Download Nervous System 2 A nerve, conducting (carrying) an impulse

Nervous System 2
A nerve, conducting (carrying) an impulse (message) inwards or
towards the central nervous system (CNS = brain and spinal cord).
Cell body found somewhere along length of neuron, outside CNS,
e.g. sensory neurons.
afferent neuron
Nerve cell that connects a sensory neuron and a motor neuron, an
interneuron.
association
neuron
An enlargement at the top of the spinal cord where most decisions
are made in response to information received from the sense
organs. In vertebrates, it is that part of the central nervous system
enclosed in the skull. Consists of the olfactory lobes, cerebrum,
pineal body, thalamus, hypothalamus, midbrain, pons, cerebellum
and medulla oblongata.
brain
Tube found in the centre of the spinal cord, filled with cerebrospinal
fluid.
central canal
That part of the human brain lying beside the medulla oblongata. It
co-ordinates voluntary muscle activity and balance in the body.
cerebellum
Fluid of the brain and spinal cord.
cerebrospinal fluid
Outer layer of the cerebral hemispheres. Composed of grey matter.
cerebral cortex
A short branched process (a piece sticking out) of a nerve cell
(neuron), which receives impulses and transmits them towards the
cell body.
dendrite
A neurotransmitter. The lack of this causes Parkinson’s disease.
dopamine
A muscle or a gland that responds when stimulated by a nerve
impulse.
effector
A mass of nervous tissue, containing the cell bodies of the neurons,
lying outside the central nervous system (CNS, i.e.brain and spinal
cord). OR
A collection of cell bodies within the peripheral nervous system
(PNS), e.g. the dorsal root ...
ganglion
Part of the brain (above the pituitary gland) responsible for appetite,
sleep, osmoregulation, body temperature. Maintains homeostasis.
hypothalamus
The carrying of messages by neurons over large distances in the
body with no loss of intensity – involves the movement of ions in
and out of the neurons.
impulse
transmission
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Sudden involuntary movement of the lower leg caused by striking
the tendon just below the patella.
knee-jerk
Part of the brain directly above the spinal cord responsible for
involuntary muscle activities, e.g. breathing, heartbeat, saliva
production and swallowing.
medulla oblongata
Efferent neuron. Carries messages from the central nervous system
(CNS) to an effector. Cell body located at end of axon, inside CNS.
motor neuron
Solid strand of nerve fibres extending backwards from the brain.
nerve (spinal) cord
A collection of nerve cells in an animal used to detect changes
(stimuli) in both the internal and external environments and to
coordinate a rapid response to the stimuli.
nervous system
Tube formed in embryo of vertebrates from which the brain and
spinal cord develop.
neural tube
Chemical substances that carry nerve impulses across synapses, e.g.
acetylcholine.
neurotransmitter
A column of cells that runs along the length of the embryo, around
which the vertebral column develops.
notochord
Progressively degenerative disease of the nervous system due to the
lack of the neurotransmitter dopamine, which regulates the nerves
controlling muscle activity. Results in trembling of the muscles, stiff
joints and slow walk. May also effect speech and facial expressions.
Parkinson’s
disease
Structure found in the brain which may have some secretory
function. Sometimes referred to as the third eye.
pineal body
Nerve cell that carries the impulse (message) towards the synapse.
presynaptic
neuron
Automatic involuntary response to an internal or external stimulus.
Not under conscious control, e.g. knee-jerk, ankle-jerk. Important in
humans for a fast response or defence against possible injury.
The ability of living organisms to react to changes in their internal
and external environments. It is a form of defence that allows the
organisms survive.
reflex action
responsiveness
Having a keen awareness of or affected by stimuli from the external
and internal environments.
sensitivity
A nerve going from the brain down the inside the spinal column. It
acts as a reflex centre and also conducts messages to and from the
brain.
spinal cord
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Neurons do not touch each other. They are separated by small gaps.
These gaps allow one-way conduction only of an impulse. When an
impulse reaches the terminal button or synaptic knob, it causes
acetylcholine to be released. This crosses the gap and sets up an
impulse in the next neuron. Enzymes then break down acetylcholine
and the gap is cleared for the next transmission. What name is given
to these small gaps?
synapse / synaptic
cleft
Part of the brain under the cerebrum responsible for pleasure and
pain.
thalamus
Area of the medulla oblongata sensitive to the level of carbon
dioxide in the blood and the pH of the blood. When carbon dioxide
levels increase, pH lowers (i.e. gets more acidic) and this area
increases the rate of breathing.
ventilation centre
Found in the spinal cord. Consists of the axons of the neurons.
white matter
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