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cardiovascular physiology > RECAP **Circulatory system : Blood vessels - structure & function > Flashcards

RECAP **Circulatory system : Blood vessels - structure & function Flashcards

1
Q

What is the function of the cardiac system?

A
  • A transport system
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2
Q

What is the role of an artery blood vessel?

A
  • distribute blood under high pressure away from the heart
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3
Q

What are the 2 types of arteries called?

A
  • elastic arteries - contain a large amount of elastic tissue
  • muscular arteries
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4
Q

what is the role of elastic tissue in arteries?

A
  • it allows them to expand to accept the stroke volume delivered by the heart
  • it also allows them to re-coil which helps to drive the blood on through the vessel
  • ‘wind- kessel effect’ - expand during systole an recoil during dystole
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5
Q

what is the stroke volume?

A
  • stroke volume (SV) is the volume of blood pumped from the left ventricle per beat.
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6
Q

What are the smallest arteries called?

A
  • arterioles - arteries with an internal diameter of less than 100 micro metres
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7
Q

what is the role of arterioles ?

A
  • regulate blood flow locally
  • regulate arterial blood pressure
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8
Q

what are the smallest vessels in the body? what is its function

A

Capillaries

  • function : the main site of exchange of substances between the blood and the tissues
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9
Q

What are examples of ‘resistance’ vessels? Why are they called this?

A
  • small arteries and arterioles are known as ‘resistance vessels’
  • they offer a frictional force that opposes blood flow
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10
Q

what happens to blood after passing through the capillaries?

A
  • Blood enters the venous system on its way back to the heart
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11
Q

what are veins and venules often referred to as and why?

A
  • capacitance vessels
  • they can store large volumes of blood
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12
Q

What are the three layers in a blood vessel called?

A
  • Lumen
  • Media ( middle )
  • Intima (inner)
  • Adventitia
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13
Q

Compare and contrast the difference in structure between the 3 layers in an artery & vein.

A
  • Arteries - smaller lumen, thicker media ( for contraction )
  • Veins larger lumen
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14
Q

Which layer is the broadest layer?

A
  • the outermost layer, the adventitia
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15
Q

Describe the structure of the Tunica Intima layer of the vessel

A
  • thin layer of squamous epithelial cells that line the inside of the blood vessel (lumen)
  • the endothelial cells are located on a thin membrane called the basal lamina/ basement membrane
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16
Q

what is located underneath the basal lamina in the intima layer of the blood vessel?

A
  • a subendothelial layer that contains connective tissue and fibroblast cells that lay down the CT
17
Q

What are the endothelial functions?

A
  • it provides a selective barrier between the blood and tissues
  • also provides surface for leucocytes to migrate to a site of inflammation
  • haemostasis - blood clotting
18
Q

Describe the structure of the media layer

A
  • contains vascular smooth muscle
  • cells are arranged in layers
  • also contains elastin arranged in porous sheets (laminae) (allows molecular movement )
  • also contains collagen ( for mechanical strength)
19
Q

Describe what causes the tunica media vascular smooth muscle to contract and dilate ie vasoconstriction & vasodilation

A

vasoconstriction : sympathetic NS, noradrenaline, adrenaline, angiotensin II

vasodilation : parasympathetic NS, adrenaline etc

20
Q

what is the lumen?

A
  • hollow opening / space inside the blood vessel
21
Q

Describe the structure of the adventitia

A
  • contains collagen and elastin fibres for mechanical support & anchoring vessel
  • autonomic nerve fibres also located here that influence the tone of the smooth muscle in the media layer
  • contains the vasa vasorum
22
Q

What is the vaso vasorum?

A

‘vessel in a vessel’ - small blood vessels that run through the adventitia and provide nourishing blood flow to the tissues within the blood vessel wall

note : blood in lumen of large vessels are too far away from outer vessel layers, so vascular walls need own blood supply

23
Q

Describe the windkessel function of large elastic arteries

A
  • ‘windkessel ’ - applied to anything that acts to smooth out pressure fluctuations
  • elastic arteries expand to accommodate stroke volume during systole
  • during diastole, no blood is ejected into the aorta but there is an elastic re-coil of the arterial walls which maintains pressure on blood & keeps it moving
24
Q

what does the term ‘ elastic re-coil’ mean?

A
  • Elastic Recoil in any tissue (including arteries) refers to the inherent resistance of a tissue to changes in shape, and the tendency of the tissue to revert to its original shape once deformed
25
Q

What is the highest & lowest pressure in the heart called?

A
  • systole pressure (highest)
  • diastole (lowest)
26
Q

Describe the elastic tissue in arteries.

A
  • made up of elastin protein
  • laid down in distinct layers called laminae ( between which are layers of smooth muscle )
  • elastin content becomes less and less as muscular content becomes greater
27
Q

what is the internal elastic lamina? IEL

A
  • distinct elastic layer that separates the smooth muscle ( media layer ) from the intima layer
  • located at the intima - media border
  • fenestrated
28
Q

what is the external elastic layer? EEL

A
  • distinct elastic layer that separates the smooth muscle from the adventitia layer ( ie between the media and adventitia)
29
Q

Is there any elastic tissue in veins?

A
  • There is no elastic tissue arranged in layers
  • there are some scattered throughout media and adventitia
30
Q

Describe the 3 layers in vein

A
  • adventitia layer - collagen fibres & some elastin fibres
  • Venous wall is thin in comparison to the lumen diameter
  • media has a few smooth muscle layers and in between them we found layers of collagenous tissue
31
Q

What are the functions of the thin walls and wide lumens in veins?

A
  • they can expand and collapse quickly which means that their volume can change quickly which encouages their function as capacitance vessels
32
Q

What do veins have that arteries do not?

A
  • VALVES
  • they prevent backflow of blood

cardiovascular physiology (23 decks)

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