EXAM #3 Essay Q's Flashcards
Baroreceptor reflex: Describe the baroreceptor reflex that occurs as an immediate response to an increase in blood pressure.
Explain how this reflex allows for a short term decrease in blood pressure (cardiac center and vasomotor center response?).
Explain how a physician can use this knowledge to decease the heart rate of a patient with tachycardia.
Is this reflex effective for long-term regulation of blood pressure? Why or why not?
BP ↑ = ↑ stretch
↑ baroreceptor stimulation
CV center response ….. ↓ BP
↓ cardioaccleratory (↓ sympath)
↑ cardioinhibitory (↑ parasymp):
↓ vasomotor: causes peripheral vasodilation, ↓ R, sends to venous reserve
doctor can do internal carotid massage
baroreceptors become stimulated, know are stretched, help drop heart rate
tachycardia = abnormally fast heart beat
not effective long-term
Response to hemorrhage: Describe in detail how your body would respond to hemorrhage in effort to maintain blood volume and pressure
Consider short-term and long-term goals
How your body tries to achieve these goals
Short term elevation of blood pressure ….up to ~20% loss total blood volume
decreased CHP / increased BCOP recalls fluids from interstitial spaces
Long term: days to restore blood volume
erythropoietin stimulates RBC production
negative feedback when BV and BP return to normal
Explain in detail how the various components of red blood cells are recycled or disposed of and how each component arrives at its final destination
don’t divide, no nucleus
macrophages in spleen (graveyard) and liver
phagocytes recycle in red bone marrow
becomes globins protein and iron
becomes heme to later become bilirubin and biliverdin
Describe excitation through the conduction system of the heart and why it is advantageous to have a brief delay at the AV node
SA node generates impulse
internodal pathways to AV node (delayed)
to AV bundle splitting into left and right bundles
left and right bundles to Purkinje cells
benefit: atria finished contraction and forcing blood into ventricles before ventricles contract
why is the SA node the pacemaker
SA node (pacemaker): Fastest depolarization of all conduction system
SA rhythm determines HR
SA node rate: ~100 BPM
BUT: Normal HR slower: 75 BPM
WHY?: under continuous parasympathetic stimulation: vagal tone
cardiac cycle
look at chart
arteries vs veins
look at table
describe the overall blood pressure in the venous system. How is venous return facilitated despite the low blood pressure in circulation
low blood pressure
move blood back to heart against gravity
valves prevent backflow, and aids venous return
respiratory pump and muscular pump aid in venous return
net filtration pressure: be able to define…
capillary hydrostatic pressure CHP
blood colloid osmotic pressure BCOP
filtration
reabsorption
How would hemorrhaging or dehydration affect NFP
CHP = blood pushing against vessel walls
BCOP = draws water back into blood via osmosis
filtration = forces fluid out of blood into interstitial tissue
reabsorption = water pulled into blood
decreased CHP / increased BCOP recalls fluids from interstitial spaces
describe autoregulation
neuroregulation
endocrine regulation
autoreg = local at tissue level, immediate
neuro-regulation = sympathetic, parasympathetic
(autonomic reflex )
Endocrine regulation = hormones
what is preload, contractility, and afterload
preload is how much cardiac muscles are stretched before contacting
contractility is force of contraction
afterload is pressure to be overcome to force blood out of ventricles
