vascular control Flashcards
why is the circulatory system called the closed system?
blood remains within the vessels
diagram of the circulatory system?
slide 4
lecture 9 Vascular control
what is the inner lumen for arterial, capillary and venous systems for?
to regulate movement of blood in/out of the circulation
what is the structure of capillaries?
single layer endothelial cells
lack smooth muscle cells
basement membrane of collagen and pericytes
fenestrations in some for movement of larger moelcules
what is the purpose of capillaries?
deliver oxygen to tissues and bring about metabolic exchnage
what arteries and veins change structure when blood is carried?
muscular arteries
elastic arteries
arterioles
valves
position of veins around arteries and skeletal muscles to push blood
how are arteries and venules connected?
capillaries
what happens at the arteriole end?
muscle constricts to regulate blood flow
what are anastomoses?
direct link between arteriole and venule
how does oncotic and hydrostatic pressure differences in capillary bed effect molecule movement?
regulates movement of molecules in circulation system
what are the systolic and diastolic ventricular wall stresses influenced by?
systemic arteriolar and venous tone
what do arteriole tones control?
vascular resistance and therefore blood pressure
what are arteries and small muscular arteries known as?
resistant vessels
what are baroreceptors and chemoreceptors for?
regulate mean arteriole pressure
where are baroreceptors and chemoreceptors located?
carotid arteries and aorta
what effects blood flow and blood pressure?
cardiac output- blood flow from the heart
compliance- ability to expand if increases in content
volume of blood- increases blood pressure
viscosity of blood-number of blood cells
blood vessel length and diameter- effects tone
what is afterload?
systolic ventricular wall stress include vascular resistance/ arteiolar tone
what is preload?
end-diastolic ventricular wall stress includes venous tone which regulates blood returning to the heart
how is tissue perfusion ensured?
balanced O2 delivery to the heart
when does coronary perfusion occur?
during diastole
when does Myocardial ischemia occur?
when O2 supply and demand isn’t balanced
what are the roles of endothelium?
transport of blood
haemostasis for clotting
vascular tone to control constriction
haemodynamic controls flow, viscosity and wall tension
Host defence
Angiogenesis for tissue repair
growth factors
what is the structure of endothelium cells?
very flat
central nucleus
long axes parallel to direction of blood flow
stress fibres
gap junctions
what is the structure and characteristics of smooth muscle cells?
lack sarcomeres
actin-myosin filaments arranged indirectly
action potentials are varied
anchor points for actin
interact with neighbouring cells
slower contraction time
sustained for longer periods
