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Physiology I > 1.3 Control of blood flow 32-42 > Flashcards

1.3 Control of blood flow 32-42 Flashcards

1
Q

a generic systemic tissue capillary bed is supplied by an_______ and drained by a _______, and the tissue is made up of ___________.

A

arteriole
venule
Metabolizing cells

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2
Q

How is vascular smooth muscle (tunica media) in blood vessels innervated?

A

sympathetic branch of the ANS

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3
Q

________ are the regulators of microvasculature by controlling entry into the capillaries.

A

arterioles

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4
Q

A decrease in blood flow with physiological decrease in blood vessel radius is called?

A

Vasoconstriction

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5
Q

A increase in blood flow with physiological increase in blood vessel radius is called?

A

Vasodilation

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6
Q

How is vascular smooth muscle different than striated muscle cells in contractions?

A

have slow, sustained, tonic contractions

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7
Q

vascular smooth muscle tone can be modified 3 basic ways:

A

mechanical stimulation
electrical stimulation
chemical stimulation

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8
Q

How is vascular smooth muscle stimulated mechanically to contract?

A

By passive stretching - rapid expansion of a vessel causes depolarization of vascular smooth muscle. This stabilizes flow and is a quick response

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9
Q

Increased flow/pressure in vascular smooth muscle causes _______ and thereby ________ (increasing/decreasing) flow.

A

Vasoconstriction: decreasing

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10
Q

Decreased flow/pressure in vascular smooth muscle causes _______ and thereby ________ (increasing/decreasing) flow.

A

Vasodilation: increasing

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11
Q

Increasing shear stress on healthy endothelial cells results in those cells secreting what to the underlying vascular smooth muscle? What does this cause?

A
  • nitric oxide and prostacyclins
  • vasodilation which serves to stabilize vessel diameter and
    reduce such shear stresses (from turbulence)
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12
Q

How is vascular smooth muscle stimulated electrically to contract?

A

opening voltage-dependent Ca+2 channels

- action potential stimulated from a neighboring smooth muscle cell

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13
Q

How is vascular smooth muscle stimulated chemically to contract?

A
  • norepinephrine, angiotensin II, vasopressin (aka ADH),
    endothelin-1, serotonin (5HT) and thromboxane A2
    all use standard signal transduction pathways to increase
    intracellular Ca+2 and elicit contraction
  • Nitric oxide, PGI2 and CO2 all ultimately causing relaxation by inhibiting the contractile machinery
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14
Q

vascular smooth muscle cells arecomplexly covered with_______ , rendering cells sensitive to paracrine agents, hormones and
neurotransmitters from the autonomic nervous system

A

receptors

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15
Q

What are adrenergic receptors?

A

Receptors on vascular smooth muscle cells that bind norepinephrine and epinephrine

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16
Q

norepinephrine, released from the axons of sympathetic fibers cause vasoconstriction when they bind to what kind of receptors?

A

α1 receptors

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17
Q

parasympathetic fibers cause vasodilation when their axon secrete factors that bind to what kind of receptors?

A

Beta 2 receptors

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18
Q

Cholinergic (M2) receptors are sensitive to_________ and cause __________.

A

acetylcholine

Vasodilation

19
Q

Vascular smooth muscle tone can be modified by 2 basic sources:

A

A. Intrinsic or “local” control

B. Extrinsic control

20
Q

Intrinsic or “local” control will cause _________ of blood vessels using local paracrine agents from tissues

A

Vasodilation

21
Q

Which modification of vascular smooth muscle is rapid and most important?

A

Intrinsic or “local” control

22
Q

Due to increased waste production during increased tissue metabolism, what will happen?

A

increased blood flow

23
Q

Low oxygen levels cause ________.

A

Hypoxia

24
Q

No oxygen is called?

A

Anoxia

25
Q

When tissues are deprived of nutrients due to oxygen deficiency?

A

Ischemia

26
Q

Accumulation of deoxygenated blood that leads to a blue color of the tissue

A

Cyanosis

27
Q

The primary method of setting tissue blood flow in the body is ______.

A

local control (which is automatic and tissue centered)

28
Q

Endothelin 1 is released form where? What does it cause in the tissue?

A

Endothelia, vasoconstriction

29
Q

Serotonin is released form where? What does it cause in the tissue?

A

Platelet activation, vasoconstriction

30
Q

Thromboxane is released form where? What does it cause in the tissue?

A

Platelets, vasoconstriction

31
Q

Nitric oxide is released form where? What does it cause in the tissue?

A

Endothelia, vasodilation

32
Q

Bradykinin is released form where? What does it cause in the tissue?

A

Damaged blood vessels, vasodilation and increased capillary porosity

33
Q

Histamine is released form where? What does it cause in the tissue?

A

Mast cells, vasodilation and increased capillary porosity

34
Q

Prostacyclin is released form where? What does it cause in the tissue?

A

Endothelia, vasodilation and increased capillary porosity

35
Q

What is reactive hyperemia?

A

Follows a brief period of ischemia where blood flow is restored in a way that matches the amount of blood that would have been delivered during ischemia. Continues until complete restoration of oxygen levels and all accumulated metabolites have been washed away. Evidence for intrinsic control

36
Q

Extrinsic control will cause _________ of blood vessels using ANS and some endocrine glands

A

Vasoconstriction

37
Q

Autonomic axons that innervate vascular smooth muscle are powerful but are completely dependent on _______.

A

Receptors, the sensitivity of vascular smooth muscle

38
Q

What releases epinephrine and norepinephrine which attaches to the alpha 1 adrenergic receptors and causes vasoconstriction which ultimately increases blood pressure due to resisted vessels.

A

Adrenal medulla

39
Q

Hormonal systems of extrinsic control differ from ANS extrinsic control how?

A

Hormonal systems are slower and have a whole body effect

Both methods are very powerful

40
Q

What releases renin which causes formation of angiotensin 2?

A

Renal cortex of the kidneys

41
Q

What is the chain reaction that occurs when renin is released from the kidneys?

A

It causes angiotensin 2 formation. Angiotensin 2 binds to receptors which causes endothelin 1 to be produced. Endothelin 1 binds to receptors which causes vasoconstriction

42
Q

What releases vasopressin (aka ADH)]?

A

Posterior pituitary gland

43
Q

What is the effect of vasopressin?

A

It effects both blood vessels and renal collecting ducts by binding to receptors that cause the production of endothelin 1 in local vascular smooth muscle which causes vasoconstriction

44
Q

The diameter of blood vessels is set by effects in the tunica media of primarily arterioles. The effects are caused by what?

A

Local (intrinsic) and distant (extrinsic) factors that strike a balance. Mose tissue responds primarily to local factors, but neurohumeral (extrinsic) factors are very important contributors that can override local control

Physiology I (15 decks)

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