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DrX Whiz Niraj
Unit 1: Nervous System
Important Questions & Answers (English + Hinglish Explanations)
Q.1: Define neuron. 2 Marks
Neuron is the structural and functional unit of the nervous system. It is a specialized cell that is responsible for receiving, processing, and transmitting nerve impulses throughout the body.
Neuron ek special type ki cell hoti hai jo nervous system ki structural aur functional unit ke roop me kaam karti hai. Ye cell body ke alag-alag parts me messages (nerve impulses) bhejne ka kaam karti hai.
Neuron ka main function hota hai:
- Information ko receive karna (dusre neurons ya sensory organs se)
- Usse process karna
- Aur phir transmit karna (next neuron, muscle ya gland tak)
Neuron ke teen main parts hote hain:
- Cell body (Soma) – Jisme nucleus hota hai aur metabolic activities hoti hain.
- Dendrites – Ye branches jese structures hote hain jo signal ko receive karte hain.
- Axon – Ye ek lambi tube jesa part hota hai jo signal ko next cell tak bhejta hai.
Neuron = Message lane wala + Process karne wala + Message bhejne wala messenger cell
Q.2: Define Neuroglia. 2 Marks
Neuroglia, also known as glial cells, are the supporting cells of the nervous system. They do not generate nerve impulses like neurons but perform vital functions such as:
- Providing structural support to neurons
- Supplying nutrients
- Removing waste
- Protecting against pathogens
- Maintaining the extracellular environment
Types of neuroglia:
- Astrocytes – maintain the blood-brain barrier and provide nutrients.
- Oligodendrocytes – form myelin sheath in the CNS.
- Microglia – act as phagocytes to remove debris and fight infection.
- Ependymal cells – help in production and circulation of cerebrospinal fluid (CSF).
- Schwann cells – form myelin sheath in the PNS.
Neuroglia yaani glial cells, nervous system ki supporting cells hoti hain. Ye neurons ki tarah signal nahi bhejti, lekin neurons ko safety, nutrition aur support deti hain.
Inka kaam:
- Neurons ko support aur structure dena
- Unko nutrients provide karna
- Waste products ko remove karna
- Nervous system ko infection se bachana
- Neurons ke aas-paas ka chemical balance maintain karna
Important types: Astrocytes, Oligodendrocytes, Microglia, Ependymal cells, aur Schwann cells.
Q.3: Classify the Nerve Fibres. 2 Marks
Nerve fibres are classified based on conduction velocity, diameter, and function. Main classification (Erlanger and Gasser):
- A fibers: Myelinated and fast-conducting (Alpha, Beta, Gamma, Delta).
- B fibers: Lightly myelinated, autonomic preganglionic.
- C fibers: Unmyelinated, slowest; pain, temperature, autonomic postganglionic.
Lloyd and Hunt Classification includes Group Ia, Ib, II, III, and IV for sensory fibres from muscle spindle.
Nerve fibres ko unki speed, diameter, aur function ke aadhar par classify kiya jaata hai. A fibres sabse fast hote hain, jabki C fibres bina myelin ke aur sabse slow hote hain.
Q.4: Write the properties of nerve fibres. 2 Marks
The main properties of nerve fibres are:
- Excitability – Ability to respond to a stimulus.
- Conductivity – Ability to transmit the nerve impulse.
- Refractory Period – Time during which a nerve fibre does not respond to a second stimulus.
- All-or-None Law – A stimulus either causes a full response or none at all.
- Summation & Adaptation
Nerve fibres ki properties jaise Excitability (उत्तेजनशीलता), Conductivity (संवहन क्षमता), Refractory period, aur All-or-none law unhe theek se signal bhejne me madad karti hain.
Q.5: Draw and label the structure of a neuron. 2 Marks
A neuron consists of three main parts: Cell Body (Soma), Dendrites, and Axon.
Neuron ek special cell hoti hai jo message ko transfer karta hai. Iske teen main parts hote hain: Soma (Center part jisme nucleus hota hai), Dendrites (Branches jo signal receive karti hain), aur Axon (Lambi nali jo signal bhejti hai).
Q.6: Write types of Neuroglia. 2 Marks
- Neuroglia of CNS: Astrocytes, Oligodendrocytes, Microglia, Ependymal Cells.
- Neuroglia of PNS: Schwann Cells, Satellite Cells.
Q.7: Write the functions of Cerebrospinal Fluid (CSF). 2 Marks
CSF acts as a cushion to protect the brain (shock absorption), reduces brain weight (buoyancy), removes waste products, and circulates nutrients and hormones.
Q.8: Write the meninges of the brain. 2 Marks
The three meninges are: Dura mater (outermost), Arachnoid mater (middle), and Pia mater (innermost delicate layer).
Q.9: Name the parts of brain. 2 Marks
The major parts are Cerebrum, Cerebellum, and Brainstem (which includes Midbrain, Pons, and Medulla oblongata).
Q.10: Name the parts of brain stem. 2 Marks
The brain stem consists of the Midbrain, Pons, and Medulla oblongata.