A&P Exam 3: Chapter 10 (Part3)

What is step 1 of skeletal muscle activity (NMJ)?

action potential arrives at the neuromuscular junction

What is step 2 of skeletal muscle activity (NMJ)?

vesicles release acetylcholine into the synaptic cleft

What is step 3 of skeletal muscle activity (NMJ)?

acetylcholine binds to receptors (opens ligand-gated Na+ channels) on sarcolemma

What is step 4 of skeletal muscle activity (NMJ)?

as action potential spreads acetylcholinesterase (enzyme) breaks down acetylcholine

What is step 5 of skeletal muscle activity (NMJ)?

return to initial state (no ACh left in synaptic cleft)

What happens where Na+ enters the cell?

the cell depolarizes/ membrane potential becomes more pos.

What is the step 1 at the synapse terminal/cleft--->Motor end plate?

Arrival of action potential

What is the step 2 at the synapse terminal/cleft--->Motor end plate?

Release of Ach

Vesicles fuse with the neuronal membrane and dumb contents into the synaptic cleft

What is the step 3 at the synapse terminal/cleft--->Motor end plate?

Ach binding at the motor end plate

The binding of ACh to the receptors increases the membrane permeability to sodium ions then rush into the cell

What is the step 4 at the synapse terminal/cleft--->Motor end plate?

Appearance of an action potential in the sarcolemma. While this occurs, AChE removes ACh.

What is the step 5 at the synapse terminal/cleft--->Motor end plate?

return to initial state

What process triggers the release of calcium ions into sarcoplasm?

Excitation-Contraction Coupling

What does the duration of a contraction depends on:

Duration of stimulation at the neuromuscular junction (action potentials) - Free calcium ions in the sarcoplasm - Availability of ATP

Tension =

force

What is force of contraction increased by:

- Summation - increasing force (increase action potentials/stimuli)

- Recruitment - increasing number of muscle fibers/motor units

What are the two types of tetanus?

infection (unfused) and max force (fused)

all the muscle fibers that are controlled by a single motor neuron

Motor unit

What determines amount of control in a muscle?

Size; the smaller the more control

Ex:Teacher with 4-6 students has better control than 1 teacher with 1000 student

What is resting tension in skeletal muscle?

Muscle tone

What are the functions of tone?

- Stabilize position of bones and joints - Maintain posture - Prevents sudden uncontrolled changes in position- produces ATP- Maintain smooth movements