Term
|
Definition
smooth inner layer repels blood cells and platelets
simple squamous and basement membrane (layer of fibrous tissue) |
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Term
|
Definition
middle layer
thickest; smooth muscle, collagen, some elastic
smooth muscle for vasomotion |
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Term
| Tunica externa (tunica adventitia) |
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Definition
outer layer
loose connective tissue with vasa vasorum |
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Term
| Conducting (elastic) arteries |
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Definition
pulmonary, aorta and common carotid
expand during systole, recoil during diastole; lessens fluctuations in BP
tunica media: perforated sheets of elastic tissue |
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Term
| Distributing (muscular) arteries |
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Definition
distributes blood to specific organs; femoral and splenic
smooth muscle layers constitute 3/4 of wall thickness |
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Term
| Resistance (small) arteries |
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Definition
| arterioles control amount of blood to various organs |
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Term
|
Definition
short vessels connect arterioles to capillaries
muscle cells form a precapillary sphincter about entrance to capillary |
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Term
|
Definition
| postcapillary venules more porous than capillaries |
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Term
|
Definition
low pressure (~ 10 mmHg)
thin elastic walls have high capacitance
valves aid upward blood flow |
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Term
|
Definition
very thin walls, large lumen
no smooth muscle |
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Term
|
Definition
| Venae cavae, pulmonary veins |
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Term
|
Definition
baroceptors
wall of internal carotid artery
monitors BP – signals brainstem
-HR dec and vessel dilation detection |
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Term
|
Definition
chemoceptors
oval bodies near carotids
monitor blood chemistry
-adjust respiration to stabilize pH, -CO2, and O2 |
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Term
|
Definition
chemoceptors
walls of aorta
aorta also contains baroceptors |
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Term
|
Definition
control bed perfusion
~25% of the capillaries are open at a given time
~90% closed in resting skeletal muscle |
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Term
|
Definition
most tissues
endothelial cells with tight junctions and intercellular clefts (passage of solutes) |
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Term
|
Definition
kidneys, small intestine
organs that require rapid absorption or filtration
filtration ‘pores’ thin glycoprotein layer; allows passage of small molecules |
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Term
|
Definition
liver, bone marrow, spleen
irregular blood-filled spaces; large fenestrations, allow proteins and blood cells to enter |
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Term
| Simple Circulation pathway |
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Definition
| heart --> arteries --> arterioles -->capillaries --> venules -->veins |
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Term
| Portal Circulatory system |
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Definition
| blood flows through two consecutive capillary networks before returning to heart |
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Term
|
Definition
| is a network of streams that both branch out and reconnect, such as blood vessels or leaf veins. |
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Term
|
Definition
| artery flows directly into vein |
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Term
|
Definition
most common, blockage less serious
alternate drainage of organs |
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Term
|
Definition
| collateral circulation (coronary) |
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Term
|
Definition
| amount of blood flowing through a tissue in a given time (ml/min) |
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Term
|
Definition
| rate of blood flow per given mass of tissue (ml/min/g) |
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Term
|
Definition
blood flow dependent on pressure and resistance
flow is proportional to the change in pressure dived by resistance of flow |
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Term
|
Definition
systolic - diastolic
important measure of stress exerted on small arteries |
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Term
| Mean arterial pressure (MAP) |
|
Definition
measurements taken at intervals of cardiac cycle, best estimate: diastolic pressure + (1/3 of pulse pressure)
varies with gravity: standing; 62 - head, 180 - ankle |
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Term
|
Definition
chronic (rest) BP > 140/90
Higher in males
weakens small arteries (aneurysm)
exacerbates athersclerosis |
