Flashcards in Blood Vessels Deck (83):
away from the heart
toward the heart
site of exchange between arteries and veins
3 Layers of the blood vessel wall
tunica intima (3)
keeps clotting from occurring
simple squamous endothelium that is continuous with endocardium of the heart
tunica media (2)
usually thickest with smooth muscle for vasomotion
tunica externa (2)
loose connective tissue
Which lumen is largest, vein or artery? Why?
Vein because they are low resistance pathway
What are the 4 types of arteries?
conduction or elastic
distributing or muscular
resistance or arterioles
control the amount of blood to various organs (vasocontrict or vasodilate)
short vessels that connect arteries to capillaries
pulmonary, aorta, and common carotid
expand and recoil to lessen fluctuation in blood pressure
distributes blood to specific organs
3 types of capillaries?
continuous capillaries (2)
occur in most tissues
endothelial cells have tight junctions with intercellular clefts
fenestrated capillaries (3)
kidneys and small intestines
organs that require rapid absorption or filtration
has filtration pores
sinusoid capillaries (2)
liver, bone marrow, spleen
irregular blood filled spaces (allow proteins and blood cells to enter)
What do capillary beds consist of? (3)
true capillaries w/ precapillary sphincter
precapillary sphincters (2)
regulates the blood flow into the true capillaries
3/4 of them are closed at anytime
what regulates the precapillary sphincters? (3)
autonomic nervous system
a type of vein with thin walls and no smooth muscles
lower blood pressure
valves aid skeletal muscles in upward blood flow
What is the capacitance of veins?
contain 75% of the total blood due to large lumen
What causes blood to be moved over to the arterial side from the venous side?
massive sympathetic stimulation
What is the classic route of the circulatory system?
blood flow that goes through 2 consecutive capillary networks before entering the heart
What are the 3 portal systems in the body?
found in kidneys
point where 2 blood vessels merge
artery flows directly into vein
venous anastomosis (2)
vein to vein
alternate drainage of organs
arterial anastomosis (2)
artery to artery
distribution of blood within the cardiovascular system
distribution of the cardiac output within the different tissues
Distribution of blood is determined by (3)
tissue blood flow? the total amount equals what?
amount of blood flowing per min
rate of blood flow through a vessel per gram of tissue
What does flow determine?
the speed of nutrient delivery and waste removal
True or False, does each organ have its own value for flow? What is it defined as?
TRUE; percentage of the total flow or cardiac output
What are the 2 factors that determine blood flow?
blood pressure differences
blood pressure? what causes this?
the force exerted by blood against the blood vessel wall; the contraction of the heart generating a hydrostatic pressure that is conducted in all directions
in the systemic loop, the delta P is the pressure differnce between....
the start of the aorta and the right atrium (95mmHg to 5mmHg)
What are the 3 types of blood pressure?
arterial blood flow
measured at brachial artery of the arm
BP during ventricular systole (contraction)
BP during ventricular diastole (relax)
normal blood pressure
120/75 mmHg in young adult
pulse pressure (3)
can be felt with finger
important measure of stress exerted on arteries
MAP? what is the best estimate?
mean arterial pressure
measurement taken at intervals of cardiac cycle
(diastolic pressure + (1/3 of pulse pressure))
Where is the largest pressure drop?
in the arterioles
what is the importance of arterial elasticity? (3)
expansion and recoil maintains steady flow of blood throughout cardiac cycle
smooths out pressure fluctuations
decrease stress on small arteries
As BP rises with age; arteries become?
less distensible (recoil and elastic capability)
Why must capillary blood pressure be low? (3)
capillaries are fragile
capillaries are permeable
capillary flow rate is very low for nutrient exchange
What are the 2 mechanisms of venous return?
skeletal muscle pump in the limbs
thoracic pump: during inhalation the thoracic cavity ______ which causes the BP to _____. The abdominal pressure _______ forcing blood ____
expands; decrease; increase; upward
any force that opposes movement
total peripheral resistance? where is most of the resistance?
the resistance that blood encounters as it travels through the circulatory system; on the arterial side
What are the resistance sources of blood flow? (3)
thickness or stickness of blood
greater the thickness the greater the resistance
blood viscosity is due mainly to? (2)
vessel length (2)
not used to regulate flow
the longer the vessel the greater the cumulative friction
blood vessel radius (2)
smaller the radius the greater the friction
is changed moment to moment
more of a pathological issue
normally blood flow is laminar (in layers)
turbulence in a vessel; turbulence in the heart
what is the main purpose of the cardiovascular system?
to provide the tissues with the appropriate amount of nutrients & remove toxic waste
blood flow is regulated by (3)
changing the cardiac output
modifying peripheral resistance
modifying blood pressure
the goal of cardiovascular regulation is to alter (3)
flow at the appropriate time
flow to the appropriate areas
flow without drastically changing flow to vital organs (heart and brain)
What are the mechanisms used to regulate blood flow?
-local control or autoregulation
auto-regulation occurs within a ______ while __ ___ and ___ ___ remain ____.How does it work?
tissue; cardiac output; blood pressure;stable
-works by adjusting peripheral resistance (blood vessel radius) within a tissue
what are some local acting vasodilators (5)
-dropping O2 levels
-rising CO2 levels
-rising K levels
what are some local acting vasocontrictors (2)
how does heat increase flow for vasodilation?
relaxing the smooth muscle of the arterial walls and precapillary sphincters
During neural mechanism, the ___ has control of the CO and peripheral resistance. Where does this mechanism originate?
What is the cardiovascular center contain? (2)
the cardiac center regulates ____; while the vasomotor center regulates ___ ___ to control flow
cardiac output; peripheral resistance
sympathetic fibers that constrict smooth muscle of vessels; "close" them
sympathetic fibers that relax vessels of the skeletal muscle; "open" them
baroreceptors; where are they found?
aortic and carotid
when there is a drop in pressure what does this cause the baroceptors to do? (2) Overall?
-stimulate cardioaccelatory center->increase CO
-stimulate vasocontriction center-> increase peripheral resistance
overall it increases flow to vital tissues
when there is an increase in the pressure what does this cause the baroceptors to do? (2)
-inhibit cardioacceleratory center->decrease CO
-inhibit vasocontriction center-> decrease peripheral resistance
the chemoreceptors in the vasomotor center stimulate what when there is a drop in O2 and increase in CO2 and acid?
-stimulate cardioacceleratory & vasocontriction
consequences of edema? (4)
low protein in liver
which mechanism that regulates blood flow has both long and short term regulation?