Nervous System Pg(1-3) Flashcards
What is need of nervous system.
1.keeps us informed
2.enables us remember,to think,and to reason
3.controls and hormonises all voluntary muscular activities
4.regulates involuntary activities
What is the another name of neuron?
Nerve cells
Nervous system consist of______ ,______,______and_____
Spinal cord,brain,sense receptors and a whole lot of nerves
The brain and spinal cord is made up of _________
Neurons or nerve cells
What is the three main parts of a neuron?
1.cell body
2.dendrites
3.axon
The myelin sheath shows gaps throughout the length which are called____________
Nodes of ranvier
Some axons have side branches what are the branchesh called?
Collaterals
What are the gaps in axon terminal called__________
Synaptic clefts
What is stimulus? Give an example
An agent ir a sudden change if the external or internal environment that results in a change in an organism or any of its body part
Ex-light,sound,heat,pain,hunger
Name the following:
1.the change in an organism resulting due to stimulus.
2. A wave of irritability
1.response
2.impulse
What is receptors?
The specialised epithelial cells which, on receiving the stimulus,set up waves of impulse towards the central nervous system.
What is a effector?
Muscle or gland which,on receiving the impulse from brain or spinal cord,contract or secrete substance
What is neurotranmitter?
The end portions of axon store’s some chemical which is called neurotransmitter
Define synapse.
Synapse is the point of contact between the terminal branch of the axon of a neuron with the dendrites of another neuron seprated by a fine gap.
As the impulse reaches the terminal end of a axon ___________chemical is released
Acetycholine
What are the three types of neuron?
- Sensory neurons
2.motor neurons
3.association neurons
Define sensory neurons.
Sensory neurons convey the impulse from receptors to main nervous system
Define motor neurons.
It carry the impulse from main nervous system to an effector
Define association neurons.
It connects the sensory and motor neuron
Where is association neuron located?
Located in brain and spinal cord
Define nerves.
Nerve is a bundle of nerve fibres of seprate neurons enclosed in a tubular sheath
The___________sheath of axon acts lika an insulation and prevents mixing of impulse in adjacent axon.
Myelin
What are the three kinds of nerves?
1.sensory nerves
2.motor nerves
3.mixed nerves
The structural and functional unit of nervous system.
Neurons or nerve cells
Define sensory nerves.
It contains only sensory fibres brining impulses from the receptors to the brain or spinal cord
Define motor nerves.
It contains only motor fibres carrying impulses from brain or spinal cord to effector organs to bring them into actions.
Give an example of sensory nerves.
Ex-optic nerve arising from the eye and ending in the brain
Give an example of motor neuron.
Ex-a nerve arising from brain and supplying the muscles of the eyeball for rotating the eye.
Long thread like part of the nerve cells.
Dendrites.
A nerve is made up of___________
Bundle of axons