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Term
|
Definition
chronic low resting BP
caused by blood loss, dehydration, anemia |
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Term
| Treatment of Hypertension |
|
Definition
Diuretics (thiazides)
a1 blockers (b blockers)
ACE inhibitors
Angiotensin II antagonists
Ca2+ channel blockers |
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Term
|
Definition
Angiotensinogen-->Angiotensin I
-->Angiotensin II(potent vasoconstrictor) |
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Term
|
Definition
kidney enzyme that converts angiotensinogen to angiotensin 1
-enzyme released when BP is low |
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Term
| angiotensin-converting enzyme |
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Definition
ACE
converts angiotensin 1 --> angiotensin 2
ACE inhibitors block this conversion to lower BP |
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Term
| Angiotensin 2 Antagonists |
|
Definition
Losartan, Valsartan
competes at glomerous of kindey
no constriction of arterioles |
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Term
|
Definition
regulated by RBC’s and albumin
dec viscosity with anemia, hypoproteinemia
inc viscosity with polycythemia , dehydration |
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Term
|
Definition
| pressure and flow dec with distance (friction) |
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Term
|
Definition
very powerful influence over flow
most adjustable variable, controls resistance quickly |
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Term
|
Definition
change in vessel radius
(vasoconstriction, vasodilation) |
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Term
|
Definition
| flows in layers, faster in center |
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Term
| Blood flow and Radius of Vessel |
|
Definition
blood flow (F) proportional to the fourth power of radius (r)
arterioles can constrict to 1/3 of fully relaxed radius
3X inc in radius results in 81X inc in flow |
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Term
| From aorta to capillaries |
|
Definition
flow dec for 3 reasons
greater distance, more friction and dec flow
smaller radii of arterioles and capillaries
farther from heart, greater total cross sectional area |
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Term
| From capillaries to vena cava |
|
Definition
flow inc again
large amount of blood forced into smaller channels
never regains velocity of large arteries |
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Term
|
Definition
local control
decreased perfusion causes waste accumulation = vasodilation |
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Term
|
Definition
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Term
|
Definition
| blood supply cut off then restored |
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Term
|
Definition
growth of new vessels
controlled by growth factors and inhibitors |
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Term
| Neural Control: Baroreflex |
|
Definition
aortic arch
aortic sinuses (behind aortic valve cusps)
carotid sinus (base of each internal carotid artery)
right atrium
detect changes |
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|
Term
Autonomic negative feedback response
to Baroreceptors |
|
Definition
inc BP causes rate of signals to rise, inhibits vasomotor center, dec sympathetic tone, vasodilation causes BP dec
dec BP causes rate of signals to drop, excites vasomotor center, inc sympathetic tone, vasoconstriction and BP inc |
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Term
|
Definition
sudden loss of input from baroceptors
sudden standing from rest pools blood in lower limbs
dec BP causes fainting |
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Term
| Autonomic response to changes in blood chemistry |
|
Definition
pH, O2, CO2
primary role: adjust respiration
secondary role: vasomotion |
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Term
| Medullary ischemic reflex |
|
Definition
inadequate perfusion of brainstem
inc cardiac output and causes widespread vasoconstriction
inc BP |
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Term
| Vasomotor center of medulla |
|
Definition
sympathetic control stimulates most vessels to constrict (dilates vessels in skeletal and cardiac muscle)
baroreflexes
chemoreflexes
medullary ischemic reflex
(all autonomic reflexes) |
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Term
|
Definition
promotes Na+ and water retention by kidneys
increases blood volume and pressure |
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Term
| Atrial natriuretic factor |
|
Definition
(ANP) (inc urinary sodium excretion)
general vasodilator
Inhibits renin and aldosterone secretion
elevated in congestive heart failure (BNP assay kits)
nesiritide (Natrecor®) recombinant human BNP |
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Term
|
Definition
antidiruetic hormone
pathologically high concentrations, vasoconstriction
(water retention) |
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Term
|
Definition
most blood vessels
binds to alpha-adrenergic receptors, vasoconstriction
skeletal and cardiac muscle blood vessels
binds to beta-adrenergic receptors, vasodilation |
