Human Biology: Module 5 NMJ Review

Human Biology: Module 5 NMJ

by Jessica Arthur

​NMJ

• Skeletal muscles contract via motor neurons (nerve cells)

• ​motor neuron & muscle fiber = motor unit

• ​Region in which axon terminal (blue) meets a muscle fiber (red) - neuromuscular junction (NMJ)

• ​Fluid fill space - synaptic cleft (gap)

• ​ACh is the neurotransmitter

Multiple Choice

Name of nerve that causes skeletal muscle contractions

• motor unit

• motor neuron

• NMJ

• Sarcolemma

Multiple Choice

Location where an axon terminal meets a muscle fiber

• Motor unit

• Motor neuron

• NMJ

• Synaptic cleft

Draw

Circle the axon terminal

Draw

Circle the synaptic vessicles

Draw

Circle the mitochondria

Draw

Label the synaptic cleft

Draw

Circle the receptor sites

​Summary of Steps for Contraction

• Neuron sends impulse releasing Ca which then releases ACh

• ACh binds with sacrolemma

• ​Na channels open (depolarization)

• ​K channels open (repolarizing)

• ​Na channels close once K channels open

• ​Ca is released in the sacroplasmic reticulum clearing the actin active site

• ​myosin attaches to actin - contraction

​

Multiple Choice

What is the name of the neurotransmitter that moves from the end of a neuron crosses the synaptic cleft and binds with receptor sites on the sarcolemma (special name for a muscle cell membrane)

• Ca

• K

• myosin

• ACh

Multiple Choice

The release of which ion causes ACh to be released (in the axon)

• K

• Na

• Ca

• Mg

Multiple Choice

Once ACh binds with receptors in the sacrolemma, what channel opens?

• Sodium channel

• Calcium channel

• Potassium channel

• ACh channel

Multiple Choice

Once an AP passes which channel opens and which channel closes?

• K, Ca

• Na, K

• K, Na

• Ca, Na

Multiple Choice

Once depolarization has occurred in the sarcoplasmic reticulum, what ion is released that when then go on to clear the actin binding sites that will trigger a muscle contraction?

• K

• Mg

• Na

• Ca