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96 Cards in this Set

  • Front
  • Back
Blood vessels in adult humans stretch for how far?
60,000 miles
Vessel Lumen (arteries) are surrounded by what three layers?
Tunica interna (intima), Tunica Media and Tunica externa
Tunica Interna is made up of what?
simple squamous epithelium
makes it perfect for gas exchange
Tunica Media is made up of what?
smooth muscle
constricts and dilates to REGULATE blood flow
Tunica Externa is made up of what?
collagen connective tissue: hold the structure: mostly in arteries
-veins just mold in with whatever tissue they're in
Characteristic of Elastic (conducting) arteries and an example of one...
large diameter; has the ability to snap back into original shape. aorta and its major branches
purpose and characteristic of Muscular (distributing) arteries
deliver blood to organs; proportionately it is the thickest media: distributes by dilating and constricting
Arterioles....
-smallest of arteries
-largest of the arterioles have all three tunics
-blood flow into capillaries determined by arteriole diameter
-distributes to specific tissues by way of capillaries
Capillaries...
-smallest blood vessels
-allow exchange of materials between blood and interstitial fluid
-tunica interna ONLY
-continuous are most common
Two different types of capillaries...
Fenestrated (oval pores) and Sinusoidal
Fenestrated...
-active capillary absorption or filtrate formation
-small intestine, kidneys
Sinusoidal...
-highly modified, leaky
-large molecules, blood cells can pass
-liver, bone marrow, lymphoid tissues, some endocrine organs
Precapillary Sphincters...
-control blood route
-rerouting controlled by vasomotor nerve fibers, local chemical conditions
Vascular "shunting" is controlled based on....
waste
Postcapillary venules, venules...
extremely porous for white blood cells and fluid to move through
Pasadence
the ability to stretch and hold, like a reservoir; a characteristic of veins
What drives blood through arteries?
smooth muscle; it constricts and dilates, redirecting blood flow
what moves blood in veins back to the heart?
skeletal muscle contraction puts pressure on the veins in order to get the blood moving back to the heart.
venous valves....
-prevent backward blood flow
-resemble semilunar valves of heart
-most abundant in limbs-to fight gravity
-varicose veins result when valves are incompetent
Venous sinuses...
coronary and dural
flattented, extremely thin, supported by tissues around them
Vascular Anastomoses
-occur where vascular channels unite
-provide alternate pathways called collateral channels
-found in joints, abdominal organs, brain, heart
Arteriovenous anastomoses...
capillary bed
Venous anastomoses
common; visible on back of hand
Blood Flow
volume of blood flowing through a vessel, organ, or entire circulation (cardiac output) in a given period
Blood Pressure
-force per unit area exerted on the blood vessel wall by its contained blood
-usually means systemic arterial pressure in largest arteries
-pressure gradient drives blood movement
Resistance...
-friction or opposition to flow
-mostly occurs away from heart, peripheral resistance
Blood viscosity...
-internal resistance to flow
-related to stickiness of fluid
-causes polycythemia and anemia
Total blood vessel length; the longer the length the...
greater the resistance
Blood vessel diameter...
-smaller diameter = greater resistance
-resistance varies with the 4th power of the vessel radius
Blood flow is directly ________ to difference in blood pressure and ______ proportional to peripheral resistance
proportional; inversely
why doesn't the blood pressure come crashing down when the heart is at rest?
arteriol elasticity; the closing of the artery causes the diastolic pressure
Systemic blood pressure is _____ in the aorta and _____ in the right atrium
highest; lowest
Arterial blood pressure pulsatile...
-peak is systolic pressure
-diastole, aorta pressure its lowest
-diastolic pressure
Pulse pressure = ...
difference between systolic and diastolic pressures
mean (average) arterial pressure = ...
diastolic pressure + pulse pressure/3
-drives blood to tissues
**2/3 of the hearts time is spent in diastole
Blood flow = ...
blood pressure/resistance (F = P/R)
OR
CO x R
OR
MAP = SV x HG x TPR
MAP stands for...
Mean Arterial Pressure
TPR stands for...
