Control and Coordinationconverted

5/22/2018 Control and Coordinationconverted

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Some important terms Stimulus- any external or internal factor that causes a

living organism to react is called a stimulus. (Pl:stimuli)

Response- the specific reaction shown by a livingorganism towards a stimulus

Impulse- a electrical wave of excitation or irritation

that travels across a neuron and carries specificmessages.


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Some important termsReceptors- group of organs that

receive sensory impulses andconvey them to the brain

Effectors- group of organs that

show responses to a specificstimulus


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Neuron- The fundamental structural and functional unit of the

nervous system that carries impulses across the body.


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Structure of a neuronA neuron is made up of two main parts;

a) Cyton

b) Axon

Cyton also called cell body, this part of neuron

contains a large prominent nucleus in the center.

The cell membrane is branched into several cytoplasmic

branches called dendrites.

Dendrites receive the impulses.


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Structure of a neuronThe cytoplasm is called neuroplasm.

Inside the neuroplasm are scattered several stainable

granules called Nissl granules.

B) Axon The long cytoplasmic projection of the neuron thatextends from the cell body.

An axon is covered by an insulating membrane called

Neurolemna.Axons carry the impulse they receive from the cyton. Theyusually terminate into another neuron or an organ or glandor muscle.


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Structure of a neuronIn some neuron there is an additional envelop inside the

neurolemna called the Myelin sheath which help in

faster conduction of the impulse. Such neurons are

called myelinated neurons and are mostly present in

cerebral medulla.

Impulse always travels from Cyton to Axon.


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Types of Neurons Sensory neurons- Those neurons that carry impulses

from the receptors (sense organs)to the brain. Theseimpulses are sensory in nature.

Motor neurons- Those neurons that carry impulsesfrom the brain to the effectors . These impulses aremotor in nature.

Associated neurons- They are also called mixedneurons as they carry impulses both to and from thebrain.


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Types of Neurons

Sensory

Motor

Interneuron


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NervesA bundle of neurons with a common envelop around the

axons called nerve membrane.

A nerve provides acommon pathway for theelectrochemical nerveimpulses that are

transmitted along each ofthe axons


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Types of Nerves Sensory nerves- Those nerves that carry impulses from

the receptors (sense organs)to the brain. Theseimpulses are sensory in nature.

Motor nerves- Those nerves that carry impulses fromthe brain to the effectors . These impulses are motor innature.

Mixed nerves- They are also called mixed nerves asthey carry impulses both to and from the brain. Theyare also called spinal nerves.


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Classification of the Human

Nervous SystemThe human Nervous System is classified into three

major divisions-

The Central Nervous System

The Peripheral Nervous System

The Autonomous Nervous System


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Central Nervous System The CNS constitutes the main division of the Nervous

system in Human Beings.

It comprises of two main organs concerned withcontrol and coordination-

A) The Brain

B) The Spinal Cord.


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The Brain Location: Head region

Protection: a) Body protection made up of immobile

bones that make up the skull. The skull is also called

the Cranium.

b) Membranous protection in the form of three

membranes called the meninges. These three layers are

called Dura mater, Arachnoid mater and Pia mater.


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Meninges of the Brain


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Parts of the BrainFore- Brain

The fore brain makes up the largest part of the brain.

The forebrain consists ofthe cerebrum,

thalamus,

and hypothalamus (part of the limbic system)


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Fore Brain Olfactory lobes:

Two small lobelike structuressituated in thelower part of theanterior brain.

Controls thesense of smell


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Submitted To: Gurinder Kang

Submitted By:

Harpreet Kaur

10thC

Roll No. 18

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Control and Coordinationconverted