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|
Term
| Localized vasoconstriction |
|
Definition
| pressure downstream drops, pressure upstream rises |
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Term
|
Definition
most control over peripheral resistance
located on proximal side of capillary beds
most numerous
more muscular by diameter |
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Term
| Capillary Exchange - Diffusion |
|
Definition
Lipid soluble substances
steroid hormones, O2 and CO2 diffuse easily |
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Term
| Capillary Exchange - Transcytosis |
|
Definition
Pinocytosis - transport vesicles across cell - exocytosis
Important for fatty acids albumin and large peptides - hormones |
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Term
| Filtration and Reabsorption |
|
Definition
blood (hydrostatic) vs colloid osmotic pressure (COP)
filtration on aterial end
absorption on venous |
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|
Term
| blood (hydrostatic) pressure |
|
Definition
drives fluid out of capillary
high on arterial end of capillary, low on venous end |
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|
Term
| colloid osmotic pressure (COP) |
|
Definition
draws fluid into capillary
results from plasma proteins (albumin)- more in blood
oncotic pressure = net COP (blood COP - tissue COP) |
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Term
|
Definition
inc cap filrtaion
poor venous return
kidney failure
inc histadine
dec capilarry reabsorption
obstructed lymphatic drainage |
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Term
|
Definition
edema
oxygen delivery and waste removal impaired |
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|
Term
|
Definition
|
|
Term
|
Definition
| result=headaches, nausea, seizures and coma |
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|
Term
| Circulatory shock Results |
|
Definition
| excess fluid in tissue spaces causes low blood volume and low BP |
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|
Term
| Mechanisms of Venous Return |
|
Definition
Gravity drains blood from head and neck
Skeletal muscle pump in the limbs
Pressure gradient
Thoracic pump
Cardiac suction of expanding atrial space |
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Term
|
Definition
| inhalation - thoracic cavity expands (pressure dec) abdominal pressure inc, forcing blood upward |
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Term
|
Definition
| Any state where Cardiac output insufficient to meet metabolic needs |
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Term
|
Definition
| - inadequate pumping of heart (MI) |
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Term
|
Definition
low venous return shock
most common
loss of blood volume: trauma, burns, dehydration |
|
|
Term
| obstructed venous return shock |
|
Definition
|
|
Term
| venous pooling (vascular) shock |
|
Definition
low venous return
long periods of standing, sitting or widespread vasodilation
neurogenic shock - loss of vasomotor tone, vasodilation
causes from emotional shock to brainstem injury |
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|
Term
|
Definition
| bacterial toxins trigger vasodilation and inc capillary permeability |
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Term
|
Definition
| severe immune reaction to antigen, histamine release, generalized vasodilation, inc capillary permeability |
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|
Term
|
Definition
| dec BP triggers baroreflex and production of angiotensin II, both stimulate vasoconstriction |
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|
Term
|
Definition
positive feedback loops
slow circulation -> disseminated intravascular coagulation -> slow circulation |
|
|
Term
| ischemia and acidosis of brainstem -> dec vasomotor tone, vasodilation -> dec CO -> ischemia and acidosis of brainstem |
|
Definition
|
|
Term
|
Definition
dilate as BP dec, constrict as BP rises
main chemical stimulus: pH
hypercapnia (CO2 inc) in brain, pH dec, triggers vasodilation
hypocapnia, inc pH, vasoconstriction |
|
|
Term
| transient ischemic attacks |
|
Definition
TIA
dizziness, loss of vision, weakness, paralysis, headache or aphasia; lasts from a moment to a few hours, often early warning of impending stroke |
|
|
Term
| cerebral vascular accident |
|
Definition
stroke
CVA
brain infarction caused by ischemia
atherosclerosis, thrombosis, ruptured aneurysm
effects range from unnoticeable to fatal
blindness, paralysis, loss of sensation, loss of speech common |
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|
Term
| Special Circulatory Routes - Skeletal Muscle |
|
Definition
During exercise
arterioles dilate in response to epinephrine and sympathetic nerves
precapillary sphincters dilate due to lactic acid, CO2
blood flow can increase 20 fold
Muscular contraction impedes flow
isometric contraction causes fatigue faster than isotonic |
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|
Term
| Special Circulatory Routes - Lungs |
|
Definition
Low pulmonary blood pressure
flow slower, more time for gas exchange
capillary fluid absorption
pulmonary arteries constrict, redirects flow to better ventilated region
during hypoxia |
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