Ch 21 Blood vessels and circulation Flashcards
(35 cards)
Functions of circulatory system
carry blood exchange nutrients, waste products, gases transport regulate blood pressure direct blood flow
Arteries
thicker muscle walls than veins, more elastic tissue and smooth muscle tissue
Capillaries
sites of exchange within tissue
Veins
thinner walls than arteries, less elastic tissue and fewer smooth muscle cells
Vasa vasorum
blood vessels that supply walls of arteries and veins.
Artery tunica externa (adventitia)
Outer layer
consists of connective tissue
dense regular near vessel and loose ct merges with surrounding ct
Artery tunica media
Middle layer
smooth muscle- allows for vasoconstriction and vasodilation
Artery tunica intima
innermost layer
thin layer of connective tissue called lamina propria (basement membrane) and internal elastic lamina which contains elastic fibers
Anatomy of veins
3 layers, but tunica media is thinner than in arteries (less smooth muscle)
have one way valves that allow blood flow to the heart only (one-way blood flow)
Elastic/conducting arteries
Large arteries
pressure is highest and fluctuates between systolic and diastolic
most elastic tissue than muscular tissue
relatively thick tunica media and thin tunica intima
Muscular arteries - medium
smooth muscle allows vessels to regulat blood suppy by constricting or dilating
most of smaller, unnamed arteries
thick walls (25-40 layers of smooth muscle)
distributing arteries- smooth muscle allows them to partially regulate blood supply to diff regions of the body
Small muscular arteries
adapted for vasodilation and constriction
arterioles
transport blood from small arteries to capillaries
capable of vasodilation and constriction
Capillaries anatomy
layer of simple squamous epithelium and basal lamina
cells called pericytes wrap around to help regulate blood flow and establish bbb
Substances move through capillaries by…
diffusion
Larger water soluble molecules move through… in capillaries
fenestrae
Continuous capillaries
found in tissue
least permeable
most abundant
allow for small substances to pass through
Fenestrate capillaries
Found in glomeruli of kidneys
have larger gaps called fenestrations for passage of more substances
Sinusoid capillaries
found in adrenal gland, liver, bone marrow, spleen
most permeable
incomplete basement membrane and intercellular gap allow for more substances to flow through
Capillary network bloodflow pathway (closed sphincters)
artieriole–>metarteriole–>thoroughare channel–>venule
Capillary network bloodflow pathway (open sphincters)
ateriole–>matarteriole–>capillaris–>thoroughfare channel–>venule
Venules
drain capillar network; made of endothelial cells and basement membrane with few smooth muscle cells
Small veins
smooth muscle cells form continuous layer; addition of tunica adventitia made of collagenous connective tissue
Medium veins
go between small and large veins