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Circulatory System - 2 hrs
Morrow 2/25 lecture
117
Histology
Undergraduate 4
02/23/2011

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Term
transport O2/CO2 & nutrients/metabolic waste
Definition
primary function of the circulatory system
Term
1)thermoregulation
2)transport of immune cells (WBC's)
3)transport of hormones
Definition
secondary functions of the circulatory system
Term
heart and blood vessels (this is distinguished from lymph system)
Definition
what is the blood vascular system made of?
Term
pulmonary circulation and systemic circulation
Definition
what are the 2 components of the circulatory system?
Term
right atrium and ventricle -> pulmonary artery -> lungs -> pulmonary veins -> left Atrium
Definition
what is the path of pulmonary circulation?
Term
Left atrium and ventricle -> aorta -> rest of body
Definition
what is the path of systemic circulation?
Term
lymph vascular system
Definition
passive drainage system for returning extravascular fluid to blood vascular system
Term
lymph vascular system
Definition
vascular system that lacks an intrinsic pump, relies on skeletal muscle contraction and body movement
Term
tunica intima
tunica media
tunica adventitia
Definition
what are the three layers of blood vessels from inner to outer layer?
Term
tunica intima
Definition
innermost layer of simple squamous endothelial cells lining the lumen
Term
thin, 1-2 cells thick

has a basal lamina (basement membrane) with variable amounts of subendothelial connective tissue

semi-permeable
Definition
how thick is the tunica intima? does it have a basement membrane? how permeable is it?
Term
internal elastic lamina, made of elastic fibers
Definition
what separates the tunica intima and tunica media if it is present? what is it made of?
Term
smooth muscle cells
fibroblastic CT
may have reticulin
elastic fibers
Definition
what types of cells/tissues are found in the tunica media?
Term
type 3
Definition
what type of collagen is reticulin?
Term
tunica media
Definition
what tunic (layer) is the thickest in arteries?
Term
between tunica media and tunica adventitia
Definition
what layers is the external elastic lamina between?
Term
elastic fibers, but less organized than the internal elastic lamina
Definition
what type of fibers are in the external elastic lamina?
Term
loose fibroblastic CT
fibroblasts (that secrete collagen)
elastic fibers
smooth muscle cells
Definition
what fibers/tissues are found in the tunica adventitia?
Term
tunica adventitia
Definition
what tunic (layer) is thickest in veins?
Term
tunica adventitia
Definition
what layer are the vaso vasorum in?
Term
in large vessels (arteries and veins both) small vessels that supply the tunica media and adventitia with blood
Definition
what are vasovasorum?
Term
tunica adventitia
Definition
in what tunic (layer) are autonmic nerves (nervi vascularis) found?
Term
control smooth muscle contraction in vessel walls causing vasoconstriciton and vasodilation
Definition
what do nervi vascularis do?
Term
due to the action of sympathetic, post-ganglionic nerve fibers

-smooth muscle of tunica media is acted on, causing constriction, and decrease in diameter
Definition
what causes vasoconstriction? what layer does this occur in the vessel?
Term
1) passive action that occurs in absense/inhibition of sympathetic stimulation
2) indirect parasympathetic innervation releases Ach which act on endothelial cells and make them release NO, secondarily causing smooth musc relaxation
3) in response to low O2 tension, smooth muscle in vessel walls relaxes to increase blood flow
Definition
what are the 3 theories of the cause of vasodilation?
Term
baroreceptors, chemoreceptors
Definition
what are the 2 specialized sensory receptors located in walls of blood vessels that can control vasodilation/constriction?
Term
found in carotid sinus and aortic arch; detect blood pressure
Definition
where are baroceptors and what do they detect?
Term
located at bifurcation of carotid artery and in aortic bodies in aortic arch

