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human structure and function > circulatory system > Flashcards

circulatory system Flashcards

1
Q

what are the three tunics of blood vessels?

A
  • intima
  • media
  • externa
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2
Q

what is the middle layer of blood vessels?

A

tunica media

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3
Q

what is the inner layer of blood vessels?

A

tunica intima

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4
Q

what is the outer layer of blood vessels?

A

tunica externa

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5
Q

what is the tunica intima composed of?

A

epithelial cells

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6
Q

what is the tunica media composed of?

A

smooth muscle cells

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7
Q

what is the tunica externa composed of?

A

connective tissue

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8
Q

what is the function of the tunica intima?

A

smooth lining to reduce friction and facilitate blood flow

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9
Q

what is the function of the tunica media?

A

alter vessel diameter via sympathetic innervation to control blood flow

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10
Q

what is the function of the tunica externa?

A

vessel protection and anchoring surrounding tissue

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11
Q

what type of vessels are elastic arteries?

A

conducting vessels- conduct blood away from the heart

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12
Q

what type of vessels are muscular arteries?

A

distributing vessels- change diameter to control blood flow

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13
Q

where are elastic arteries located?

A

near heart

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14
Q

what is present in all the tunicas of elastic arteries?

A

elastin

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15
Q

where are muscular arteries located in relation to elastin arteries?

A

distally

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16
Q

do muscular arteries have a thick or thin tunica media?

A

thick

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17
Q

what are the smallest arteries?

A

arterioles

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18
Q

whats the diameter of elastic arteries?

A

1-2.5cm

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19
Q

what is the diameter of arterioles?

A

10um-0.3mm

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20
Q

what tunica predominately makes up arterioles?

A

tunica media

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21
Q

what type of vessels are arterioles?

A

resistance vessels- change their diameter to control resistance into capillary beds

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22
Q

what tunica are capillaries made up of?

A

intima

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23
Q

what type of vessels are capillaries?

A

exchange vessels- exchange nutrients, wastes, gases and hormones etc. with ISF

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24
Q

what are the three types of capillaries?

A
  • continuous
  • fenestrated
  • sinusoidal
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25
Q

what do intercellular clefts in continuous capillaries allow?

A

limited passage of fluids and small solutes

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26
Q

in continuous capillaries what carries fluids and larger solutes across capillary wall?

A

pinocytotic vesicles

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27
Q

what do endothelial cells do in continuous capillaries?

A

join tight junctions to form smooth lining

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28
Q

what do endothelial cells in fenestrated capillaries contain?

A

pores (fenestrations)

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29
Q

what do the pores in fenestrated capillaries increase?

A

permeability to allow rapid exchange of fluids and small solutes

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30
Q

where are fenestrated capillaries found?

A

in areas of active filtration (kidneys), absorption (small intestines or in endocrine glands

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31
Q

what is the most leaky type of capillary?

A

sinusoidal

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32
Q

why are sinusoidal capillaries leaky?

A

there are large spaces between endothelial cells (sinusoids) and large fenestrations, incomplete basement membrane

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33
Q

where are sinusoidal capillaries found?

A
  • liver
  • lymphoid organs
  • adrenal medulla
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34
Q

what does the slow blood flow of sinusoidal capillaries allow?

A

large molecules and cells to pass between blood and tissues

35
Q

what arteriole supplies capillary bed?

A

terminal arteriole

36
Q

what venule drains capillary bed?

A

postcapillary venule

37
Q

what do capillaries unite to form?

A

venules

38
Q

what do venules unite to form?

A

veins

39
Q

what does the large lumen in veins allow?

A

easy blood flow

40
Q

what does the tunica intima in veins fold to form?

A

valves

41
Q

what do veins have little of?

A

smooth muscle or elastin

42
Q

what does the thick tunica externa of veins contain?

A

collagen fibres

43
Q

what type of vessels are veins?

A

capacitance vessels- thick tunica externa provides support for large blood volume

44
Q

what is blood flow?

A

the volume of blood flowing through a vessel, organ or the entire circulation(= CO) in a given time period

45
Q

what is blood flow determined by?

A
  • blood pressure

- resistance

46
Q

what is blood pressure?

A

force exerted on a vessel wall by the blood. in that vessel

47
Q

what is resistance?

A

the opposition to blood flow

48
Q

what is resistance a measure of?

