Blood vessels Flashcards
what are pre-capillary sphincters
controls blood flow to specific capillary beds selectively
what is smooth muscle
supplies the vessels with contractile power and regulates lumen diameter
what is the endothelium
filtering interface between blood and the body
what is elastin for
gives vessels mechanical strength and their elastic properties
what is adventitia
provides structural strength and tethers the vessels in place
what are arterioles responsible for
altering the levels of resistance to blood flow in order to distribute the available amount of blood
what do conduits do to divert blood
they change their shape to restrict bloodflow
what is active hyperamia
the increase in blood flow according to the metabolic needs of the tissue in question
what is flow auto regulation
concerns with the maintenance of blood flow rather than changing it, blood to brain has to be maintained for example as to not enlarge
what is myogenic regulation of arterial diameter
increase in pressure leads to muscle stretch that is followed by constriction, myogenic response prevents flow from getting to high
describe capillaries
there are numerous of them all across the body and are one cell thick to facilitate diffusion
what dictates the velocity of blood flow
the total cross sectional area of capillaries not individual capillaries
is the velocity of capillaries high or low
low
where are capillaries found
surrounding every muscle fibre
when does filtration take place
when hydrostatic pressure exceeds colloid osmotic pressure
when does absorption take place
when colloid osmotic pressure exceeds hydrostatic pressure
characteristics of veins compared to arteries
larger diameter, have valves, less elastic tissue, thinner walls, less smooth muscle
what are characteristics of healthy veins
flow is only towards heart, back flow is prevented by shut valves
what are characteristics of diseased veins
allow blood flow to move in opposite direction, can cause blood to accumulate in extremities
how much blood is in veins
about 60% of total blood volume
what is the pressure of blood in veins
only ~10mmHg
what is the veins contribution level
not as active as arteries but ability to change from a reservoir to a condyle plays a big role
how is central venous pressure determined
blood volume and compliance
info of changing compliance of a vein on onenote
how does the skeletal muscle pump work
compression on the veins by muscle contraction pushes blood towards the heart
how does the respiratory pump work
the diaphragm contracts and moves downwards increasing the volume of the thoracic cavity and decreasing volume of abdominal cavity
what do lymph vessels do
collect filtered fluid from interstitial space and return to circulating blood volume
where are lymph vessels
they match the veins but aren’t by any arteries
what is oedema
accumulation of excess fluid in interstitial spaces, filtration exceeds lymphatic drainage
