Neural Control
and Coordination
Action potential: A sudden change in the electrical charges in the plasma membrane of
a nerve fibre.
Aqueous humour : The thin watery fluid that occupy space between lens and cornea in
eye.
Blind spot: A spot on retina which is free from rods and cones and lack the
ability for vision.
Cerebrospinal fluid: An alkaline fluid present in between inner two layers of meninges.
Cerebellum: A part of hind brain that
controls the balance and posture of the body.
Cochlea: A spirally coiled part of
internal ear which is responsible for hearing.
Corpus callosum: A curved thick bundle of nerve fibres that joins two cerebral hemisphere.
Depolarisation: A condition when polarity of
the plasma membrane of nerve fibre is reversed.
Endolymph: The fluid filled within
membranous labyrinth.
Eustachian tube: A tube which connects ear cavity with the pharynx.
Fovea: An area of highest vision on
the retina which contain only cones.
Meninges: Three sheets of covering of
connective tissue wrapping the brain.
Grey Matter: This shows many convolutions which increase the amount of vital nerve
tissue.
Medulla oblongata: Posterior most part of the brain which is continuous with spinal cord
and
control respiration, heart
rate, swallowing, vomiting.
Pons: Thick bundles of fibres on
the ventral side of brain below cerebellum.
Foramen magnum: A big aperture in the skull posteriorly through which spinal cord emerges
out.
Spinal cord: A tubular structure
connected with medulla oblongata of brain and situated in the
neural canal of the
vertebral column, covered by meninges.
Synaptic cleft: A narrow fluid filled space
which separates two membranes of the two neurons at
the synapse.
Synaptic vesicles: These are membrane bound
vesicles in the axoplasm of the axon terminal and
these store
neurotransmitter.
Neurotransmitter: These are chemicals stored
in synaptic vesicles, diffuse to reach the membrane
of next neuron for its
stimulation.
Synapse: A physiological junction
between axon of one neuron and dendrite of next neuron.
CNS − Central neural system
PNS − Peripheral neural system
ANS − Autonomic neural system
Functions of parts of brain:
Cerebrum: Centre of intelligence,
memory and imagination, reasoning, judgement, expression
of will power.
Thalamus: Acts as relay centre to
receive and transmit general sensation of pain, touch and
temperature.
Hypothalamus: Centre for regulation
of body temperature, urge for eating and drinking.
Mid brain: Responsible to
coordinate visual reflexes and auditory reflexes.
Cerebellum: Maintains posture and
equilibrium of the body as well as coordinates and regulates
voluntary movement.
Pons varoli: Relays impulses between
medulla oblongata and cerebral hemisphere and between the
hemisphere of cerebrum and cerebellum.
Medulla oblongata: Centre that
control heart beat, breathing, swallowing, salivation, sneezing,
vomiting and coughing.
Reflex Action: as a spontaneous, automatic and mechanical response to a stimulus
acting on a specific
receptor without the will of an animal.
Eg.- movement of diaphragm
during respiration, blinking of eyes, coughing, yawning,
sneezing etc.
Reflex arc –
The path travelled by an impulse in a reflex action is called a reflex arc.
It comprises - i) A specific
receptor, ii) an afferent nerve iii) a portion of central
nervous system, iv) an efferent nerve, v) an effector.
STEP 1
Nerve cell is at resting potential with
diffusion of Na+ & K+ down concentration gradient as cell pumps up the
gradient
STEP 2
neurons recieve stimulation causing local
potentials which may lead to reach threshold
STEP 3
sodium channels in trigger zone of axon
opens
STEP 4
sodium ions diffuse inward, depolarizing
the membrane
STEP 5
potassium channels in the membrane open
STEP 6
potassium ions diffuse outward,
repolarizing the membrane
STEP 7
action potential causes electric current
that stimulates adjacent portions of the membrane
STEP 8
action potentials occurs sequentially along
the length of axon as nerve impulse
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