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Neural control and coordination are important for controlling body functions and giving a reaction to stimuli. The nervous system helps in receiving, processing, and passing on information by neurons, which makes the communication rapid. NCERT Solutions for Class 11 Biology Chapter 18 Neural Control and Coordination provide clear answers that allow the students to understand how the brain and nervous system control all voluntary and involuntary actions, including muscle movement, reflexes, and organ functions. Going through the NCERT Solutions gives students a clear idea of this chapter, with better retention of the concepts.
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NCERT Solutions for Class 11 Biology Chapter 18 Neural Control and Coordination answers all your doubts. The chapter also describes the structure and functions of neurons, the human nervous system, and sensory organs, making it easier for you to learn how body coordination occurs. The structure of the human brain, including midbrain, forebrain, and hindbrain, is very well explained here in easy language, along with the well-labelled diagram provided by our subject experts. Students need to go through the NCERT Solutions Class 11 Biology of this chapter thoroughly and understand the mechanism of how coordination occurs in our body.
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Given below is the PDF of this chapter after going through these, you must be able to understand all the answers to the following questions:
The detailed solutions for in-text and exercise questions are provided below to make the concepts clear and to understand how the brain and nervous system work.
Q1. Briefly describe the structure of the brain.
Answer:
The brain is the main coordinating centre of the body. It is a part of the nervous system that controls and monitors every organ of the body.
It is well protected by cranial meninges, an outer layer called dura mater, a thin middle layer called arachnoid, and an inner layer called pia mater.
It is divided into three regions —
Forebrain: The largest part of the brain, responsible for thinking, memory, emotions, and controlling body temperature, hunger, and thirst. It includes the cerebrum (main thinking area), thalamus (sensory and motor coordination), and hypothalamus (controls body functions and emotions).
Midbrain: Connects the forebrain and hindbrain. It helps process visual and auditory information and controls some movements and reflexes.
Hindbrain: Controls basic life functions like breathing, heartbeat, and balance. It has three parts: the pons (connects parts of the brain), the cerebellum (balance and coordination), and the medulla oblongata (controls heart rate, breathing, and other automatic functions).
(a) Central nervous system (CNS) and Peripheral nervous system (PNS)
Answer: The major difference between the Central nervous system (CNS) and the Peripheral nervous system (PNS) is discussed below in the table:
Central Neural System (CNS) | Peripheral Neural System (PNS) |
1. The CNS is made up of the brain and the spinal cord. | 1. PNS consists of cranial nerves and spinal nerves. |
2. The brain is protected by the skull, and the spinal cord by the vertebral column. | 2. There are no protective structures for PNS. |
3. CNS does not have any subdivisions. | 3. PNS is divided into the somatic nervous system and the autonomic nervous system. |
4. CNS processes the information and controls the response to impulses. | 4. Nerves of the PNS carry impulses to the CNS and responses from the CNS to different organs of the body. |
5. The group of neurons in the CNS is called nuclei. | 5. The group of neurons in the PNS is called ganglia. |
(b) Resting potential and action potential
Answer:
Resting Potential | Action Potential |
1. It is the potential difference (difference in electric charge) across the membrane when the neuron is at the resting phase. | 1. It is the potential difference (difference in the electric charge) across the membrane when the neuron is stimulated or excited. |
2. The outer side of the neuron is positively charged and the interior of the neuron is negatively charged. | 2. The outer side of the neuron is negatively charged, and the interior of the neuron is positively charged. |
3. The plasma membrane of the neuron is more permeable to K+ ions. | 3. The plasma membrane of the neuron is more permeable to Na+ ions. |
4. The sodium-potassium-ATPase pump is active and sends Na+ ions outside the neuron to maintain the resting potential. | 4. The sodium-potassium-ATPase pump functions in a reverse manner and sends Na+ ions into the neuron. |
(a) Polarisation of the membrane of a nerve fibre
Answer:
Polarisation of the membrane of a nerve fibre:
When the nerve fibre is in the resting phase, it is said to be in the polarised state. In a polarised state, the membrane of the nerve fibre experiences a resting potential. The following steps take place during the process of polarisation of the membrane of a nerve fibre:
Q3. Explain the following processes:
(b) Depolarisation of the membrane of a nerve fibre
Answer:
When the nerve fibre is stimulated, it is said to be in a depolarised state. In a depolarised state, the membrane of the nerve fibre experiences an action potential. The following steps take place during the process of depolarisation of the membrane of a nerve fibre:
Q3. Explain the following processes:
(c) Transmission of a nerve impulse across a chemical synapse
Answer:
A synapse is the junction between two nerve cells (neurons).
