Exam review Flashcards
collaterals
multiple arteries that contribute to 1 capillary bed
arterial anastomosis
fusion of 2 collateral arteries
arterial anastomosis function
allows capillary circulation to continue if an artery is blocked
arteriovenous anastomoses
direct connections between arteries and venules to bypass the capillary bed and flow directly into venous circulaion
3 factors the affect circulation
pressure, resistance, and venous return
amount of blood in veins & venules at rest
60-65%
amount of blood in arteries and arterioles at rest
13%
capillary blood flow in peripheral tissues and organs maintained by
ΔP (pressure gradient) = the difference between pressure of left side (at heart), and pressure returning to right side (at peripheral capillary beds)
capillary blood flow equals
cardiac output
capillary blood flow determined by
pressure and resistance (ΔP/R = force/flow)
how are pressure and resistance related to flow
pressure= directly related
resistance= inversely related (R increase, flow decrease)
laminar flow
turbulent flow
abnormal turbulence caused by
4 factors associated with blood pressure
systolic pressure
diastolic pressure
systolic pressure
diastolic pressure
pulse pressure
pulse pressure formula
mean arterial pressure (MAP)
MAP formula
CO x TPR
factors that affect MAP

3 regulatory mechanisms
autoregulation, neural mechanisms, and endocrine mechanisms
regulatory mechanism purpose
control CO & BP to restore adequate blood flow
autoregulation is
the ability to make changes as needed by demand for O2 and waste removal
autoregulation is adjusted by
peripheral resistance while CO stays the same
local vasodilators dilate precapillary sphincters
to accelerate blood flow at tissue level in response to physical changes
local vasodilator examples
low O2 or high CO2 levels
low pH
histamines
warmer temp
local vasoconstrictors released by
damaged tissues
local vasoconstrictor examples
prostaglandins and thromboxanes
neural mechanisms
autoregulation, neural mechanisms, and endocrine mechanisms
cv centers adjust
CO & peripheral resistance
each cardiac center has
cardioacceleratory center (increase CO thru SNS)
cardioinhibitory center (decrease CO thru PNS)
sympathetic nervous system
increase HR & contractility
fight or flight
parasympathetic nervous system
decreases HR
rest or digest
vasomotor center controls
the activity of sympathetic motor neurons (vasodilation & vasoconstriction)
vasoconstriction
controlled by adrenergic nerves (NE)
stimulates smooth muscle contraction
vasodilation
controlled by cholinergic nerves (NO)
relaxes smooth muscle
vasomotor tone
produced by constant action of sympathetic vasoconstriction nerves
keeps arterioles partially constricted
hormonal regulation
has short and long term effects on CV regulation
types of hormones
anti diuretic (ADH)
angiotensin II
erythropoietin (EPO)
atrial natriuretic peptide (ANP)
anti diuretic (ADH)
released by posterior lobe of pituitary to elevate BP & reduce water loss at kidneys
anti diuretic (ADH) responds to
low blood volume
high plasma osmotic concentration
circulating
angiotensin II
appears in blood when decrease in BP or decreased blood flow to kidneys
release of renin results in
formation of angiotensin II and aldosterone
angiotensin II important functions
aldosterone production
secretion of ADH
stimulates thirst
stimulates CO & triggers constriction of arterioles
aldosterone
H2O & Na+ reabsorption
increase total blood volume
erythropoietin (EPO)
is released at kidneys to stimulate RBC production
erythropoietin (EPO) responds to
low BP
low O2 content
atrial natriuretic peptide (ANP)
is produces by cells in right atrium to lower blood volume and pressure
reduces stress on heart
atrial natriuretic peptide (ANP) responds to
excessive diastolic stretching
shock
failure of CV system to deliver enough O2 & nutrients
what happens in shock
inadequate perfusion
cells forced to switch to anaerobic respiration
lactic acid builds up
cells & tissues become damaged and die
hypovolemic shock
due to loss of blood or body fluids (hemorrhage, sweating, diarrhea)
venous return to heart declines, output decreases
cardiogenic shock
