cardiovascular system-blood vessels and circulation: capillaries Flashcards
the contraction and relaxation of smooth muscles control the flow of
blood
capillaries join together to form
venules–> veins, which have thin walls
in veins smooth muscles in ________ contract to prevent backflow
in veins smooth muscles in Tunica Adventitia contract to prevent backflow
_____ act as low pressure blood reservoirs
Veins act as low pressure blood reservoirs
_______ nerves stimulates the _______ of veins
Sympathetic nerves stimulates the constriction of veins
what arteries are elastic arteries
aorta
pulmonary artery
Tunica media of these arteries contain a lot of
elastic fibers and few smooth muscles
during ventricular systole
pressure within the heart rises
aortic semilunar valves open
blood flows in to aorta
walls of aorta and major arteries are stretched
aorta acts as a
reservoir
aorta’s walls store
energy from contraction of heart
during ventricular diastole
pressure in the heart falls
semilunar valves are closed
walls of aorta recoil and propel blood onwards
aorta acts as a
subsidiary pump
aorta’s walls use the
energy previously stored from the heart’s contraction
pulse wave
during systole as blood is pumped from the heart the distension and increase in pressure which starts in the aorta passes along the arterial system as a wave
“the pulse” at the wrist
the expansion and subsequent relaxation of the wall of the radial artery
blood vessels to take pulse
carotid artery
radial artery
brachial artery
dorsalis pedis artery- supplies dorsal surface of feet
femoral artery
popliteal artery
near the ankle joint
posterior tibial artery
arterioles
less than 30 micrometer diameter
smallest of the muscular arteries with undefined tunica externa, and 1 or 2 layers of smooth muscles in tunica media
resistance vessels
resistance vessels
responsible for maintenance of blood pressure
what is an ex of resistance vessels
arterioles
capillaries have the largest
total cross-sectional area and the lowest blood flow velocity for the exchange of substances between the blood and the cells
in capillaries, exchange of ____ takes place
in capillaries exchange of substances take place
in capillaries the wall is made up of a
single layer of endothelium and a basal lamina
in capillaries what 2 layers are absent
tunica media
tunica adventitia
capillaries form a
network among the cells of the body
in the capillaries, there is continuous movement of
fluid through the arteriolar end of the capillaries in to the interstitial fluid and in to the capillaries at the venular end
what dissolves into the ECF
nutrients, gases, water, and hormones present in the blood diffuses out in to the ECF
what diffuses in to the capillaries
water dissolves wastes such as carbon dioxide diffuse in to the capillaries
the capillaries help to regulate
body temperature by vasoconstriction and vasodilation
capillaries are absent
epidermis of the skin
hair and nails
cornea of the eye
articular hyaline carilage
network of capillaries
capillary bed (capillary plexus)
precapillary sphincter
at the entrance of each capillary reduces or stops the flow blood
capillary bed contains direct connections between
arterioles
venules
collaterals
multiple arteries that supply blood to the capillary bed
anastomosis
the fusion of two collaterial arteries
sinusoids
dilated fenestrated capillaries
lumen is irregular
found in liver, spleen, and bone marrow
cavernous tissue (sinus)
blood filled spaces lined by endothelium and surrounded by smooth muscle
present in the erectile tissue of penis, clitoris
short term elevation of blood pressure
hormonal effects
increase cardiac output
increase peripheral vasoconstriction (epinephrine, norephinephrine, antidiuretic hormone, angiotensin 2)
autoregulation of blood flow within tissues
adjusted by peripheral resistantce while cardiac output stays the same
local vasodilators
accelerate blood flow at tissue level
local vasodilators ex
low O2
high CO2
low pH (acids)
nitric oxide (NO)
high K+ or H-
chemicals released by inflammation (histamine)
elevated local temp
local vasoconstrictors
prostaglandins and thromboxanes
released by damaged tissure
constrict precapillary sphincters
affect a single capillary bed
baroreceptor reflex
when blood pressure rises, CV centers
decrease cardiac output
cause peripheral vasodilation
baroreceptor reflexes
when blood pressure falls, CV centers
increase cardiac output
cause peripheral vasoconstriction
chemoreceptors reflexes
peripheral chemoreceptors in
carotisd bodies and aortic bodies monitor blood
central chemorecptors below medulla oblongata
monitor cerebrospinal fluid
control respiratory function
control blood flow to brain
