Module 3.2 Lecture 2 continued

Question 1

True or False
The somatic nervous system uses a single neuron to travel form the central nervous system to the actual skeletal muscle fibre itself?

Answer 1

True

Question 2

Where is the cell body of the motor neuron?

Answer 2

central nervous system

Question 3

What does the final common pathway refer to?

Answer 3

all the output from you central nervous system towards your muscles fibres have to come through the motor neuron

Question 4

is the somatic nervous system voluntary or non voluntary?

Answer 4

voluntary

Question 5

What is the neuromuscular junction?

Answer 5

link between each axon terminal of a motor neuron and the skeletal muscle fibre

Question 6

terminal button is what?

Answer 6

axon terminal but enlarged

Question 7

What is the motor end plate?

Answer 7

specialized area of the skeletal muscle fibre where the terminal button is

Question 8

Which neurotransmitters do the motor neurons use?

Answer 8

Acetylcholine

Question 9

is out skeletal muscles excitable cells?

Answer 9

yass, it has sodium-potassium channels and what not

Question 10

True or False
All of our motor nerves are myelinated

Answer 10

True

Question 11

What is the step by step process of the nerve sending a signal to the muscle fibres?

Answer 11

1. Action potential occurs in a motor neuron and “jumps due to myelination” to the terminal button
2. This triggers the opening of voltage-gated Calcium channels, Ca+ enters the terminal button
3. Ca+ triggers the release of ACh by exocytosis
4. ACh diffuses and binds with receptor channels on the motor end plate
5. These channels allow for Na+ to enter the muscular cell
6. This results in an end plate potential, causing local depolarization at the end plate in the muscle cell
7. The local depolarization causes voltage-gated sodium channels to open which will eventually meet the threshold where an action potential occurs through the muscle fibres
8. ACh is destroyed by acetylcholinesterase an enzyme located on the motor end plate membrane, finishing the muscles response

Question 12

What is the end plate potential?

Answer 12

Same as EPSP
- Depolarizing the new cell

Question 13

What is the name of the receptor we would find attached the the skeletal muscle fibres?

Answer 13

Nicotinic, acetylcholine receptor

Question 14

Where in skeletal muscle cells do the motor neurons go to send a neuromuscular junction?

Answer 14

in the middle of the long cylinder skeletal muscle cells

• theres volatge-gated sodium channels on both ends from where the neuron reaches the skeletal cell and therefore the action potential, the depolarization will occur in both directions

Question 15

True or False
One End plate potential will ALWAYS cause one action potential in the muscle fibres itself?

Answer 15

Trueeeee

Question 16

is there any inhibitory behaviour within nerve to muscle communication?

Answer 16

yes there can be inhibitory responses on the motor neurons itself but NEVER on the neuromuscular junction

Question 17

What are some examples (4) of toxins that can begin to affect the neuromuscular junction? and what does it lead to?…

Answer 17

• Leads to death from the respiratory system

ie.
- Venom from a black widow spider, all our synaptic vesicles being release at once, having no neurotransmitters to commit further muscle movement

• Botilium toxin (Botox), blocks the release of ACh, so no action potentials in the skeletal muscles
• Cura, acts as an antagonist by blocking the ACh receptors on the motor end plate
• Sarin, inhibits Acetylcholinesterase, which blocks the cell having future depolarization

*Acetylcholinesterase is the enzyme that gets ride of access neurotransmitters (ACh) in the synaptic cleft