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