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2 - CVS > deck_485971 > Flashcards

deck_485971 Flashcards

1
Q

How does exchange occur between blood and tissues?

A

Diffusion

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2
Q

Give three factors which affect rate of diffusion

A

Area available for exchangeDiffusion ‘resistance’ Concentration gradient

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3
Q

What affect does increased capillary density have and why?

A

Increased rate of diffusion as larger surface area for diffusion

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4
Q

What do highly metablolically active tissues have?

A

A high capillary density

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5
Q

Why is area available for exchange conisdered a maximum?

A

Because not all capillaries are perfused

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6
Q

In the body is areaa) Rate Limitingor b) Not rate limiting

A

It is b, not rate limiting

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7
Q

What are the three factors which affect diffusion resistance?

A

Nature of molecules crossing the capillariesNature of the barrierPath length

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8
Q

How do lipophillic molecules reach cells from capillaries?

A

By directly crossing capillary wall due to the nature of the lipid bilayer of endothelial cells

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9
Q

How do hydrophillic molecules reach cells?

A

Pass through pores, which offer little resistance

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10
Q

What property do small moleules posses when compared to large?

A

Diffuse more easily

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11
Q

How the nature of the barrier affect diffusion?

A

Increasing pore size and number facilitates the diffusion of large and hydrophillic molecules

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12
Q

What does path length depend on?

A

Capillary density and interstitial space

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13
Q

How does conc gradient affect diffusion?

A

The greater the concentration gradient, the greater the rate of diffusion. Must be maintained in order for exchange to continue.

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14
Q

What is the conc gradient in capillaries between?

A

Capillary contents and nearby cells

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15
Q

What is the most important variable in conc grad?

A

The flow of blood

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16
Q

What happens if blood is not supplied at appropriate rate?

A

Conc grad driving exchange will dissipate, and nutrients will not be supplied at the right rate

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17
Q

What is the cardiac output of an average male at rest?

A

5 l/min

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18
Q

What is the minimum rate of blood flow required by the brain?

A

750 ml/min

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19
Q

What three organs must have blood at ALL times?

A

Kidney, heart muscle and brain

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20
Q

What are the four main components of circulation?

A

PumpDistribution vesselsFlow controlCapacitance

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21
Q

What is the bodies pump?

A

Take a guess, wise guy.

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22
Q

What is the bodies main distribution vessels for circulation?

A

Arteries

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23
Q

What type of vessels are used in flow control?

A

Resistance vessels, such as arterioles and pre-capillary sphincters

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24
Q

What two things do resistance vessels ensure?

A

Blood flow to areas of the body which are difficult to perfuseBlood flow is restricted to areas which are easy to perfuse

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25
Q

What is capacitance?

A

Store of blood to be called upon to cope with temporary imbalances between the amount of blood returning to the heart and the amount that is required to pump out.

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26
Q

Where is capacitance generated?

A

In the veins

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27
Q

What is the function of an artery?

A

Carry blood away from the heart to the capillary beds

28
Q

Give two types of artery

A

Elastic (conducting) or muscular (distributing)

29
Q

What are arterioles?

A

Arteries with a diameter of less than 0.1mm

30
Q

What are capillaries?

A

Vessels 7-10 micrometers in diameter

31
Q

What is a post capillary venule?

A

Receive blood from capillaries, have a diameter of 10-30 micrometers and are even more permeable than capillaries

32
Q

What is a merging venule?

A

Diameter more than 50 micrometers. Tunica media reappears

33
Q

describe a vein

A

Very large diameterThin wall with more connective tissuesFewer elastic and muscle fibresUsually have semi-lunar valves

34
Q

What are veins and arteries comprised of?

A

Three layersTunica intima, media and adventitia

35
Q

Describe the tunica intima of elastic arteries

A

Endothelial cells with long axes parallel to axis of arteryNarrow subendothelium of CT with discontinuous internal elastic limina

36
Q

Why do epithelial cells in tunica intima of elastic arteries have endothelial cells with long axes parallel to axis of artery

A

to reduce friction

37
Q

Why does the tunica intima of elastic arteries have a narrow subendothelium of CT with discontinuous internal elastic lamina?

A

to allow for expansion

38
Q

Describe the structure of the media of elastic arteries

A

40-70 layers of fenstrated elastic membrane, with smooth muscle and collagen between these lamellae.

39
Q

How is the smooth muscle in the media of elastic arteries controlled?

A

Smooth muscle is involuntary and allows for controlled contraction in order to move the blood through the lumen

40
Q

Describe the adventitia of elastic arteries

A

Thin layer of fibroelastic CT containing lymphatic vessels and nerve fibers

41
Q

Describe the intima of muscular arteries

A

Endothelium, subendothelium, thick internal elastic lamina

42
Q

Describe the media of muscular arteries

A

40 layers of smooth muscle cells connected by gap junctions Prominent external elastic lamina

43
Q

Why is does the media of muscular arteries have 40 layers of smooth muscle cells connected by gap junctions?

A

For coordinated contraction

44
Q

Describe the structure of the adventitia of muscular arteries

A

Thin layer of fibroelastic CT with nerve fibersVasa vasorum

45
Q

Why does the adventitia of the arteries have nerves?

A

For vasoconstriction and dilation

46
Q

What are vasa vasorum?

A

Dekiever blood to tissues in muscular artery which are inadquately nourished by luminal blood

47
Q

Describe the structure of the intima of arterioles

A

Endothelium and thin subendothelium

48
Q

Describe the structure of the media of arterioles

A

1 to 3 layers of smooth muscle

49
Q

Describe the structure of the adventitia of arterioles

A

Hardly present

50
Q

How do metarterioles differ from arterioles?

A

Smooth muscle layer discontinuous. spaced apart and encircle endothelium of capillary arising from metarterioles, forming pre-capillary sphincter

51
Q

What is a pre-capillary sphincter?

A

Formed from metarterioles, can contract and prevent blood flow into capillary bed

52
Q

Describe the structure of capillaries

A

Single layer of endothelium with basement membrane

53
Q

Give three types of capillary

A

Continous, fenstrated and sinusoidal

54
Q

what is a fenstrated capillary?

A

Interruptions between thin parts of endothelium

55
Q

What is a sinusoidal capillary?Where are they found?

A

Large diameter, special linings and an incomplete basal lamina which allows blood cells to enter tissue space.Liver, spleen and bone marrow

56
Q

Why are venules more permeable than capillaries?

A

Lower pressure so fluids tend to drain into them

57
Q

Describe the structure of merging venules

A

Intima - endothelium or thin smooth muscle form thin wallValves which are thin extensions of intima and prevent backflowMedia - 2 to 3 layers of smooth muscle

58
Q

Describe the intima of veins

A

Thicker tunica intima than venules (smooth muscle, valves)

59
Q

Describe the media of veins

A

2 to 3 laers of smooth muscle

60
Q

When does the media of veins differ?

A

In superficial veins of leg, where muscle thick to resist distension caused by gravity

61
Q

Adventitia of veins?

A

Well developed

62
Q

What is a vena comitante?

A

A vein or usually a pair of veins found either side of and artery whose pulsations aid venous return

63
Q

What happens to veins if pressure is not maintained?

A

They collapse

64
Q

How is pressure in arteries maintained?

A

Systolic blood flow

65
Q

How is blood pressure in veins maintatined?

A

The muscle pump action in the leg and pressure factor in abdominal and thoracic cavity

66
Q

Name three structures blood vessels do not reach in body

A

Cartilage, epithelia and cornea

2 - CVS (28 decks)

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