NERVOUS SYSTEM
The nervous system may be divided into
1. Central nervous system: the brain and spinal cord
2. Peripheral nervous system: peripheral nerves and ganglia
associated with them.
3. Autonomic nervous system: the sympathetic and
parasympathetic nervous system.
NEURON
• The nervous system is made up of specialized cells called
neurons.
• They are the structural and functional units of nervous
system.
• It is otherwise called nerve cell.
• Within the brain and spinal cord, neurons are supported
by a special kind of connective tissue called neuroglia.
STRUCTURE OF NEURONS
• Each neuron consists of a cell body and its processes
(neurites) that is one axon and many dendrites.
NERVE CELL BODY
• The cell body is called soma or perikaryon.
• Like a typical cell, it consists of a mass of cytoplasm
surrounded by a cell membrane.
• The cytoplasm contains a large central nucleus,
numerous mitochondria, lysosomes and Golgi complex.
, • The cytoplasm shows the presence of a granular material
that stains intensely with basic dyes.
• Cell bodies of neurons form the gray matter of the
nervous system.
NEURITES
• The processes arising from the cell body of a neuron are
called neurites.
• These are of two kinds, axon and dendrites.
• They form the white matter of the nervous system.
• The dendrite is the branched process of the neuron and it
is branched repeatedly.
• The dendrite contains Nissl granules and neurofibrils.
• Dendrite is conductive in nature, and it transmits
impulses towards the nerve cell body.
• The axon is longer than dendrite.
• Each neuron has only one axon, axon arises from axon
hillock of the nerve cell body.
• They carry nerve impulses away from the cell body and
vary in length.
• The axon has a long central core of cytoplasm called
axoplasm and a membrane called axolemma.
• Axoplasm contains mitochondria, neurofibrils and
axoplasmic vessels, but Nissl bodies are absent in the
axon.
The nervous system may be divided into
1. Central nervous system: the brain and spinal cord
2. Peripheral nervous system: peripheral nerves and ganglia
associated with them.
3. Autonomic nervous system: the sympathetic and
parasympathetic nervous system.
NEURON
• The nervous system is made up of specialized cells called
neurons.
• They are the structural and functional units of nervous
system.
• It is otherwise called nerve cell.
• Within the brain and spinal cord, neurons are supported
by a special kind of connective tissue called neuroglia.
STRUCTURE OF NEURONS
• Each neuron consists of a cell body and its processes
(neurites) that is one axon and many dendrites.
NERVE CELL BODY
• The cell body is called soma or perikaryon.
• Like a typical cell, it consists of a mass of cytoplasm
surrounded by a cell membrane.
• The cytoplasm contains a large central nucleus,
numerous mitochondria, lysosomes and Golgi complex.
, • The cytoplasm shows the presence of a granular material
that stains intensely with basic dyes.
• Cell bodies of neurons form the gray matter of the
nervous system.
NEURITES
• The processes arising from the cell body of a neuron are
called neurites.
• These are of two kinds, axon and dendrites.
• They form the white matter of the nervous system.
• The dendrite is the branched process of the neuron and it
is branched repeatedly.
• The dendrite contains Nissl granules and neurofibrils.
• Dendrite is conductive in nature, and it transmits
impulses towards the nerve cell body.
• The axon is longer than dendrite.
• Each neuron has only one axon, axon arises from axon
hillock of the nerve cell body.
• They carry nerve impulses away from the cell body and
vary in length.
• The axon has a long central core of cytoplasm called
axoplasm and a membrane called axolemma.
• Axoplasm contains mitochondria, neurofibrils and
axoplasmic vessels, but Nissl bodies are absent in the
axon.
