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human physiology and exercise > arteries. capillaries and veins > Flashcards

arteries. capillaries and veins Flashcards

1
Q

what do arteries do ?

A
  • carry blood away from the heart
  • regulates mean arterial pressure and blood flow distribution
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2
Q

how much blood volume and pressure do arteries contain ?

A
  • 15% of total blood volume
  • pressure of 100mmHg
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3
Q

describe anatomy of arteries

A
  • each layer plays a functional role but not all layers present in arteries
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4
Q

what provides structure strength and tethers vessels in place? what is found in large vessels?

A
  • adventitia
  • in large vessels the adventitia contains small blood vessels, the vase vasorum
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5
Q

what does elastin do?

A
  • gives vessels mechanical strength and their elastic properties allows expansion and recoil
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6
Q

what is the inner layer for? what does it do?

A
  • endothelium
  • filtering interface between blood and body
  • secretes various vasoactive products
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7
Q

what does smooth muscles supply vessels with?

A
  • contractile power
  • regulates diameter of lumen
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8
Q

what controls blood flow to specific capillary bed?

A
  • pre- capillary sphincter
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9
Q

what are arterioles responsible for?

A
  • responsible with altering levels of resistance to blood flow in order to distribute available amount of blood to where it is needed without disturbing control of mean arterial pressure
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10
Q

what is active hyperaemia?

A
  • increase in blood flow according to metabolic needs of tissue
  • diameter changes in order to facilitate the blood flow
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11
Q

what happens when there is an increase in metabolic activity?

A
  • less oxygen available and more metabolites in organ interstitial fluid
  • arteriolar digestion in organ
  • increased blood flow to organ
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12
Q

what is flow autoregulation concerned with?

A
  • maintenance of blood flow rather than changing it
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13
Q

what happens when driving pressure drops?

A
  • vessels dilate
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14
Q

what happens when driving pressure increases?

A
  • vessels constrict
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15
Q

what does reduction in arterial pressure in a organ mean?

A
  • less blood flow and hence less oxygen so metabolites accumulate
  • decreased vessel wall stretch
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16
Q

what does arteriolar dilation in organs result in?

A
  • restoration of blood towards normal in organ
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17
Q

what does increased arterial pressure cause a rise in?

A
  • blood flow
  • this removes vasodilators so vessels then constricts and flow is restored to its normal value
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18
Q

what is the intrinsic property of arterial smooth muscle that regulates arterial diameter known as?

A
  • myogenic regulation
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19
Q

what does increase in pressure lead to?

A
  • muscle stretch that is followed by constriction
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20
Q

what does regulation of arterial diameter involved?

A
  • neural control, hormonal control and local controls
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21
Q

what are vasoconstrictors?

A
  • sympathetic nerves that release norepinephrine
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22
Q

what are vasodilators?

A
  • neurons that release nitric oxide
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23
Q

what state is arterial smooth muscle constantly in? explain this

A
  • tonic state
  • partially contracted so there is almost no involvement of parasympathetic system
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24
Q

how can relaxation occur in tonic state?

A
  • withdrawal of sympathetic stimulation
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25
Q

what can circulating epinephrine cause?

A
  • vasodilation or vasoconstriction depending on what receptors it binds to
26
Q

what are capillaries?

A
  • network of small tissues that sit between arteries and veins
27
Q

what are the two main properties of capillaries?

A
  • numerous so they reach every part of body and create large surface area
  • thin so can facilitate diffusion as only contain endothelium
28
Q

what does slow blood flow provide?

A
  • enough time during which diffusion reaches equilibrium
29
Q

what is the pressure of the capillaries and why is it greater than veins?

A
  • around 35mmHg
  • greater to help maintain a pressure difference
30
Q

how do you work out flow of gas using Fick’s law of diffusion?

A

area / thickness x D x (P2-P1)

31
Q

what dictates the velocity of blood flow?

A
  • total cross- sectional areas of capillaries
32
Q

where do endothelial cells sit?

A
  • on the basement membrane
33
Q

what do endothelial cell arrangement depend on?

A
  • function and this relates to if the exchange with tissue should be selective or conducted freely
34
Q

what does continuous structure of endothelial cells mean?

