Term | Definition |
Neurons/nerve cells | transmit information in the form of nerve impulses |
The central nervous system | is made up of the neurons of the brain and the spinal cord and receives information from sensory receptors all over the body |
Peripheral nerves | network of neurons that carry information to and from the central nervous system |
Sensory neurons | carry information to the central nervous system |
Motor neurons | transmit impulses from the central nervous system to muscles and glands that then cause a response |
Relay neurons | form connection between sensory and motor neuron |
The cell body | contains the nucleus and most of the cytoplasm of the cell |
Small dendrites | receive information from relay neurons and and transmit the impulses to the cell body |
Myelin sheath | has a high lipid content and forms an electrical insulation layer that speeds the transmission of impulses along the axon |
How do neurons transmit information | in the form of impulses |
Impulses | short-lived changes in electrical potential across the membrane of the neuron |
What do all neurons contain? | Sodium (NA+) and potassium (K+) ions |
How do impulses occur? | They occur as sodium and potassium ions move in and out through the plasma membrane |
Resting potential | the condition of a neuron when it´s not transmitting impulses |
Action potential | the reversal and restoration of the resting potential across the plasma membrane of a neuron as an electrical impulse passes along it |
Depolarized membrane | is when the distribution of charge across the membrane is reversed during a nerve impulse |
Threshold potential | is the electrical potential across the plasma membrane of a neuron that is required in order to trigger an action potential |
Refractory period | a period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation. |
What does a larger diameter mean with regard to rate of conduction along an axon? | Faster reduction |
Nodes of Ranvier | gaps in the myelin sheath of an axon where the membrane can initiate action potentials. |
Saltatory conduction | is when the myelin sheath prevents the flow of ions across the membrane so the current must jump from node to node which speeds up transmission of nerve impulse |
Synapse | is a place where two neurons meet |
Synaptic cleft | is the gap between two neurons (20nm) |
Acetylcholine (ACh) | binds to receptors and causes depolarization of the post-synaptic membrane and the initiation of an action potential |
Nicotine | is an excitatory drug and affects the post-synaptic membrane so that it transmits an action potential |
Cocaine and amphetamines | excitatory drugs which stimulate synaptic transmission |
Cannabis and alcohol | suppress the activity of the nervous system |
Neonicotinoids | chemical pesticides used in insects. They block the transmission at the synapses of insects by binding to acetylcholine receptors. |