Nervous Control of the Muscular System - Motor Unit

Question 1

How a muscle is stimulated

Answer 1

1. Brain
   a. Brain sends a message in the form of action potential to the spinal cord
2. Spinal cord
   a. Spinal cord is responsible for the transmission between the brain and the muscle and vice versa
3. Motor neurons
   a. Motor neurons receive the message/action potential from the spinal cord and delivers it to the targeted muscle and movement occurs
4. Sensory neurons
   a. Sends messages back to the brain via the spinal cord
5. Brain
   a. Analyses the information delivered by the spinal cord to determine the next action or to process repeats

Question 2

Nervous system functions

Answer 2

To receive information about changes in the body and the environment through sense organs and sensory nerves, and to send this information to the spinal cord and brain.
The brain determines a suitable response
The brain sends commands to muscles to carry out selected response

Question 3

Division of nervous system

Answer 3

Central nervous system (CNS)
Peripheral nervous system (PNS)

Question 4

Central nervous system

Answer 4

The brain and spinal cord are a part of the CNS

The spinal cord is responsible for:
- Delivering messages from the body to the brain
- Delivering messages from the brain to the body

The brain is responsible for:
- Analysing the information received by the sensory neuron
- Determines the most suitable response
- Sends a message to targeted muscles via the spinal cord

Question 5

Peripheral nervous system (PNS)

Answer 5

The sensory division
This carries messages from the body and environment to the spinal cord and brain.
It is made up of sensory neurons

The motor division
This carries messages from the brain to the muscles to respond as appropriate
It is made up of motor neurons

Question 6

Motor neuron parts

Answer 6

Dendrites
Act as antenna to detect the impulse from the sensory receptors and then deliver it to the cell body

Cell body
Contains the nucleus, which directs the neurons activities and sends messages to the axon

Axon
Transmits the message away from the cell body to the muscle

Motor neurons attach to muscles at motor end plates.
The neural impulse is transmitted to the muscle which initiates the process of a muscle contraction

Question 7

Motor neuron diagram

Answer 7

see onenote (functional anatomy) 6

Question 8

Motor unit

Answer 8

The motor neuron and the fibres it activates

A whole muscle contains many separate motor units to generate different amounts of force needed

A kick 10m out needs less motor units than a 50m kick

Question 9

Muscle fibres must be stimulated by nerve or electrical impulses sent via motor neurons or nerves to contract

Answer 9

For this to take place
1. A message is sent from the brain in the form of action potential

2. The action potential is detected by the dendrites in the motor neuron which send the information to the cell body 

3. The cell body directs the information down the axon to the motor end plate

    4. The action potential is delivered to the muscle which is activated as long as the stimulus is strong enough