Micro-neuroanatomy

Question 1

What is the nervous system comprised of?

Answer 1

The nervous system is comprised of over 100 billion cells, known as neurons.

Question 2

What is a neuron?

Answer 2

A cell in the nervous system whose function is to receive and transmit information.

Question 3

What are the components of a neuron?

Answer 3

A neuron is made up of 3 major parts:
1. Soma - a Cell Body: contains the nucleus of the cell and keeps the cell alive.
2. Dendrite - a branching tree-like fibre: collects information from other cells and sends to the Soma.
3. Axon - a long, segmented fibre: transmits information away from the cell body to other neurons or to the muscles and glands.

Question 4

Myelin Sheath

Answer 4

Is a layer of fatty tissue surrounding the axon that acts as both an insulator and allows faster transmission of electrical signals.

Question 5

How does the nervous system operate?

Answer 5

The nervous system operates using an electrochemical process.

Question 6

What does an electrochemical process mean?

Answer 6

A signal received by the dendrites -> transmitted to the soma = electrical signal -> passed onto the Axon -> terminal buttons -> signalled to emit chemicals known as neurotransmitters.

Question 7

What is a resting potential?

Answer 7

Is a state in which the interior of a neuron contains a larger number of (-) charged ions than the area outside the cell.

Question 8

What is the action potential?

Answer 8

Is the change in electrical charge that occurs in a neuron when a nerve impulse is transmitted. (The axon segment closest to the cell body opens for positively charged sodium ions to enter cell body).

Question 9

What is a node of Ranvier?

Answer 9

Is a series of breaks/gaps between sausage-like Myelin Sheath segments of the Axon.

Question 10

A refractory period

Answer 10

A brief time after the firing of the axon when the axon cannot fire again because the neuron has not yet returned to its resting potential.

Question 11

Synapses

Answer 11

Junction areas where the terminal buttons at the end of the axon of one neuron nearly, but don’t quite, touch the dendrites of another.

Question 12

What is the function of synapses?

Answer 12

They allow an axon to communicate with many dendrites in the neighbouring cells.

Question 13

Neurotransmitter

Answer 13

A chemical that relays signal across the synapses between neurons.

Question 14

How a neurotransmittter is released?

Answer 14

When the electrical impulse from the action potential reaches the end of the axon, it signals the terminal buttons to release neurotransmitters into synapses.

Question 15

How are neurotransmitters released from one neuron admitted to another?

Answer 15

Neurotransmitters travel across the synaptic space and bind to the receptor sites on the dendrites of other neurons if they fit the receptor shape => referred to as a lock and key.

Question 16

Excitatory potential

Answer 16

Is when the neurotransmitters accepted by the receptors on the receiving neuron make the cell more likely to fire.

Question 17

Inhibitory potential

Answer 17

Is when the neurotransmitters accepted by the receptors on the receiving neuron make the cell less likely to fire.

Question 18

Neurotransmitter reuptake

Answer 18

Is a process in which the neurotransmitters in the synapses are reabsorbed into the transmitting terminal buttons, ready to be released again after the neuron fires.

Question 19

Agonist

Answer 19

Is a drug that has chemical properties that are similar to a particular neurotransmitter and thus mimics the effect of the neurotransmitter.

Question 20

Antagonist

Answer 20

Is a drug that stops or reduces the normal effect of a neurotransmitter.