Histology of heart and blood vessels Flashcards
layers of blood vessels
tunica intima, tunica media, tunica externa/adventitia
what are endocardium and tunica intima made up of
simple squamous epithelium and connective tissue and BM
what are myocardium and tunica media made up of
muscle and elastic tissue
what are epicardium and tunica externa made up of
fibrous connective tissue
what does endocardium do
forms valves
what does myocardium contain
striated muscle, lots of mitochondria, rich capillary bed, myocytes connected to intercalated disc
intercalated discs
anchoring structures containing gap junctions
functional syncytium
action potential travels through all cells connected together and cells function as a unit
myocardium is arranged in a spiral around a
dense connective cardiac fibrous skeleton
what does epicardium contain
main branches of coronary arteries, may be fatty
arteries
thick muscle wall, smaller and rounded, thin adventitia
vein
thin muscle wall, large flattened, thick adventitial, contains valves to prevent back flow
types of arteries
elastic (large conducting), muscular (distributing arteries), arterioles (terminal branches)
elastic arteries examples
aorta, common carotid, pulmonary
muscular arteries examples
coronary arteries, radial, femoral
arterioles
terminal branches which supply blood to capillary beds
elastic arteries histology
pressure recevoir, stretched during systole, during diastole heart relaxes and then pressure falls, the artery recoils thereby maintaining pressure on the blood, elastic fibres are secreted by smooth muscle cells, recoil and stretchability is due to presence of extensive amounts of elastic fibres in T media in the form of layers= laminae
muscular arteries histology
controls distribution of blood to regions, thick T media has smooth muscle cells, no elastic laminae between muscle cells in T media, Elastic fibres are concentrated in 2 well defined sheets called internal elastic lamina (IEL) just under epithelium and the thin external outer elastic lamina (OEL) between T media and T adventitia
arterioles histology
smaller muscular arteries gradually change histologically to become arterioles, only 1-2 layers of smooth muscle in T media, no IEL or EEL, no T adventitia, rich sympathetic nerve innervation, control blood flow to capillary beds, control blood pressure
capillaries structure
very thin T intima, no T media, no T adventitia, pericytes, low BP
pericytes
incomplete layer of cells surrounding a capillary and have contractile properties which control blood flow
3 types of capillaries
continuous, fenestrated, discontinuous/sinusoids
continuous capillary
can control what is exchanged, material must pass through cell or between cell, selective transport mechanisms, eg in muscle
fenestrated capillary
have fenestrations (pores), diaphragms filter molecules by MW and or charge eg endocrine glands, kidney renal corpuscle
discontinuous capillary
gaps between endothelial cells and basement membrane, allow free passage of fluid and cells, eg liver spleen bone marrow
sinusoids
large diameter discontinuous capillaries, found where large amount of exchange takes place, T intima contains phagocytic cells eg liver
arteriovenous AV shunts
bypasses capillary beds eg skin for thermoregulation, s
veins and venules structure of layers
T intima, T media, T adventitia- all thin
what forms valves
folds of the tunica intima
superficial veins
thick walled and no surrounding support
deep veins
thin walled, surrounding support from deep fascia and muscles, superficial veins drain into deep veins, DVT
lymphatic system does what
drains tissue fluid lose from blood capillaries into the systemic venous system. valves direct flow
lymph capillaries
blind ended capillaries, lined by very thin endothelium, anchoring filaments, no red blood cells in lumen
anchoring filaments
fine collagenous filaments link endothelial cell to surrounding tissue keeping lumen open
blood vessels are organs because
they receive nerve supply, blood supply (vasa vasorum) and lymphatics in T adventitia