(b) Brain
Answer:
Brain-
Q5. Write short notes on the following:
(a) Neural coordination
Answer:
Coordination helps different organs work together in living things. In humans, coordination happens in two ways: neural and chemical. Neural coordination uses special cells called neurons to send messages quickly.
Neurons connect receptors (which sense things) to effectors (which respond).
This system controls body actions, like moving muscles or activating glands.
It helps us remember, learn, think, and reason.
Neural coordination also manages vital functions like breathing, heartbeat, and digestion.
By linking all these processes, it keeps the body balanced and working well.
Q5. Write short notes on the following:
(b) Forebrain
Answer:
The forebrain has three main parts: the cerebrum, thalamus, and hypothalamus. The cerebrum is the biggest part and controls thinking, memory, and actions.
The cerebrum is split into two halves and joined by nerve fibres.
It has grey matter (outer layer) for thinking and white matter (inner part) for sending signals.
The limbic system, located within the cerebrum, is responsible for handling emotions and memory.
The thalamus passes messages between the body and brain and helps with emotions and senses.
It helps us feel things like heat, cold, and pain.
The hypothalamus keeps the body balanced.
It controls hunger, thirst, sleep, and temperature.
It also manages hormones and emotions.
Q5. Write short notes on the following:
(c) Midbrain
Answer:
The midbrain has two main parts: the cerebral peduncles and the corpora quadrigemina. The cerebral peduncles are thick nerve bundles that connect the cerebrum and cerebellum.
They help carry sensory and motor signals between the forebrain and hindbrain.
The corpora quadrigemina are two pairs of lobes on the back of the midbrain.
The superior colliculi control visual reflexes, like moving your head and eyes towards something you see.
The inferior colliculi manage auditory reflexes, helping you turn your head towards sounds.
Q5 . Write short notes on the following:
(d) Hindbrain
Answer:
The hindbrain has three main parts: the cerebellum, pons Varolii, and medulla oblongata. The cerebellum is at the back of the brain.
It has an outer grey matter layer and an inner white matter layer.
It helps coordinate muscle movements and keeps the body balanced.
The pons Varolii sits above the medulla oblongata.
It is made of white nerve fibres and links the two sides of the cerebellum.
It also controls breathing.
The medulla oblongata is at the lower part of the brain, connecting to the spinal cord.
It carries signals between the brain and spinal cord.
It controls vital functions like heartbeat and breathing, so damage to it can be life-threatening.
Q5. Write short notes on the following:
(e) Synapse
Answer:
Synapse:
Q6. Give a brief account of the Mechanism of synaptic transmission.
Answer:
The mechanism of synaptic transmission at the electrical synapse:
The mechanism of synaptic transmission at the chemical synapse:
Q7. Explain the Role of Na+ in the generation of an action potential.
Answer:
Sodium ions diffuse from the outside to the intracellular fluid because of the electrochemical gradient. The potassium ions move out, and the membrane becomes negatively charged from the outside and positively charged from the inside. This sudden change in the membrane potential is called the action potential, and the membrane is said to be depolarised.
