Simplified note
The senses that evoke responses in organisms are called stimuli. These are two types,
External stimuli :- Sound, touch, heat, chemicals, pressure, cold, radiations.
18. How is human nervous system classified ?
Central Nervous System
- Brain
- Spinal cord
Peripheral Nervous System
- Cranial nerves (12 pairs)
- Spinal nerves (31 pairs)
Prepared by RASHEED ODAKKAL, 9846626323, GVHSS Kondotty, for www.mathematicschool.blogspot.in
Source: BIOVISION VIDEOBLOG (FOR MORE VISIT BIOVISION)
ONLINE TUITION:-
Contents
• External and internal stimuli
• Neuron -structure, Impulse generation and transmission.
• Types of nerve.
• Central nervous system
- Brain & Spinal cord – structure and functions.
- Reflex actions
• Peripheral nervous system
- Sympathetic and parasympathetic nerves
• Disorders of nervous system
- Alzheime'rs, Parkinsons & Epilepsy.
Questions and answers
1. Define stimulus.
External stimuli :- Sound, touch, heat, chemicals, pressure, cold, radiations.
Internal stimuli :- Hunger, touch, infection, pressure variation, thirst, exhaust.
2. What is the function of nervous system ?
To generate and coordinate responses according to external and internal changes.
3. Name the parts included in our nervous system.
Brain, spinal cord, nerves and receptors.
4.The structural and functional units of the nervous system ?
Neurons (nerve cells).
5. Structure of a model neuron.
A neuron has mainly the following parts; a cyton (cell body), impulse receiving dendrons (branches are known as dendrites), impulse transmitting axon (branches are axonites) and synaptic knobs for secreting neurotransmitter.
In certain neurons, the nerve fibres are covered by myelin sheath, made up of white shining Schwann cells.
6. The protective covering of nerve fibres (axons) ? Mention its function.
Myelin sheath.
• Provide nutrients and oxygen to the axon.
• Accelerate impulses.
• Act as an electric insulator.
• Protects the axon from external shocks.
• Gives white appearance ('white matter') to the neural parts.
7. Differentiate between white matter and grey matter.
The part of nerve, where myelinated neurons are present in abundance,is called as the white matter.
The part of nerve where the cell bodies and nonmyelinated neurons are present, is called as the grey matter.
8. Table showing the function of different parts of nerve cell.
9. Name the swollen ends of axon . How is it important in the transmission of impulse ?
Synaptic knobs, from which neurotransmitter secretes. The impulses are transmitted across the synaptic cleft only through a chemical (neurotransmitter), secreted from the synaptic knobs.
10. Give example for neurotransmitter.
Acetyl choline (Dopamine is another example)
11. Define synapse.
The junction between neurons or between neurons and muscles or glands is known as the synapse.
It helps to regulate the speed and direction of impulses. The impulses are transmitted across the synaptic cleft only through a chemical (neurotransmitter), secreted from the synaptic knobs.
12. The electrical messages conducted through nerves ?
Impulses
13.How is an impulse generated ?
The difference in the distribution of ions maintains positive charge on the outer surface and negative charge inside the plasma membrane of the receptor part of neuron. When stimulated, this ionic equilibrium (polarity) changes there and the outer surface becomes negatively charged and inner become positively charged. As a result, impulse generated. This charge difference stimulates its adjacent parts and similar changes occur there too. Thus a continuous flow of the impulse becomes possible.
14. How is the impulses transmits through the neurons ?
Impulse due to stimulus →dendrites→ dendrons →cyton→ axon →axonites→
synaptic knob→ secretion of neurotransmitter to the synaptic cleft →Stimulation in the adjacent dendrites →Impulse forms.
When impulses reach at the synaptic knobs, a chemical substance, known as neurotransmitter, released in the synaptic cleft. This chemical stimulates the adjacent dendrites to form new electric impulses.
15. Name the two types of neurons ?
Sensory neurons – (carry impulses from different body parts to the brain and spinal cord)
Motor neurons - ( carry impulses from the brain and spinal cord to various parts of body)
16. Define a nerve ?
A nerve is a group of axons or nerve fibres, covered by connective tissue.
17. Show different kinds of nerves with their functions in a table.
18. How is human nervous system classified ?
- Brain
- Spinal cord
Peripheral Nervous System
- Cranial nerves (12 pairs)
- Spinal nerves (31 pairs)
19. The protective measures for human brain ?
The brain is protected inside a hard skull and is covered by a three layered membrane, called the meninges.
