Term
| actin and myosin form a ____________ ____________ that faciliate a transmission of electrical impulses in all directions. |
|
Definition
|
|
Term
|
Definition
| irregular, transverse thickenings of plasma membrane that lie between the muscle cells |
|
|
Term
| Intercalated discs contain |
|
Definition
| gap junctions and desmosomes |
|
|
Term
|
Definition
| hold adjacent cells together |
|
|
Term
|
Definition
small channels, which allow electrical impulses to pass quickly from one cell to the next
they allow action potentials to spread rapidly throughout heart muscle |
|
|
Term
| first event of cardiac muscle excitation is |
|
Definition
| depolarization of SA node |
|
|
Term
| Explain how the atria have time to empty before the ventricles contract |
|
Definition
| the prescence of poorly conducting tissue at the AV border slows the heart excitation down by .1 sec |
|
|
Term
| Explain how the atria have time to empty before the ventricles contract |
|
Definition
| the prescence of poorly conducting tissue at the AV border slows the heart excitation down by .1 sec |
|
|
Term
| The bundle of his transmits the action potential to |
|
Definition
| both ventricles, the lower part contracting first and therefore pushing the blood upwards. |
|
|
Term
| Cardiac muscle action potential is a result of |
|
Definition
| depolarization of a muscle or nerve cells |
|
|
Term
| Three major phases of cardiac action potential: |
|
Definition
| rapid depolarization, the plateau, and repolarization |
|
|
Term
| Rapid depolarization due to |
|
Definition
| Sodium inflow when voltage gated Sodium channels open. |
|
|
Term
|
Definition
| maintained depolarization, calcium inflow when voltage gated slow calcium channels open and potassium outflow when some potassium channels open |
|
|
Term
|
Definition
| closure of calcium channels and potassium outflow when additional potassium channels open |
|
|
Term
refractory period means
absolute v relative |
|
Definition
unresponsive;stubborn
absolute- cell will not respond regardless of stimulus strength
relative-the cell will respond only if the stimulus is “suprathreshold” |
|
|
Term
| How long is the absolute refractory period in heart/skeletal muscle? |
|
Definition
|
|
Term
| Intrinsic System- Autorhythmic cells (3) |
|
Definition
initiate Actionpotentials
have unstable resting potentials called( pacemaker potentials)
use calcium influx(as opposed to sodium) for rising action potential |
|
|
