Chapter 19 - Blood Vessels Flashcards
blood vessels
long tubes that transport blood to/from the heart
arteries
carry blood away from the heart
veins
carry blood to the heart
capillaries
connect small, arterial arteries to small venule veins
in what type of vessel does gas and nutrient exchange occur
capillaries
common circulatory route
heart -> arteries -> arterioles -> capillaries -> venules -> veins
layers of vessel walls are called
tunics
tunica interna/intima
lines blood vessel lumen
tunica intima is made of
simple squamous epithelium
function of tunica intima
secretes chemicals to stimulate dilation/constriction into the tunica media
tunica media
middle, muscular layer of a vessel
tunica media is made of
smooth muscle, collagen, elastic tissue,
function of the tunica media
contracts and relaxes to change vessel diameter, provide strength and prevent rupture
tunica externa
outermost layer of vessels
tunica externa is made of
loose connective tissue
tunica externa function
anchor the vessel and merge with other structures
arteries are ___ walled, veins are ___ walled
thick, thin
arteries are thought of as ____ vessels, veins are thought of as ___ vessels
resistance vessels, capacitance vessels
what does it mean for arteries to be resistance vessels
resultant, rigid structure that resists damage by BP change
what does it mean for veins to be capacitance vessels
expand easy
what percentage of blood is held in veins
64%
other names for large arteries
conducting, elastic
large arteries can be found
aorta, common carotid, subclavian, common iliac, pulmonary trunk
large arteries compostion
two elastic lamanae
internal elastic lamina is between
tunica intima and media
external elastic lamina is betwen
tunica media and externa
when do large arteries expand and recoil
expand in systole, recoil in diastole
function of large arteries
keep blood flowing, blood pressure constant
medium arteries are also called
distributing, muscular
medium artery functions
distribute blood to specific organs
examples of medium arteries
brachial, femoral, renal, splenic
the tunica media of medium arteries make up how much of the vessel wall
3/4
small arteries are also called
resistance arteries
small artery composition
thick tunica media, little tunica externa
most common example of small arteries
arterioles
arteriole
small artery that leads to capillaries and controls the amount of blood in a capillary bed
arteriole composition
20mm diameter, thin layer of smooth muscle
metarterioles
short vessels that link arterioles to venules and allow blood to bypass capillary beds
metarterioles are thought of us
thoroughfare channels
capillary composition
made of endothelium and basal lamina, no tunica media or externa, microscopic
capillaries are everywhere but
tendons, ligaments, epithelial, cornea and lens of eye
continuous capillary
endothelial cells joined by tight junctions with small intercellular clefts
continuous capillary function
allow passage of solutes, most common, least permeable
pericyte
contractile cell that wraps around continuous capillaries to restrict blood flow
fenestrated capillary
a thin endothelial layer with holes to allow small molecules to pass through quickly
where are fenestrated capillaries commonly found
kidneys, small intestine
sinusoid capillaries
an irregular endothelium with many fenestrations to allow proteins and blood cells to pass through
sinusoid capillaries are commonly found
in liver, bone marrow, and the spleen
postcapillary venules compositon
tunica intima and fibroblasts
postcapillary venule function
where leukocytes exit the blood stream
muscular vein composition
all three layers of tunics
thick tunica externa
1-2 layers of tunica media
muscular vein function
receive blood from postcapillary venules
medium vein composition
all three layers
tunica intima forms venous valves
medium vein function
venous valves prevent blood from pooling in lower extremities
large vein composition
thin tunica media, thick tunica externa
venous sinus composition
thin walls, large lumens, no smooth muscles
venous sinus function
hold lots of blood, cannot vasoconstrict
capillary exchange
two way movement of fluid and solutes across the capillary walls
where is the only place blood and other tissues exchanged
capillaries
routes of passage for capillary exchange
endothelial cell cytoplasm, intercellular clefts, filtration pores or fenestrations
diffusion
movement of molecules from areas of high concentration to low concentration
capillary diffusion
glucose and O2 out and co2 and waste out of cells
permeable solutes in diffusion
lipid soluble molecules and gases
solute passages in diffusion
fenestrations, intercellular clefts
solute passages allow the passage of
glucose and ions
transcytosis
vesicle mediated transport of materials across the endothelium
steps of transcytosis
vesicles form around material entering cell
vesicle moves across the cell
