Questions: Neural Control and Coordination

Q1. What are the parts of the human neural system?

Answer (English): The human neural system has two parts: the central neural system, made of the brain and the spinal cord, and the peripheral neural system, made of the nerves that connect the central system to the body. The peripheral system is divided into the somatic division, which supplies the skeletal muscles, and the autonomic division, which supplies the smooth muscles, the heart and the glands.

Hinglish: Human neural system central (brain aur spinal cord) aur peripheral (nerves) mein banta hai. Peripheral ki somatic division skeletal muscles ke liye aur autonomic division smooth muscle, heart aur glands ke liye hoti hai.

Q2. Distinguish between the somatic and autonomic neural systems.

Answer (English): The somatic neural system carries impulses to the skeletal muscles and controls voluntary movements, and a person can decide to move those muscles. The autonomic neural system carries impulses to the smooth muscles, the heart and the glands, works without conscious control, and keeps the internal organs working steadily. Its sympathetic and parasympathetic divisions have opposite effects on the same organs.

Hinglish: Somatic system skeletal muscles ko control karta hai aur voluntary movement karta hai; autonomic system smooth muscle, heart aur glands ko control karta hai, involuntary hota hai, aur iski sympathetic aur parasympathetic divisions opposite effects deti hain.

Q3. Draw a labelled diagram of a neuron.

Answer (English): A neuron has a cell body with the nucleus and Nissl's granules, several branched dendrites that receive signals, and a single long axon that carries the impulse away. The axon may be covered by a myelin sheath formed by Schwann cells, with gaps called the nodes of Ranvier, and it ends in a synaptic knob that releases the neurotransmitter.

Hinglish: Neuron mein cell body (nucleus aur Nissl's granules), dendrites jo signal receive karte hain, aur ek lamba axon hota hai jo impulse le jata hai; axon par myelin sheath (Schwann cells) aur nodes of Ranvier hote hain, aur axon terminal par synaptic knob hota hai.

Q4. What is resting potential and how is it maintained?

Answer (English): The resting potential is the difference in charge across the membrane of a resting neuron, with the outside positive and the inside negative, about minus seventy millivolts. It is maintained because the membrane is more permeable to potassium than to sodium, so potassium tends to leave and the inside becomes negative, and the sodium-potassium pump continuously moves three sodium ions out and two potassium ions in using ATP.

Hinglish: Resting potential resting neuron ki membrane ke across charge difference hai, bahar positive aur andar negative, lagbhag -70 mV. Membrane K+ ke liye zyada permeable hai isliye K+ bahar nikalta hai, aur sodium-potassium pump ATP se 3 Na+ bahar aur 2 K+ andar bhej kar yeh difference banaye rakhta hai.

Q5. What happens during an action potential?

Answer (English): A strong enough stimulus opens the sodium channels of the membrane at the point of stimulation. Sodium ions rush into the axon, the inside becomes positive and the outside negative, and this depolarisation is the action potential. The sodium channels then close, potassium ions move out and the membrane is repolarised. The region just behind the impulse stays briefly refractory, so the impulse travels only forward.

Hinglish: Stimulus se Na+ channels khulte hain, Na+ andar aata hai, membrane depolarise hoti hai aur action potential banta hai; phir K+ bahar jaakar repolarisation hota hai. Refractory period ki wajah se impulse sirf aage ki taraf jata hai.

Q6. What is saltatory conduction?

Answer (English): In a myelinated axon the myelin sheath insulates the segments between the nodes of Ranvier, so the current cannot leak out easily. The action potential is therefore regenerated only at the nodes, and the impulse appears to jump from one node to the next. This jumping is called saltatory conduction, it is faster than conduction along an unmyelinated axon, and it uses less energy because fewer ions have to be pumped back.

Hinglish: Myelinated axon mein myelin insulation ki wajah se impulse nodes of Ranvier par regenerate hota hai aur node se node tak jump karta hai; isse saltatory conduction kehte hain, jo tez aur energy-efficient hai.

Q7. Explain transmission across a chemical synapse.

Answer (English): When the impulse reaches the synaptic knob, calcium ions enter and the vesicles of neurotransmitter fuse with the membrane and release the transmitter into the synaptic cleft. The transmitter diffuses across the cleft and binds receptors on the post-synaptic membrane, which opens ion channels and starts a new electrical change in the next cell. The transmitter is then removed by an enzyme or by reuptake, so the synapse can work again.

Hinglish: Impulse synaptic knob tak pahunchta hai, Ca2+ andar aata hai, vesicles neurotransmitter chhodti hain, transmitter cleft se diffuse hokar post-synaptic receptors se bind karta hai aur next cell mein naya signal shuru karta hai; baad mein transmitter remove ho jata hai.

Q8. How is the brain protected?

Answer (English): The brain is protected by the skull outside and by three cranial meninges inside: the dura mater, the arachnoid and the pia mater. The cerebrospinal fluid between the membranes cushions the brain against shocks, and it also carries nutrients and removes wastes. The brain and spinal cord are also protected by the bones that surround them and by the fluid that fills their internal spaces.

Hinglish: Brain bahar se skull aur andar se teen cranial meninges (dura mater, arachnoid, pia mater) se protected hota hai; cerebrospinal fluid shocks se bachata hai aur nutrients-waste exchange bhi karta hai.

Q9. Name the parts of the forebrain and give one function of each.

Answer (English): The forebrain has the cerebrum, the thalamus, the hypothalamus and the limbic system. The cerebrum is the seat of thinking, memory, reasoning, voluntary movement and the interpretation of sensation. The thalamus is the relay station that sorts sensory impulses on their way to the cortex. The hypothalamus controls body temperature, hunger, thirst and the pituitary gland. The limbic system is concerned with emotions, sexual behaviour and motivation.

Hinglish: Forebrain mein cerebrum (thinking, memory, reasoning, movement), thalamus (sensory relay), hypothalamus (temperature, hunger, thirst, pituitary control) aur limbic system (emotions, motivation) hote hain.

Q10. What is a reflex arc and why is reflex action useful?

Answer (English): A reflex arc is the path followed by the nerve impulses in a reflex action. A receptor detects the stimulus, an afferent neuron carries the signal to the spinal cord, an interneuron passes it on, and an efferent neuron carries the command to the muscle, which contracts at once. Reflex action is useful because it gives a quick response to a harmful stimulus before the brain has time to think about it, as in the withdrawal of the hand from a hot object or the knee-jerk reflex.

Hinglish: Reflex arc mein receptor stimulus pakadta hai, afferent neuron signal spinal cord tak le jata hai, interneuron aage bhejta hai aur efferent neuron muscle ko command deta hai; reflex action jaldi response deta hai isliye harmful stimulus se bachata hai.

Quiz pointer. A five question chapter quiz follows this page. Attempt it without looking back and read the explanation for every question you miss, because the quiz retests the neuron parts, the resting potential and the brain divisions.