-diff types detect changes in O2, CO2 tension, pH, ion changes etc.
Definition
where are chemoreceptors; what do they detect?
Term
arterial system
Definition
conducts blood away from the heart to capillary bed (doesn't always carry oxygenated blood)
Term
venous system
Definition
returns blood from capillaries to heart(can carry oxygenated blood)
Term
ventricle contraction
Definition
causes systole and a pressure wave
Term
ventricle relaxation
Definition
causes diastole and decrease in pressure
Term
120/80 mmHg
Definition
what is a normal BP reading?
Term
expansion and recoil of elastic arteries (this is why the walls are thicker)
Definition
what maintains BP?
Term
changes in the diameter of blood vessels due to sympathetic control of smooth musc in vessel walls
Definition
how is BP regulated?
Term
arteries
Definition
which vessels have a thick vessel wall compared to the lumen diameter due to presence of large amoutns of elastin and smooth muscle?
Term
greater than 1 cm diameter
Definition
how big are elastic arteries?
Term
elastic artery
muscular artery
arterioles
metarterioles
capillaries
Definition
list the artery types from biggest to smallest:
Term
elastic arteries
aorta, common cartotid, subclavian, pulmonary arteries
Definition
large conducting vessels, receive blood directly from the heart (give examples)
Term
sheets of elastic tissue
Definition
what do elastic arteries have in their tunica media to help maintain bp between systolic and diastolic pressure?
Term
elastic arteries, muscular artries (large ones have external elastic lamina, but the smaller ones just have a distinct internal elastic lamina)
Definition
have tunica media as the thickest layer and posess both internal and external elastic lamina
Term
2-10 mm diameter
Definition
how big are muscular arteries?
Term
muscular arteries
Definition
have more smooth musc and less elastin in tunica media than elastic arteries
Term
10-100 um in diameter
Definition
how big are arterioles?
Term
arterioles
Definition
contain realtively little smooth musc as they are only 2-3 cells thick and lack elastic lamina
Term
arterioles
Definition
terminal branches of the arterial system that supply capillary beds
Term
arterioles
Definition
major sites of vasoconstriction and vasodilation despite their relativley little smooth muscle
Term
arterioles
Definition
regulate distribution of blood to capillaries via pre-capillary sphincters
Term
pre-capillary sphincters
Definition
intermittent rings of smooth muscle within walls of arterioles
Term
metarterioles
Definition
smaller diameter arterioles, intermediate size between arterioles and capillaries characterized by a discontinuous layer of smooth muscle in tunic media
Term
CT decreases, smooth muscle increases
Definition
in general as the size of the vessel increases, the amount of CT ___ and the amount of smooth muscle ___
Term
microcirculation
Definition
concerned with exchange of fluids, nutrients, metabolites, waste products
Term
arterioles and venules
Definition
microcirculation occurs primarily in capillaries, but where else can it occur?
Term
8-10 um
Definition
size of capillaries
Term
capillary
Definition
lined by a single layer of endothelial cells supported by a basal lamina and small #s of pericytes
Term
same precursor cell as endothelial cells
Definition
what are pericytes derrived from?
Term
endothelial cells or smooth muscle
Definition
what can pericytes differentiate into following tissue injury?
Term
just tunica intima (no CT-adventitia, no smooth musc-media)
Definition
what layers (tunics )do capillaries have?
Term
no
Definition
do capilaries exhibit vasomotor activity themselves (constrict/dilate)?
Term
smooth musc. of arterioles/ pre-capillary sphincters cause a PASSIVE change in capillary diameter
Definition
how does vasoconstriction/dilation occur in capillaries?
Term
continuous
fenestrated
discontinuous
Definition
what are the 3 types of capillaries?
Term
continuous

-in muscle, lung, CNS
Definition
endothelium forms continuous lining, most common type of capillary

give examples
Term
fenestrated

-endocrine glands, GI tract (move molecules in and out of blood here)
Definition
this type of capillary has endothelial cells with pores WITHIN cells

give examples
Term
discontinous

-liver, spleen, bone marrow, Lymph nodes
Definition
capillary with a non-continuous basal lamina and so endothelial cells are separated by large gaps BETWEEN cells

give examples
Term
large diameter capillaries (30-40 um) formed from discontinuous capillaries
Definition
how big are sinusoids and what are they formed from?
Term
fenestrae, trancytosis, diapedesis
Definition
what are the 3 methods of transport across capillaries?
Term
venous system
Definition
low pressure collecting system for returning blood from capillary beds to heart
Term
veins
Definition
thinner walled vessels with larger lumen than the corresponding artery
Term
less
Definition
do veins have more ore less smooth muscle in the tunica media?
Term
valves
Definition
what prevents backflow in veins especially in the limbs and thorax?
Term
valve failure in the legs -> pressure in the superficial veins
Definition
what causes varicose veins?
Term
no tunica media and no elastic lamina
Definition
what tunics/layers do venules have?
Term
muscular veins
collecting venules
post capillary venules
Definition
list the veins from biggest to smallest
Term
10-50 um, tunica media and adventitia are reduced or absent
Definition
how big are post-capillary venules and what layers/tunics do they have?
Term
50-100 um in diameter,
-tunica intima
-thin smooth muscle layer in tunica media
-thicker adventitia
Definition
how big are collecting venules, what layers do they have?
Term
venules
Definition
vasoactive substances such as histamine and seratonin act on _____ and enlarge intercellular spaces causing greater permeability for diapedesis and edema
Term
post-capillary venules
Definition
preferential site for diapedesis
Term
muscular veins
Definition
name of large and medium sized veins
Term
internal and external elastic lamina in large ones, medium only have internal elastic, small may or may not have elastic lamina (all tunics present)
Definition
what layers do muscular veins have?
Term
smooth muscle in the tunica media
Definition
what controls luminal diameter of muscular veins and venules?
Term
AV shunts
Definition
direct connection between arterial and venous system -bypass capillary bed
Term
portal vessels

