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Biology
IB Biology 6.5
| 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. |
Created by:
Wengel
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