Science biology

1. The Nervous System
The Nervous
System
𝔹𝕚𝕠𝕝𝕠𝕘𝕪

2. Function of the Nervous System
Keeps us informed about the outside world through sensory
organs.
Controls and harmonises all voluntary muscular activities, e.g
running and writting.
Enables us to remember, think and reason.
• Our nervous system consist of brain, spinal cord, sense
receptors and nerves.
The Nervous System

3. Neuron: The Unit of the Nervous System
Structure of the Neuron
Three main parts of the neuron:
 Cell body: It has a well- defined nucleus and granular
cytoplasm.
 Dentrites: They are the branched sytoplasmic projections
of the cell body.
 Axon:
 It is the long process of the body.
 The Axon is covered by a myelin sheath.
 The myelin sheath shows graps throughout its lenght known as Nodes
of Ranvier.

4. Synapse
• A Synapse is a point of contact between the terminal branches of the
axon of the neuron and the dentrites of the another neuron.
• As the nerves impulse reaches the axon terminal of the neuron, tha
neurotransmitter Acetycholine is released by the bulbs present in the
axon.
• Acetycholine is then broken down by an enzyme to ensure the synapse
is ready for the transmission of the next nerve impulse.

5. Types of Neurons
• Sensory Neurons: Convey the impulse from the receptors (sense organs) to the
main nervous system (the brain or spinal cord).
• Motor Neurons: Carry impulse from the main nervous system to an effector
e.g gland or muscle.
• Associated Neurons: They interconnect sensory and neurons.
Types of Nerves
Tha nerve is thee bundle of nerve fibers (axon) separate neurons enclosed ina
tubular sheath.
Ganglia are an aggregation of the nerve cells (cell bodies) from which
the nerve fibers arise or enter.

6. Division of the Nervous System
The Central Nervous System
The central nervous system includes the brain and the spinal cord.

7. MidBrain:
 This small tube like part is responsible for reflexes involving the eyes and ears.
Hind Brain:
 The cerebellum coordinates mascular activity and balance of the body.
 The pons carrise impulses from one hemisphere to the other hemisphere and
coordinates muscular movements on both sides of the body.
 The medulla oblongata controls the activity of internal organs, hearthbeat, breathing,
etc.
Parts of the brain

8. The Spinal Cord

10. • Cranial Nerves: 12 pairs emerge from the brain.
• Spinal Nerves: 31 pairs: 8 pairs in the neck region, 12 pairs in the thorax, 5
pairs in the lumbar region, 5 pairs in the sacral region and 1 pair in the
coccygeal region.
Autonomic Nervous System
The Autonomic Nervous System controls the involuntary of the internal organs.
Somatic Nervous System

11. The reflex action is a automatic, quick and involuntary action in the body
brought about by stimulus.
Reflexes

13. The Sense Organs
The sense of organs enables us to be aware of the condition of the invironment.
A receptor is any specialised tissue or cell sensitives to a specific stimulus.

17. Function of the ear
Two function of the ear are hearing and body balance.