A
  • selective; muscle, nerve, fat, lymph nodes
35
Q

what does fenestrated structure of endothelial cells mean?

A
  • generous with what can go across; glands, kidneys, intestines
36
Q

what does discontinuous structure mean?

A
  • loosely packed so can fit large structures; liver, bone marrow, spleen
37
Q

what are the three types of transport that occurs in body?

A
  • diffusion for 02 and C02
  • vesicle transport for larger molecules i.e. proteins via AT
  • bulk flow for water and solutes
38
Q

what does filtration mean?

A
  • fluid movement from capillaries to interstitial fluid
  • takes place when hydrostatic pressure exceeds colloid osmotic pressure
39
Q

what does absorption mean?

A
  • fluid movement from interstitial fluid to capillaries
  • takes place when colloid osmotic pressure exceeds hydrostatic pressure
40
Q

what exceeds the other; filtration or absorption and what does this cause?

A
  • filtration exceeds absorption
  • net accumulation of fluid in tissues is dealt with by lymphatics system
41
Q

what do veins do? describe structure

A
  • carry blood back to the heart
  • contains valves, thinner walls, larger lumen, less elastic, lie closer to the skin > arteries
42
Q

describe diseased veins

A
  • leaky valves which allow the backflow of blood
  • blood accumulates in extremities
43
Q

list the properties of veins

A
  • large volume capacity
  • large diameter
  • less thickness of layers
  • valves prevent backflow
  • lie close to skin surface
44
Q

why can veins act as a blood reservoir ?

A
  • contain more than 60% of total blood volume
45
Q

why is the vein a major contributor to cardiac output?

A
  • pressure is only 10mmHg
  • pressure is low and non- pulsatile
46
Q

what does Frank Starling mechanism relate?

A
  • relates cardiac output and displacement of blood from veins to heart
47
Q

what is the driving pressure for venous return?

A
  • difference between central nervous pressure and right atrial pressure
48
Q

what is central venous pressure determined by?

A
  • blood volume
  • compliance
49
Q

what is the neural factors that affects compliance of veins?

A
  • sympathetic stimulation releases norepinephrine to smooth muscle causing vasoconstriction
50
Q

what is the hormonal factor that affects the compliance of veins?

A
  • diameter of veins is affected by epinephrine
51
Q

what are the endothelial factors that affect the compliance of veins?

A
  • paracrine vasoconstrictors and vasodilators
52
Q

what is the skeletal muscle pump?

A
  • constant pump whereby the rhythmic contractions ensures venous pressure is maintained
  • compression of veins by contraction empties them of blood towards the heart
53
Q

what does the skeletal muscle pump ensure in exercise?

A
  • ensures central venous pressure is maintained or becomes slightly increased
54
Q

why does pressure in distal veins fall?

A
  • falls as blood drains into empty veins so blood flow increases
55
Q

why does the blood flow increase after blood drains into empty veins?

A
  • greater arteriovenous pressure difference in exercising muscles
56
Q

describe the respiratory pump

A
  • during inspiration, the diaphragm contracts and moves downwards
57
Q

what does the diaphragm contracting and moving down cause? why does this happen

A
  • increases volume of thoracic cavity
  • decreases volume of abdominal cavity
  • more blood returns due to fall in intrathoracic pressure and rise in intrabdominal pressure
58
Q

what happens to respiratory pump during exercise?

A
  • opposite occurs to inspiration
  • decreases return of blood
  • rises intrathoracic pressure
59
Q

what is the lympathetic system?

A
  • system of vessels parallel to CV system on venous side
  • lymph vessels collect filtered fluid from interstitial space and return it to circulating blood
60
Q

why is lympathetic system important?

A
  • due to hydrostatic pressure exceeding colloid osmotic pressure resulting in net filtration
61
Q

what is oedema?

A
  • accumulation of fluid in interstitial spaces (swelling)
62
Q

what are the two causes of oedema?

A
  • capillary hydrostatic pressure increase due to increase in venous pressure caused by posture
  • decrease in plasma osmotic pressure due to poor nutrition, liver failure,

human physiology and exercise (18 decks)

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