-hepatic portal vessel system
Definition
Vein or artery directly connecting two capillary beds (give example)
Term
AV shunts
Definition
type of anastomosis common in skin; functions in thermoregulation with assistance of pre-capillary sphincters
Term
lymph vascular system
Definition
structurally similar to veins but thinner endothelial cells with greater permeability
Term
yes
Definition
are there valves in the lymph vascular system?
Term
lymph vessels
Definition
thin tunica media, basement membrane and pericytes may be absent, drains excess fliud from ECS and returns it to the blood stream
Term
high hydrostatic pressure in arterioles exceeding colloidal oncotic pressure exerted by plasma proteins causing leakage of water, electrolytes, and plasma proteins from capillaries into ECS
Definition
why does lymph form?
Term
ECS
Definition
___ is drained by a series of interconnected blind, ending tubules (lymphatics)
Term
thoracic duct and right lymphatic duct

yes
Definition
what are the largest lymph vessels in the body?do they have a tunica media?
Term
junction of Left internal jugular Vein and left subclavian vein
Definition
where is lymph returned to the bloodstream?
Term
tells about tumor metastesis since tumors hijack the lymph subway because they are easy to squeeze through-> esp thoracic cancers, breast cancer tell you if you need to chop off an entire breast or both or what.
Definition
why is assymetrical lymph drainage important?
Term
skeletal muscle contraction, body movement
Definition
how is movement of lymph accomplished?
Term
can cause peripheral edema (swollen feet) can also cause you to faint b/c of lack of venous return ex: soldiers can fall over after standing in formation
Definition
what happens with lymph when the body is immobile?
Term
lymph nodes
Definition
interspersed along lymph vessels, contain lymphoid tissue for antigeninc sampling & recognition, acitvation of immune cells, and production of antibodies
Term
lymph vessels, they filter out tumors, busted vessels, dead cells and debris
Definition
what works like a lint trap in the dryer?
Term
lack blood, contain lymph (smooth eosinophillic proteinaceous fluid)

-basement membrane rudimentary or absent, no pericytes
Definition
what is the easist way to ID lymph vessels in section?
Term
lipid deposits(atherosclerosis) -> foam cells form
Definition
normally the tunica intima is thin, but in older adults this causes it to thicken
Term
atherosclerosis
Definition
accompanied by proliferation of smooth muscle cells and formation of fibrous CT capsule with calcification and necrosis
Term
atheroscelrosis
Definition
can be generalized or focal, most common ACQUIRED abnormaility of blood vessels
Term
hypertension
Definition
atherosclerosis is often associated with ____ due to decrease in diameter of vesel lumen and increase in systolic BP

also associated with increased risk of heart attack or stroke
Term
atherosclerosis- lumen of coronary artery may decrease by 90%
Definition
most common cause of ischemic heart disease
Term
stenosis
Definition
narrowing of a blood vessel
Term
thrombosis
Definition
gradual stenosis by thrombus(plaque) causes this aka occlusion of a blood vessel (formation of a thrombus)
Term
thromboembolic disease
Definition
when thrombi break apart what does this cause?
Term
embolus
Definition
blood clot that moves through the bloodstream until it lodges in a narrowed vessel and blocks circulation -> thrombosis -> acute ischemic event (anoxia)
Term
thrombus
Definition
a blood clot that forms inside a blood vessel or cavity of the heart.
Term
angina
Definition
chest pain due to lack of oxygen (anoxia) to heart muscle
Term
myocardial infarction (death by ischemia)
Definition
if angina is untreated, a portion of muscle dies, this is referred to as a
Term
G0, they are terminally differentiated

-in an ischemic event, they cannot regenerate, so fibrosis forms which is non-contractile tissue
Definition
what phase of the cell cycle are cardiac myocytes? why is this significant?
Term
decreased or partial loss of heart function (PERMANANTLY)
Definition
fibrosis of heart muscle causes what?
Term
inflammation of the inside lining of the heart chambers and heart valves (esp AV valves)

associated with valvular incompetence and may involve bacteria which can cause vegetative endocarditis and thromboembolic disease
Definition
what is endocarditis?
Term
vegetative endocarditis and thromboembolic disease & stroke (eternally at risk because the plaques on the valves can bust off at any time)
Definition
what can endocarditis cause?
Term
both tissues terminally differentiated and can't heal (neurons and cardiac muscle cells)

both are due to occluded vessels causing an ischemic attack (cerebral infarct vs myocardial infarct)
Definition
how is a stroke similar to an MI?
Term
location of the clot
Definition
how is the severity of a stroke determined?
Term
blood vessels dilate and form thin walled, baloon like regions

this is due to elastic firbers degrading causing the tunica media to separate from other layers and blood filling inbetween the layers
Definition
what causes aneurisms?
Term
aorta and brain
Definition
where are aneurisms common?
Term
transient ischemic attacks (TIA's)

TIA-an episode in which a person has stroke-like symptoms for up to 1-2 hours
Definition
what often follows aneurisms?
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