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A Physiology > Local control of circulation > Flashcards

Local control of circulation Flashcards

1
Q

What are the 2 regulatory task(s) of the cardiovascular system?

A
  1. Ensure adequate tissue perfusion
  2. Ensure physiological blood pressure levels
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2
Q

A regulatory task(s) of the cardiovascular system is to ensure adequate tissue perfusion
-> What type of mechanism we need to use in this task?

A

Local control mechanisms
(Locally: only resistance)

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3
Q

A regulatory task(s) of the cardiovascular system is to ensure physiological blood pressure levels
-> What type of mechanism we need to use in this task?

A

Systemic control mechanisms
(Systemic: pressure AND resistance)

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4
Q

What are the cardiovascular parameters that can be influenced?

A

heart: CO=HR x SV
vessels: TPR
BP= CO x TPR
Ohm’s law: I=P/R

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5
Q

Do local and systemic regulation overlap on the arterioles?

A

Yes

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6
Q

Physiological vasoconstrictors and vasorelaxants

A
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7
Q

What are the 3 major factors affecting arteriolar radius?

A
  1. Neural controls
  2. Hormonal controls
  3. Local controls
    -> Affect arteriolar smooth muscle
    -> altered arteriolar radius
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8
Q

What is Autoregulation (Bayliss effect)?

A

Intrinsic ability of a body part to maintain a constant blood flow despite changes in perfusion pressure

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9
Q

Autoregulation (Bayliss effect) is a passive process that occur in the absence of ___

A

neural and hormonal influences

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10
Q

One of the major factors affecting arteriolar radius is NEURAL CONTROLS
-> What are the vasoconstrictors?

A

Sympathetic nerves that release norepinephrine

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11
Q

One of the major factors affecting arteriolar radius is HORMONAL CONTROLS
-> What are the vasoconstrictors?

A

Epinephrine
Angiotensin II
Vasopressin

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12
Q

One of the major factors affecting arteriolar radius is HORMONAL CONTROLS
-> What are the vasodilators?

A

Epinephrine
Atrial natriuretic peptide

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13
Q

One of the major factors affecting arteriolar radius is LOCAL CONTROLS
-> What are the vasoconstrictors?

A
  1. Internal blood pressure (myogenic pressure)
  2. Endothelin-1
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14
Q

One of the major factors affecting arteriolar radius is LOCAL CONTROLS
-> What are the vasodilators?

A
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15
Q

What are the 3 actors of local circulation?

A
  1. Smooth muscle
  2. Endothelium cell (with basal membrane)
  3. (laminal) blood flow, lighter color represents higher velocity
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16
Q

What is the myogenic tone?

A

Myogenic tone is a state of muscle tone in living creatures that originates from the muscle itself rather than from the autonomic nervous system or from hormone processes.

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17
Q

How to calculate the blood flow?

A

Blood flow=Pressure/Resistance

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18
Q

The contribution of the myogenic tone to the regulation of the local blood flow
-> What happen if pressure increases?

A

Pressure increases
-> radius decerases
-> resistance increases

(Blood flow remains constant)

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19
Q

An example of vessels that can be seen during systemic circulation

A

kidney-type vessels
-> Typically: systemic circulation (so-called kidney-type vessels)

(BUT! Lung-type vessels relax when the pressure elevates)

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20
Q

What happen during Hypoxia-related vasorelaxation?

A

Local hypoxia
→ intracellular ATP decreases
→ ATP-sensitive K+ channels open
→ hyperpolarization
→ L-type Ca++–channels opening decreases → cytoplasmic Ca++ –level decreases
→ vasorelaxation
-> velocity of blood flow increases as the resistance decreases

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21
Q

How does Parenchima: the working tissue work?