material released on the other side through exocytosis
transcytosis makes up what percentage of capillary exchange
small
transcytosis transports what materials
fatty acids, albumin, hormones like insulin
filtration
fluid exiting the capillary into surrounding tissue
filtration location
arterial end of capillary
reabsorption
fluid entering the capillary from surrounding tissue
reabsorption location
venous end of capillary
hydrostatic pressure
physical force exerted against a surface by a liquid
blood hydrostatic pressure
bp in a vessel pushes fluid out of a capillary
blood hydrostatic pressure in a capillary
high on arterial end, low on venous end
interstitial hydrostatic pressure
force exerted by fluids outside the capillary push fluids into cells and draw fluids out of the capillary
interstitial hydrostatic pressure in a capillary
consistent on both capillary ends
colloid osmotic pressure is the force that causes
osmosis
blood colloid osmotic pressure
osmosis into capillaries
tissue fluid colloid osmotic pressure
osmosis out of capillaries
only capillary pressure that changes from end to end
blood hydrostatic presssure
only capillary pressure that causes reabsorption
blood colloid osmotic pressure
colloid osmotic pressure is cause by
concentration of proteins and albumin
colloid osmotic pressure levels
consistent at both ends
oncotic pressure
net colloid osmotic pressure (blood-tissue cop)
does filtration equal reabsorption
no
how much of fluid filtered out is reabsorbed
85%
how much of fluid filtered out is absorbed into the lymphatic system
15%
net filtration/reabsorption pressure
sum of hydrostatic and colloid osmotic pressure
what must be specified in net capillary pressure calculation
if fluid movement is in or out
net fluid in means
reabsorption
net fluid out means
filtration
hydrostatic pressure favors on the arterial end
filtration
COP favors on the arterial end
reabsorption
is net filtration or reabsorption larger on the arterial end
filtration because blood hydrostatic pressure is higher
hydrostatic pressure favors on the venous end
filtration
COP favors on the venous end
reabsorption
is net filtration or reabsorption higher on the venous end
reabsorption
edema
pooling of liquid in body tissue
edema occurs
when filtration is greater than reabsorption
edema is often caused by
heart failure of the ventricles
edema symptoms
swelling, disfunction of affected tissue
hemodynamics
physical principles of blood flow based on pressure and resistance
blood flow
amount of blood flowing through an organ tissue, or vessel in a given time
blood flow is measured in
mL/min
blood flow is proportional to
difference in pressure divided by resistance
blood pressure
force blood exerts against a vessel wall
measurement of blood pressure determines
pressure of the brachial artery
systolic pressure
peak BP taken in ventricular systole
diastolic pressure
minimum BP in ventricular diastole
healthy blood pressure
120/80 mm/Hg
pulse pressure
difference between systolic and diastolic pressure
pulse pressure measures the stress on
small arteries
mean arterial Pressure
average blood pressure at one time
mean arterial pressure calculation
diastolic pressure + 1/3 of pulse pressure
blood pressure in arteries changes/is steady
changes
blood pressure in veins and capillaries changes/is steady
steady
cardiac output
amount of blood expelled by each ventricle per minute
a higher cardiac output is equated to
a higher blood pressure
blood volume
amount of blood in the body
a high blood volume is equated to
a high blood pressure
blood volume is regulated by
the kidney
resistance to flow
forces that prevent blood from flowing
resistors to flow are in the heart or peripheral
peripheral
a higher resistance is equated to
higher Blood Pressure
blood viscocity
thickness of blood
high viscosity means
thicker blood, more resistance
blood viscosity is impacted by
RBC count and albumin
polycythemia
high RBC, very viscous blood
anemia
fewer RBC, less viscous blood
high albumin means
more viscous blood
hypoproteinemia
low albumin levels
longer the blood vessel means what for resistance
more resistance
the farther blood travels from the heart, more/less friction is encountered
more
larger vessel radius means
less resistance
laminar flow
normal blood flow through vessels
the faster blood flow is toward the center or periphery of the vessel
center
vasomotion
quick and powerful alteration of blood pressure and flow
vasoconstriction
contraction of the tunica media
vasoconstriction effect on radius and blood flow
reduction
vasoconstriction effect on blood pressure
increases
vasodilation
relaxation of tunica media
vasodilation effect on vessel radius and blood flow
increases
vasodilation effect on blood pressure
reduction
vasomotion purposes
control blood pressure, route blood from region to region
vasomotion effect on blood pressure
prevents cerebral perfusion
blood flow increases/decreases in areas of no vasoconstriction
increases