unit 2 flashcards: blood vessels

this is only the beginning

define arteries

carry blood AWAY from heart; elastic, muscular, arterioles; split repeatedly

thinner tunica externa than media, strong + thick tunica media, wavy tunica interna

oxygenated blood exceptions - pulmo trunk, artery, umbilical artery

define veins

carry blood TOWARDS the hear; venules - smallest veins; converge

tunica externa thickest, thinner tunica media, smooth tunica interna (endothelium)

deoxy blood except - pulmo veins, umbilical vein

define capillaries

endothelium (single layer of cells); directly serve cellular metabolic demands of tissues and organs

exchange happens thru thin walls of caps; plasma + nutrients pass thru becoming the interstitial fluid that later returns thru lymphatic syst

desc tunica externa

mostly made of CT w collagen + elastin; anchors it to surrounding structures, provides support, protects

contains numerous nerves + lymphatic vessels - vasa vasorum (bvs of bvs), nervi vasorum (nerves of bv)

desc tunica media

smooth musc + elastic fibers; mainly responsib for bp + maintain circulation

vasodilation vs vasoconstriction (vasometer nerve/symp NS): norepinephrine (NE) always released, maintaining arteries + arterioles partially contracted : more NE → more contraction

in brain + skel musc, ACh can be released and stim release of nitric oxide, which causes vasodilation

check chart in guided notes

desc tunica interna (intima)

endothelium, continuous w endocardium; reduces friction; wavy due to constriction of smooth musc

arteries - presence of internal elastic mm

which layer responsib for keeping bp

tunica media

name of neurotransmitter involved in keeping bp? explain connection between NT lvls and diameter of bv

norepinephrine: the more NE, the more contraction of bvs, and vice versa

desc continuous capillaries (anatomical/physiological diffs)

most common, least permiable; plasma mm of endothelial cells form continuous tube w tight junctions interrupted by intercellular clefts (gaps between neighboring cells)

brain capillaries have tight junctions instead of intracellular clefts

desc fenestrated caps (anatomical/physiological diffs)

fenestra = windows; small pores in plasma mm (more permiable)

allows for greater exchange of solutes; examples - kidneys (filtration), endocrine glands (hormones), villi of small intestine

desc sinusoid caps (anatomical/physiological diffs)

most permiable, least abundant; v wide lumen w spaces between endothelial cells + lacking complete basement mm; large intercellular clefts + fenestrations; endothelium not continuous

blood flows v slowly thru these (for nutrient deposit/pick up)

kupffer cells: large macrophages form part of lining; remove + destroy contained bacteria; eg - liver, spleen, bone marrow (bc blood cells need to squeeze thru)

desc elastic arteries

largest in body: L common carotid, L subclavian, brachiocephalic, aorta, pulmo trunk

its tunica media dominated by elastic fibers; help propel blood even when ventricles are relaxed; accomm surge of blood + fxn as pressure resovoir; expands + contracts as heart pumps; elastic fibers recoil, pushing blood forward

desc musc arteries

throughout body, thickest tunica media, fewer elastic fibers; capable of greater vasoconst

dist blood in various parts of body (dist arteries); ex - brachial artery, femoral, external carotid, mesenteric

desc arterioles

literally means small arteries; all 3 layers, but externa + media shrink, interna stays same

smaller arterioles lead into capi bed; regulate blood flow to caps by arteriole diameter

terminal arterioles, metarteriole - ones before capi beds

what happens to elasticity in arteries during arteriosclerosis?

walls thicken and harden, elasticity decreases + bp inc

how is anat of capillaries + capillary beds well suited to their fxn?

thin, single walls so nutrients, hormones, gases, blood cells (prob other things) can pass thru walls and get into bloodstream to be distrib around body

which bv permits exchange of nutrients + gases between blood and tissue cells? why?

capillaries bc thin walls

differ between metarteriole, true capillaries, and thoroughfare channel

metarteriole - act as bridge between arterioles and caps; w precap sphincter; ctrls blood flow into cap bed; chems released by endothelial cells such as nitric oxide causes vasodilation

true caps - (10 -100 caps) where actual exchange happens

thoroughfare channel - intermediate between cap and venule; provides direct route from arteriole to venule; if precap sphincter closed, blood flows from metarteriole to thoroughfare channel

what are veins and venules?

