6.7 Blood vessels Flashcards
What are the 3 tunics of blood vessels? What are they made of?
Tunica Intima
endothelium (simple squamous epithelium)
subendothelium
internal elastic membrane (arteries only)
Tunica Media
smooth muscle
external elastic membrane (arteries only)
Tunica Externa (tunica adventitia)
CT – collagen
internal blood vessels (vasa vasorum), lymphatics
What are realistic arteries?
largest, most elastic
expand/recoil
maintain continuous blood flow, even out blood pressure as heart ejects blood
What are muscular arteries?
medium size, most smooth muscle
most arteries named in lab, deliver to specific body organs/regions
distribute blood, less recoil, less elastic
What are arterioles? What kind of innervation do they have?
small arteries
small, mostly smooth muscle
SNS nervous system innervation (No PNS)
High resistance, slow down the flow of blood from the arteries to decrease pressure and regulate blood flow to the tissues
Where does the vasomotor response have the most effect?
In arterioles
Allows for LOCAL effect
What is the function of endothelium?
thin layer of squamous type epithelial cells
controls passage of materials between lumen and surrounding tissues
secretes factors that balance local vasodilation/vasconstriction as well as clot formation/clot inhibition
What kinds of factors are secreted from the endothelium?
Nitric Oxide (NO): stimulates vasodilation
Endothelin: stimulate vasoconstriction
VEGF: stimulates vessel growth
Thromboxane A2: stimulates clotting
von Willebrand factor: stimulates clotting
Prostacyclin: inhibits clotting
What is arteriosclerosis? Some common types?
“artery hardening” blood vessel walls develop lesions, become stiff and thickened major types: atherosclerosis arteriolosclerosis calcific (Moenckeberg) arteriosclerosis hyperplastic arteriosclerosis hyaline type arteriosclerosis
How is plaque formed in arteries?
INJURY: injury to endothelium causes inflammatory mediator release and WBC recruitment and differentiation into macrophages
LDL build up: macrophages release cytokines, attract fibroblasts, increase LDL receptors, LDL builds up
FOAM CELL FORMATION: macrophages ingest LDL become Foam Cells
LDL high – foam cells accumulate FATTY STREAK
LDL low foam cells release LDL back to blood stream for liver excretion via HDL
FIBROSIS: Fibroblasts invade tunica media, cause initial hypertrophy, then decrease elasticity
LOSS of VASODILATION: with hardening, vasodilation capability is decreased
Fatty streak calcifies PLAQUE
Fibrous, calcified plaque with platelet cap ATHEROMA
What is the difference between turbulent and laminar flow?
laminar flow: a normal blood vessel has smooth, low friction flow of blood
turbulent flow: in areas where blood vessel is injured, inflamed, not smooth
can predispose to stagnant areas of flow, RBC, WBC, platelet, coagulation buildup thrombus (clot) formation
What is peripheral artery disease?
arteriosclerosis, occlusion of arteries in the extremities
can lead to ischemia–> infarction–> necrosis
common in femoral artery, iliac, popliteal, tibial arteries
What is intermittent claudication? Significance?
leg cramping during exercise - pain upon exertion is a sign of tissue ischemia
What are the characteristics of veins? How innervated?
vessels returning blood from the capillaries/tissues back toward the heart
large, thin walled, with valves
SNS nervous system innervation
Easily stretched to retain blood, but NOT elastic (do not recoil)
Slow blood flow, low pressure
require movement of skeletal muscles to help pump blood to heart.
Blood reservoir: veins contain >60% of total blood volume at any given time
What is a venous sinus?
specialized, large, flattened veins with very thin walls, endothelium supported by surrounding tissue large “drainage” areas dural sinuses (brain) coronary sinus (heart)
What is chronic venous insufficiency?
impaired venous return, venous congestion, edema caused by damage to valves
poor circulation leads to edema, thin skin, discoloration, poor healing
