1.
absolute refractory period: a second response is not possible regardless of strength or duration of the stimulus
2.
actin: doubled stranded alpha helical polymer of actin monomers
3.
alkali light chain: this type of light chain is essential for myosin head structure
4.
anions: (-) charge, z, move with the electric field
5.
ATP hydrolysis: energy source for myosin action
6.
Ca2+ binding proteins: these are located inside the SR to help free [Ca2+] low
7.
Ca2+ release channel: when the L-type channel opens, a little Ca2+ comes in and interacts with the ...........; this causes the Ca2+ channel to open and let LOTS of Ca2+ out of the SR to promote cardiac muscle contraction
-this is the concept of calcium-induced calcium release (CICR)
8.
Ca2+ release channels: -Ca2+ entry from L-type channels does not provide much increase in intracellular [Ca2+]
-it is the rise in intracellular [Ca2+] due to long open time of...............
9.
cations: (+) charge, z, move against the electric field
10.
current: an unbalanced movement of charge over time is called a ........ ( I, which is amps)
11.
decreased intracellular Ca2+: signal for relaxation
12.
diffusion potential: eventually, the electrical potential will balance the ........... , according to the Nernst equation
13.
excitation-contraction: the process by which excitation triggers an increase in intracellular [Ca2+]
14.
false: T or F: there is a physical connection between the L-type channel and the Ca2+ release channel
15.
force: potential is an electric ........... which moves from low to high by definition
16.
gap junction: action potential in one cell causes current to flow through a ........., which depolarizes the neighboring cardiac cell
17.
increased intracellular Ca2+: signal for contraction
18.
inward current: positive charge in is an ..........., also called a negative current
19.
inward rectification: Na+ exhibits this type of ion current since Na+ is higher outside the cell than inside the cell
-it is difficult to have Na+ current sending more Na+ ions out of the cell
20.
inward rectification: large change in inward current for a small change in V, very little change in outward current for change in V
21.
ion gradients: if change Vm, ............. will change
22.
K+: this ion is high inside cells and low outside cells
23.
K+; Na+: during cell resting potential, ...... channels are open and .......... channels are closed
24.
L-type: action potential activates .......... Ca2+ channels (DHP receptor)
-"voltage sensor"
-allows Ca2+ to pass
-activates the Ca2+ release channel by direct contact
-Ca2+ release channel allows large amounts of Ca2+ to flow from SR into muscle cell and stimulates muscle contraction
25.
L-type channels: cardiac muscle depends on Ca2+ entry through ........... channels to spark Ca2+ release. ESSENTIAL!
26.
Na+: this ion is low inside cells and high outside cells
27.
negative: inward current is...........
28.
one: cardiac muscle cross bridge formation is the same as skeletal muscle, except that cardiac troponin C has only .......... low affinity Ca2+ site
29.
outward current: positive charge out is an .............., also called a positive current
30.
outward rectification: large change in outward current for a small change in V, very little change in inward current for change in V
31.
outward rectification: K+ exhibits this type of ion current since K+ is higher inside the cell than outside the cell
-it is difficult to have K+ current sending more K+ ions into the cell
32.
plasma membrane: in addition to the sarcoplasmic reticulum, the ............ is also a major mechanism for Ca2+ removal from the cell
33.
plateau phase: -cardiac muscle contains this phase in its action potentials
-due to Ca2+ entry into the cell required for contractile function
-cell remains depolarized longer
-there is NO hyperpolarization
34.
positive: outward current is............
35.
positive charge: by convention, current is in the direction of ............. (i.e. cations movement)
36.
rectification: -if current flows more easily in one direction or the other, IV plots will NOT be linear. this is called........
37.
regulatory light chain: this type of light chain regulates enzyme function of the myosin head
38.
regulatory proteins: Ca2+ interacts with .................., NOT with contractile proteins
39.
relative refractory period: a second response can be elicited, but at a greater "cost" (i.e. strength and/or duration)
40.
sarcolemma: -aka plasma membrane that has invaginations that extend the membrane deep into the muscle cell
-penetrate at the A and I bands ONLY
-highly organized
41.
summation: -if APs are spread out, muscle can relax to resting level. if not, AP-induced contractions will be additive
-tension is GREATER when summed
42.
triad: an action potential travels down the T-tubule to the.......
43.
triad junction: the sarcolemma comes into direct contact with the sarcoplasma reticulum at the .............
-SR membrane component called cisternae
-SR is specialized ER for Ca2+ store
44.
tropomyosin: two alpha helices that sit by (but not in) the grooves in the actin polymer
45.
tropomyosin and troponin: these two molecules regulate the interaction of myosin and actin
46.
troponin: heterotrimer of troponin T, troponin C, and troponin I
T: binds to a single molecule of tropomyosin
C: binds to Ca2+, very similar to calmodulin
I: binds to actin to inhibit contraction
47.
troponin C: when intracellular Ca2+ increases, Ca2+ binds to ............, which induces a conformational change that repositions the troponin complex, allowing myosin to bind
48.
troponin complex: in skeletal muscle at rest, ............. blocks myosin from binding to actin
49.
Vm: if change ion gradients, ......... will change
50.
Z disk: connects two myofibrils and provides structural rigidity
-also connects to actin
