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Circulatory System II
Chapter 19
108
Anatomy
Undergraduate 2
05/01/2012

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Term
What are the three major types of blood vessels?
Definition
arteries, capillaries, and veins
Term
Arteries carry blood ______ _____ the heart?
Definition
away from
Term
Veins carry blood _____ _____ heart?
Definition
toward the
Term
What are the three tunics of arteries and veins?
Definition
interna, media, externa
Term
What are capillaries composed of?
Definition
endothelium with sparse basal lamina
Term
Where is the tunica interna located?
Definition
lines the lumen of all vessels
Term
If the vessel is larger than 1mm, what else is present in the tunica interna?
Definition
a subendothelial connective tissue basement membrane
Term
Which vessel has a thicker tunica media?
Definition
arteries
Term
What is the tunica media's composition?
Definition
smooth muscle and elastic fiber layer
Term
How is the tunica media regulated by?
Definition
sympathetic nervous system
Term
What is the role of the tunica media?
Definition
controls vasoconstriction, vasodilaiton of vessels
Term
When is vasoconstriction/vasodilation of vessels needed?
Definition
heat regulation, food, oxygen need
Term
What is the tunica externa composed of?
Definition
collage fibers that protect and reinforce vessels
Term
What do larger vessels contain by the tunica externa?
Definition
vasa vasorum
Term
How are the tunica interna and the tunica media fed?
Definition
via blood from the lumen
Term
How is the tunica externa fed?
Definition
Via the vasa vasorum
Term
What is a vasa vasorum?
Definition
network of arterioles, capillares and vessels provide vessel wall with metabolites
Term
What is common between the elastic (conducting arteries)?
Definition
thick-walled, near the heart
Term
What are the elastic (conducting) arteries?
Definition
aorta and its major branches
Term
What are characteristics of conducting arteries?
Definition
large lumen, elastin in all 3 tunics
Term
What are functions of the conducting arteries?
Definition
low-resistance conduction of blood, with and smooth out large bp fluctuations, pressure reservoirs
Term
What is common between the muscular (distributing arteries)?
Definition
distal to elastic arteries; deliver blood to body organs
Term
What are the characteristics of muscular arteries?
Definition
thick tunica media with more smooth muscle
Term
Function of muscular arteries
Definition
active in vasoconstriction
Term
Characteristics of arterioles?
Definition
smallest arteries, lead to capillary beds, control flow into capillary beds via vasodilation and constriction
Term
How thick are capillaries?
Definition
walls consist of a thin tunica interna, one cell thick
Term
What stabilies the outerwalls of capillaries?
Definition
pericytes
Term
What are the three types of capillaries?
Definition
continuous, fenestrated, and sinusoids
Term
Where are continuous capillaries abundant?
Definition
skin and muscles
Term
Characteristics of a continuous capillary?
Definition
uninterrupted lining, adjacent cells are connected with tight junctions, intercellular clefts allow passage of fluids
Term
Where are fenestrated capillaries found?
Definition
wherever active capillary absorption or filtrate formation occurs (small intestines, endocrine glands, kidneys)
Term
Where are sinusoid capillaries found?
Definition
liver, bone marrow, lymphoid tissue, some endocrine organs
Term
What are the characteristics of a sinusoid capillary?
Definition
leaky, fenestrated, with large lumens
Term
Role of sinusoids?
Definition
allow large molecuels (proteins and blood cells) to pass between the blood and surrounding tissue
Term
What is a capillary bed?
Definition
microcirculation of interwoven metwrosk of capillaries
Term
What do capillary beds consist of?
Definition
vascular shunts and true capillaries
Term
What is a vascular shunt?
Definition
metarteriole-thoroughfare channel. connects an ateriole directly with a postcapillary venule
Term
What is a true capillary?
Definition
10-100 per capillary bed, branch of the metarteriole and return to the thoroughfare channel at the distal end
Term
What is the precapillary sphincter?
Definition
cuff of smooth muslce that surrounds each true capillary
Term
What is the role of the precapillary sphincter?
Definition
regulate blood flow into the capillary
Term
How is blood flow through capillary beds regulated?
Definition
vasomotor nerves and local chemical conditions
Term
What are the parts of the venous system?
Definition
veins and venules
Term
How are venules formed?
Definition
when capillary beds unite
Term
What are postcapillary venules?
Definition
smallest venules, composed of endothelium and a few pericytes
Term
How are large venules different?
Definition
one ore two layers of smooth msucle (tunica media)
Term
How are veins formed?
Definition
when venules converge
Term
What is different about the tunica media of veins?
Definition
it is thin
Term
What is different abut the tunica externa of veins?
Definition
thick, consisting of collagen fibers and elastic networks
Term
What is the role of veins?
Definition
capactiance vessels (blood reservoirs) contain 65% of blood supply
Term
Which has lower blood pressure arteries or veins?
Definition
veins
Term
Which has thinner walls? Arteries or veins?
Definition
Veins
Term
What special adaptations do veins possess to return blood to the heart?
Definition
Large-diameter lumens, valves
Term
What do the large-diameter lumens of veins allow?
Definition
little resistance to blood flow
Term
What do the valves of the veins resemble?