A
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22
Q

List 8 local metabolites

A
  1. CO2
  2. Hydrogen ions
  3. Adenosine
  4. K+ ions
  5. Eicosanoids
  6. osmotically active products
  7. bradykinin
  8. nitric oxide ,
23
Q

carbon dioxide, a local metabolites is an end product of __

A

oxidative metabolism

24
Q

Local metabolites
-> adenosine, a breakdown product of ___

A

ATP

25
Q

Local metabolites
-> K+ ions, accumulated from ___

A

repeated action potential repolarization

26
Q

Local metabolites
-> eicosanoids, breakdown products of ____

A

membrane phospholipids (arachidonic acid to PGs)

27
Q

Local metabolites
-> osmotically active products from the breakdown of ___

A

high-molecular-weight substances

28
Q

bradykinin is a local metabolite
-> It is a peptide generated from ___

A

a circulating protein called kininogen

29
Q

bradykinin is a local metabolite
-> It is a peptide generated from a circulating protein called kininogen by the
action of ___, secreted by ___

A

an enzyme, kallikrein , secreted by active gland cells

30
Q

Local metabolites
-> nitric oxide , a gas released by ____, which acts on the immediately adjacent vascular smooth muscle.

A

endothelial cells

31
Q

Local metabolites
-> nitric oxide , a gas released by endothelial cells, which acts on ___

A

the immediately adjacent vascular smooth muscle.

32
Q

How does active hyperemia occur?

A
33
Q

How does reactive hyperemia occur?

A
34
Q

Parallel and perpendicular forces in the vessels

A

Hydrostatic pressure – vasoconstriction elevates the pressure
Shear stress– higher, when blood flow is faster –increased pressure slows it

35
Q

What type of force is used for Flow- mediated vasodilation?

A

shear stress

36
Q

RBCs may contribute to vasodilation, mainly during ___

A

hypoxia

37
Q

Hb-NO is a source of __ and ___

A

adenosine and ATP

38
Q

Endothelial relaxing mechanism
-> The role of Ca2+ signal

A

Ca++-signal in endothelial cells activates cyclooxigenase (COX), that converts arachidonic acid (AA) to relaxing prostaglandins (PGI2, PGE2)

-> Hyperpolarization may propagate from endothelial cells to vascular smooth muscle

39
Q

Steps of Endothelial relaxing mechanisms

A

Endothelial eNOS
-> NO
-> Diffuses into Smooth muscle
-> Soluble guanylyl cyclase
-> Increased cGMP↑
-> vasodilation

40
Q

Flow Mediated Dilatation – FMD II
-> How do we make Ultrasound Measurement?

A

1) a. brachialis - vascular diameter
2) a. brachialis - velocity of blood flow

41
Q

Make a graph of Model of regulation of tissue blood flow – contemporary view

A
42
Q

List the Platelets that contribute to vasoconstriction

A
  • Thromboxane A2
  • Serotonin
  • ATP, ADP, Ca++, epineprine
43
Q

Endothel that contribute to vasoconstriction

A
  • Thromboxane A2
  • Endothelin
  • Lack of NO and PGE2/PGI2 release
44
Q

Platelets and coagulation factor contribute to vasoconstriction
-> How does Contribution of blood clotting occur?

A
  • Thrombin (activated IIa coagulation factor)
  • triggers endothelial endothelin 1 production
45
Q

List Inflammatory vasoactive mediators

A
  1. Histamine causes systemic vasodilation
  2. Cytokines and chemokines
  3. Kinins
  4. Eicosanoids
  5. Lysosomal enzymes
  6. NO
  7. Reactive oxygen and nitrogen species
46
Q

How do Kinins work as an inflammatory vasoactive mediators?

A

Kallikreins in plasma and tissue→bradykinin→vasodilation in inflammation

47
Q

The role of histamine as an inflammatory vasoactive mediator

A

Histamine causes systemic vasodilation (H1: Gq, H2: Gs)
-> Endothelium-mediated vasodilation (Gq on endothel -> Ca++- signal -> NO release)

48
Q

The role of Inflammatory vasoactive mediators

A
  1. Increased blood flow
  2. Increased vascular permeability
  3. Osmotically active particles in intestitium (e.g. degrading cells)
49
Q

What happen if Starling-forces shift?

A

edema occur
(The definition of edema is a swelling due to the expansion of interstitial fluid volume in tissues or an organ)

50
Q

The role of Angiotensin

A

It has a leading role in blood pressure elevation

51
Q

The role of Endothelin 1

A

one potent vasoconstrictor protein (e.g. activated platelets activate)

52
Q

What is the Long-term regulation of local blood flow?

A

HIF serves as transcription factor for Vascular Endothelial Growth Factor

53
Q

Make a Vascular function curve

A
54
Q

Make a graph that demonstrate Equilibrium point of the cardiovascular system

A

A Physiology (20 decks)

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