Exam 2 Study Guide Flashcards
Why are the chordae tendinae important for pumping blood?
they prevent the valve flaps from everting into the atria; helps so blood doesn’t go back up
Why are gap junctions important to the heart?
they allow ions to pass from cell to cell in order to behave as a single coordinated unit; they electrically couple adjacent cells
What can happen if gap junctions close?
fatal arrhythmias, heart would not beat properly
Why are sodium channels important for cardiac muscle contraction?
they do depolarization
What is the cardiac conduction system?
network of noncontractile cells that initiate and distribute impulses
How does electrical activity produce a coordinated heartbeat?
through gap junctions
What two factors determine cardiac output?
heart rate and stroke volume
What is resting membrane potential?
separation of oppositely charged particles across membrane in all cells
What is heart rate?
number of beats per minute
What is stroke volume?
volume of blood pumped out by one ventricle with each beat
Why do gap junction make the heart independent of the nervous system?
Either all fibers contract together(via gap junctions) or they do not contract at all. Unlike skeletal muscle, which is controlled by the nervous system
Discuss the sinoatrial node
located in the right atrial wall; sets the pace for the heart; it is the heart’s pacemaker
Discuss the atrioventricular node
from the SA node, the depolarization wave spreads(via gap junctions) throughout atria via internodal pathway to the atrioventricular node; AV node conducts impulses slower than other parts of system
What happens when the SA node is defective?
ectopic focus may appear and take over pacing of heart rate; or the AV node may become the pacemaker
Why is sodium important for action potentials and cardiac muscle contraction?
depolarization; voltage gated Na channels open up, so all Na previously pumped outside leaks back in; voltage gated Na channels allow depolarization to happen
Why is calcium important for action potentials and cardiac muscle contraction?(plateau phase)
need Ca for contraction to happen; Ca comes in via Ca channels, generating contraction
Why are potassium channels important for action potentials and cardiac muscle contraction?(repolarization)
K lets muscle relax; K channels open & K that was pumped in, is pumped out, which is what resets the whole thing back to rest
Arteries have a higher blood pressure than veins. T/F
true
What are the three important sources of resistance?
blood viscosity, total blood vessel length, blood vessel diameter
Smaller vessels have ______ resistance.
greater
Blood pressure can be regulated by:
cardiac output
Why doesn’t blood flow backwards in the veins?
one way valves prevent blood from flowing backwards
What does systole mean?
contraction
What does diastole mean?
relaxation
What are baroreceptors?
nerve endings that sense pressure
Where does blood flow fastest?
the aorta
Where is blood flow slowest?
in capillaries, allowing time for exchange between blood and tissues
Why is the brain different than other tissues in its vascular needs?
neurons are intolerant of ischemia(inadequate blood supply); can cause a stroke
Why does blood flow to skin?
to help get rid of heat
What is hydrostatic pressure?
pushes fluid out of capillary
What is osmotic pressure?
pulls fluid into capillary
Why are plasma proteins like albumin important for osmotic pressure?
albumin is like rice sucking up water; pulls water into blood vessels
What is hypovolemic shock?
results from large scale blood loss
What is vascular shock?
results from extreme vasodilation and decreased peripheral resistance; system wide vasodilation ex: not enough oxygen getting to tissues
What is cardiogenic shock?
results when an inefficient heart cannot sustain adequate circulation; what happens if heart is not pumping enough blood into system
What is filtration?
net fluid flow OUT at arterial end
What is reabsorption?
net fluid flow IN at venous end
How do phagocytes destroy pathogens?
must adhere to particle, phagocyte forms a pseudopod that engulfs the particle forming a phagosome, lysosome fuses w the phagocytic vesicle forming a phagolysosome, enzymes digest it leaving residual body, exocytosis is performed to throw out trash
How do natural killer cells attack?
death whisperers; secrete signal to target to program apoptosis
What is the inflammatory response?
triggered when body tissue is injured; sets stage for repair, stops spread of damaging agent
How do interferons provide antiviral death?
protect against viruses by warning other cells to protect themselves
How does the complement system destroy pathogens?
kills things that have been marked for destruction; proteins circulate in inactive form in blood; kills bacteria and other cell types by cell lysis
What is the membrane attack complex and how does it kill?
it is the insertion of complement proteins into a cell’s membrane; if CP’s see antibodies, they hogpile
Complement activation: classical pathway
activated by antibodies coating target cell
Complement activation: lectin pathway
activated by lectins binding to specific sugars on microorganisms surface
Complement activation: alternative pathway
activated spontaneously
Why is fever beneficial?
controlled hyperthermia; discourages growth of bacteria allowing body to kill them off faster than they can grow
What are pyrogens?
chemicals that raise the body’s temperature
What do lymphocytes do?
mediate adaptive immunity; B&T
B lymphocytes
humoral(antibody based)
T lymphocytes
cellular(cell recognition and destruction)
Why are antibodies important?
they fight infection
humoral immunity
antibodies mark pathogens for destruction; seen it before; carried out by B lymphocytes
cellular immunity
T lymphocytes act against infected cells
Immunocompetence
has the ability to recognize antigen by binding to it
Where do B cells mature?
red bone marrow
Where do T cells mature?
thymus
What are naive cells?
immunocompetent B and T cells not yet exposed to antigen
plasma cells are _______ cells that produce _______.
effector; antibodies
What is titer?
measure of how big of immune response; level of antibody in blood plasma
Is titer higher after a primary or secondary infection?
secondary bc of memory cells
