Lecture 5- Structure and Function of Blood Vessels Flashcards

1
Q

what supply do all tissues have

A

arterial supply

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2
Q

what drainage do all tissues have

A

venous drainage

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3
Q

3 core functions of blood vessels

A

-resilient
-flexible
-always remain open

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4
Q

what is the standard blood vessel structure

A

tunica intima->tunica media-> tunica adventitia/ externa

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5
Q

what epithelium is found in the tunica intima?

A

simple squamous epithelium

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6
Q

endothelium

A

epithelium that lines blood vessels

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7
Q

what do the epithelial cells in the tunica intima have

A

basal lamina (extracellular matrix of epithelial cells)

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8
Q

what connective tissue is found in the tunica intima

A

subendothelial connective tissue

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9
Q

what is found in the loose connective tissue of the tunica media

A

smooth muscle fibres

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10
Q

which fibres may the tunica media contain

A

elastic fibres

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11
Q

structure of the tunica externa/adventia

A

Connective tissue
Merges with surrounding connective tissue
May contain vaso vasorum (vessles of the vessels)

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12
Q

why do arteries have thick walls

A

blood is under high pressure

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13
Q

what do arteries resemble and what do veins resemble

A

arteries- garden hoses (smaller lumen)
veins- fire hoses (larger lumen)

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14
Q

why do valves have thin walls

A

as blood travels under low pressure

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15
Q

which is more resilient: arteries or veins?

A

arteries

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16
Q

what are the 3 types of arteries

A

elastic (conducting)
muscular (distributing)
arterioles (resistance vessels)

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17
Q

examples of elastic (conducting) arteries

A

aorta, brachiocephalic and common carotid

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18
Q

diameter of elastic (conducting arteries )

A

up to 2.5 cm

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19
Q

function of elastic (conducting arteries)

A

withstand changes in pressure during the cardiac cycle and ensure continuous blood flow

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20
Q

structural adaptations of elastic ( conducting arteries)

A

thick tunica media with many elastic fibers and few smooth muscle cells

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21
Q

examples of muscular (distributing) arteries

A

brachial and femoral arteries

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22
Q

diameter of muscular (distributing) arteries

A

0.5 mm – 0.4 cm

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23
Q

function of muscular (distributing) arteries

A

-Distribute blood to muscles and organs
-Capable of vasodilation and vasoconstriction
in order to control the rate of blood flow to
suit the needs of the organ
-e.g contracting muscles during exercise- dilate blood vessels

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24
Q

structural adaptations of muscular (distributing) arteries

A

smooth muscle cells in tunica media
distinct internal (IEL) & external elastic laminae (EEL)
thick tunica externa

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25
Q

diameter of arterioles (resistance vessels)

A

</= 30 um

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26
Q

function of arterioles (resistance vessels)

A

-Capable of vasoconstriction &
vasodilation
-Control blood flow to organs
-Involved in blood pressure control

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27
Q

structural adaptations of arterioles (resistance) vessels

A

one to two layers of smooth muscle
cells in tunica media
poorly defined tunica externa

28
Q

functions of capillaries

A

Connect arterioles and venules
(microcirculation)
Site of gaseous exchange

29
Q

why are there thin walls of capillaries

A

facilitate diffusion

30
Q

why is blood flow through the capillaries slow

A

ensures enough time for exchange of gases

31
Q

what exchange does the structure of capillaries allow

A

2 way exchange

32
Q

diameter of capillaries

A

8-μm (micrometres) in diameter

33
Q

what else aids the thin walls of the capillaries

A

endothelium and basement membrane

34
Q

what are the 3 types of capillaries

A

continuous
fenestrated
sinusoidal

35
Q

features of continuous capillaries

A

no gaps between cells, all next to each other
Skeletal and smooth muscle, CT, and the
lungs

36
Q

features of fenestrated capillaries

A
  • Pores penetrate the endothelial lining
  • Rapid exchange of water or large solutes
    (e.g. small peptides)
  • Absorption (kidney, choroid plexus and
    endocrine glands
37
Q

choroid plexus

A

area where we produce cerebral spinal fluid in the brain

38
Q

intracellular clefts

A

gaps between adjacent cells of fenestrated capillaries

39
Q

features of sinusoidal capillaries

A
  • Spaces between endothelial cells
  • Incomplete or absent BM
  • Exchange of large solutes i.e.
    plasma proteins
  • Specialised lining cells (e.g. in
    the liver, phagocytic cells engulf
    damaged RBCs)
  • Blood moves slowly through
    sinusoids
40
Q

how are capillaries organised

A

into groups called capillary beds

41
Q

what do capillary beds allow

A

allow slow flow between arteriole and venule to allow exchange of gases and nutrients

42
Q

what supplies a single capillary bed

A

metarteriole

43
Q

structure of metarteriole

A

Each metarteriole continues
as a thoroughfare channel
which leads directly to a vein
and has numerous
capillaries leading off it

44
Q

what can reduce flow to a whole capillary bed

A

constriction of the metarteriole

45
Q

precapillary sphincter

A

guards the entrance to each capillary (controls entrance diameter)

46
Q

constriction of the precapillary sphincter

A

narrows the entrance therefore reduces flow

47
Q

relaxation of the precapillary sphincter

A

relaxation dilates entrance therefore increases flow

48
Q

arteriovenous anastomosoes

A

Form direct communication
between the arteriole and
venule (no capillaries tunning off them)

49
Q

dilated arteriovenous anastomoses

A

blood
bypasses the capillary bed
and flows directly to the venous
circulation

50
Q

venules

A

collect blood from capillary beds and deliver it to small veins

51
Q

diameter of venules

A

varies, average 20 m

52
Q

structural adaptations of venules

A

Small– endothelium on a basement
membrane
Larger– increasing numbers of smooth
muscle cells located outside endothelium

53
Q

how are veins (capacitance vessels) classified

A

according to size
Small < 2mm in diameter
Medium 2-9 mm in diameter
Large > 9mm in diameter e.g. superior and inferior vena cava

54
Q

features of veins

A

low-pressure system
easily distensible (capacitance- can store/ hold more blood in the vein)

55
Q

structural adaptations of veins

A

Thin walled
Tunica externa is predominant
Valves to aid blood flow

56
Q

anatomical planes- sagittal

A

passes from front to back splitting body
into right and left sides

57
Q

anatomical planes- coronal/frontal

A

passes from side to side-splitting body into front and back

58
Q

anatomical planes - transverse/ horizontal

A

splits the body into upper and lower parts

59
Q

anterior

A

passes from front to back splitting the body
into right and left sides

60
Q

distal

A

a direction away from the point of attachment or origin e.g. for a limb, away from its attachment to its trunk

61
Q

inferior

A

Below, in reference to a particular structure,
with the body in the anatomical position.

62
Q

lateral

A

pertaining to the side

63
Q

medial

A

towards the midline of the body

64
Q

posterior (dorsal)

A

towards the back

65
Q

superior

A

Above, in reference to a portion of the body
in the anatomical position

66
Q

anatomical position

A

An anatomical reference position; the body viewed from the anterior
surface with the palms facing forward.