Physiology - Cardiovascular Physiology

Front 1

a calculation of mean arterial blood pressure is the product of which two factors?

Back 1

cardiac output and total peripheral resistance (COxTPR=MAP)

Front 2

how is TPR calculated from a series of parallel vascular beds?

Back 2

adding the inverse of the resistances for each bed.

Front 3

what is the RMP of a cardiac muscle cell?

Back 3

approx. -90mV

Front 4

are the proteins at the interior of a cardiac muscle cell positively or negatively charged?

Back 4

negatively

Front 5

what are the approximate concentrations of Na+, K+, and Ca++ in an average cardiac muscle cell?

Back 5

Inside:
K+ = 145mM
Na+ = 5mM
Ca++ = 10^-7mM

Outside:
K+ = 4mM
Na+ = 140mM
Ca++ = 2mM

Front 6

which two pumps are responsible for maintaining the extra- and intracellular ion concentrations? how many of each ion is exchanged in each of these two pumps?

Back 6

Na+/K+ pump and Na+/Ca++ pump; 3Na+/2K+ and 3Na+/1Ca++

Front 7

Which of the constitutive pumps on cardiac muscle cells requires ATP for energy?

Back 7

Na+/K+ pump

Front 8

what effect do proteins inside muscle cells have on cations?

Back 8

attract cations into cell

Front 9

at rest, is cardiac muscle cell permeability to K+ or Na+ greater? by how much?

Back 9

K+ by almost 100 times

Front 10

which, K+ or Na+, has a higher tendancy to leak from the cell at rest?

Back 10

K+, due to large permeability

Front 11

what does the Nernst equation determine?

Back 11

the electrical equilibrium potential

Front 12

why is the RMP much closer to the K+ equilibrium constant than to that of Na+?

Back 12

Because the cell is much more permeable to K+

Front 13

which equation accounts for both resting concentrations AND permeabilities in cells?

Back 13

Goldman

Front 14

what activity characterizes phase 0 in cardiac muscle cell action potentials? which type of channel is mostly responsible for this action?

Back 14

rapid depolarization; tetrodotoxin-sensitive (fast) Na+ channels.

Front 15

the small repolarization that characterizes phase 1 is the result of what 2 factors?

Back 15

1) transient outward movement of K+
2) inactivation of the fast Na+ channel

Front 16

phase 2 is also known as which phase in the cardiac muscle cell action potential?

Back 16

plateau

Front 17

which three events characterize phase 2 of the cardiac muscle cell action potential?

Back 17

1) inward Ca++ current from L-type Ca++ channels, catecholamine-sensitive
2) increase in Na+ permeability via slow channel
3) decrease in K+ permeability , minimizing K+ loss from cell.

Front 18

which event in phase 2 is often referred to as 'inward rectification'?

Back 18

decrease in K+ permeability

Front 19

phase 3 is characterized by which 3 events?

Back 19

1) inactivation of slow Na+ channels
2) inactivation of L-type catecholamine-sensitive Ca++ channels
3) increase in K+ permeability

Front 20

what is the main difference between action potentials in nerve cells and cardiac cells?

Back 20

nerve cells have much shorter refractory period; cardiac cells need more refractory time to allow heart to beat in a regulated fashion

Front 21

what is the definition of the absolute refractory period? what channel action characterizes this period?

Back 21

a period during which no stimulus, regardless of how large, can produce a response; the inactivation of fast Na+ channels

Front 22

what is the definition of the relative refractory period? what channel action characterizes this period?

Back 22

a period during which a larger-than-normal stimulus is required to generate a new action potential; many (but not all) of the fast Na+ channels are reset

Front 23

the supranormal period is characterized by _____ than normal stimuli which result in responses that are often _____ than normal.

Back 23

lower; lower

Front 24

what is tetany?

Back 24

sustained uncontrolled muscle contractions

Front 25

which 3 factors determine the time course of cardiac action potentials, both slow- and fast-response?

