Contraction Physiology

Question 1

Transmembrane potential

Answer 1

Differences in the concentrations of ions on opposite sides of a cellular membrane.

Question 2

Resting potential

Answer 2

The electrical potential of a neuron or other excitable cell relative to its surroundings when not stimulated or involved in passage of an impulse.

Question 3

Depolarization

Answer 3

Loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior.

Question 4

Action potential

Answer 4

The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

Question 5

Threshold potential

Answer 5

The action potential is an explosion of electrical activity that is created by a depolarizing current. This means that some event (a stimulus) causes the resting potential to move toward 0 mV. When the depolarization reaches about -55 mV a neuron will fire an action potential. This is the threshold.

Question 6

Leak channels

Answer 6

Leak channels allow Na and K to move across the cell membrane down their gradients(from high concentration to low concentration).

Question 7

Voltage gated ion channels

Answer 7

Are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alter the conformation of the channel proteins, regulating their opening and closing.

Question 8

Neuromuscular junction

Answer 8

Is a chemical synapses between a motor neuron and a muscle fiber.

Question 9

Motor neuron

Answer 9

A nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.

Question 10

Acetylcholine (ACh)

Answer 10

A neurotransmitter that motor neuron release in order to activate a muscle. Parts of the body the use or are affected by ACh are cholinergic. Substances that inhibit ACh activities are called antichlinergics.

Question 11

Acetycholinesterase (AChe)

Answer 11

The enzyme that breaks down ACh.

Question 12

Axon terminal

Answer 12

Neurotransmitters are packaged into synaptic vesicles that cluster beneath the axon terminal membrane on the the persynaptic side of the synapse. The axon terminals release the neurotransmitters into the synapses.

Question 13

Synaptic cleft

Answer 13

A gap between neurons or motor neurons and muscle cells.

Question 14

Twitch

Answer 14

Single stimulus

Question 15

Latent period

Answer 15

The delay between the receipt of stimulus by a sensory nerve and the response to it.

Question 16

Contraction phase

Answer 16

The powerstroke. Tension increases due to the binding of acting dumb myosin.

Question 17

Relaxation phase

Answer 17

Detachment of myosin, tension decreases.

Question 18

Incomplete tetanus

Answer 18

Does not allow complete relaxation, tension rises but is not stable.

Question 19

Complete tetanus

Answer 19

Fast stimuli to keep Ca levels high. Tension remains strong and constant. Allows for complete, sustained contraction to do work.

Question 20

Wave summation

Answer 20

Occurs because that are rapidly stimulated are not able to relax between repeated stimulations.

Question 21

Recruitment

Answer 21

Refers to the activation of additional motor units to increase contractile strength in a muscle.

Question 22

Concentric contraction

Answer 22

An isotonic contraction where the muscle shortens.

Question 23

Isometric contraction

Answer 23

A muscular contraction in which the length of a muscle does not change.

Question 24

Isotonic contraction

Answer 24

A muscular contraction in which the length of the muscle changes.

Question 25

Eccentric contraction

Answer 25

An isotonic contraction where the muscle lengthens.