Anatomy Quiz 7

1. Involuntary-does not require nervous input to contract. 2. Striations-stripes due to specific arrangement of actin & myosin contractile proteins. 3. Branching cells-one cell divides into two cells. 4. Intercalated disks-special communication channels called gap junctions that are designed to allow all cardiac muscle cells to be signaled by a depolarization at one time. 5. Functional syncytium-property of cardiac muscle that allows all cardiac muscle cells to contract as one unit to eject blood from the heart.

1. Autorhythmic cells 2. Contractile cells

Spontaneously depolarize due to "leaky" sodium and calcium ion channels. Found in certain areas of the heart know as the cardiac conduction system.

Special signals that begin depolarization of cardiac muscle cells.

1. ramp - due to sodium and potassium entering the cell through the leaky channels. 2. depolarization - due to sodium entering the cell through sodium channels. 3. repolarization - due to potassium leaving the cell through potassium channels.

The majority of the cardiac muscle cells

Electrical events signaling contraction of the cardiac muscle cell

1) threshold 2) depolarization 3) plateau 4) repolarization

Stimulus from the pacemaker potential that begins the cardiac muscle cell depolarization.

Reversal of membrane polarization due to sodium ions entering the cardiac muscle cell. inside the cell becomes positive charged.

A period where the cardiac muscle membrane is maintained at a positive charge due to calcium ions entering the cell

The return of membrane polarization to rest due to potassium leaving the cell. inside the cell returns to negative charged

1) threshold 2) depolarization 3) repolarization 4) hyperpolarization

Minimum stimulus required to begin an action potential

Reversal of membrane polarization where inside the cell membrane becomes positive charged due to sodium ions entering the cell