venules are smallest veins

venule’s smaller than veins, come after capillaries and lead to veins

compared to arteries, veins have ______

thinner tunica media, thicker tunica externa, smoother endothelium (tunica intima), larger lumen, contain valves, ability to fold or grow to hold more blood, deoxy blood usually

desc pressures in diff bvs

veins contain lowest bp

arteries have highest bp, esp around heart; maintain bp thru thick walls + elasticity

cap bp lower than arteries in order to allow for efficient exchange of substances

is vasoconstriction the same in arteries and veins? explain

in arteries, vasconst capabilities greater bc thick tunica media,

in veins, thinner tunica media means less muscular strength and structure to be able to constrict

what is the fxn of valves in the veins?

prevent backflow of blood thru veins

how is the venous blood returned to the heart?

venous return - occurs due to pressure generated by contractions of heart’s left ventricle

at rest, which vessel(s) act as blood resovoirs

veins bc large lumen

define anastomosis

in vasc syst creates backup pathway for blood flow if a bv becomes blocked

know info abt blood flow covered in lecture

as in the order of blood flow thru bvs?

define bp and what are norm vals?

force exerted by blood against bv wall (mmHg); determined by various factors - cardiac output, compliance, blood vol, blood viscosity, bv length + diameter

systolic/diastolic pressure - varies w elasticity of arteries close to heart and vol of blood

normal vals at rest: syst (highest pressure attained, heart contraction) 120mmHg; diast (lowest pressure attained, heart relax) 60-80 mmHg

how is bp determined?

i think vasoconstriction and dilation of bvs?

what are the effects of vasodilation and vasoconstriction on bp?

vasodilation decreases bp, vasoconstriction inc bp

what does systolic and diastolic pressure mean?

systolic: first number - force of blood flow when blood pumped out of heart, less than 120 mmHg; highest pressure in aorta

diastolic: second num - measured between beats when your heart is filling w blood, 60-80 mmHg; lowest pressure S + i vena cavae

what is mean arterial pressure? why is it important?

ave pressure in aorta thruout cardi cyc; pressure propelling blood into tissues

MAP = diastolic pressure + 1/3 (systolic BP - diastolic BP)

important bc determines how well blood flow is and if tissues are getting enough blood: 70 - 150 mmHg

MAP < 60 cause fainting, above 160 cause cerebral edema (build up fluid)

define pulse and give norm vals. define tachy and bradycardia

pressure wave felt by alternating expansion and recoil of arteries during cardi cyc; measure of hr (bpm); norm = 60-100bpm

tachycardia - rapid resting rate over 100 bpm

bradycardia - slow resting rate under 60 bpm

how does body regulate bp (neutral and hormonal ctrls)? (chart is best way to study this part)

what is autoregulation?

ability of tissue to auto adjust own blood flow to match metabolic demand for delivery of oxy + nutrients + removal of wastes

phys + chem stim can lead to autoreg, like stretch, nitric oxide, inc lvl CO2

define bulk flow

passive process in which large num of ions, molecules, or particles in fluid move together in one direction down a pressure gradient; occurs from area of high pressure to low pressure, and continues if pressure diff exists

define hydrostatic + osmotic pressure. what are their norm vals in capillary and interstitial fluid at beginning (arterial end) and end of capillary (venous end)?

hydrostatic: force exerted by fluid pushing against wall; arterial end: 35mmHg, venous: 18mmHg

osmotic: equal thruout caps, created by presence in fluid of large nondifusible molecules; arterial and venous: 20mmHg

define hydrostatic pressure and ID its norm vals in capillary and interstitial fluid at beginning (arterial end) and end of capillary (venous end)

force exerted by a fluid pressing against a wall

arterial end: 35mmHg; venous end: 18mmHg

define osmotic pressure and ID its norm vals in capillary and interstitial fluid at beginning (arterial end) and end of capillary (venous end)

equal throughout caps; created by presence in a fluid of large nondiffusible molecules (plasma proteins)

arterial + venous end: 25mmHg

what is filtration and reabsorption? where in the capillary do they happen? where is fluid moving towards in each one?

filtration - fluid pushed out of cap; moving from bloodstream to tissues, high pressure in cap to low pressure externally

reabsorption - fluid pushed into cap; moving from interstitial fluid back into caps, high pressure externally to lower pressure in venous cap end

happens at arterial and venous ends of caps

what is the norm NFP (net filtration pressure) at the beginning of capillary and end?

beginning of cap: 10mmHg

end: -7mmHg

what happens to extra fluid left in interstitial fluid after capillary exchange

goes back thru lymph syst