3. Characteristics of NervousCharacteristics of Nervous
systemsystem
► Brain, Spinal cord, Nerves and Sensory receptorsBrain, Spinal cord, Nerves and Sensory receptors
constitute Nervous systemconstitute Nervous system
► Information received by Sense organs reach theInformation received by Sense organs reach the
brain through Nervous systembrain through Nervous system
► Controls and coordinates the functions of theControls and coordinates the functions of the
body.body.
► Neuron or Nerve cell is the basic unit of NervousNeuron or Nerve cell is the basic unit of Nervous
systemsystem
4. NeuronNeuron
► Basic unit of Nervous systemBasic unit of Nervous system
► They are seen more inThey are seen more in
number in Brain and Spinalnumber in Brain and Spinal
CordCord
► Millions of Neurons are thereMillions of Neurons are there
in human bodyin human body
► Not capable of divisionNot capable of division
► Carry messages related toCarry messages related to
responses that are formed asresponses that are formed as
a result of changes ina result of changes in
environmentenvironment
5. Neuron consist of 3 partsNeuron consist of 3 parts
Neuron
a) Cyton or
Cell body
b) Axon c) Dendron
6. a) Cyton or Cell bodya) Cyton or Cell body
►The central body of the neuron containingThe central body of the neuron containing
the nucleusthe nucleus
►Axon and Dendrons are developed fromAxon and Dendrons are developed from
CytonCyton
7. b) Axonb) Axon
► Developed from CytonDeveloped from Cyton
► Covered with a sheath made of the lipid , myelin andCovered with a sheath made of the lipid , myelin and
is called Myelin sheathis called Myelin sheath
► It has a glistening white colorIt has a glistening white color
► Function of Myelin Sheath are to provide nutrientsFunction of Myelin Sheath are to provide nutrients
and protection to the nerve cell. It enhances theand protection to the nerve cell. It enhances the
transmission of nerve impulses by acting as antransmission of nerve impulses by acting as an
insulatorinsulator
► Branches of Axon are called AxonitesBranches of Axon are called Axonites
► The swollen tip of Axonites are known as SynapticThe swollen tip of Axonites are known as Synaptic
knobsknobs
8. c) Dendronc) Dendron
►Developed from CytonDeveloped from Cyton
►Branches of Dendrons are DendritesBranches of Dendrons are Dendrites
9. Three types of neuronsThree types of neurons
►Sensory neuronsSensory neurons which convey the impulsewhich convey the impulse
from receptor to the main nervous systemfrom receptor to the main nervous system
►Motor neuronsMotor neurons carrycarry impulse from the mainimpulse from the main
nervous system to muscle or glandnervous system to muscle or gland
►Association (connecting ) neuronsAssociation (connecting ) neurons which arewhich are
located in the brain and spinal cord, whichlocated in the brain and spinal cord, which
interconnect the sensory and motor neuronsinterconnect the sensory and motor neurons