Q8. Differentiate between:
(a) Myelinated and non-myelinated axons
Answer: The major difference is discussed below:
Myelinated Axons | Non-myelinated Axons |
1. Myelin sheath is present. | 1. Myelin sheath is absent. |
2. Nodes of Ranvier are present. | 2. Nodes of Ranvier are absent. |
It is found in the grey matter of the brain, spinal cord, and autonomic nervous system. | 3. It is found in the white matter of the brain, spinal cord and autonomic nervous system. |
4. The conduction of nerve impulses is from node to node. | 4. The conduction of nerve impulses is smooth. |
5. The speed of conduction of the impulse is 50 times faster than in non-myelinated axons. | 5. The speed of conduction of the impulse is slow. |
Q8. Differentiate between:
(b) Dendrites and axons
Answer:
Dendrites | Axons |
1. They are short processes. | 1. Axons are long processes. |
2. Dendrites carry impulses towards the cell body of the neuron. | 2. Axons carry impulses away from the cell body of the neuron. |
3. Dendrites are always branched. | 3. Axons may or may not be branched. |
4. Nissl's granules are present in the neuroplasm. | 4. Nissl's granules are absent in the neuroplasm. |
(c) Thalamus and Hypothalamus
Answer: The major difference is discussed below:
Thalamus | Hypothalamus |
1. It is made of only grey matter. | 1. It is made of white and grey matter. |
2. The thalamus does not secrete any hormones. | 2. The hypothalamus secretes certain hormones which control the activity of the pituitary gland. |
3. It is situated superior to the midbrain. | 3. It is situated at the base of the thalamus. |
4. It contains the centres of sensations such as heat, cold and pain. | 4. It contains the centres which control body temperature, blood pressure and homeostasis. |
(d) Cerebrum and Cerebellum
Answer: The major difference is discussed below:
Cerebrum | Cerebellum |
1. It is the largest part of the brain. | 1. It is the second-largest part of the brain. |
2. It is part of the forebrain. | 2. It is part of the hindbrain. |
3. The cerebrum is divided into two cerebral hemispheres. | 3. The cerebellum is divided into three lobes: the central vermis and the two lateral cerebellar hemispheres. |
4. It is the site of memory and intelligence. | 4. It is the site of body equilibrium and posture. |
(a) Which part of the human brain is the most developed?
Answer:
The cerebrum is the most developed.
(b) Which part of our central neural system acts as a master clock?
Answer:
The hypothalamus of the central nervous system acts as a master clock.
Q10. Distinguish between:
(a) afferent neurons and efferent neurons
Answer: The major difference is discussed below:
Afferent Neurons | Efferent Neurons |
1. They conduct sensory impulses from the receptors to the central nervous system. | 1. They conduct motor impulses from the central nervous system to the effector organs, such as muscles. |
2. They are present in the sense organs. | 2. They are present in the brain and the spinal cord. |
3. They are sensory neurons. | 3. They are motor neurons. |
Q10. Distinguish between:
(b) Impulse conduction in a myelinated nerve fibre and an unmyelinated nerve fibre
Answer: The major difference is discussed below:
Impulse Conduction in a Myelinated Nerve Fibre | Impulse Conduction in Non-Myelinated Nerve Fibre |
1. Impulse travels from node to node. | 1. Impulse travels along the length of the entire nerve fibre. |
2. The speed of conduction is 50 times faster than that of a non-myelinated nerve fibre. | 2. The speed of conduction is slower. |
3. Energy expenditure during impulse transmission is less. | 3. Energy expenditure during impulse transmission is higher. |
Q10. Distinguish between:
(c) cranial nerves and spinal nerves.
Answer: The major difference is discussed below:
Cranial Nerves | Spinal Nerves |
1. There are 12 pairs of cranial nerves. | 1. There are 31 pairs of spinal nerves. |
2. They arise from the brain and extend to the other parts of the body. | 2. They arise from the spinal cord and extend to other parts of the body. |
3. They may be sensory, motor, or mixed. | 3. They are mixed nerves. |
NCERT Solutions for Class 11: Subject-wise
Provided below are some easy and effective strategies to help you solve questions from this topic with a better understanding and accuracy.
Understanding how our body senses, processes, and responds to stimuli is key to understanding this chapter. The question below focuses on the most critical concepts that often appear in exams and require a clear vision.