Definition
semilunar heart valves
Term
What is the role of valves in veins?
Definition
prevent backflow of blood
Term
What are anastomoses?
Definition
merging of blood vessels
Term
What is cardiac output?
Definition
blood flow considering the entire vascular system
Term
What is blood flow/cardiac output?
Definition
Actual volume of blood flowing through a vessel, organ, or the entire circulation in a given period
Term
How is blood flow measured?
Definition
ml / min
Term
How varied is the blood flow between individual organs?
Definition
widely varied
Term
What is blood pressure?
Definition
force per unit area exerted on the wall of a blood vessels by its ocntained blood
Term
How is blood pressure expressed?
Definition
mmHg
Term
How is BP measured?
Definition
reference to system arterial BP in large arteries near the heart
Term
What do the differences in BP within the vascular system provide?
Definition
Driving force that keeps blood moving from high to low pressure areas
Term
What are the three important of sources of blood resistance?
Definition
blood viscosity, total blood vessel length, and blood vessel diameter
Term
What are the resistance factors that remain releatively constant?
Definition
viscosity, blood vessel length
Term
What causes an increase in blood vessel length?
Definition
increase in body volume such as pregnancy or obesity
Term
How often are there changes in blood vessel diameter?
Definition
frequent and significantly alter peripheral resistance
Term
What is the relationship between resistance and blood vessel radius?
Definition
resistance = 1/(change in) radius^4. so doubling the radius, makes 1/16 of original resistance
Term
What are the major determinants of peripheral resistance?
Definition
small-diameter arterioles, fatty plaques from atherosclerosis
Term
What changes occur to blood flow as a result of fatty plaques?
Definition
turbulent blood flow dramatically increases resistance
Term
As resistance _____ and blood flow ______ BP ________
Definition
increases, decreases, increases
Term
Which has a greater influence on changing blood pressure, resistance or flow?
Definition
resistance
Term
Where is systemic pressure highest?
Definition
aorta
Term
What happens to systemic pressure after leaving the aorta?
Definition
declines throughout the length of the pathway
Term
What is the BP measure in the right atrium?
Definition
0 mm HG
Term
WHere does the steepest change in bp occur?
Definition
arterioles
Term
Why is there such a steep change in bp in the arterioles?
Definition
so the capillaries are not blown out
Term
Where is capillary pressure higher in the body?
Definition
in the kidney
Term
What two factors does arterial bp reflect?
Definition
elasticity, amount of blood forced into them at any given time
Term
What is systolic pressure?
Definition
pressure exerted on arterial walls during ventricular contraction
Term
What is diastolic pressure?
Definition
lowest level of arterial pressure during a ventricular cycle
Term
What is pulse pressure?
Definition
difference between systolic and diastolic pressure
Term
What are the capillary BP ranges?
Definition
20-40 mm HG
Term
How much does venous BP fluctuate?
Definition
it is steady and changes little during cardiac cycle
Term
What is the pressure gradient in the venous system?
Definition
about 20 mm HG
Term
What does blood flow from a cut vein look like?
Definition
even blood flow
Term
What does blood flow from a lacerated artery look like?
Definition
flows in spurts
Term
Is venous bp enough to promote adequate blood return to the heart?
Definition
no
Term
What aids venous BP in adequate blood return?
Definition
respiratory "pump", muscular "pump"
Term
What is the respiratory "pump"?
Definition
pressure changes created during breathing, drawing blood toward the heart by squeezing local veins
Term
What is the muscular "pump"?
Definition
contraction of skeletal muscles "milk" blood toward heart
Term
What else aids in venous bp blood return?
Definition
Valves to prevent backflow
Term
What does the maintenance of blood pressure require?
Definition
cooperation of heart, blood vessels, and kidneys, supervision of the brain
Term
What are teh main factors influencing blood pressure?
Definition
cardiac output, peripheral resistance, blood volume
Term
What effect does cardiac output have on blood pressure?
Definition
If normal, very little
Term
What effect does peripheral resistance have on BP?
Definition
higher viscosity, increased blood vessel length, and blockages increase BP the most
Term
Which factors of peripheral resistance have the greatest effect on increasing blood pressure?
Definition
blood vessel length and blockages
Term
Cardiac Output x Peripheral Resistance = ?
Definition
Blood Pressure
Term
Difference between arteries and veins: Artery Delivery
Definition
blood pumped into single systemic artery - the aorta
Term
Difference between arteries and veins: Artery Location
Definition
deep, and protected by tissue
Term
Difference between arteries and veins: Artery Pathways
Definition
fair, clear, and defined
Term
Difference between arteries and veins: Artery Supply/Drainage
Definition
predictable supply
Term
Difference between arteries and veins: Artery Supply/Drainage
Definition
predictable supply
Term
Difference between arteries and veins: Veins Delivery
Definition
blood returns via superior and inferior venae cave and the coronary sinus
Term
Difference between arteries and veins: Veins Location
Definition
both deep and superficial
Term
Difference between arteries and veins: Veins Pathways
Definition
convergent interconnections
Term
Difference between arteries and veins: Veins supply/drainage
Definition
dural sinuses and hepatic portal circulation
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