peripheral circulation Flashcards
capillaries` structures of transportation
presence of clefts and pores between them
mode of transport in continuous capillaries
clefts and transcytosis
mode of transport in fenestrated capillaries
pores and transcytosis
structure of a continuous capillary
no clefts no pores for example in the brain
some have clefts only for example in the muscle
structure of a fenestrated capillary
both clefts and pores
structure of a discontinuous capillary
clefts and massive pores for example the liver
exchange in capillaries
non polar substances through phospholipid bilayer
polar substances through clefts and pores
via transcytosis
osmotic pressure
pressure exerted by proteins which causes the movement of fluid into the capillaries
drainage of the excess fluid
lymphatic system
amount of fluid that drains into the lymphatic system
3l
diseases of the lymphatic system
oedema
what causes oedema
raised central venous pressure which is caused by ventricular failure
lymphatic obstruction by organisms like in elephantitis
hypoproteinaemia which leads to less oncotic pressure
increased capillary permeability which can be caused by inflammation
control of peripheral blood flow
decrease in the radius and redirect blood flow of blood
Calculation of mean arterial pressure
MAP = CO x TPR
control of resistance on blood vessels
regulation of diameter of vessels
through local factors
through extrinsic factors
example of local controls
1.active metabolic hyperaemia - increase in metabolite products triggers paracrine signals that lead to arteriolar dilatation in order to flow out the metabolites
2.pressure flow - increase in MAP will cause a decrease in flow which triggers paracrine signals that dilate the vessel and flow is back to normal.
3.reactive hyperaemia
4.injury response by histamine which causes permeability of blood vessels and dilation
central control of blood flow
sympathetic nerves releases noradrenaline that binds on alpha 1 receptors and cause constriction which decreases the flow and increases TPR and MAP
sympathetic nerve system effect on the receptors
alpha 1 receptors
mean arterial pressure calculation
total peripheral resistance and cardiac output
special regions of blood flow
pulmonary circulation
coronary circulation
cerebral circulation
renal circulation
receptors in coronary circulation
displays many beta 2 receptors and they swamp any arteriolar constriction
how is cerebral circulation pressure and flow diff from other systems ?
has to be kept stable and shows excellent pressure autoregulation
how is pressure and flow in the pulmonary circulation diff from the rest of the body
increase in metabolites in one region causes vasoconstriction of that arteriole to redirect blood to well perfused regions
how is pressure and blood flow different in renal circulation?
Main job is filtration
Filtration rate kept relatively constant during normal fluctuations in MAP
Due to excellent pressure autoregulation
regions that express active hyperaemia
coronary circulation
circulation that shows excellent pressure autoregulation
cerebral circulation