Question 1: Match List I with List II :
List I | List II | ||
A | Pons | I | Provides additional space for neurons and regulates posture and balance. |
B | Hypothalamus | II | Controls respiration and gastric secretions. |
C | Medulla | III | Connects different regions of the brain. |
D | Cerebellum | IV | Neurosecretory cells |
Choose the correct answer from the options given below :
1. A-II, B-III, C-I, D-IV
2. A-III, B-IV, C-II, D-I
3, A-I, B-III, C-II, D-IV
4. A-II, B-I, C-III, D-IV
Answer:
A. Pons → III. Connects different regions of the brain: The pons facilitates signal transmission and connections between various brain regions.
B. Hypothalamus → IV. Neurosecretory cells: The hypothalamus contains cells that produce hormones and regulate vital bodily processes like appetite and body temperature.
C. Medulla → II. Controls respiration and gastric secretions: The medulla aids in digesting and regulates breathing.
D. Cerebellum → I. Provides additional space for Neurons, and regulates posture and balance: The cerebellum helps with balance and movement, and gives space for brain cells to work.
Hence, the correct answer is option 2)A-III, B-IV, C-II, D-I.
Also, check the NCERT Books and NCERT Syllabus here:
To prepare well for NEET, it’s good to go a little beyond NCERT. Some questions need a deeper understanding that comes from extra study.
Below are the Chapter-wise solutions for easy access and quick revision:
The benefits of NCERT solutions of Class 11 Biology chapter 18 are listed below:
These are the important topics of NCERT solutions for class 11 biology chapter 18:
Dendrites | Axons |
1. They are short processes. | 1. Axons are long processes. |
2. Dendrites carry impulses towards the cell body of the neuron. | 2. Axons carry impulses away from the cell body of the neuron. |
3. Dendrites are always branched. | 3. Axons may or may not be branched. |
4. Nissl's granules are present in the neuroplasm. | 4. Nissl's granules are absent in the neuroplasm. |
Synapses are points of interconnection between two neurons where impulses are communicated. They are important in neural coordination because they enable the transfer of communication between neurons in the form of chemical or electrical signals. This facilitates the efficient functioning of the nervous system by enabling the regulation of response and reflexes.
The anatomy of a neuron is optimized for its job of conducting nerve impulses. Dendrites gather information from other neurons, the cell body analyzes the data, and the axon conducts the impulse to the next neuron or target cell. The myelin sheath, which covers the axon, accelerates the transmission of the impulse, making for effective communication within the nervous system.
Sensory neurons receive stimuli from the environment and send signals to the central nervous system (CNS). Interneurons, which are in the CNS, process and analyze these signals, making connections between sensory and motor neurons. Motor neurons send commands from the CNS to muscles or glands, which results in a response. This coordination enables the body to respond appropriately to stimuli. All of these neurons work together to facilitate perception, reflexes, and voluntary movements.
The autonomic nervous system (ANS) controls involuntary bodily functions such as heartbeat, digestion, and breathing. It has the sympathetic and parasympathetic branches, which function in opposition to each other to ensure balance. The sympathetic division readies the body for emergencies or stress, whereas the parasympathetic division induces relaxation and conservation of energy. They work together to provide homeostasis and normal organ function.
Neurotransmitters are chemical messengers that carry signals across synapses between neurons. They are released by the presynaptic neuron and attach to receptors on the postsynaptic neuron, initiating a response. Excitatory neurotransmitters facilitate signal transmission, and inhibitory ones decrease neural activity. This process maintains nerve cell communication and governs different body functions.
Myelinated nerve fibres possess a fatty sheath (myelin) covering the axon, with a possibility of quicker conduction of nerve impulses via saltatory conduction. The fibres that do not have a sheath are non-myelinated and transmit impulses more slowly and continuously. Myelinated fibres exist in the peripheral and central nervous systems, which provide quick responses. Non-myelinated fibres are in the autonomic nervous system, regulating involuntary functions. The disparity in speed of conduction influences reaction times and coordination.
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