caused by damage to pumping action of the heart (ischemia, valve problems, arrhythmias)
vascular shock
causing drop inappropriate vasodilation
head trauma
obstructive shock
caused by blockage of circulation
pulmonary embolism
homeostatic responses to shock
activation of renin-angiotensin-aldosterone
secretion of ADH
activation of SNS
release of local vasodilators
CV response to light exercise
extensive vasodilation
venous return increases
CO rises
CV response to heavy exercise
CV centers activate the SNS
CO increases
blood flow to most tissues is diminished
skin perfusion increases because temp increases
diffusion
substances move down concentration gradient to pass freely thru lipid bilayer, fenestrations, or channels
blood brain barrier
does not allow diffusion of water soluble materials
water, ions, small molecules diffusion route
between adjacent endothelial cells
fenestrated capillaries
Na+ K+ Ca2+ Cl- diffusion route
channels in cell membrane
large water soluble compound diffusion route
fenestrated capillaries
lipids, O2, CO2 diffusion route
thru endothelial cell membranes
plasma protein diffusion route
endothelial lining in sinusoids
filtration
is the removal of large solutes thru porous membrane
filtration driven by
hydrostatic pressure
filtration leaves
larger solutes in the blood stream by forcing water and small solutes thru capillary wall
reabsorption
is the result of osmosis
osmotic pressure
pressure required to prevent osmosis
blood colloid osmotic pressure (BCOP)
created by suspended blood proteins that are too large to cross capillary walls
hydrostatic pressure forces
water out of a solutions
osmotic pressure forces
water into a solution
net filtration pressure (NFP)
the difference between
net hydrostatic pressure
net osmotic pressure
NFP formula
(CHP + ICOP) - (IFHS + BCOP)
(filtration factors - reabsorption factors)
net outward pressure on arterial end
10 mm Hg
net inward pressure at venous end
9 mm Hg
net hydrostatic pressure
the difference between
capillary hydrostatic pressure (CHP)
interstitial fluid hydrostatic pressure (IHP)
pushes water & solutes out of capillaries, into IF
net colloid osmotic pressure
the difference between
blood colloid osmotic pressure (BCOP)
interstitial fluid colloid osmotic pressure (ICOP)
pulls water & solutes into capillary from IF
edema
an abnormal increase in IF if filtration exceeds reabsorption
edema result of excess filtration
increase in BP
increase permeability of capillaries allows plasma proteins to escape
edema result of inadequate reabsorption
decrease concentration of plasma proteins lowers BCOP
affects of aging general changes
decreased compliance of aorta
cardiac muscle fiber size reduce
reduced CO & max HR
increase systolic pressure
blood pressure measures
arterial pressure
capillary hydrostatic pressure (CHP) measures
pressure w/in capillary beds
venous pressure measures
pressure in venous system
circulatory pressure must overcome
total peripheral resistance (the resistance of entire CV system)
vascular resistance
R of blood vessels due to friction between blood & vessel walls
R depends on
avg blood vessel radius
blood viscosity
total blood vessel length
smaller vessels offer
more R to blood flow
cause fluctuations in P
blood viscosity (thickness) is
the ratio of RBCs to plasma volume
increase in viscosity =
increase in R = decrease in flow
dehydration or polycythemia (elevated RBC count)
the longer vessels =
greater R to flow
every pound of fat =
200 miles of vessels
R formula
R= (8ln)/(pi r^4)
greatest influence on R
vessel radius
r increase, R decrease
vary r the most by vasoconstriction & vasodilation
velocity
speed of blood flow is inversely related to cross sectional area
arterial wall elastic rebound feature
helps absorb pressure waves that come with each heartbeat
hypertension
abnormally high blood pressure
hypotension
abnormally low blood pressure
venous return
volume of blood flowing back to the heart from the systemic veins
skeletal muscle pump
contractions of skeletal muscles near vein compress it helping to push blood towards the heart and valves ensure it only flows in one direction
respiratory pump
