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[Y1] Anatomy and Physiology > The circulation > Flashcards

The circulation Flashcards

1
Q

what 3 things does a circulatory system consist of?

A

-fluid (for transporting materials)
-tubes (where fluid flows)
-force (which drives the fluid)

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2
Q

what 2 kingdom has no circulatory system and what do they do instead?

A

Protozoans (amoeba and paramecium) and Hydra
transport accomplished by diffusion or active transport

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3
Q

how do substances move within a cell and between parts of an organism?

A

circulation

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4
Q

what is the equation for the limits of diffusion?

A

t= x^2 /2D
t: time for diffusion
x: distance for diffusion
D: diffusion coefficient

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5
Q

why do larger organisms need circulation?

A

because of the limits of diffusion

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6
Q

define diffusion

A

the passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration

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7
Q

what 4 things does the circulation help to maintain?

A

-transport of nutrients and waste
-maintain pH
-maintain osmotic pressure
-heat

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8
Q

what are the 2 functions of circulation?

A

-maintain optimal environments for cells
-transport hormones: communication

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9
Q

how close can circulation transport nutrients to the cell?

A

within 10-20µm

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10
Q

how are nutrients transfered from the circulation to the cell?

A

diffusion takes them to the cell surface

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11
Q

what are arteries used for?

A

transport blood away from the heart, therefore under high pressure

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12
Q

what are the veins used for?

A

transport blood to the heart

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13
Q

what are the capillaries used for?

A

exchange transported material with interstitial fluid (between vessels and cells)

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14
Q

how much of the blood volume is in the arteries?

A

13%

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15
Q

how much of the blood volume is in the heart?

A

7%

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16
Q

how much of the blood volume is in the arterioles and capillaries?

A

7%

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17
Q

how much of the blood volume is in the pulmonary circulation?

A

9%

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18
Q

how much of the blood volume is in the veins, venules and venous sinuses?

A

64%

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19
Q

what are the 3 layers of vessel walls from inside to outside?

A

-Tunica intima
-Tunica media
-Tunica adventitia

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20
Q

what makes up the adventita?

A

fibroblasts and fibrous elements gradually merge with surrounding connective tissue-
-Vasa vasorum – blood vessels in arterial wall
-Nervi vascularis – nerves ending on vascular smooth muscle

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21
Q

what makes up the media? (3 things)

A

elastic fibers, collagen fibers and circumferentially arranged smooth muscle cells

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22
Q

what makes up the intima?

A

endothelial cells, surrounded by subendothelium (collagen and smooth muscle) and elastic fibers

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23
Q

what are the 2 types of arteries?

A

elastic arteries
muscular arteries

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24
Q

what is the function of elastic arteries?

A

convert pulsative flow into smoother continuous flow

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25
Q

what is the diameter of terminal arteries?

A

100-150µm

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26
Q

what is the diameter or arterioles?

A

10-100µm

27
Q

what is the roles of the arterioles?

A

control release of blood to capillaries

28
Q

describe veins (3 things)

A

-thinner walls than arteries but muscular so can act as reservoir
-approx. 2/3 of blood is in veins
-contains valves to ensure one-way blood flow

29
Q

what are small veins called and what are there diameters?

A

venules
50-200µm

30
Q

what makes up venules?

A

an endothelial layer surrounded by longitudinal smooth muscle and occasional pericytes

31
Q

how long and wide are capillaries?

A

0.5-1mm long
4-6µm wide

32
Q

what is the transit time of capillaries?

A

0.5-2 seconds
can fall to 0.25 seconds upon exercise

33
Q

what is the capillary density in skeletal muscles?

A

300-1,000 / mm2

34
Q

what is the capillary density in brain and myocardium

A

3000 / mm2

35
Q

what do terminal arterioles regulate?

A

the number of perfused capillaries

36
Q

what is the cycle of terminal arterioles called and how long is each cycle?

A

Vasomotion
approx. 15 sec

37
Q

what is the diffusion distance of continuous capillaries?

A

300µm

38
Q

what are the 2 places solute exchange in continous cappilaries?

A

-intercellular clefts
-caveolae-mediated transport

39
Q

where are continuous capillaries found?

A

fat, muscle and the nervous system

40
Q

what is the diameter of fenestrated capillaries?

A

50-60nm

41
Q

how thick is the membrane of a fenestrated capillary?

A

4-5nm

42
Q

why are fenestrated capillaries more useful than continuous capillaries in some cases?

A

more permiable to water and small water-soluble substances

43
Q

where are fenestrated capillaries found?

A

-intestinal villi
-endocrine glands
-kidney glomeruli

44
Q

what is the alternative name for discontinuous capillaries?

A

sinusoids

45
Q

where are discontinous capillaries found?

A

liver, bone marrow and spleen

46
Q

what are discontinuous capillaries permeable to?

A

plasma proteins

47
Q

how wide are the gaps in discontinuous capillaries?

A

100nm

48
Q

what is hydostatic pressure?

A

the pressure in the circulatory system exerted by the volume of blood when it is confined in a blood vessel

49
Q

what is osmotic pressure?

A

the pressure exerted by the flow of liquid through a semi-permeable membrane separating two solutions with different concentrations of solute

50
Q

what happens if:
hydrostatic pressure > osmotic pressure

A

fluid leaks out

51
Q

what happens if:
osmotic pressure > hydrostatic pressure

A

fluid seeps in

52
Q

what is darceys law?

A

google it

53
Q

what are the 3 types of flow through blood vessels

A

-laminar
-turbulent
-single-file

54
Q

what can liquid be modelled as in laminar flow?

A

a set of thin concentric shells sliding past eachother

55
Q

how much velocity does laminar that touches the vessel wall have?

A

zero velocity

56
Q

where do rbc concentrate in laminar flow?

A

in the middle

57
Q

what is the thickness of marginal plasma layer?

A

2-4µm

58
Q

what blood vessels does laminar flow occur?

A

arteries, arterioles, venules and veins

59
Q

what is the pressure pulse in young and old people?

A

young: 4 m/sec
old: 10 m/sec

60
Q

when does turbulent flow occur?

A

when the pressure difference is above a critical point

61
Q

where does turbulent flow occur?

A

heart ventricles

62
Q

how does flow increase in turbulent flow?

A

as squre root of pressure difference

63
Q

how is the friction between blood cells and vessel walls minimised in single-file flow?

A

glycocalyx or a thin film of plasma

64
Q
A

[Y1] Anatomy and Physiology (23 decks)

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