11

vasodilation

Question 12

Nutrient (Oxygen) Theory states that O2 and other nutrients are required to cause

Answer 12

vascular muscle contraction

Question 13

In the absence of O2, blood vessels will

Answer 13

dilate and relax

Question 14

Increasing metabolism will result in increase of ____, which would decrease the availability of O2 to the smooth muscle fibers in local blood vessels causing ____

Answer 14

O2; vasodilation

Question 15

The # of precapillary sphincters that are open at any given time is roughly proportional to the

Answer 15

requirements of tissue for nutrition

Question 16

Opening and closing of the precapillary sphincters is cyclical depending on the (also known as…)

Answer 16

metabolic needs of the tissue (Vasomotion)

Question 17

Oxygen is a requirement for what muscle type to remain contracted?

Answer 17

smooth

Question 18

Strength of the contraction of the sphincters increases with`

Answer 18

O2 concentration

Question 19

Sphincters remain closed until the cells…

Answer 19

consume excess O2

Question 20

When O2 is gone, or the O2 concentration falls low enough, the sphincters would

Answer 20

open once more to being cycle again

Question 21

Reactive Hyperemia is the

Answer 21

occlusion of blood flow for a few seconds or longer

Question 22

When blood flow is restored, it increases immediately to

Answer 22

4-7x the normal

Question 23

Active Hyperemia is

Answer 23

any tissue becomes highly active

increase in metabolism causes cells to consume tissue fluid nutrients rapidly and release large quantities of vasodilator substances

blood flow increases immediately as much as 20-fold during intense exercise

Question 24

A rapid increase in arterial pressure causes an immediate rise in

Answer 24

blood flow

Question 25

A compensatory mechanism occurs within less than a minute and blood flow returns to almost normal levels even though arterial pressure is kept elevated. This is known as...

Answer 25

autoregulation

Question 26

Metabolic Theory of Autoregulation states

Answer 26

too much O2 causes vasoconstriction

Question 27

Myogenic Theory of Autoregulation states

Answer 27

stretch of small blood vessels causes smooth muscle of vessel wall to contract

Question 28

Endothelial-derived relaxing factor

Answer 28

substances derived from endothelial cell lining blood vessels; major one is Nitric Oxide (NO)

Question 29

NO is a

Answer 29

lipophilic gas released from endothelial cells in response to stimuli

Question 30

NO causes

Answer 30

blood vessels to relax

Question 31

Damage to the endothelial cells can lead to

Answer 31

hypertension or artherosclerosis

Question 32

Impairing NO synthesis contributes to excess

Answer 32

vasoconstriction (think: tight chest pain, angina)

Question 33

Nitroglycerin and nitrate derivatives treat angina because they increase

Answer 33

coronary blood flow via vasodilation

Question 34

Which powerful vasoconstrictor prevents bleeding out and greatly increases when vessels are injured?

Answer 34

Endothelin

Question 35

Drugs that block endothelin receptors have been used to treat what?

Answer 35

pulmonary hypertension because you want to vasodilate & decrease BP

Question 36

Humoral control of the circulation means

Answer 36

control by substances secreted or absorbed into the body fluids such as hormones and locally produced factors

Question 37

A powerful vasoconstrictor that is released when the sympathetic nervous system is stressed or exercising is

Answer 37

Norepinephrine (noradrenalin) Excited the heart, contracts veins and arteries

Question 38

A less powerful vasoconstrictor that can cause mild vasodilation (such as decreasing an allergic reaction via Epi-Pen) is

Answer 38

Epinephrine

Question 39

A powerful vasoconstrictor hormone that constricts the small arterioles and increases blood pressure dramatically is

Answer 39

Angiotensin II

Question 40

Angiotensin II increases BP dramatically by (2)

Answer 40

increasing total peripheral resistance | decreasing sodium and water excretion by kidneys

Question 41

An even more powerful vasoconstrictor than Angiotensin II that helps to control body fluid volume by increasing water reabsorption from renal tubules back into the blood is

Answer 41

Vasopressin (ADH)

Question 42

A powerful vasodilatory only activated for a few minutes that causes powerful arteriolar dilation, increased capillary permeability, local edema and has a special role in regulating flow and fluids in inflamed tissue

Answer 42

Bradykinin

Question 43

Derived from mast cells and released in every tissue of the body if it is damaged/inflamed/allergically reacting is known as

Answer 43

Histamine also a powerful arteriolar dilator, increases capillary permeability and plays large role in edema

Question 44

What increases in both number and size within a few weeks to match the needs of tissues?

Answer 44

Arterioles & Capillary Vessels

Question 45

If metabolism in tissue is increased for a prolonged period, what increases?

Answer 45

its vascularity

Question 46

If metabolism in tissue is decreased for a prolonged period, what decreases?

Answer 46

its vascularity

Question 47

Where atmospheric oxygen is LOW such as in high altitudes, what increases?

Answer 47

vascularity example: mountain goats have a high vascularity due to the formation of angiogenic growth factors aiding in the increased need for O2

Question 48

Why do premature babies tend to have eye issues?

Answer 48

Increased O2 in the NICU causes retinopathy

Question 49

Formation of new blood vessels is known as

Answer 49

angiogenesis

Question 50

Deficiency of tissue oxygen or other nutrients leads to formation of what factors?

Answer 50

angiogenic

Question 51

What are 4 main angiogenic factors?

Answer 51

1. VEGF - vascular endothelial growth factor 2. Fibroblast growth factor 3. PDGF - platelet derived growth factor 4. Angiogenin

Question 52

What are 2 main angiogenesis inhibitors?

Answer 52

1. Angiostatin - fragment of protein plasminogen 2. Endostatin - derived from breakdown of collagen type XVII can impair the rapid growth of cancerous tumors

Question 53

4 main application to know in regards to Vascularity

Answer 53

1. Chronic Exercise Training 2. Development of Collateral Circulation 3. Hypertension 4. Bypass Graft Procedures

Question 54

In chronic exercise training, vascularity of trained muscles _____ to accommodate their higher blood flow

Answer 54

increases

Question 55

Development of collateral circulation is when a blockage of a vein or artery will facilitate a

Answer 55

new vascular channel to develop around the blockage to allow partial resupply of blood to affected tissues

Question 56

HTN causes what kind of remodeling? What does it do?

Answer 56

Hypertrophic Remodeling Occurs in large arteries to increase the size of smooth muscle cells and stimulate formation of the extracellular matrix proteins in order to reinforce the strength of the vascular wall **MAKES THE LARGE BLOOD VESSELS STIFFER

Question 57

Bypass Graft Procedures usually take which vein from the leg to sew into the aorta and connect to a coronary artery?

Answer 57

Saphenous

Question 58

Take Homes of Control of Tissue Blood Flow (5)

Answer 58

1. Less O2 OR increased metabolism will increase vasodilator substances in tissue cells 2. Active Hyperemia/Reactive Hyperemia increase blood flow acutely 3. Endothelial Nitric oxide synthase will synthesize NO and thus dilate larger blood vessels 4. Powerful humoral vasoconstrictors include Norepinephrine, Vasopressin and Angiotensin II (acutely) 5. Increase in metabolism or decrease in O2 over a prolonged period of time causes increase in vascularity (angiogenesis) which contributes to long-term blood flow regulation