Nerves

Question 1

Central Nervous System

Answer 1

The brain and the spinal cord

Question 2

Peripheral Nervous System

Answer 2

All of the nervous system apart from the brain and the spinal chord, made up of nerves (containing axons and dendrons of neurones)

Question 3

Neurone

Answer 3

A nerve cell, specialised for the rapid transmission of electrical impulses called action potentials

Question 4

Action Potential

Answer 4

A fleeting reversal of the resting potential, generally to about +40mV inside, which sweeps along an axon

Question 5

Motor Neurone

Answer 5

A neurone that transmits action potentials from the central nervous system to an effector

Question 6

Dendrites

Answer 6

Short cytoplasmic processes that transmit action potentials from other neurones to a motor neurone

Question 7

Axon

Answer 7

A long cytoplasmic process that transmits action potentials away from the cell body of a neurone

Question 8

Transmitter Substance

Answer 8

A chemical that is released by a presynaptic neurone and diffuses across the synaptic cleft to slot into receptors on the postsynaptic neurone

Question 9

Sensory Neurone

Answer 9

A neurone that transmits action potentials from a receptor to the central nervous system

Question 10

Dendron

Answer 10

A kong cytoplasmic process that transmits action potentials toward the cello body of a neurone

Question 11

Intermediate Neurone

Answer 11

A neurone in the central nervous system that transmits nerve impulses between a sensory neurone and a motor neurone

Question 12

Relay Neurone

Answer 12

Same as an intermediate neurone. A neurone in the central nervous system that transmits nerve impulses between a sensory neurone and a motor neurone.

Question 13

Schwann Cells

Answer 13

A cell that wraps itself around an axon producing a multiple layer of membranes, called myelin

Question 14

Myelin Sheath

Answer 14

An insulating layer around an axon or dendron

Question 15

Node of Ranvier

Answer 15

Gap in the myelin sheath

Question 16

Reflex Arc

Answer 16

The path travelled by an action potential from a receptor to an effector to bring about a reflex action

Question 17

Spinal Reflex Arc

Answer 17

Reflex arc in which the nerve impulses are carried into and out of the spinal cord (without involving the brain)

Question 18

Effector

Answer 18

An organ that carries out an action in response to a stimulus, such as a muscle that contracts or a gland that secretes a substance

Question 19

Reflex Action

Answer 19

A fast, stereotyped response to a stimulus, not involving conscious thought

Question 20

Perineurium

Answer 20

Protective connective tissue surrounding neurones

Question 21

Resting Potential

Answer 21

The potential difference, usually about -70mV inside, across the plasma membrane of a neurone while it is not transmitting an action potential

Question 22

Voltage-gated channel

Answer 22

An ion channel in the plasma membrane that responds to a change in voltage (potential difference) across the membrane by opening or closing

Question 23

Electrical Gradient

Answer 23

Difference in electrical potential across a membrane

Question 24

Chemical Gradient

Answer 24

Difference in concentration of a molecule inside and outside the cell

Question 25

Electrochemical Gradient

Answer 25

A situation in which the concentration and charge on one side of the membrane differs from that on the other

Question 26

Depolarisation

Answer 26

The loss or reversal of the resting potential

Question 27

Repolarisation

Answer 27

The recovery of a resting potential following depolarisation

Question 28

Refractory Period

Answer 28

The time immediately following an action potential when an axon cannot transmit another action potential, because of the time needed to restore the resting potential

Question 29

Saltatory Conduction

Answer 29

Conduction of an action potential along a myelinated neurone by 'jumping' from one node of Ranvier to the next

Question 30

Synaptic Cleft

Answer 30

The tiny gap between two neurones, or between a neurone and an effector

Question 31

Transmitter Substance

Answer 31

A substance that is released by a presynaptic neurone and diffuses across the synaptic cleft to slot into receptors on the postsynaptic neurone

Question 32

Noradrenaline

Answer 32

A transmitter substance

Question 33

Acetylcholine (ACh)

Answer 33

A transmitter substance

Question 34

Dopamine

Answer 34

A neurotransmitter substance found in the brain

Question 35

Glutamate

Answer 35

A transmitter substance found in the brain

Question 36

Cholinergic Synapses

Answer 36

A synapse at which the transmitter substance is acetylcholine

Question 37

Neuromuscular Junction

Answer 37

A synapse between a motor neurone and a muscle fibre

Question 38

Acetylcholinesterase

Answer 38

An enzyme that hydrolyses acetylcholine to acetate and choline

Question 39

Nicotine

Answer 39

A substance found in cigarette smoke, whose molecules have a similar shape to part of the acetylcholine molecule, and that can slot into acetylcholine receptors on postsynaptic membranes