Total Peripheral Resistance
If blood pressure homeostasis is affected, body compensates by changing what two things?
-peripheral resistance (short term controls)
-blood volume (slower-acting renal mechanisms)
Neural controls act on _____ to accomplish what?
peripheral resistance;
-alter blood distribution
-maintain adequate MAP by altering vessel diameter
baroreceptors measure blood pressure in _______ if they detect change, they send a message to the _____, smooth muscle ____, increasing _____, increasing blood pressure
aortas; medulla; increases; resistance
Vasomotor center (sympathetic neurons in medulla)...
-oversee changes in diameter of blood vessels
-vasomotor efferents innervate smooth muscle of arterioles praimarily
-any increase in sympathetic response increases vasoconstriction and blood pressure
Baroreceptors are found where?
carotid sinuses, aortic arch, walls of large elastic arteries of neck and thorax
What does the baroreceptor do?
sends signal to inhibit vasomotor center
peripheral resistance and CO regulated in tandem by baroreceptor inputs
they are ineffective at protecting against sustained pressure changes
MAP is not a change in pressure because when it kicks in, pressure from the heart is basically _____
zero
TPR: what it stands for and definition....
Total Peripheral Resistance; resistance of all the veins in the systemic system
Chemoreceptors are located in...
aortic arch and large arteries of the neck
How are chemoreceptor s stimulated?
When oxygen content decreases, pH drops, or carbon dioxide rises
Impulses to cardioacceleratory center to increase CO and to vasomotor center to increase vasoconstriction
What do chemoreceptors tell us?
when to breathe more in order to get rid of waste or bring in more oxygen
the Hypothalamus mediates what?
fight or flight response and redistribution of blood flow during exercise/body temperature change
what are the short term mechanisms?
adrenal medulla, atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), Angiotensin II, endothelium-derived factors, inflammatory chemicals, alcohol
How does the adrenal medulla control blood pressure?
-stress increases epinephrine and epinephrine and NE are released into blood
-NE causes vasoconstriction
-Epinephrine increases CO and vasoconstriction but vasodilates skeletal and cardiac muscle
how does atrial natriuretic peptide (ANP) effect blood pressure?
-ANP is produced in atria
-decreases blood volum and blood pressure by forcing kidneys to excrete more sodium and water
how does Antidiuretic hormone (ADH) effect BP?
-ADH is produced in hypothalamus
-stimulates kidneys to conserve water
-much released when blood pressure very low
-can cause vasoconstriction
how does Angiotensin II affect BP?
-inadequate blood through the kidneys stimulates release of Renin
-Renin causes intense vasoconstriction
-stimulates release of aldosterone and ADH (this part is long term)
How do Endothelium-derived factors affect bp?
-vasoconstrictors: endothelin and PDGF
-nitric oxide has major role in producing vasodilation
Inflammatory chemicals...
histamine, prostacyclin; promote capillary permeability
how does alcohol control BP?
blood pressure drops by inhibiting ADH release, depressing vasomotor center, skin vasodilation (that's why people who have drank a lot have a red face)
Long-term mechanisms....
kidneys regulate blood volume
Direct mechanism and Indirect mechanism
How do the kidneys regulate blood volume?
through the use of ADH and Aldosterone, any increase in blood volume causes increased blood pressure
how does Direct mechanism work?
if blood pressure rises-kidneys are unable to filter all of the fluid, more leaves as urine
-blood volume decreases
-water is conservedin the converse situation
how does Indirect Mechanism work?
-renin and angiotensin
-decreased blood pressure, kidneys release renin into blood
-angiotensin II produced (vasoconstrictor
-angiotensin II stimulates adrenal cortex to secrete adosterone (renal reabsorption of sodium) and posterior pituitary to realease ADH
Hypotension can indicate...
poor nutrition, inadequate blood proteins, addison's disease
if Hypertension continues long term untreated, it can cause...
heart failure, vascular disease, renal failure and stroke
how is hypertension treated?
by controlling factors through drugs that include diuretics, beta-blockers, calcium channel blockers, and ACE inhibitor5s
What are some secondary causes of hypertension?
