L16_Muscle_2

What is the role of Ca2+ in muscle contraction?

Ca2+ binds to troponin, removing the blocking action of tropomyosin and exposing cross-bridge binding sites on actin.

What initiates the action potential in a motor neuron?

An action potential is initiated and propagates to the motor neuron axon terminals.

What is the function of the neuromuscular junction?

The neuromuscular junction facilitates the communication between the motor neuron and the muscle fiber, causing muscle contraction.

How does the muscle relax after contraction?

Ca2+ is actively transported back into the sarcoplasmic reticulum, lowering cytosolic Ca2+ concentration and restoring tropomyosin's blocking action.

What is the sequence of events from motor neuron action potential to skeletal muscle contraction?

The sequence includes action potential propagation, Ca2+ entry and ACh release, end-plate potential generation, action potential in muscle fiber, Ca2+ release, cross-bridge binding, and a cycle of cross-bridge movement.

What happens when there is high cytosolic Ca2+?

High cytosolic Ca2+ exposes cross-bridge binding sites, allowing energized cross-bridges to bind to actin and generate force.

What is the sliding filament mechanism of muscle contraction?

It describes the process where myosin cross-bridges pull thin filaments over thick filaments, causing muscle contraction.

What role does ATP play in muscle contraction?

ATP hydrolysis energizes cross-bridges, allows for dissociation from actin, and helps maintain Na+ and K+ gradients for action potentials.

What do muscle spindles respond to?

Muscle spindles respond to muscle stretch and the speed of that stretch.

What is the function of the golgi tendon organ?

The golgi tendon organ senses muscle tension and inhibits muscle contraction if the tension is too high.

Define excitation-contraction coupling in muscle physiology.

Excitation-contraction coupling is the process through which an action potential triggers muscle contraction via Ca2+ release and cross-bridge cycling.

What are the steps to power stroke?

1. cross bridge binds to actin

2. cross bridge moves produces adp and pi

3. atp binds to myosin causing cross bridge to detach

4. hydrylysis of atp energizes cross bridge

What is a muscle spindle proprioceptor?

sense organ that receives info from the muscle that senses stretch and speed of stretch

what is the golgi tendon organ proprioceptor?

sense organ that recieves info from the tendon that sense tension

tells you how much tension the muscle is exerting

How do you get the message that you are at your endpoint?

sends a reflex arc signal to your spinal column telling you not to stretch any further

What does the sense organ protect you from?

from overstretching or stretching to fast