session 5 Flashcards

1
Q

main types of blood vessels (5)

A
  • arteries
  • arterioles
  • capillaries
  • venules
  • veins
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2
Q

define blood vessels

A

closed system of tubes which carry blood from heart to regions of the body and back to heart

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3
Q

what is angiogenesis

A

growth of new blood vessels

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4
Q

where is most blood stored

A

in veins and venules

This is why they are called blood reservoirs

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5
Q

arteries vs arterioles

A
  • artery carry blood from heart to tissues
  • arteriole small arteries that connect capillaries
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6
Q

what occurs in capillaries

A

exchange of oxygen and other nutrients between blood and the body tissue

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7
Q

veins vs venules

A
  • veins blood from tissues back to heart
  • venules connect capillaries to larger veins
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8
Q

vaso vasorum

A
  • Small blood vessels which supply the outer wall layers of arteries and veins
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9
Q
A
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10
Q
A
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11
Q

blood vessel wall layers

A
  • tunica intima
    • has endothelium, basement membrane and internal elastic lamina
  • tunica media
    • smooth muscle and elastic fibers
  • tunica externa
    • elastic and collagen fibers
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12
Q

elasticity of vessles

A

due to elastic tissue in tunica interna and media

Beneficial in arteries to receive high pressured blood flow

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13
Q

contractility of vessels

A

Due to smooth muscle in tunica media

Allows for changed lumen size

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14
Q

Vascular smooth is innvervated by

A

sympathetic nervous system

  • increased stimulation = vasoconstriction
  • decreased stim = vasodilation
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15
Q

What chemicals also cause vasodilation

A

nitric oxide (NO), hydrogen and lactic acid

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16
Q

Two artery types

A
  • elastic arteries
    • largest type
    • tunica media has more elastic fibers and less smooth muscle
    • conduct blood into muscular arteries
  • muscular arteries
    • medium sized
    • Tunica media with more smooth muscle
    • direct blood flow to tissue and can constrict/dilate
17
Q

anastomoses

A
  • union of 2 or more arteries supplying the same body region
    • blockage of one pathway has no effect on circulation
  • eg GIT, coronary circulation
18
Q

arterioles

  1. structure
  2. function as
  3. define metarteriole
  4. precapillary sphincters
A
  1. very few layers
  2. deliver blood to capillaries. Regulate blood flow and BP
  3. terminal end of the arteriole before it becomes capillaries
  4. between metarteriole and capillaries. Can contract and relax to control blood flow into capillary bed
19
Q

capillaries

  1. structure
  2. function
A
  1. smallest blood vessel. Only have tunica interna with one single layer of endothelial cells
  2. exchange of nutrients and waste between blood and tissue fluid
20
Q

types of capillaries

A
  • continuous capillaries
    • continuous tube
    • located in CNS, lungs, muscle tissue and skin
  • fenestrated capillaries
    • many holes in plasma membrane of endothelial cells
    • located in kidneys, endocrine glands
  • sinsoidal capillaries
    • endothelial cells have large fenestrations
    • basemement membrane is incomplete or absent
    • allows even proteins or blood cells to pass
    • located in liver, bone marrow, spleen, pituitary
21
Q

Two types of venules

A
  • Post capillary venule
    • change of nutrients and wastes
  • Muscular venules
    • no exchange
22
Q

veins structure

A
  • all vessel layers (intima, media and externa) are thinner than in the artery
  • veins also have one way valves which prevent backflow
23
Q

what are varicrose veins

A
  • twisted superficial veins
  • Caused by leaky venous valves
    • can be congenital or from stress like pregnancy
  • Backflow of blood = pooling of blood
    • particularly in lower limbs, oesophagus and anal canal (haemorrhoids)
  • Treatment eg surgical stripping
24
Q

blood distribution in veins/venules and arteries/arterioles

A
  • veins/venules
    • 64% of blood at rest
    • blood reservrois
  • artery/arteriole
    • 13% of blood volume
25
Q

capillary exchange

A
  • movement of substances between blood in capillaries and interstitial fluid
  • methods include
    • diffusion
      • eg o2, co2, glucose, hormones
      • pass down concentration gradient through fenestrations, sinusoids
    • transcytosis
      • in tiny vesicles by endo/exocytosis
      • eg proteins across placenta
    • bulk flow
      • movement of large amount of material
      • movement in response to pressure
26
Q

blood brain barrier

A
  • block movement of certain materials into and out of brain
  • formed by non fenestrated epithelial with tight junctions
  • Materials tha can pass BBB are
    • glucose (by active transport)
    • creatinine, urea
    • lipid soluble substances like oxygen, CO2, alcohol
  • Proteins and most antibiotic drugs wont pass
27
Q

starlings law of capillaries

A

volume of fluid and solutes reabsorbed is almost as large as the volume filtered

28
Q

oedema

A
  • abnormal increase in interstitial fluid
    • filtration exceeds reabsorption meaning not enough blood going back into capillaries
  • Excess filtration can be caused by
    • hypertension (high BP)
    • increased permeability of capillaries = proteins to escape
  • Inadequate reabsorption
    • reabsorption is controlled by colloid osmotic pressure which is the result of protein concentration
      • low plasma proteins = low osmotic pressure = inadequate reabsorption