A system made up of nerve cell - Nervous System
The Control and Coordination in higher animals called [Vertebrates] takes place through nervous system as well as hormonal system called [Endocrine system]
Five sense organ in our body:-
Eyes
Nose
Tongue
Ears
Skin
Sense organ contain [receptors]
Receptor - It is a cell in a sense organ which is sensitive to a particular type of stimulus such as {light, sound, smell, taste, heat, pressure, etc}
Eye have [Light Receptors]{Photoreceptors}
Nose have [Smell Receptors]{Olfactory receptors}
Ear have [Sound Receptors]{Phonoreceptors}
Tongue have [Taste Receptors]{Gustatory receptors}
Skin have receptors for detecting heat, touch, pressure, cold and pain, etc.
{Thermoreceptors detect heat or cold}
Control and Coordination in human
Two system of Coordination of activities in human:-
a) Nervous System
b) Endocrine System [Hormonal System]
Human Nervous System
Function:- Coordinate the activities of our body.
Nervous system helps all other systems of our body to work together.
Human Nervous System receives information from the surroundings.
UNIT OF NERVOUS SYSTEM : NEURON
Structural and functional unit of nervous system [Neuron]
Nervous System is made of special
cells called [Neurons]
Largest cell in our body [Neuron]
Neurons carry message in the form of electrical signals called [electrical impulses or nerve impulses]
Neuron [or nerve cell] has three components
a) Cell Body
b) Dendrites, and
c) Axon
Cell body of the neuron also contain [cytoplasm and nucleus]
Number of long or thin fibres are stretching out from the cell body of the neuron are called [Nerve fibres]
On the body of the neuron, have short fibres called [Dendrites]
Longest fibre on the cell body of a neuron is called [Axon]
Axon has an insulating and protective sheath around it of [Myelin]
Myelin is made of [Fat and protein]
Both [Dendrites and Axon] arise from the cell body of a neuron.
[Dentrites] pick up the nerve impulses from receptors.
They pass the impulses to the [cell body] and then along the [axon]
[Axon] passes the impulse to another neuron through a junction called [synapse]
Neurons are of three types:
a) Sensory Neurons
b) Motor Neurons
c) Relay Neurons
Sensory Nerrons transmit impules from the sensory cells [or receptors] towards the central nervous system [Spinal cord and brain]
Motor sensory transmit impulses from the central nervous system [spinal cord and brain] towards the mucles cells [or effectors]
Relay neurons occur in the central nervous system [brain and spinal cord] where they serve as links between other neurons.
How nerve impulses are transferred from one neuron to another in the nervous system.
There is not a complete joint of neuron in the rervous system.
Synapse - Very little gap between the two neurons where they join.
[Nerve impulses] are carried over this small gap between a pair of neurons by means of a chemical substance called [Neurotransmitter substance]
[Synapses] insure that nerve impulses travel in only one direction.
Organs of Human Nervous System
Main organs of human nervous system are:-
a) Brain
b) Spinal cord
c) Nerves
Brain location [Inside the skull of our head]
Spinal cord [It is a very thick nerve which runs inside the cavity of backbone in our body]
Upper end of [Spinal cord] is attached to the [Brain]
[Brain and Spinal cord] are connected to all sense organs and other parts of our body by millions of nerves.
Two types of nerves in our body:
a) Cranial nerves
b) Spinal nerves
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