Circulatory System Part 2 Flashcards
what does the venous system function as?
a low pressure collecting system for returning blood from capillary beds to heart
Vv in comparison to Aa (2)
Thinner walled vessels with larger relative luminal diameter than corresponding Aa
Fewer layers of smooth Mm in tunica media compared to similar sized Aa
thickest of the three layers in the venous system
tunica adventitia
what prevent backflow ?
valves
where do valves prevent back flow typically? (2)
limbs and thorax
what is valve failure in the legs called?
varicose veins
small veins
venues
what do venues lack? (2)
elastic laminae and smaller venues may lack tunica media
post-capillary venules
diameter and what is reduced or absent?
10-50 um in diameter; both tunica media & adventitia reduced or absent
what is the preferential site for diapedesis
post-capillary venules
where do venues drain?
into larger collecting venules, then muscular venules
venues
diameter and description
~50-100 um in diameter, with thin smooth Mm layer in tunica media
what layer is thick in venuoles?
tunica adventitia
what substances act on venuoles?
vasoactive substances (histamine, serotonin)
how do vasoactive substances act on venuoles?
they enlarge the intercellular spaces which increases permeability of vessels
what are large & medium sized Vv called?
muscular Vv
small muscular veins may or may not contain
internal elastic lamina
medium muscular veins contain only
internal elastic lamina
large muscular veins contain both
internal and external elastic lamina
what does smooth muscle in tunica media control the luminal diameter of? (2)
muscular veins and venuoles
what are AV shunts?
direct connections between arterial and venous system
AW shunts bypass
capillary beds
what are capillary beds?
common in –
function in –
a type of anastomosis, common in the skin to function in thermoregulation
portal vessels
arteries or veins connecting two capillary beds
examples of portal vessels (2)
hepatic portal vein
a venous portal system
When endothelium of vessel damaged, cholesterol adheres to
exposed proteins
Once endothelium heals, cholesterol patch is
reabsorbed
what does phagocytosis by macrophages and later by endothelial and subintimal cells result in
foam cells
what happens if the inflammatory response becomes chronic?
atherosclerosis and plaque formation
atherosclerosis can be (2)
generalized or focal
the most common acquired abnormality of blood vessels is
atherosclerosis
as plaque enlarges, or if endothelium is damaged, it exposed
underlying collagen
what does atherosclerosis initiate? (2)
the clotting cascade, thrombus formation
what is it called if a piece of thrombus breaks off? what disease is associated to this?
embolus
thromboembolic disease
atherosclerosis is later accompanied by proliferation of smooth muscle cells and formation of
fibrous, connective tissue capsule
what happens as cells within the plaque die? (2)
necrosis and secondary calcification (hardening of Aa)
what is atherosclerosis often associated with?
hypertension due to a decrease in the diameter of vessel lumen and an increase in systolic blood pressure
what is the most common cause of ischemic heart disease?
atherosclerosis
what occurs during ischemic heart disease
lumen of coronary arteries may decrease by 90%
stenosis
gradual narrowing by plaque
what does gradual narrowing by plaque result in
thrombosis of vessel
what does thrombosis mean
occlusion
what occurs after sudden occlusion by an embolus?
acute ischemic event
what does a decrease in oxygen to the heart muscle result in?
angina
angina
chest pain
decrease in oxygen
anoxia
myocardial infarction
death by ischemia
if ischemic heart disease/thrombo-embolic disease is left untreated and a portion of muscle dies,
myocardial infarction
Since cardiac Mm cells in Go phase (terminally differentiated), unable to regenerate; all healing occurs via
fibrosis
connective tissue is less contractile than
muscle
because connective tissue is less contractile than muscle, you may experience a decrease in
function or partial loss of function
in endocarditis, what might also be effected?
heart valves
Inflammation & thickening of AV valves often associated with valvular incompetence leads to
increased turbulence (blood leakage when they should be closed)
increase turbulence can lead to (2)
vegetative endocarditis and thromboembolic disease
Strokeis similar to MI, except affects — instead of heart
brain
Neurons are also
terminally differentiated
what does stroke result in?
cerebral infarct, with similar cell death & loss of function
what determines symptoms and severity of stroke?
location
aneurism
blood vessels dilation to form thin-walled, balloon-like regions
what do aneurisms commonly do?
burst
where are aneurisms common? (2)
aorta (death)
brain (stroke)
lymph vascular system in comparison to veins
Structurally similar to Vv, but endothelial cells thinner, with greater permeability
Lymph endothelial cells highly active in
phagocytosis
what is thin in the lymph vascular system?
tunica media
are valves present in the lymph vascular system?
yes
what else is present in the lymph vascular system? (2)
basement membrane and pericytes may be present or absent
what is the function of the lymph vascular system?
Drain excess fluid (lymph) from ECS & return it to bloodstream
Lymph formed as result of
high hydrostatic pressure in arterioles
what happens if the hydrostatic pressure in arterioles exceeds colloidal oncontic pressure exerted by plasma proteins? (3)
leakage of water, electrolytes, and plasma proteins from capillaries into the ECS
define lymphatics
ECS drained by a series of interconnected, blind-ending tubules
where does the lymph vascular system converge? (2)
on the thoracic duct and right lymphatic duct
what is the largest lymph vessel in the body?
thoracic duct
where does lymph return to the bloodstream?
the junction of the left internal jugular vein and left subclavian vein
does the lymph vascular system have a central pumping mechanism?
no
how is movement of lymph accomplished?
skeletal muscle contraction, body movement
immobility may lead to (2)
peripheral edema
swollen feet
where are lymph nodes located?
interspersed along lymph vessels
what do lymph nodes contain?
lymphoid tissue for antigenic sampling and recognition
antigenic sampling
activation of immune cells and production of antibodies
asymmetrical lymph draining is important in…
tumor metastasis
what is the easiest way to identify lymph vessels in section?
thin walled, lack blood, contain smooth, eosinophilic, proteinaceous fluid (lymph), occasional WBC
elephantiasis
due to a worm that sets up in the lymph vessels and prevents/blocks lymphatic return, often in the legs
why is it called elephantiasis?
thickening of CT and skin which looks leathery, like an elephants skin
