These notes cover all topics relevant to the NSC Biology papers (1+2). With these notes, I was able to achieve above 80% for my final result. These notes are thorough and provide visual aids to assist learning.
Central Nervous System – Brain + Spinal cord
Peripheral Nervous System – 12 pairs cranial nerves + 31 pairs spinal nerves
Stimulus
*
Receptor
*
Sensory System
*
CNS processes + interprets sensory input
*
Motor System
*
Effectors e.g. Muscles + Glands make correct response
*
Response
NERVOUS TISSUE
All living cells have the ability to react to stimuli; Some cells = developed for
communication between different parts of the body; Nerve cells (Neurons)
Central Nervous System: Brain + Spinal Cord
Peripheral Nervous System: 12 Pairs Cranial Nerves + 31 Pairs Spinal Nerves
NEURONS:
Cells that carry messages; Very long; Swollen area called cell body;
Have 1+ outgrowths from this cell body called Fibre/s
UNIPOLAR: Have one outgrowth from
cell body; Also known as Sensory/ Afferent
neurons; Function – Take messages (Impulses)
to Central Nervous System
MULTIPOLAR: Many outgrowths from
cell body; One outgrowth is very long;
Also known as Motor/ Efferent neurons;
Function – Take messages (Impulses) away
from Central Nervous System
, BIPLOAR: Two outgrowths from cell body;
Found in the retina of eye + in the olfactory
region of the nose
IMPORTANT TERMS
Neuron: Nerve Cell
Nerve: Large number of nerve fibres bound together by connective
tissue
Nerve Fibre: Extensions of neurons – Axons + Dendrites
Ganglion: Collection of nerve cell bodies
Effector: Muscle/ Glands that respond to stimuli
Receptors: Cells receiving stimuli
Neurotransmitters: Chemicals released to transmit impulses
NEUROPLASM
} (Called the grey
matter of the
nervous system)
ON
SCHWANN CELL
IPOLAR NEUR
(Protective cell membrane
NEURILEMMA + generates axons)
NUCLEUS OF SCHWANN CELL
(Myelinated ∴ White in colour)
AXON (Unbranched; Takes impulse away
MULT
from cell body)
NODE OF RANVIER
(Interruption in Myelin sheath;
OF
Between Schwann cells)
E
MYELIN SHEATH
R
TU
(Formed by Schwann Cells wrapping around
C
U axon; Fatty sheath that insulates axon)
STR
TERMINAL BRANCHES
SYNAPTIC KNOB (Message passed on)
, Pre-Synaptic
Synaptic Knob
Synaptic Vesicle membrane
AX
ON Neurotransmitters
SYNAPSE: Microscopic in Synaptic Cleft
gap over which impulses
are transmitted
chemically from
one neuron to the
next (Ensures impulses Neuroreceptors
travel in one Mitochondrion in
direction). Post-Synaptic
Mitochondria provide energy for Membrane
the transmission of impulse.
Impulses can only
TE
D E N D RI
travel one way.
Neurotransmitter only Burst Synaptic
produced on Vesicle
one side. Some
enzymes on post-synaptic
side destroy neurotransmitter
1. When the impulse reaches the end of the axon, the vesicles in the
synaptic knob are stimulated to burst releasing neurotransmitters
2. The neurotransmitters diffuse across the synapse + are received by the
special receptors on the post-synaptic membrane
3. This generates an electrical impulse in the receiving neuron
Impulses Travel:
- Along nerve fibres as electrical transmission
- Across synapses as chemical substances
Brain:
Protected by – Cranium + 3 Meninges
- PIA MATER
Closest to brain; Rich in blood capillaries;
Supplies nutrients + oxygen to brain
tissue
- DURA MATER
Tough membrane closest to skull
- ARACHNOID
Between the PIA + DURA MATER
Between the Pia mater + the Arachnoid is the Sub-arachnoid space filled
with cerebro-spinal fluid – shock absorber
, Disorders of the Nervous System
Name of disease Alzheimer’s disease Multiple sclerosis
(CNS – brain) (PNS – Nerves)
Ages affected Over 65 Between 20-40
Causes Unknown – probably Unknown – genetics +
caused by genetic + childhood infections
environmental may play a role
influences
Effects on the body The build-up of amyloid Body’s immune system
plagues (protein gradually destroys the
deposits) in parts of the myelin sheaths in the
brain CNS so impulses travel
more and more slowly
Symptoms - Increasing loss of Problems in controlling
memory muscles resulting in:
- Confusion, irritability + - Clumsiness, loss of
aggression balance + walking
- Difficulty in finding the difficulties
right words - Speech difficulty
- General withdrawal - Visual problems
from society - Incontinence
Treatment No cure but mental No cure but
stimulation, exercise + a medications help to
balanced diet help to control the symptoms +
manage the disease slow down the
progression of the
disease
Ventricles + CSF
- Ventricles are hollow spaces in the brain
- Filled with cerebro-spinal fluid (CSF)
- Lined with ciliated epithelium to keep the fluid in motion
- CSF is just like tissue fluid formed from clusters of capillaries lining the
ventricles
- Fresh fluid is constantly being formed, replacing the drained fluid
- Fluid provides nutrients + oxygen to the brain tissue as well as draining
carbon dioxide + wastes
- Fluid provides pressure to support the very soft brain tissue + acts as a
shock absorber
- There are 4 Ventricles
- 1st + 2nd on each side of the cerebral cortex
- 3rd in the thalamus
- 4th in the medulla oblongata (Brain stem)+ is continuous with the
spinal canal (a thin tube that runs through the spinal cord)
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