General structure of neurones

Question 1

Cell body (soma)

Answer 1

-The cell body (soma) contains the nucleus, which contains all the genetic information of the cell
-It also contains a cytoplasm and other organelles required for basic function
-The cell body maintains neurone health and regulates function

Question 2

Dendrites

Answer 2

-Dendrites are branch-like structures that extend from the cell body
-Dendrites recieve signals from other neurones (or in the case of sensory neurones; sensory receptors) and carry them to the cell body

Question 3

Axon

Answer 3

-The axon is a fiber that carries electrical signals away from the cell body and towards the axon terminals

Question 4

Axon terminal

Answer 4

-Axon terminal is the end of the axon
-The axon terminal allows communication with other neurones across a synapse via neurotransmitters

Question 5

Myelin sheath

Answer 5

-Myelin sheath is an insulating layer made up of schwann cells that surrounds the length of the axon
-The myelin sheath speeds up the transmission of electrical impulses across the length of the axon
-The gaps in the myelin sheath are called nodes of Ranvier, and they speed up the rate of transmission by allowing the signal to jump from node to node (saltatory conduction)

Question 6

General function of neurones

Answer 6

-Neurone’s main function is to carry signals between the brain, the spinal cord, and the rest of the body
-Sensory neurones carry information from sensory receptors to the central nervous system, relay neurones connect the sensory neurone and motor neurone in the CNS, motor neurones carry information from the CNS to effectors (muscles, glands)
-This allows the body to detect stimuli, process information, and carry out an appropriate response

Question 7

Why can neurones only transmit signals in one direction

Answer 7

1. Neurotransmitters are only released from vesicles in at the axon terminal of the pre synaptic neurone
2. Specific receptor sites for neurotransmitters are only present on the membrane of the post synaptic neurone
3. Neurotransmitters diffuse across the synaptic cleft from a high to low concentration; diffusion is a passive, one-way process that prevents the chemical signal from moving backwards
4. After the neurotransmitters have binded to receptors on the post synaptic membrane, enzymes in the synaptic cleft break them down or they are reabsorbed into the pre synaptic neurone via reuptake; this prevents the backwards movements of the chemical signal and the continued stimulation of the post synaptic membrane