NCERT Class 11 Biology Chapter 21 Notes Neural Control And Coordination- Download PDF Notes

Did you know that humans have a complex nervous system that controls all body actions and responses? The NCERT Notes for Class 11 Biology Chapter 18 are written in clear language for better understanding. It includes well-labeled diagrams which make learning more effective. This chapter gives an idea of the human nervous system and how it plays an important role in coordinating body functions. These NCERT notes help in building a strong foundation for board and entrance exams like NEET.

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1. Download NCERT Notes for Class 11 Chapter 18 PDF
2. NCERT Notes for Class 11 Chapter 18
3. Chapter 18 Biology: Previous Year Questions and Answers
4. Chapter-Wise NCERT Class 11 Notes Biology

The NCERT Notes for Class 11 Biology are useful for clear revision before exams and saves a lot of time. The chapter include the definition of the neural system, a summary of the human neural system, and the neuron as the structural and functional unit. In addition, Neural Control and Coordination chapter also deals with the central nervous system (CNS), reflex action and reception and processing of sense. The NCERT Notes for Class 11 help students understand complex topics in a simple way and improves exam performance.

Also, students can refer to:

• NCERT Solutions for Class 11 Biology Chapter 18 Neural Control and Coordination

Download NCERT Notes for Class 11 Chapter 18 PDF

Students preparing for school exams and for NEET can download the PDF notes for quick revision of important concepts. The notes explain the structure and functions of the nervous system in a simple and clear way. Diagrams and key points are included to make learning easier. This PDF can be accessed both online and offline to do study at anytime.

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NCERT Notes for Class 11 Chapter 18

The notes given below are a helpful resource for easy and quick revision. The Neural Control and Coordination chapter includes topics like the structure of neurons, reflex action, and coordination through the nervous system. It also explains the brain and sense organs in a clear and simple way.

Neural System

• The neural system gives an organized network for the rapid coordination of body functions.

• Coordination: Coordination among organs to support each other's functions.

• Made up of neurons that perceive, receive, and conduct stimuli.

Complexity grows:

1. Lower vertebrates: Uncomplicated neuron network.

2. Insects: Brain with ganglia and neural tissues.

3. Vertebrates: Advanced neural system.

Human Neural System

The human nervous system is divided into two parts:

Subdivisions of PNS:

• Somatic Nervous System: Regulates voluntary muscles (e.g., skeletal muscles).

• Autonomic Nervous System (ANS): Regulates involuntary muscles (e.g., smooth muscles).

• Sympathetic Nervous System: "Fight or flight" response.

• Parasympathetic Nervous System: "Rest and digest" response.

Diagram: Structure of the Human Neural System

Neuron: Structural and Functional Unit

A neuron consists of three parts:

Types of Neurons

The types of neurons based o structure are give below:

• Multipolar: One axon, multiple dendrites (e.g., cerebral cortex).

• Bipolar: One axon, one dendrite (e.g., retina).

• Unipolar: Only axon present (found in embryos).

Axon Types:

The types of axons are:

Myelinated Axons:

• Covered with a myelin sheath formed by Schwann cells.

• Found in the spinal cord and cranial nerves.

• Gaps between myelin sheaths are called Nodes of Ranvier.

Unmyelinated Axons:

• No myelin sheath; found in autonomic and somatic systems.

Diagram: Structure of a Neuron

Generation and Conduction of Nerve Impulse

The stage and process of nerve impulse can be discussed In the table given below:

Diagram: Generation of Nerve Impulse

Central Neural System (CNS)

The CNS includes the brain and spinal cord.

Brain:

Protected by the skull and covered by three layers called cranial meninges:

1. Dura mater

2. Arachnoid

3. Pia mater

Divisions of the Brain:

The divisions of the brain are as follows

Diagram: Divisions of the Brain

Forebrain

• Includes cerebrum, thalamus, and hypothalamus.

Functions:

• Cerebrum: Memory, sensory processing.

• Thalamus: Sensory relay center.

• Hypothalamus: Regulates temperature, hunger, and thirst.

Structure of Forebrain:

Midbrain

• Connects forebrain to hindbrain.

• Midbrain contains corpora quadrigemina for visual/auditory reflexes.

Structure of Midbrain:

Hindbrain

• Hindbrain includes pons, cerebellum, and medulla oblongata.

Functions:

1. Pons: Relays signals between brain regions.

2. Cerebellum: Maintains posture/balance.

3. Medulla oblongata: Controls heart rate, breathing.

Structure of Hindbrain:

Reflex Action and Reflex Arc

Reflex action is an involuntary response to a stimulus.

Components of a reflex arc:

1. Receptor

2. Sensory neuron

3. CNS (spinal cord)

4. Motor neuron

5. Effector

Diagram: Reflex Arc

Also, Read

• NCERT Notes for Class 11 Physics
• NCERT Notes for Class 11 Chemistry
• NCERT Notes for Class 11 Mathematics

Chapter 18 Biology: Previous Year Questions and Answers

Some previous year questions given below help students get familiar with the exam format and test their level of preparation.

Question 1: Which of the following is not involved in the Knee reflex?

Option 1. Muscle spindle

Option 2. Motor neuron

Option 3. Brain

Option 4. Inter neurons

Answer:

An automatic response channel that does not directly engage the brain is known as the reflex arc. It consists of parts including motor neurons, which send signals to muscles for contraction, interneurons, which let sensory and motor neurons in the spinal cord communicate, and muscle spindles, which sense changes in muscle length.

Hence the correct answer is Option (3) Brain

Question 2: Resting membrane potential is maintained by

Option 1. Hormones

Option 2. Neurotransmitters

Option 3. Ion pumps

Option 4. None of the above

Answer:

The sodium-potassium pump and leak channels are examples of ion pumps and channels that preserve a cell's resting membrane potential:
Potassium-sodium pump
For every ATP molecule, this pump transports two potassium ions into the cell and three sodium ions out of it. The potassium ion concentration gradient produced by this action adds to the resting membrane potential.

Hence, The correct answer is option (3) Ion pumps.

Question 3: Potential difference across the resting membrane is negatively charged. This is due to differential distribution of the following ions

Option 1. Na⁺ and K⁺ ions

Option 2. CO³⁺⁺ and Cl^- ions

Option 3. Ca⁺⁺ and Mg⁺⁺ ions

Option 4. Ca⁴⁺ and Cl^- ions

Answer:

The potential difference across the resting membrane is negatively charged. This is due to the differential distribution of Na⁺ and K⁺ ions. The electrical charge differential across a cell membrane caused by the combined forces of ions and their permeability is known as the membrane potential. It is essential for both cellular communication and general bodily processes.

Hence, the correct answer is Option (1) Na⁺ and K⁺ ions.

Also Read:

• NCERT Solution

• NCERT Solutions for Class 11

• NCERT Solutions for Class 11 Biology

Chapter-Wise NCERT Class 11 Notes Biology

The chapter-wise notes are given below by which students can easily access all the chapter and start practicing to score well in the exam.