Topic 11: Cardiovascular System - Capillary Exchange Flashcards

1
Q

What is capillary exchange between?

A

blood and ISF

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2
Q

What three methods allow solutes to enter and leave capillaries?

A
  • diffusion
  • vesicular transport
  • Mediated Transport
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3
Q

What is the role of diffusion in capillary exchange?

A
  • major route, except for brain
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4
Q

Which ions and molecules can diffusion occur for in capillary exchange? (6)

A
  • CO2
  • O2
  • ions
  • aa
  • glucose
  • hormones etc
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5
Q

Between which cells does diffusion occur?

A

between endothelial cells

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6
Q

Which molecules is vesicular transport for?

A

large proteins (ie antibodies)

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7
Q

How does vesicular transport in capillary exchange occur? (3)

A
  • via transcytosis
  • endocytosis from blood into endothelial cell
  • then exocytosis from endothelial cell into ISF
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8
Q

What does mediated transport require? (2)

A
  • membrane carrier protein
  • important mainly for brain
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9
Q

Through which mechanisms does fluid (water) enter/absorb or leave/filtrate capillaries? (2)

A
  • osmosis
  • bulk flow
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10
Q

Why does bulk flow allow for absorption/filtration in capillaries?

A
  • due to pressure differences
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11
Q

What 4 pressures are involved in bulk flow of capillaries?

A

1) Blood hydrostatic pressure (BHP) - blood pressure
2) blood osmotic P (BOP) - due to plasma proteins
3) ISF hydrostatic P (IFHP) - 0 mmHg
4) ISF osmotic P (IFOP) - due to ISF proteins

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12
Q

Net filtration pressure (NFP) diagram

A
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13
Q

What is net filtration pressure? (2)

A
  • sum of hydrostatic and osmotic pressures acting on the capillary
  • across a capillary from arteriolar to venous end
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14
Q

Formula for net filtration pressure

A
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15
Q

Example given of NFP important

A
  • negative means absorption
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16
Q

What occurs in the body in NFP? (3)

A
  • 90% of filtered fluid reabsorbed to blood
    -10% enters lymph
  • therefore ISF volume remains relatively constant
17
Q

One clinical application of NFP is edema. What is edema? (20

A
  • accumulation of fluid in the tissue (ISF)
  • causes swelling
18
Q

What is edema due to? (4)

A

1) high bp (high BHP)
2) leakage of plasma proteins into ISF, causing inflammation (increased IFOP)
3) decreased plasma proteins (malnutrition, burns) (decreased BOP)
4) obstruction of lymph vessels (elephantiasis, surgery)