Cerebrospinal fluid,a fluid formed inside the meninges, also protects the brain.
20. The outer covering of brain and spinal cord ?
Meninges.
21. The fluid which provides nutrients and oxygen to brain tissues ?
Cerebrospinal fluid (CSF).
22. How is the CSF form? Give its function ?
Cerebrospinal fluid is a fluid formed from the blood inside the meninges and eventually reabsorbed to the blood. Functions of CSF are,
• CSF provides nutrients and oxygen to brain tissues.
• Regulates the pressure inside the brain.
• Protects brain from injuries.
23. Name the functional parts of human brain.
Human brain has outer cerebrum, cerebellum and medulla oblongata and inner thalamus and hypothalamus.
24. Table showing different parts of brain, peculiar feature and functions of each.
25. The largest part of human brain ?
Cerebrum.
26. The peripheral part of brain is the ----------- .
Cerebral cortex.
27. There are many fissures and folds in the cerebral cortex. What is the advantage of this ?
This is an adaptation to include more number of neurons and there by increase the efficiency of cerebrum.
28. Any mild injury to the medulla oblongata may lead to sudden death. Why?
Medulla oblongata controls involuntary actions like heart beat and breathing. Any mild injury to medulla oblongata results malfunctioning of breathing and heartbeat and this may lead to death.
29. A person could not walk easily after drinking alcoholic beverage. Can you say which part of his brain is affected ?
Cerebellum, which maintains equilibrium of the body through muscular coordination.
30. After a road accident, a person lost his memory for a few days. In which part of his brain got injured ?
Cerebrum.
31. The central nerve, seen as the continuation of medulla oblongata ?
Spinal cord.
32. How is our spinal cord protected ?
Spinal cord is protected inside the vertebral column and is covered by the meninges.
33. The ------------- of the spinal cord is filled with cerebrospinal fluid.
Central canal.
34. Describe the structure of our spinal cord.
Spinal cord, which is the continuation of medulla oblongata, is situated with in the vertebral column and is covered by a three layered membrane, called meninges. The outer part of spinal cord is white matter and inner is grey matter. The central canal at its centre is filled with CSF.
Spinal nerves originate from the spinal cord as dorsal root (sensory) and ventral root(motor).
35. Spinal cord : Sensory impulse : Dorsal root;
Spinal cord : Motor impulse : ...................
Ventral root.
36. Mention the functions of spinal cord.
• Transmitting impulses from different parts of our body to and fro the brain.
• Coordinates the rapid and repeated movements during walking, running etc.
• Effects certain reflex actions.
37. What do you mean by reflex action ?
Reflex actions are the accidental and involuntary responses of the body, in response to a stimulus.
These are two types,
1. Cerebral reflexes (Eg:-Blinking of eyes, sudden fright when hearing a loud noise or seeing a snake, sneezing)
2. Spinal reflexes (Eg :- On touching hot object, the hand is withdrawn, withdrawal of the leg when a spine pierce in to the feet)
38.The pathway of impulses in a reflex action. Reflex arc.
39. What are the parts that involve in a reflex arc ?
a. stimulus receiving receptor
b. sensory neuron
c. inter neuron
d. motor neuron
e. effecting muscles.
40. The central neuron, which converts sensory impulse in to motor impulse, is usually known as an --------
Inter neuron.
41. A few nerves in the peripheral nervous system that function automatically and involuntarily, is known as ------------ ?
Autonomous nervous system.
It includes sympathetic and parasympathetic nerves.
42. How the contrasting actions of Sympathetic and Parasympathetic nervous systems help to maintain the normalcy of the physiological activities ?
Sympathetic and parasympathetics nervous system activate with or with out the endocrine gland system involuntarily. The contrasting actions of both systems help to maintain the normalcy of the physiological activities.
43. List out the physiological changes that may occur when a boy facing the audience during a competition.
(see the activities of the sympathetic nerves)
44. The table showing neural disorders, reason and symptoms.
45. Name a neurotransmitter, which is secreted in the brain. What will happen when the production of this hormone cease in a person ?
Dopamine.
The deficiency of dopamine may result a disease called parkinsons.
Dopamine.
The deficiency of dopamine may result a disease called parkinsons.
Prepared by RASHEED ODAKKAL, 9846626323, GVHSS Kondotty, for www.mathematicschool.blogspot.in
Source: BIOVISION VIDEOBLOG (FOR MORE VISIT BIOVISION)
ONLINE TUITION:-
Part 1
Part 2
Part 3
Part 4