excessive renin secretion, arteriosclerosis, endocrine disorders
Tissue perfusion refers to...
blood flow to the tissues
oxygen/nutrient delivery and waste removal from tissues
absorption of nutrients from digestvie tract
urine formation by kidneys
exercise ________ blood flow.
redistributes
when blood vessels branch out to capillaries, blood pressure in the capillaries ____. is this good or bad and why?
drops; good; so that gas exchange can more effectively occur
Autoregulation....
automatic adjustment of blood flow to each tissue in proportion to its requirements at any given time
Organs regulate their own blood flow by varying _____ of their arterioles
resistance
organs autoregulate in response to _____ and ____ stimuli
metabolic; myogenic
Metabolic Controls (4)....
-decline in nutrients (oxygen)
-metabolic products (potassium, hydrogen ions, adenosine, lactic acid)
-prostaglandins and inflammatory chemicals (histamine, kinins)
-trigger vasodilation of arterioles feeding the capillary bed
myogenic controls ...
-keep tissue perfusion constant in spite of varying systemic pressure
-gnerally both metabolic and myogenic controls involved
explain how tissue perfusion is kept constant in spite of varying systemic pressure?
high arterial pressure and perfusion:
passive stretch, vascular smooth muscle resists, causing vasoconstriction, prevents damage
converse: reduced stretch promotes vasodilation
blood flow in special areas: skeletal muscles...
-blood flow extremely changeable
-exercise hyperemia
-arterioles have cholinergic but alpha and beta adrenergic receptors: cholinergic mediate vasodilation; low epinephrine, binds beta adrenergic receptors and get vasodilation; high epinephrine, binds alpha adrenergic receptors and get vasoconstriction
what two hormones come from the adrenergic gland?
epinephrine and norepinephrine
if your blood pressure is low, then you need to increase ______. this will ______ everything.
TPR; constrict
ischemia: definition...
a tissue that doesn't receive blood
Syncope: definition....
faing, causes you to fall over so that the blood flow doesn't have to work against gravity
Medullary cardiovascular centers trigger rise in systemic pressure occurs where?
in the brain
why would you send more blood to the lungs?
-in order to conduct gas exchange: opposite from the gas exchange that occurs in the capillaries
-if there is a portion of the lungs that have less oxygen and more carbon dioxide, you want to send less blood there.
-vessels will constrict until you ventilate (breathe): once you breathe, the vessels will dilate allowing more blood flow to come in and pick up more oxygen
autoregulatory mechanism opposite of other organs occurs where and give details....
lungs; low oxygen, vasoconstriciton and fits gas exchange role
vasomotion: definition....
slow and intermittent blood flow of the capillaries
Capillary Dynamics: four possible transport mechanisms....
-intercellular cleft
-simple diffusion
-Fenestrations
-endo/exocytosis
intercellular clefts....
allows for transport of fluid and solutes dissolved in the fluid from the capillaries and to the tissues and vise versus
simple diffusion...
gases can move through the simple squamous epithelium whether there are intercellular clefts or not
Fenestrations....
found in the kidneys and small intestines; holes right in the middle of the more permeable capillaries
Endocytosis...
when things are just too big to fit through fenestrations,
transcytosis....
is the entire mechanism of endo and exo-cytosis: this is very important in the blood brain barrier: not intercellular cleft or fenestration: just simple diffusion and transcytosis: allows for better control
Bulk fluid flow....
direction and amount of fluid flow depends upon two opposing forces: hydrostatic pressure (HP) and colloid osmotic pressure (OP)
NFP = (HP-HP) - (OP - OP)
net fluid loss or gain determined from net filtration pressure (NFP)
overall net movement is
_____ to tissues, lymphatics recover
loss
what is blood pressure?
-pushing of blood against the walls of the blood vessels
-blood still has a pressure pushing on the walls of the capillaries
-the pressure causes the fluids to be pushed out through the intercellular clefts and fenestrations
osmotic pressure...
pressure determined by the things dissolved in it: moves from high concentration to low.
water moves from _____ solute concentration to ____ solute concentration
low; high