Histology of Blood Vessels: Structure & Function Flashcards
what are the classifications of blood vessels and their function
- elastic arteries: conducting
- muscular arteries: distributing
- arterioles: resistance (to flow/regulate)
- metarterioles: resistance (to flow/regulate)
- capillaries: exchange
- sinusoids: exchange
- post capillary venules: capacitance (reservoir)
- muscular venules: capacitance (reservoir)
- veins: capacitance (reservoir)
what are the 3 layers of blood vessel
- tunica adventitia
- tunica media
- tunica intima
what are blood vessels lined with
endothelium
low frictional resistance
what is the aorta an example of
elastic artery
what is the function of aorta
conducting blood at high pressure
elastic component/shock absorber/dampens pulsatory blood flow
what is the main structural component of the aorta
tunica media
with high amount elastic laminae (fenestrated so things can pass through)
what are the structural components of the aorta
what is vasa vasorum
small blood vessels in the adventita –> nourish outer 2/3 of media and adventitia in aorta
how do muscular arteries change from other organs
blood flow changes with activity –> diverted from other organs
constriction of muscular distributing ateries (and arterioles) and dilation of vessels supplying muscles
cardiac output increased
what are the characteristics of a muscular artery
intima
prominent internal elastic lamina between intima and media (ex. elastic lamina larger vessels)
media: mainly small muscle under control of sympathetic system + elastic fibres
adventitia: connective tissue and vaso vasorum
what is the function of muscular artery
distribution in relation to varying demand
what are the structures of muscular artery
1,2. tunica intema (1. endothelium, 2. inner elastic membrane)
- tunica media
- tunica adventitia
- vaso vasorum
what are the structures of the muscular arteries
what are the structures of the muscular artery
what is the structure of arterioles
how is the structure of arterioles associated with function
- peripheral resistance to slow rate of flow and cause drop in BP
- regulation of amount of blood entering capillary bed
- metarteriole (terminal) - 1 layer SM –> linking the arteriole system and leading into the capilarry bed, terminal part of blood vascular system that is responsible for delievering the blood to the capillary bed
what are the structures
arteriole: 2 layers of smooth muscle, round, quite small
lymphatic structure
what are the structures of microcirculation
- arteriole
- venule
- communicating (low resistance) channel
- closed capillaries
- open capillaries
- precapillary sphincters
what type of microcirculation is this
precapillary AV (arteriovenous) anastomosis (skin and small intestine)
- artery (metarteriole)
- vein
- arteriovenous anastomosis
- capillary plexus
what are these other types of microcirculation
- arterial portal system: ex. kidney glomerulus
- venous portal system: ex. hepatic portal system liver
what are the general structure of capillaries
what is the pericyte in capillaries
not a functioning role –> but does contract
stem cell and can differentiate into smooth muscle if it recieves the right signals
what are the structure and functional considerations of capillaries
adapted to maximize exchange
thin wall –> high SA:volume ration
2 way exchange between plasma and tissue fluid
what are the structures
red blood cell in capilllary
what are the different types of capillary structures
- continuous capillaries
- fenestrated (porous) capillaries
- sinusoids (liver and spleen)
what are the structure of continuous capillaries
majority
variably permeable
what is the structure of fenestrated capillaries
glomerulus of kidney
clusters of larger openings –> pores of fenestra
the wall of the cells is leaky and junctional complexes are leaky
rapid exchange of material
what is the structure of sinusoids
liver and spleen
discontinuous endothelium
absence basal lamina
large holes in wall
lost the outer basement membrane covering
what is the function of the venous system
capacitance/storage
>60% total blood volume
what are these structures
post capillary and muscular venules
what is the function of the muscular venules
capacitance
what are post capillary venules
pericytes/important in inflammatory response (diapedisis)
what is the structure of muscular venule
small muscle in media/capacitance
what is the difference in the structure of artery and vein
vein: designed for capacitance –> thin wall with respect to lumen, no internal elastic lamina, media thin, valves in larger veins
artery: media is by far the thickest, internal elastic lamina not found in vein,
both: endothelium, media, adventitia
identify the vein and artery
A: artery –> 3 layers of smooth muscle, round
B: venule –> flimsy and not round (doesn’t hold shape), intima = darker layer is not as thick as in the arteriole
what are the structures
what is the structure of valves in the larger peripheral veins
flaps lined with endothelium
what is the function of valves in larger peripheral veins
prevent back flow/pressure
act as muscular pumps
what are the structures of the large veins (ex. caudal vena cava)
what are the features of adventitia in the caudal vena cava
bundles longditudinal –> small muscle propulsion
spiral network of collagen bundles interwoven with elastic fibres (action diaphragm)
cardiac muscle in media near heart
what do lymphatic vessels begin as
lymphatic capillaries
what are lymphatic vessels lined by
endothelium (simple squamous)
what do lymphatic vessels lack
basal lamina
what are the walls of lymphatic vessels
thin walled like veins
do lymphatic vessels contain valves
yes
what do lymphatic vessels carry
lymph from tissues all the way to the heart and dumped back into vascular system through the thoracic duct/treacheal duct/right lymphatic duct
what are the structures
