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Flashcards in Session 1 Deck (18):

What is the total perfusion rate in an average 70kg male at rest?

5 litres per minute


How is blood flow to different tissues controlled?

Using resistance vessels: arterioles and pre-capillary sphincters


What is capacitance in relation to blood vessels?

Ability to cope with changes in cardiac output; a store of blood that can be used to cope with temporary imbalances in blood flow to and from the heart


What are the layers of artery and vein walls from inside to outside?

Tunica intima, tunica media, tunica adventitia


Describe the contents of the tunica intima of an artery

Endothelial calls with long axes orientated parallel to the long axis of the artery; narrow sub-endothelium of connective tissue with discontinuous elastic lamina


Describe the contents of the tunica media of an artery

Fenestrated elastic membranes with smooth muscle cells and collagen between the lamellae; may also have a thin external elastic lamina


Describe the contents of the tunica adventitia of an artery

Layer of fibroblast if tissue containing vasa vasorum, lymphatic vessels and nerve fibres


What structural differences exist between arteries and arterioles?

Layers of smooth muscle in the tunica media decrease; thin elastic lamina only present in larger arterioles; external elastic lamina is absent in arterioles


What structural differences exist between arterioles and metarterioles?

Smooth muscle layer isn't continuous in metarterioles


What are the features of continuous capillaries?

Pericytes form a branching network on the outer surface of the endothelium


What are the features of fenestrated capillaries?

Fenestrations in the endothelium; pericytes present


What are the features of sinusoid capillaries?

Fenestrated capillaries with larger openings to allow RBCs and WBCs to pass through


What is the function of pericytes in capillaries?

Can divide into muscle cells or fibroblasts during angiogenesis, tumour growth and wound healing


Which veins have a well defined muscle wall and why?

Superficial veins of the legs; allows them to resist distension due to gravity


What are the features of the structure of large veins?

Well developed longitudinally oriented smooth muscle in tunica adventitia; circularly arranged muscle in the tunica media


What are the features of the structure of veins?

Larger diameter than any accompanying artery; thinner wall with more connective tissue and fewer elastic & muscle fibres than any accompanying artery


What differences are there in the structure of postcapillary venules and venules?

Smooth muscle fibres begin to be associated with the endothelium in venules


What factors affect diffusion rate in capillaries?

- Area: determined by capillary density
- Diffusion resistance
- Concentration gradient