4: Nervous Communication Flashcards
Axon
Structure extending from a Neurone that conducts action potentials away from the cell body.
Central Nervous System (CNS)
The complex of nerve tissues that controls the activities of the body. In vertebrates, it comprises of the brain and spinal cord.
Dendrite
A structure, usually branched, extending from the cell body of a Neurone, which conducts impulses towards the cell body.
Effector
An organ that responds to stimulation by a nerve impulse resulting in a change or response.
Impulse
A series of action potentials. Transmitted by Salvatore conduction in myelinated axons.
Motor Neurone.
Neurone that transmits action potentials from the CNS to the effector (e.g. muscle or gland).
Myelin
A fatty substance that surrounds the axon and dendrites in certain neurones.
Myelin Sheath
Composed of Schwann cells wrapped around the axon of a Neurone.
Neurone
A nerve cell, compromising of a cell body, axon and dendrites, which is adapted to conduct action potentials.
Node of Ranvier
A gap in the myelin sheath that surrounds the axon in the Neurone.
Peripheral Nervous System
The part if the Nervous System that consists of the nerves on the outside of the brain and spinal cord.
Receptor
A cell adapted to detect changes in the environment.
Relay Neurone
Neurone that transmits impulses between sensory neurones and motor neurones, or between other relay neurones. Normally found in the CNS.
Schwann cell
Cell around a Neurone whose cell-surface membrane wraps around the axon to form the myelin sheath.
Sensory Neurone
Neurone that transmits an action potential from a sensory receptor to the CNS.
Sypnatic knob/ axon terminal
End of the axon that synapses with the dendrites or cell body of another Neurone or with an effector.
Action Potential
Change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulse passes.
Axoplasm
The cytoplasm of a neurone
Depolarisation
Temporary reversal of charges on the cell-surface membrane of a neurone that takes place when a nerve impulse is transmitted.
Hyperpolarisation
When the membrane potential becomes more negative than the resting potential following an action potential or as a result of an inhibitory impulse.
Ion Channel
A passage across a cell-surface membrane made up o a protein that spans the membrane and opens and closes to allow ions to pass in and out of the cell.