A

the amount of friction blood encounters as it flows through a vessel

49
Q

what are the three primary sources fbof total peripheral resistance (TPR)?

A
  • blood viscosity
  • total blood vessel length
  • blood vessel diameter
50
Q

what does blood viscosity alter with?

A

blood cell numbers

-plasma volume

51
Q

does increased haematocrit increase or decrease viscosity?

A

increases

52
Q

does resistance to blood flow increase or decrease with increasing vessel length?

A

increases

53
Q

what is systolic pressure?

A

peak pressure generated in the large arteries when the ventricles contract

54
Q

what two factors does arterial pressure reflect?

A
  • how much elastic arteries can be stretched

- the volume of blood forced into elastic arteries by ventricular contraction

55
Q

what is diastolic pressure?

A

pressure in large arteries during ventricular relaxation

56
Q

what is the equation for pulse pressure?

A

systolic pressure - diastolic pressure

57
Q

what is mean arterial pressure?

A

the pressure that propels blood through vessels

58
Q

what is the equation for mean arterial pressure?

A

diastolic pressure + (1/3 x pulse pressure)

59
Q

why is low capillary pressure required?

A
  • high pressure would damage thin-walled, fragile capillaries
  • most capillaries are very. permeable so low pressure is adequate
60
Q

what are 5 aspects apart of venous return?

A
  1. valves
  2. muscular pump
  3. respiratory pump
  4. pulsation
  5. venoconstriction
61
Q

what are factors that determine blood pressure?

A
  • cardiac output
  • peripheral resistance
  • blood volume
62
Q

what is a slower more long-term regulation factor of blood pressure?

A

blood volume

63
Q

what is a rapid more short-term regulation factor of blood pressure?

A

cardiac output and peripheral resistance

64
Q

what is resistance primarily altered by to regulate blood pressure?

A

changing arteriole diameter

65
Q

what is blood volume controlled by to regulate blood pressure?

A

renal and endocrine mechanisms

66
Q

what are the different levels that regulate blood pressure?

A
  • autoregulation
  • neural regulation
  • renal mechanisms
  • endocrine mechanisms
67
Q

where does auto regulation of blood pressure occur?

A

occurs within tissues and is dependent on local conditions

68
Q

what does neural regulation of blood pressure involve?

A

cardiovascular centres, ANS and baroreceptor reflex

69
Q

what are the three centres in the medulla oblongata that are apart of neural regulation of blood pressure?

A
  • cardioinhibitory
  • cardioacceleratory
  • vasomotor
70
Q

where are baroreceptors located?

A
  • carotid artery sinuses
  • aortic arch
  • walls of most large arteries in neck and thoracic
71
Q

what does the carotid baroreceptor sinus reflex monitor?

A

blood pressure to ensure adequate blood flow to brain

72
Q

what does the aortic baroreceptor reflex monitor?

A

blood pressure to maintain blood flow to systemic circuit

73
Q

what does the direct mechanism of the renal mechanism determine to alter blood pressure?

A

urine formation altering blood volume and therefore pressure

74
Q

what does the indirect mechanism of the renal mechanism involve to alter blood pressure?

A

hormones: renin-angiotensin-aldosterone system (RAAS)

75
Q

what is a hormone that decreases BP?

A

atrial natriuretic peptide

76
Q

what are hormones that increase BP?

A
  • adrenaline
  • noradrenaline
  • angiotension II: secretes aldosterone and ADH
77
Q

where do fluids move through in capillaries?

A
  • intercellular clefts
  • fenestrations
  • sinusoids
78
Q

what are the two opposing forces that determine direction and volume of fluid movement?

A

hydrostatic and colloid osmotic pressures

79
Q

what is hydrostatic pressure?

A

force exerted by fluid pushing against a tissue wall

80
Q

what does capillary hydrostatic pressure do to fluid?

A

pushes fluid and solutes out of capillaries through intercellular clefts/fenestrations/sinusoid at arterial end of bed

81
Q

what does capillary colloid osmotic pressure do to fluids?

A

solutes pull fluid back into capillaries at venous end of bed

82
Q

what is oedema?

A

an abnormal increase in the volume of ISF

83
Q

what can oedema be due to?

A
  • increased capillary hydrostatic pressure
  • inflammation
  • decreased colloid osmotic pressure
  • blockage of lymphatic vessels

human structure and function (21 decks)

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