Exam 2 - part 2, aneurysm, arterial sense organs, capillaries

a weak point in an artery or heart wall that forms a thin-walled bulging sac which pulsates with each beat and may rupture at any time is called an

aneurysm

what are the most common sites for an aneurysm

abdominal aorta, renal arteries, arterial circle at base of brain

what is the most common cause of aneurysms

atherosclerosis and high blood pressure

baroreceptors and chemo receptors transmit information to the ____ to regulate ___ ___, ___ ___ diameter, and ____

brainstem, heart rate, blood vessel, repiration

where are baroreceptors located

aortic arch, carotid sinuses

where are chemoreceptors found

carotid bodies, aortic bodies

chemoreceptors in the carotid bodies are located at the bifurcation of the __ artery and they transmit signals through the ___ nerve to the brainstem to adjust ____ rate

carotid, glossopharyngeal, respiratory

what nerve innervates the chemoreceptors found in the aortic arch

vagus

how is the flow through capillaries often described? why?

microcirculation, blood flow velocity is slow

what composes capillaries

tunica intima, basal lamina (basement membrane)

where are capillaries scarce or absent

tendons, ligaments, epithelia, cornea, lens

what are the types of capillaries

continuous, fenestrated, sinusoids

which type of capillary occurs in most vascularized structures such as skin and muscle

continuous

what do continuous capillaries allow passage of

glucose, water, hormones

what wraps around continuous capillaries which contain contractile protein and provide stabilization

pericytes

where are fenestrated capillaries often found

kidneys, small intestine

organs that require rapid absorption or filtration

what kind of molecules can pass through fenestrated capillaries

small

where are sinusoids (discontinued) capillaries found

liver, bone marrow, spleen, adrenal medulla

what are sinusoids

irregular blood-filled space with large fenestrations

what is allowed to pass through sinusoids

proteins, clotting factors, new blood cells

t/f

capillary beds are usually supplied by a single arteriole or metarteriole

true

at what end of the capillary bed to capillaries transition to venules

distal

at any given time what fraction of the body's capillaries are shut down

3/4

what controls flow within the capillary bed

precapillary sphincters

a ____ is a type of vessel which has structural characteristics of both an arteriole and capillary but is slightly larger than a capillary

metarteriole

what does the smooth muscle of a metarteriole do as it enters the capillary

forms rings

are the precapillary sphincters usually open or closed

closed

when precapillary sphincters of a capillary bed are closed, blood will flow from the ___ directly into the ____ channel and ultimately end in ___ circulation. This is known as a _______

metarteriole, thoroughfare, venous, vascular shunt