as you exhale the thoracic cavity decreases in size, pressure rises and air is forced out of lungs and pushes venous blood into right atrium
syncope
fainting or a sudden temporary loss of consciousness not due to trauma because BP isnt sufficient enough to move blood
vasodepressor syncope
sudden emotional stress
situational syncope
pressure stress of coughing, defecation, or urination
drug induced syncope
antihypertensives, diuretics, vasodilators, tranquilizers
orthostatic hypotension
decrease in BP upon standing
tissue perfusion affected by
CO
peripheral R
BP
proprioceptors
input during physical activity
chemoreceptors
monitors concentration of chemicals in the blood
H CO2 O2
baroreceptors
changes in pressure w/in blood vessels
stretch receptors
lymph capillaries
start as pockets rather than tubes
larger diameters
thinner walls
flat/irreg in section
lacteals
specialized lymph capillaries in small intestine that transports lipids from digestive tract
lymph capillary structure
endothelial cells loosely bound together with overlap to act as one way valve
lymph vessels
travel with veins
superficial & deep lymphatics join to form large lymphatic trunks
lymphatic trunks empty into
thoracic duct
right lymphatic duct
thoracic duct
expands into cisterna chyli to recieve lymph from right & left lumbar trunks and intestinal trunks
inferior thoracic duct
collects lymph from left bronchiomediastinal trunk, left subclavian trunk, left jugular trunk
thoracic duct empties into
left subclavian vein
right lymphatic duct
collects lymph from right jugular trunk, right subclavian trunk, right bronchiomediastinal trunk
right lymphatic duct empties into
right subclavian vein
cytotoxic t cells
attack cells infected by viruses
produce cell mediated immunity
helper t cells
stimulate functions of t & b cells
suppressor t cells
inhibit function of t & b cells
keep balance in immune system
memory t cells
remembers foreign antigen
b cells
differentiate into plasma cells with exposure to interleukin 7
nk cells
immunological surveillance
attack foreign cells, virus infected cells, cancer cells
flow of lymph thru lymph node
subcapsular sinus- macrophages
outer cortex- b cells
deep cortex- t cells
medulla- b & plasma cells
hilus & efferent lymphatics
thymus gland function
to mature t cells
lymphocytes divide in cortex, t cells migrate to medulla, mature t cells leave by medullary blood vessels
spleen function
remove abnormal blood cells & blood components
store recycled iron from RBC
initiate immune response by b & t cells
white pulp
specific immune response
t cells directly attack & destroy antigens
b cells develop into antibodies
macrophages destroy antigens
red pulp
clean up
lymph composition
similar to plasma
doesnt have plasma proteins
artery wall layers
tunica interna usually rippled, elastic membrane
tunica media thick, smooth muscle & elastic fibers
tunica externa collagen & elastic fibers
vein wall layers
tunica interna smooth
tunica media thin, smooth muscle cells & collagen fibers
tunica externa collagen & elastic fibers, smooth muscle cells
elastic arteries
largest diameter
help propel blood onward despite ventricular relaxation (stretch & recoil)
muscular arteries
more muscle than elastic
capable of vasoconstriction and vasodilation to adjust rate of flow
arterioles
deliver blood to capillaries
tunic media contain few layers of muscle
metarterioles
form branches into capillary bed
capillary
connect arterioles to venules for exchange of nutrients & wastes between blood and tissue fluid
continuous capillary
intercellular clefts are gaps between neighboring cells
CT
lungs
skeletal & smooth muscle
sinusoids
very large fenestrations
liver
bone marrow
spleen
capillary bed
connect one arteriole and one venule
capillary sphincter
guards entrance to each capillary
opens and closes causing capillary blood to flow in pulses (vasomotion)
thoroughfare channels
direct capillary connections between arterioles and venules
varicose veins
twisted dilated superficial veins caused by leaky venous valves that allow backflow & pooling of blood
vasa vasorum
vessels of vessels
walls of large vessels contain small arteries and veins that supply the smooth muscle cells and fibroblasts of the tunica media and tunica externa