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What are the tunics that compose the Arteries and Veins?
Tunica Interna (Intima), Tunica Media, Tunica Externa (Adventitia).
the central blood filling space surrounded by the tunics?
What are Capillaries composed of?
Endothelium with sparse basal lamina.
What is the Tunica Interna (Intima)?
Endothelial layer that lines the lumen of all vessels.
What is the Tunica Media?
Smooth muscle and elastic fiber layer, regulated by sympathetic nervous system.
What does the Tunica Media control?
Vasoconstriction/vasodilation of vessels. SNS vasomotor nerves ad chemical factors
What is the Tunica Externa (Adventitia)?
Collagen fibers that protect and reinforce vessels.
What is the Vasa Vasorum?
Vessels of the vessels - small blood vessels nourish the wall of larger blood vessels
What are Elastic (Conducting) Arteries?
Thick walled arteries near the heart. Aorta and its major branches. Large lumen allow low-resistance conduction of blood. Contain elasin in all three tunics. Act as pressure reservoirs - expand and recoil as blood is ejected from the heart.
What are Muscular (Distributing) Arteries?
Distal to elastic arteries, deliver blood to body organs, have thick tunica media with more smooth muscle, active in vasoconstruction.
What are Arterioles?
Small arteries, lead to capillary beds, control flow into capillary beds via vasodilation and vasoconstriction.
What are Capillaries?
Microscopic blood vessels, walls of thin tunica intima, one cell thick. Size only allows one RBC at a time.
Where are Capillaries found?
In all tissues except for cartilage, epithelia, cornea and lens of eye.
What is the funciton of Capillaries?
Exchange of gases, nutrients, wastes, hormones etc.
What are the 3 types of Capillaries?
Continuous capillaries, Fenestrated capillaries, sinusoidal capillaries (Sinusoids).
What are Continuous Capillaries?
endothelial cells are joined by tight juctions but may be iterruppted by itercelluar clefts Abundent capillaries in the skin and muscles, continuous capillaries of the brain - forms the blood brain barrier.
What is Fenestrated Capillaries?
like Continuous capillaries,but the endothelial cells contain pores (fenestrations), covered by a thin membrane MORE permeable then continuous capillaries. Functions in absorption or filtrate formation (small intestines, endocrine glands, and kidneys).
What are Sinusoidal Capillaries?
Fewer tight junctions & intercellular clefts, large lumen, usually fenestrated, allos large molecules &blood cells to pass b/t the blood & surrounding tissues. Found in LIVER, BONE MARROW &SPLEEN
What are Venules?
carry blood from capillary beds to veins, Formed when capillary beds unite. Allow fluids and WBC's to pass from the bloodstream to tissues. Large ones have one or two layers of smooth muscle (tunica media).
What are Postcapillary Venules?
SMALL venules, endothelim few podocytes , extremly POROUS
What are Veins?
carries blood TOWARDS the heart,all three tunics present ,tunica externa is THICK tunica media is thin lumen has irreglar shape, holds up to 50%blood volume
What are Capacitance Vessels?
collects from VENULES & carries it to the heart
Do veins or arteries have lower blood pressure and thinner walls?
VEINS have low BP & THIN walls
What are the special adaptations veins have in returning blood to the heart?
Large-diameter lumes, which offer little resistance to flow. Valves (resembling semilunar heart valves), which prevent backflow of blood.
What is Venous Sinuses?
large diameter veins consisting oly of endothelim, flattened veins (ex. coronary sinus of the heart dural sinuses of the brain).
What are Vascular Anastomoses?
Merging blood vessels, more common in veins than arteries. Provdealternate pathways (collateral channels) for blood to reach a given body region. If one branch is blocked, the collateral channel can supply the area with adequate blood supply.
A vasular shunt that connects ARTERIOLES & CAPILLARIES ia capillary bed
A vasular shunt that connects CAPILLARIES & VENULES in a capillary bed
these vessels branch off of metarterioles & return blood to throughfare channels;flow is controlled by opening/closing PRECAPILLARY SCHINCHTERS;diffuson b/t the blood &intestial fluid occurs here
____ are connective tissue cells that stabalize the capillary wall
What are the endothelial cell products in Tunic Intima?
- Nitric Oxide- relaxes vascular smooth muscle
- Prostacyclin- relaxes vascular SM & REPEALS PLATELETS
- Endothelin CONTRACTS vasular SM causing vasoconstriction
___ reduces the diameter of the artery & decreases the flow of blood to and organ? Type of vessel??
VASOCONSTRICTION/ muscular artery
____dilates and constrict to control distributation of blood to organs ?
Type of vessel??
distributing artery/ muscular artery
____increases the diameter of flow to artery & increases the flow of blood to an organ
THICK tunic media
THIN tunic externa
THIN tunic media
THICK tunic externa
irregular shape LUMEN
during ___ the artery fills w/ a stroke volume & is streched
during ___ the artery maintains pressure as it recoils on the blood, propelling it further along
causes & effects
- causes aging, hypertension, diabetes, smoking, herditary, high cholesterol
- effects abnormal thickness & abnormal hardening of vessel walls in the arterial system ; SM cells & collegen fibers migrate into the tunic intima; lumen becomes narrowed
causes & effects
elevated cholesterol, smoking, diabetes, infection, autoimmune phenomena
- effects endothelial injured inflammation occurs; macrophages release free radials & enzymes that further damage the vessel wall; LDL becomes oxidized & ingested by marcophages(foam cells) ; foam cells invade the vessel wall & accummate (fatty streak); SM cells proliferate ,secrte collegen & form a fibrous plaque; vessel becomes narrowed & OBSTRUCTED
Damage to one or more veins; venouis distention & pooling of blood; veins become TORTUOUS & PALPABLE
What disorder CAUSES localized dilation or outpouchimg of a blood vessel or cardiac chamber?
What are the EFFECTS??
- effects: arterial walls become weakened & may rupture
- common sites: abdominal aorta, renal arteries, cerebral arteries
What disorder causes inflammation of a vein due to infection or trama??
What could this lead to??
Phlebits ; may lead to pooled blood & edema
What disorder causes inflammation of a vein assocaiated with a ablod clot??
Effects of this disorder??
THROMBOPHLEBITS; redness, heat,swelling, & pain in the affected area, the clot may break off and become an embolus that blocks smaller vessels in other areas