Final (rest of information) Flashcards
(70 cards)
Blood vessels go into…
capillary beds then into the venous system, where most blood volume is (60%)
All vessels consist of what?
A lumen (central blood containing space, blood vessels are tubes), walls of all vessels minus capillaries have three layers
3 layers of blood vessels:
Tunica intima: innermost layer, made of endothelium and subendothelial layer
Tunica media: middle layer composed of smooth muscle and sheets of elastin, bulkiest layers responsible for maintaining blood flow/pressure
Tunica Externa: outermost later, composed of loose collagen fibers, infiltrated with nerve fibers
What is the vaso vasorum?
conceptually similar to the conary blood supply, small blood vessels that feed larger blood vessels and remove waste
Flow of blood?
Arteries- Capillaries- Veins
3 groups of arteries?
Elastic, Muscular, Arterioles
Elastic arteries? (big)
Thick-walled, low-resistance lumen, found in the aorta, inactive in vasoconstriction, pressure reservoirs that expand/recoil as blood leaves heart
Muscular arteries? (medium)
delivering blood to organs
Thickest tunia media with more smooth muscle, less elastic tissue, Active in vasoconstriction
Arterioles? (small)
Larger contain all 3 tunics, small are single layer of smooth muscle
Control flow into capillary beds via vasodilation/constriction, change diameters change resistance to blood flow
What are capillaries?
walls thin tunica intima, one cell forms entire circumference
Functions: exchange gases, nutrient, waste, etc. between blood and interstitual fluid
What stabilizes capillaries?
Pericytes: spider-shaped stem cells help stablize capillary walls, control permeability
How are capillaries joined?
endothelial cells joined by tight junctions with intercellular clefts
3 kinds of capillaries?
Continuous, fenestrated, sinusoidal
Continuous capillaries? (least permeable)
Abundant in skin, muscles, and lungs, often have pericytes, Pinocytotic vesicles ferry fluid
Brain capillary lack intercellular clefts, and only have tight junctions
Fenestrated capillary? (medium permeable)
Occur in areas of filtration or absorptions (kidney, small intestine)
Holes that tunnel through endothelial cells
Usually covered by a thin diaphragm made of glycoproteins
Sinusoidal capillaries (most permeable)
In the liver, bone marrow, spleen
Large intercellular clefts, incomplete basement membrane, irregularly shaped
Blood flows slowly
What are capillary beds?
where arterioles and venules meet, referred to as the microcirculation
2 features of capillaries in serous intestine?
Vascular shunt: channel that connects arteriole with venule, bypasses capillaries
Precapillary sphincter: cuff of smooth muscle surrounding capillary that branches off metarteriole, acts as valve regulating blood flow to capillary bed
Defintion of veins
Carry blood toward the heart, beginning when capillary beds unite and merge into larger veins
Have tunics but thinner walls with large lumens
Definiton of venules
Capillaries unite to form postcapillary venules
Endothelium, few pericytes, very porous
Large venues have layers of smooth muscle cells
How is blood pressure maintained?
Blood pressure is lower than in arteries, large diameter lumens offer resistance, venous valves prevent backflow, Skeletal Muscles help blood flow through veins, and pulsing of nearby arteries
What are anastomoses?
Interconnections of blood vessels, provide alternate pathways
What are the 3 sources of blood flow resistance?
Blood viscosity- higher viscosity= more resistance
Total blood vessel length- longer= more resistance
Blood vessel diameter- thinner= more resistance, the greatest impact on resistance,
Blood flow proportional?
Blood flow (F) is directly proportional to blood pressure gradient (P), as P increases blood flow speed up
Blood flow inversely proportional to peripheral resistance (R) F= DeltaP/ R