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PT 6282: Cardiopulmonary Physiology & Rehabilitation > Control of Tissue Blood Flow > Flashcards

Control of Tissue Blood Flow Flashcards

1
Q

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

A

their own specific metabolic needs

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2
Q

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?
A
  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
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3
Q

Acute control of blood flow occurs within (time frame)

A

seconds to minutes

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4
Q

Long term control of blood flow occurs within

A

days, weeks or even months

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5
Q

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

A

arterioles, meta-arterioles, pre-capillary sphincters

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6
Q

Angiogenesis

A

new vessel formation

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7
Q

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

A

slow
size
tissues

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8
Q

Effect of Oxygen availability examples (3)

A
  1. High Altitude
  2. Pneumonia
  3. Carbon Monoxide Poisoning
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9
Q

Vasodilator Theory includes either

A

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

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10
Q

What intense vasodilator is important for the body?

A

Adenosine

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11
Q

Substances will diffuse through the tissues to cause

A

vasodilation

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12
Q

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

A

vascular muscle contraction

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13
Q

In the absence of O2, blood vessels will

A

dilate and relax

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14
Q

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

A

O2; vasodilation

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15
Q

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

A

requirements of tissue for nutrition

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16
Q

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

A

metabolic needs of the tissue (Vasomotion)

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17
Q

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

A

smooth

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18
Q

Strength of the contraction of the sphincters increases with`

A

O2 concentration

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19
Q

Sphincters remain closed until the cells…

A

consume excess O2

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20
Q

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

A

open once more to being cycle again

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21
Q

Reactive Hyperemia is the

A

occlusion of blood flow for a few seconds or longer

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22
Q

When blood flow is restored, it increases immediately to

A

4-7x the normal

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23
Q

Active Hyperemia is

A

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

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24
Q

A rapid increase in arterial pressure causes an immediate rise in

A

blood flow

25
Q

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…

A

autoregulation

26
Q

Metabolic Theory of Autoregulation states

A

too much O2 causes vasoconstriction

27
Q

Myogenic Theory of Autoregulation states

A

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

28
Q

Endothelial-derived relaxing factor

A

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

29
Q

NO is a

A

lipophilic gas released from endothelial cells in response to stimuli

30
Q

NO causes

A

blood vessels to relax

31
Q

Damage to the endothelial cells can lead to

A

hypertension or artherosclerosis

32
Q

Impairing NO synthesis contributes to excess

A

vasoconstriction (think: tight chest pain, angina)

33
Q

Nitroglycerin and nitrate derivatives treat angina because they increase

A

coronary blood flow via vasodilation

34
Q

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

A

Endothelin

35
Q

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

A

pulmonary hypertension because you want to vasodilate & decrease BP

36
Q

Humoral control of the circulation means

A

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

37
Q

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

A

Norepinephrine (noradrenalin)

Excited the heart, contracts veins and arteries

38
Q

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

A

Epinephrine

39
Q

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

A

Angiotensin II

40
Q

Angiotensin II increases BP dramatically by (2)

A

increasing total peripheral resistance

decreasing sodium and water excretion by kidneys

41
Q

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

A

Vasopressin (ADH)

42
Q

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

A

Bradykinin

43
Q

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

A

Histamine

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

44
Q

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

A

Arterioles & Capillary Vessels

45
Q

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

A

its vascularity

46
Q

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

A

its vascularity

47
Q

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

A

vascularity

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

48
Q

Why do premature babies tend to have eye issues?

A

Increased O2 in the NICU causes retinopathy

49
Q

Formation of new blood vessels is known as

A

angiogenesis

50
Q

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

A

angiogenic

51
Q

What are 4 main angiogenic factors?

A
  1. VEGF - vascular endothelial growth factor
  2. Fibroblast growth factor
  3. PDGF - platelet derived growth factor
  4. Angiogenin
52
Q

What are 2 main angiogenesis inhibitors?

A
  1. Angiostatin - fragment of protein plasminogen
  2. Endostatin - derived from breakdown of collagen type XVII

can impair the rapid growth of cancerous tumors

53
Q

4 main application to know in regards to Vascularity

A
  1. Chronic Exercise Training
  2. Development of Collateral Circulation
  3. Hypertension
  4. Bypass Graft Procedures
54
Q

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

A

increases

55
Q

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

A

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

56
Q

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

A

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

57
Q

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

A

Saphenous

58
Q

Take Homes of Control of Tissue Blood Flow (5)

A
  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

PT 6282: Cardiopulmonary Physiology & Rehabilitation (14 decks)

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