Circulatory SYstem Flashcards
Flow of blood
arterioles through capillary beds and converge on venules
pre capillary sphincters open and close
to allow blood to pass through capillaries
When precapillary sphincter is open
capillaries are more perfused
When pre capillary sphincters are closed
there is little to no blood flow to capillary
veins are known as capacitence vessels, bc
they hold majority of bodys’ blood. approx 54 %
the smallest veins are called
venules
Weak valves in veins that allow blood to pool are referred to as
varicose veins
Varicose veins in the anal canal are
hemorrhoids
When blood travels through 1 network of capillary beds, that is
a simplest pathway
When blood passes through 2 consecutive capillary beds, it is a
portal system
When there is a convergence point between 2 vessels other than capillaries and can be considered the body’s natural shortcut, that is an
anastomosis
artery flows directly into vein, bypassing capillary
AV anastomosis
veins empties into another; most common anastomosis
venous anastomosis
when 2 arteries merge
arterial anastomosis
The force of blood pushing against blood vessel wall is the
blood pressure
Blood flow is proportional to pressure
EX: Flow increases, pressure increases
Blood flow is inversely proportional to resistance
Ex: Blood flow increase, resistance decreases
Arteries have a pulsatile flow, while
veoms have a steady flow
The difference between systolic and diastolic is the
pulse pressure
Factors that determine blood pressure
cardiac output, blood volume, resistance flow
Factors that affect resistance to flow.
viscosity, vessel length, and vessel radius
Blood volume is regulated by the
kidneys
The vessel radius adjusts by vasomotion, which is both
vasodilation and vasoconstriction
What allows vessel radius to experience vasomotion?
SMooth muscle in tunica media
Blood flow is proportional to _____ power of radius.
4th, r^4
These capillaries are found in organs where absorption and filtration is needed
Fenestrated capillaries
This capillary passes proteins, new blood cells, etc. These capillaries allow big things in & out
Sinusoidal “Discontinuous Caps”
These vessels carry blood away from the heart
arteries
These vessels carry blood toward the heart
Veins
Nerves and vessels run together are considered a
neurovascular bundle
Vessel wall layers include
tunica interna, tunica media, tunica externa
This lines the vessel, has endothelium, smooth & selectively permeable
tunica interna
This enables vessel diameter/radius to change, and has involuntary, smooth muscle
tunica media
This is loose connective tissue that contains vaso varosum
tunica externa
These supply blood to larger vessels
vasa vasorum
Large arteries contain
plenty elastic fibers
Elastic fibers allow expansion, which
allow control of BP during systole & diastole
During systole, elastic fibers allow BP
not to go as high
During diastole, elastic fibers allow BP
not to go as low
Arteries ____ during systole and ____ during diastole
expand, recoil
Vasoconstriciton and vasodilation occur in
arterioles
Three ways of controlling vasomotor activity
Local , neural and hormonal control
When tissues regulates own blood flow, it is ____
local control
Neural Control include both
baroreflex & chemoreflex
Automatic, negative feed back response in BP located in carotid sinus in carotid arteries
baroreflex
automatic response to changed in blood chemistry in carotid & aortic bodies
chemoreflex
automatic response to drop in perfusion of brain
medullary ischemic reflex
Insufficient perfusion is
ischemia
Vasomotor center of medulla exerts what kinda of control over blood vessels
sympathetic
This hormones raises Blood pressure (vasoconstrictor) & promotes sodium and water retention by kidneys
Angiotensin II
This hormone lowers blood pressure & blood volume) (vasodilator)
Atrial Natriuretic Peptide
This hormone raises Blood pressure, and promotes water retention
ADH- Anti Diuretic Hormone
The speed of blood decreases when moving from
aorta to capillaries
The speed of blood increase while moving from
capillaries to Vena Cava
Blood moves slower
in veins than arteries
Most important blood in body is in the
capillaries
Routes for chemical exchange in capillaries include
through endothelium/ cytoplasm, via intercellular clefts, and through filtration pores/ fenestras.
Mechanisms for chemical exchange through capillaries include
diffusion, transcytosis, filtration and reabsorption.
Diffusion across cell from one side to another end
Transcytosis
Movement from high to low concentration, most important form of capillary exchange
diffusion
diffusion of water through a semi permeable membrane
osmosis “reabsorption”
movement of fluid in and out of capillary
filtration
More water is lost from blood on arterial end than venous end and results in
excess fluid in tissue space, which can lead to swelling/ edema if not corrected
Flow of blood back to heart
Venous Return
Mechanisms of venous return include
skeletal muscle pump, thoracic pump, exercise
when cardiac output does not meet the needs of the body
circulatory shock
when the body compensates and corrects problem
compensated shock
when body compensation fails
decompensated shock
