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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
what do intercellular clefts in continuous capillaries allow?
limited passage of fluids and small solutes
26
in continuous capillaries what carries fluids and larger solutes across capillary wall?
pinocytotic vesicles
27
what do endothelial cells do in continuous capillaries?
join tight junctions to form smooth lining
28
what do endothelial cells in fenestrated capillaries contain?
pores (fenestrations)
29
what do the pores in fenestrated capillaries increase?
permeability to allow rapid exchange of fluids and small solutes
30
where are fenestrated capillaries found?
in areas of active filtration (kidneys), absorption (small intestines or in endocrine glands
31
what is the most leaky type of capillary?
sinusoidal
32
why are sinusoidal capillaries leaky?
there are large spaces between endothelial cells (sinusoids) and large fenestrations, incomplete basement membrane
33
where are sinusoidal capillaries found?
- liver - lymphoid organs - adrenal medulla
34
what does the slow blood flow of sinusoidal capillaries allow?
large molecules and cells to pass between blood and tissues
35
what arteriole supplies capillary bed?
terminal arteriole
36
what venule drains capillary bed?
postcapillary venule
37
what do capillaries unite to form?
venules
38
what do venules unite to form?
veins
39
what does the large lumen in veins allow?
easy blood flow
40
what does the tunica intima in veins fold to form?
valves
41
what do veins have little of?
smooth muscle or elastin
42
what does the thick tunica externa of veins contain?
collagen fibres
43
what type of vessels are veins?
capacitance vessels- thick tunica externa provides support for large blood volume
44
what is blood flow?
the volume of blood flowing through a vessel, organ or the entire circulation(= CO) in a given time period
45
what is blood flow determined by?
- blood pressure | - resistance
46
what is blood pressure?
force exerted on a vessel wall by the blood. in that vessel
47
what is resistance?
the opposition to blood flow
48
what is resistance a measure of?
the amount of friction blood encounters as it flows through a vessel
49
what are the three primary sources fbof total peripheral resistance (TPR)?
- blood viscosity - total blood vessel length - blood vessel diameter
50
what does blood viscosity alter with?
blood cell numbers | -plasma volume
51
does increased haematocrit increase or decrease viscosity?
increases
52
does resistance to blood flow increase or decrease with increasing vessel length?
increases
53
what is systolic pressure?
peak pressure generated in the large arteries when the ventricles contract
54
what two factors does arterial pressure reflect?
- how much elastic arteries can be stretched | - the volume of blood forced into elastic arteries by ventricular contraction
55
what is diastolic pressure?
pressure in large arteries during ventricular relaxation
56
what is the equation for pulse pressure?
systolic pressure - diastolic pressure
57
what is mean arterial pressure?
the pressure that propels blood through vessels
58
what is the equation for mean arterial pressure?
diastolic pressure + (1/3 x pulse pressure)
59
why is low capillary pressure required?
- high pressure would damage thin-walled, fragile capillaries - most capillaries are very. permeable so low pressure is adequate
60
what are 5 aspects apart of venous return?
1. valves 2. muscular pump 3. respiratory pump 4. pulsation 5. venoconstriction
61
what are factors that determine blood pressure?
- cardiac output - peripheral resistance - blood volume
62
what is a slower more long-term regulation factor of blood pressure?
blood volume
63
what is a rapid more short-term regulation factor of blood pressure?
cardiac output and peripheral resistance
64
what is resistance primarily altered by to regulate blood pressure?
changing arteriole diameter
65
what is blood volume controlled by to regulate blood pressure?
renal and endocrine mechanisms
66
what are the different levels that regulate blood pressure?
- autoregulation - neural regulation - renal mechanisms - endocrine mechanisms
67
where does auto regulation of blood pressure occur?
occurs within tissues and is dependent on local conditions
68
what does neural regulation of blood pressure involve?
cardiovascular centres, ANS and baroreceptor reflex
69
what are the three centres in the medulla oblongata that are apart of neural regulation of blood pressure?
- cardioinhibitory - cardioacceleratory - vasomotor
70
where are baroreceptors located?
- carotid artery sinuses - aortic arch - walls of most large arteries in neck and thoracic
71
what does the carotid baroreceptor sinus reflex monitor?
blood pressure to ensure adequate blood flow to brain
72
what does the aortic baroreceptor reflex monitor?
blood pressure to maintain blood flow to systemic circuit
73
what does the direct mechanism of the renal mechanism determine to alter blood pressure?
urine formation altering blood volume and therefore pressure
74
what does the indirect mechanism of the renal mechanism involve to alter blood pressure?
hormones: renin-angiotensin-aldosterone system (RAAS)
75
what is a hormone that decreases BP?
atrial natriuretic peptide
76
what are hormones that increase BP?
- adrenaline - noradrenaline - angiotension II: secretes aldosterone and ADH
77
where do fluids move through in capillaries?
- intercellular clefts - fenestrations - sinusoids
78
what are the two opposing forces that determine direction and volume of fluid movement?
hydrostatic and colloid osmotic pressures
79
what is hydrostatic pressure?
force exerted by fluid pushing against a tissue wall
80
what does capillary hydrostatic pressure do to fluid?
pushes fluid and solutes out of capillaries through intercellular clefts/fenestrations/sinusoid at arterial end of bed
81
what does capillary colloid osmotic pressure do to fluids?
solutes pull fluid back into capillaries at venous end of bed
82
what is oedema?
an abnormal increase in the volume of ISF
83
what can oedema be due to?
- increased capillary hydrostatic pressure - inflammation - decreased colloid osmotic pressure - blockage of lymphatic vessels

human structure and function (21 decks)

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