A&P II Exam 2 (Ch 20 - Systemic Circulation)

tunica intima - endothelins

constrict vessels

tunica intima - basal lamina

binds endothelium to connective tissue; provides strength flexibility and permeability

tunica media - circular elastic fibers

helps in vasoconstriction, vasodilation, nervi vasorum

tunica externa arteries

thickest layer in veins and some arteries; outer layer continuous with connective tissue for stability

elastic arteries

stronger stretch and recoil for higher pressure; closer to heart

muscular arteries

distributing arteries; vasoconstriction; decreased elasticity

arterioles

primary site of pressure regulation; lead to capillaries; very thin layers; resistance vessels; vascular tone

3 types of capillaries

continuous, fenestrated, sinusoidal

perfusion

process of supplying blood to the tissues

microcirculation

flow through the capillaries

metarterioles

links arterioles and capillaries; rings of sphincters; diapedesis

continuous capillaries

most vascular tissue; complete endothelium; tight junctions; transport vesicles (except brain); blood-brain barrier

fenestrated capillaries

pores in addition to tight junctions; permeable to larger molecules; small intestine, kidneys; choroid plexuses

sinusoidal capillaries

most permeable; occurs in specialized locations only

venules

post capillary; very thin; diapedesis

veins

oxygen poor blood going towards heart

edema

pooling of blood leads to increase in interstitial fluid due to pressure

hypertension, heart failure, renal failure

varicose veins

defective valves allow for blood accumulation

capacitance

ability to distend even at low pressure

blood flow

movement through vessel, tissue, or organ

systole

ventricular contraction

diastole

ventricular relaxation

pulse pressure

difference between systolic and diastolic

should be 25% of systolic

mean arterial pressure

avg pressure of arterial blood

pulse

expansion and recoil from elastic fibers in arteries

sphygmomanometer

cuff attached to measuring device for blood pressure

sounds of korotkoff

turbulent blood flow; 1st sound is systolic 2nd is diastolic

variables affecting blood pressure

CO, compliance, blood volume, blood viscosity, blood vessel length and diameter

compliance

ability to expand to accommodate increased content; veins more compliant

Poiseuille’s equestion

Blood flow = Δ P/Resistance

Resistance = Δ P/Blood flow

Poiseulle’s equation related 3 variables

Viscosity, vessel length, and radius

hypovolemia

low blood volume due to bleeding, dehydration, vomiting, etc

hypervolemia

excessive fluid volume due to water or sodium retention or heart failure, liver disease, kidney disease, etc

relationship between viscosity and resistance

directly proportional

relationship between length and resistance

directly proportional

relationship between diameter and resistance

inversely proportional

arteriosclerosis

reduced compliance due to injury, high glucose, infection, tobacco, etc

emboli

ischemia

emboli

can lead to sudden heart attack or stroke

ischemia

leads to hypoxia

arteriosclerosis management

lifestyle changes, angioplasty, endarterectomy, coronary bypass

atrial pressure is low during

diastole

physiological pumps for veins

skeletal muscle and respiratory

increase in thoracic volume =

lower pressure and increased flow into thoracic veins

hydrostatic pressure

pressure of any fluid enclosed in a space; force exerted on vessel walls

blood hydrostatic pressure

force exerted by the blood confined within blood vessels or heart chambers

capillary hydrostatic pressure

pressure exerted by blood against wall of capillary

interstitial fluid hydrostatic pressure

as fluid exits a capillary and moves into tissues, the hydrostatic pressure in the interstitial fluid correspondingly rises

bulk flow

mass movement of fluids through capillary beds and tissues

filtration

movement from higher pressure in capillary to lower pressure in tissues

reabsorption

movement from higher pressure in tissues to lower pressure in capillaries

osmotic pressure

pressure driving reabsorption; draws fluid back to capillaries

what determines osmotic gradient

plasma proteins

plasma proteins form

colloid rather than solution

lymph capillaries

pick up excess and return recycled blood plasma to circulation

cardiovascular center in the brain

medulla oblongata

cardioacceleratory center

increases heart rate directly via sympathetic cardiac nerves which interact with the SA node to increase heart rate

cardioinhibitory center

slows cardiac function by decreasing heart rate and stroke volume via parasympathetic stimulation from vagus nerve

vasomotor center

causes vasoconstriction of the peripheral blood vessels and therefore increases cardiac outpute

3 mechanisms ensure adequate blood flow, pressure, distribution, and perfusion

neural, endocrine, autoregulatory

neural regulation

chemoreceptors near baroreceptors in aortic and carotid sinuses monitor oxygen, CO2, and pH

autocrine regulation of perfusion

chemical signals work at the level of precapillary sphincters

myogenic response at the level of smooth muscle stretch in arteriole walls

hypertension

chronically elevated blood pressure

hemorrhage

uncontrolled blood loss

circulatory shock

system unable to maintain blood flow to supply oxygen, nutrients, etc

hypovolemic shock

typically caused by hermorrhage/fluid loss

tachycardia, weak pulse, rapid shallow breathing

cardiogenic shock

inability of heart to maintain cardiac output

vascular chock

artertioles lose normal muscular tone or dilate dramatically

sepsis

overwhelming immune response to bacterial infection; leads to blood clotes, leaky vessels to possible organ failure

Hemangioblasts
differentiate

angioblasts

angioblasts gives rise to

formed elements and
blood islands

Angiogenesis

creation of new vessels from existing ones; follows nerve development