Back 25

1) ion channel permeability
2) membrane potential
3) ion concentration gradients

Front 26

while phase 4 in fast-type cardiac action potentials is characterized by a return to RMP, the phase 4 in slow-type AP's is characterized by what?

Back 26

spontaneous depolarization

Front 27

the unique action of phase 4 in slow-type cardiac action potentials is characterized by which 3 processes?

Back 27

1) slowly decreasing K+ permeability
2) slow increase in Ca++ permeability
3) small increase in Na+ permeability (non-fast Na+ channels)

Front 28

phases 0-2 in slow-type cardiac action potentials are characterized by which 2 processes?

Back 28

1) Ca++ entry
2) slow Na+ channels

Front 29

phase 3 (repolarization) in slow-type cardiac action potentials are characterized by which 3 processes?

Back 29

1) inactivation of Ca++ channels
2) inactivation of Na+ channels
3) increased K+ permeability

Front 30

which cells use the slow-type cardiac action potentials?

Back 30

SA and AV nodes

Front 31

which cells in the heart are responsible for the rate of the heart's beating?

Back 31

SA node cells

Front 32

does parasympathetic stimulation increase or decrease heart rate? sympathetic?

Back 32

decreased; increased

Front 33

trace blood through the heart from the superior and inferior vena cavae to the aorta

Back 33

Superior/inferior vena cavae, bring blood into heart --> right atrium --> tricuspid valve --> right ventricle --> pukmonary artery --> lungs --> via pu,onary veins to left atrium (thin walled) --> left ventricle --> mitral valve --> aorta, rest of body.

Front 34

what controls the size of the arteries which enter the capillaries?

Back 34

smooth muscle

Front 35

what is the approximate RMP of AV and SA node cells?

Back 35

-55mV

Front 36

what is the driving force for the Na+/Ca++ exchange pump? how many Na+ atoms are pumped for how many Ca++ atoms? in which direction?

Back 36

Na+ gradient; 3 Na+ pumped inside cell for every 1 Ca++ pumped out of cell

Front 37

the flow out K+ out of the cell is balanced by which force

Back 37

attractive force from negatively charged proteins attracting K+ ions into cell

Front 38

what happens if KCl is injected into someone's blood? why?

Back 38

it would most likely cause an MI because all cells would contract at same time.

Front 39

what is the action of ouabain and digitalis?

Back 39

poisoning of Na+ pump

Front 40

at what points during the fast-type cardiac AP are inactivation and activation gates of tetrodotoxin-sensitive Na+ channels open and closed?

Back 40

initially, activation gate closed and inactivation gate closed. following stimulation, activation gates open, resulting in depolarization. immediately following depolarization, inactivation gates close, throwing cell into absolute refractory period. As many inactivation gates open and activation gates simultaneously close, the relative refractory period begins. Eventually, all channels have a closed activation and open inactivation channel open and the cell has been reset for another AP.

Front 41

which channel which contributes significantly to fast-type cardiac AP plays nearly no role in slow-type AP's?

Back 41

fast-type, tetrodotoxin-sensitive Na+ channel

Front 42

what effect do sympathetic and parasympathetic stimulation have on slow-type cardiac AP's?

Back 42

SYMPATHETIC stimulation makes a stronger, faster heartbeat and PARASYMPATHETIC stimulation makes a slower heartbeat.

Front 43

in which cardiac chamber is the SA node located? the AV node?

Back 43

right atrium; between atria and ventricles

Front 44

why is it helpful that AV node rate is slightly slower than that of SA node?

Back 44

so that ventricles have time to fill completely before contracting

Front 45

why is conduction in Purkinje fibers so much quicker than that of AV or SA nodes?

Back 45

because you want entire ventricle muscle to contract forcefully at the same moment

Front 46

what is represented by the P wave in an ECG? QRS wave? T wave

Back 46

P = atrial depolarization and contraction
QRS = ventricular depolarization and contraction
T = ventricular repolarization