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PATH100 > LP #106 Understanding Factors Influencing BF > Flashcards

LP #106 Understanding Factors Influencing BF Flashcards

1
Q

*amount of blood moving through a vessel/organ w/in a given time period (ml/min)= tissue perfusion

A

Blood flow

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2
Q

5 critical fxn

A
  • deliver O2, nutrients & hormones to tissues
  • remove O2 & waste products from tissues
  • gas exchange in lung & tissue capillaries
  • nutrients absorption GT tract
  • waste filtration in kidneys
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3
Q

Atrerial shunts

A

small capillaries that control vasodilation & vasoconstriction

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4
Q

Factors affecting BF

A
  • blood pressure

- peripheral resistance

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5
Q

Vasodilation & vasoconstriction

A

Increase BF
&
Decrease BF

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6
Q

Relationship b/w BP & PR:

  • w/ constant BP: __ in PR will __ BF
  • w/ constant PR: __ in BP will __ BP
  • __ PR & bl flow obstructed= __ BP
  • PR is more important in influencing BF
A
  • increase & decrease
  • increase & increase
  • increase & increase
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7
Q

PR influenced by 3 factors to determine BF:

A
  1. Diameter of bv
  2. length of the vascular bed
  3. viscosity of blood
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8
Q

*measures distance blood travels along a bv in a given time period

A

Velocity of blood flow

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9
Q

Factors affect BF & velocity:

A

P gradient & PR

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10
Q

Changes in blood velocity:

  • greatest?
  • intermediate?
  • weakest?
A

Greatest- in conducting aa (pulmonary aa, aorta & main branches)

Intermediate- in distributing aa & Iarge vv

Weakest- in capillary beds supplying tissues (gas exchange)

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11
Q

Short-term Regulation of BF to tissues:

A

-response to changing needs of tissues at various times

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12
Q

Short-term regulation of BF:

  • ability of tissues to control BF via capillary beds
  • determined by local conditions
  • local changes in BF controlled by intrinsic mechanisms (modify diameter of precapillary arterioles)
A

Autoregulation

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13
Q

2 autoregulation of BF

A
  1. Metabolic factors: d/t changes in O2, nutrients or waste levels (ex. Vasodilation)
  2. Myogenic control:
    - vascular smooth m response (NS)
    - activated when BF to tissues is poor
    - affects smooth vascular m of pre-capillary sphincters
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14
Q
  • occurs when intrinsic mechanisms are inadequate
  • systemic adjustments allow circulatory system to meet increase tissue demands:
  • angiogenesis (d/t increase body mass & m hypertrophy)
  • increase in size of existing bv’s (ex. As in coronary heart disease)
A

Long-term regulation of BF

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15
Q
  • highly variable (depends on activity level)
  • w/ exercise:
  • receives rapid increase in BF
  • autoreglation responds to changing blood O2 level & rapid buildup of CO2/lactic acid
  • Vasomotor centre diverts blood from viscera (vasoconstriction) & shunts to contracting skeletal mm
A

BF in skeletal mm

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16
Q
  • cerebral BF: ~750ml/min (constant)
  • increase in arterial blood= increase in venous drainage (ensures intracranial P does not increase)
  • regulation of BF in cerebral bv’s:
  • metabolic controls activated by decrease blood pH & increases CO2 levels- vasodilation (increase venous return)
  • myogenic controls activated by decrease BP- vasodilation (ensure perfusion)
  • both mechanisms ensure adequate perfusion to brain w/out major changes in systemic BP
A

BF in the brain

17
Q

*blood reservoir
*variable flow in skin bv’s: 50-2500ml/min
*vasconstriction restricts BF to skin & reverts blood to where its needed
*vasodilation: increase BF to skin when core temp increase (thermoregulation)
changes in bv lumen reflect neural adjustment of BF through stimulation of precapillary sphincters
*precapillary sphincters innervated by sympathetic nn which mediate lumen size

A

BF in the skin

18
Q
  • BF through coronary bv’s:
  • restricted during ventricular contraction
  • occurs during ventricular diastole
  • during strenuous exercise:
  • heart requires increase O2 & accumulates increase wastes
  • w/vasodilation, BF increase 3-4x in coronary aa to ensure adequate O2 & waste removal
A

BF in the heart

19
Q
  • autoregulation in pulmonary vessels in lungs in unique
  • in most body tissues:
  • decrease O2 levels leads to vasodilation (increase BF/oxygenation)
  • in pulmonary circulation, the opposite occurs:
  • decrease O2 levels in lung airways leads to vasoconstriction
A

BF in the lungs

PATH100 (15 decks)

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