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26 terms

IGCSE Biology - The Nervous System

Key terms from Edexcel IGCSE Biology on the topic of The Nervous System
STUDY
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Stimulus
A change in an animal's surroundings
Response
A reaction to a change in one's surroundings
Transduction
When energy is changed from one form to another
Central Nervous System (CNS)
Consists of the brain and spinal cord and is linked to sense organs by nerves
Reflex action
A rapid automatic (or involuntary) action in response to a stimulus that is not started by impulses from the brain
Reflex arc
The nerve pathway of a reflex e.g. stimulus > receptor > sensory neurone > CNS > relay neurone > motor neurone > effector > response
Dorsal root
Where sensory neurones enter the central nervous system
Ventral root
Where motor neurones emerge from the central nervous system
Dorsal root ganglion
A swelling in the dorsal root where the cell bodies of sensory neurones are located
White matter
Composed mainly of nerve axons. Forms the outer part of the spinal cord and the middle part of the brain.
Grey matter
Composed of mainly nerve cell bodies. Forms the middle part of the spinal cord and the outside of the brain.
Sensory neurone
A neurone conducting impulses from receptors to the brain or spinal cord
Motor neurone
A neurone transmitting impulses from the brain or spinal cord to a muscle or gland
Axon
The long threadlike part of a nerve cell that carries impulses
Myelin sheath
Fatty insulation that surrounds axons and helps to speed up the conduction of impulses
Dendrons
The fine cytoplasmic extensions of a nerve cell body
Synapse
A junction between two nerve cells
Nerve-muscle junction
A special type of synapse where nerve endings from an axon connect with a muscle
Neurotransmitter
A chemical substance released from a nerve cell, allowing an impulse to travel from a nerve cell to another nerve, muscle, organ or tissue
Cerebrum
Consisting of two hemispheres, it is the largest part of the brain and is the source of all conscious thought
Cerebral cortex
Folded layers of grey matter covering the cerebral hemispheres
Cerebellum
Region of the brain concerned with coordinating the contraction of sets of muscles, as well as maintaining balance.
Medulla
Connects the spinal cord with the rest of the brain. Is responsible for controlling basic body activities such as heartbeat and breathing rate.
Pituitary gland
Located at the base of the brain. It secretes a number of different hormones into the blood, including those that regulate reproduction.
Hypothalamus
A region of the brain that coordinates the activity of the pituitary gland
Hormone
Chemical messenger