chapter 21 A&P
Capillary Beds (Capillary Plexus)
-connect one arteriole and one venule -precapillary sphincter -guards entrance to each capillary -opens and closes, causing capillary blood to flow in pulses
vasoconstriction and vasodilation (arteries)
Affect: Afterload on heart Peripheral blood pressure Capillary blood flow
blood-brain barrier
Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out
Arteries
Blood vessels that carry blood away from the heart
continuous capillaries
Have complete endothelial lining Are found in all tissues except epithelia and cartilage
fenestrated capillaries
Have fenestrations or pores
arterial anastomosis
Interconnection between arteries Found in brain, heart, stomach and other parts with circulatory needs. Guarantees a reliable blood supply to tissues in case one is blocked.
cardiovascular center
Medulla Oblongata: cardiac center adjusts force and rate of heart contraction, vasomotor center adjusts blood vessel diameter for blood pressure regulation
Angiogenesis factors
PDGF, EGF, FGF, IL-8, hypoxia
Capillaries function
Serve as exchange vessels for nutrients, wastes, fluids.
tunica media
The middle and thickest layer of tissue of a blood vessel wall, composed of elastic tissue and smooth muscle cells that allow the vessel to expand or contract in response to changes in blood pressure and tissue demand.thickest layer in small artery,thin band of elestic fibers called external elastic membrane
cappilaries
The smallest vessels where materials are exchanged between the blood and body cells. chemical and gases diffuse across walls
Capilaries are important because____.
They connect arteries to viens.
peripheral resistance
Total force against which the blood must be pumped
circulary system
a body system that moves blood through the body and includes the heart, blood, and blood vessels
venous return
affects cardiac output and periphial blood flow
aneurysm
an excessive localized enlargement of an artery caused by a weakening of the artery wall.
" In the _____________, pressures are high enough to keep the blood moving forward. In the ____________, blood pressure is too low to keep the blood moving on toward the heart. Valves in veins prevent blood from flowing back toward the capillaries whenever the venous pressure drops"
arterial system, venous system
Five general classes of blood vessels
arteries, arterioles, capillaries, venules, veins
precapillary sphincters
arteriolar smooth muscle; degree of constriction determines resistance, blood flow passes through artiovenous anastomoses
Venous valves prevent
backflow of blood
continous capillaries
blood brain barrier
why are valves located in the veins
blood pressure is low enough to keep blood moving to the heart, valves in veins prevent blood from flowing back toward the capiliaries whenever venous pressure drops
___________ with thin walls and very little smooth muscle tissue in the tunica media are veins. __________have a large amount of smooth muscle tissue in a thick, well-developed tunica media"
blood vessels, Arteries and arterioles
arteries and arterioles
carry blood away from the heart. Thick and muscular with elastic walls
Veins
carry blood to the heart
elastic arteries
closer to the heart; allow stretch as blood is pumped into them and recoil when ventricles relax
Atherosclerosis
condition in which fatty deposits called plaque build up on the inner walls of the arteries
tunica externa
connective tissue, outer layer, ateries contain collagen fibers scattered bands of elastic fibers, smooth muscle cells
Precapillary sphincters will
control blood flow into the true capillaries cause blood to flow directly from the met arteriole into the post capillary venule open when the tissue needs nutrients close when the tissues needs have been met (all answers correct)
Vasomotion is associated with the presence of
d) smooth muscle in the tunica media.
Vasodilation will ____________ blood pressure.
decrease
Cardionhibitory center
decrease cardiac output
pulse pressure
difference between systolic and diastolic pressure
epitheal and cartliage
does not carry oxygen
Vascular endothelial growth factor (VEGF)
embryonic fetal development as tissues and organs
continuous capillaries
endothelial cells form a continuous tube
tunica intima
endothelium,outer margin contains thick layer of elastic fibers called internal elastic membrane, thin wall
valves inside veins
facilitate the transport of blood from body tissues back to the heart
pulmonary circulation
flow of blood from the heart to the lungs and back to the heart
Microcirculation
flow of blood through capillary bed
fenestrated capillaries
have pores in vessel wall; found in kidneys, intestines, and endocrine glands
heart cycle
heart-large arteries-medium a-small a-artiroles-capillaries-venules-small medium veins-large veins-heart
Vasoconstriction will ___________ blood pressure.
increase
cardioacceleratory center
increases heart rate
osmotic pressure
is the force caused by the net movement of water by osmosis
Sinusoids (discontinuous capillaries)
liver, bone marrow, spleen Irregular blood-filled spaces with large fenestrations Allow proteins (albumin), clotting factors, and new blood cells to enter the circulation
muscular arteries
medium-sized arteries, distribute blood to skeletal muscles and internal organs
thoroughfare channel
metarteriole that continues through capillary bed to venule
baroreceptor reflex
monitor degree of strecth, located carotoid sinus , aortic sinus, right atrium
Collaterals are
multiple arteries that contribute to one capillary bed
respitory pump
passive movement of blood through the central circulation as a function of pressure changes during breathing
largest blood vessels
pulmonary trunk , carries blood from right ventricle to pulmonary circulation Aorta, carries blood from left ventricle to systemic circulation
medium veins
up to 10 mm in diameter; thin tunica media and thick tunica externa; tunica interna forms venous valves; varicose veins result in part from the failure of these valves; skeletal muscle pump propels venous blood back toward the heart
Large veins have ________ to prevent the backflow of blood.
valves
which type of vessel is characterized by thin walls with very smooth muscle tissue in the tunica media
veins
venules, veins
vessels that return blood toward the heart
elastic arteries
Carry large volumes of blood away from the heart
arteriovenous
Dilated vessels where arterioles flow directly into veins (congenital tangled vessels)
----------- are located where fluids and small solutes move freely into and out of the blood, including endocrine glands, the choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys."
Fenestrated capillaries
capillary beds
sites of chemical exchange between the blood and interstitial fluid
Fenestrated capillaries have
small openings in the lining, pores
Venules are
small veins gathering blood from the capillaries and joining together to form veins
Arterioles
small vessels that receive blood from the arteries
vasa vasorum
small vessels that supply blood to outer part of the larger vessels
anastomosis
surgical joining of two ducts, vessels, or bowel segments to allow flow from one to another
hemorrhoids
swollen, twisted, varicose veins in the rectal region
vascular resistance
the resistance of the blood vessels to blood flow