6. BIOPSYCHOLOGY (THE STRUCTURE AND FUNCTION OF SENSORY, RELAY AND MOTOR NEURONS)

Question 1

What is a neuron?

Answer 1

• A neuron is a nerve cell that receives and transmits impulses to and from other cells using electrical and chemical signals.
• There are approximately 100 billion neurons in the brain and 1 billion in the spinal cord.

Question 2

What are the two main ways neurons interact with the body and brain?

Answer 2

1. Neurons transmit electrical impulses to and from the body through the central nervous system (CNS).
2. All behaviour is brought about by neural activity, which is facilitated by these impulses.

Question 3

What are the main parts of a neuron?

Answer 3

1. Cell Body (Soma) – Control centre, includes the nucleus.
2. Nucleus – Contains the genetic material of the cell.
3. Dendrites – Receive signals from other neurons or sensory receptor cells.
4. Axon – Long, slender fibre that carries nerve impulses (action potentials).
5. Myelin Sheath – Insulates the axon, allowing faster impulse transmission.
6. Axon Terminal – Connects to other neurons or organs, allowing synaptic transmission.

Question 4

What is the function of the cell body (soma) in a neuron?

Answer 4

• The cell body is the control centre of the neuron, containing the nucleus that governs the cell’s functions.

Question 5

What role do dendrites play in a neuron?

Answer 5

• Dendrites receive signals from other neurons or sensory receptor cells and transmit these signals to the cell body.

Question 6

What is the axon and its function?

Answer 6

• The axon is a long, slender fibre that carries nerve impulses in the form of an action potential from the cell body to the axon terminal, allowing communication with other neurons or organs.

Question 7

What is the myelin sheath, and what is its function?

Answer 7

• The myelin sheath is an insulating layer surrounding most axons. It speeds up the transmission of electrical impulses along the axon.

Question 8

What is the function of the axon terminal in a neuron?

Answer 8

• The axon terminal connects the neuron to other neurons or organs, allowing communication through synaptic transmission.

Question 9

What is the function of sensory neurons?

Answer 9

• Sensory neurons transmit nerve impulses from sensory receptors (e.g., touch, sight, smell) to the brain and spinal cord.
• Some sensory information terminates in the spinal cord for reflex actions, bypassing the brain.

Question 10

Where do sensory neurons transmit impulses?

Answer 10

• Sensory neurons transmit impulses from sensory receptors to the brain and spinal cord. Some impulses are processed at the spinal cord for reflexes.

Question 11

How do sensory neurons contribute to reflex actions?

Answer 11

• Not all sensory information reaches the brain; some sensory neurons terminate in the spinal cord, enabling reflex actions to occur more quickly without waiting for brain processing.

Question 12

What is the function of motor neurons?

Answer 12

• Motor neurons carry impulses from the central nervous system (CNS) to muscles or glands.
• They control muscle movement by releasing neurotransmitters that trigger muscle contraction when stimulated.

Question 13

How do motor neurons control muscle movement?

Answer 13

• When stimulated, motor neurons release neurotransmitters that bind to receptors on muscles, leading to muscle contraction.
• Muscle relaxation occurs when the motor neuron is inhibited.

Question 14

What is the function of relay neurons?

Answer 14

• Relay neurons connect sensory and motor neurons. They are located in the brain and spinal cord, playing a role in transmitting signals between sensory and motor neurons.

Question 15

Where are relay neurons found?

Answer 15

• Relay neurons are found exclusively in the brain and spinal cord. They link sensory neurons to motor neurons.

Question 16

Label this diagram:

Answer 16

Question 17

label the diagram:

Answer 17