Neural Control and Coordination Class 11
In this article, you will get a great idea about the topic concerned with the central nervous system and the peripheral nervous system. Thus, the students will be beneficial in attaining neural control and coordination class 11 notes.
What is Neural Control and Coordination?
It is an important topic of human physiology. The nervous system constituting neurons have great significance and one should understand all the basics and functional parts of the nervous systems including classification of neurons in order to perform well in the examinations and this topic is well covered in the NEET MCQs too.
The process through which two or more organs can interact and complement the functions of one another is called coordination. When we are exercising, the supply of oxygen as well as demand of energy increases with increase in muscular activity. When we stop physical exercise, all activities of nerves, heart, lungs and kidney are normalized. Therefore, the functions of all the organs are well coordinated to perform physical exercise and render necessary conditions during the physical exercise. Similarly, in our bodies, the neural system and the endocrine system together coordinate and integrate all the organs’ activities to function in a synchronized manner.
The neural system or nervous system is an organised network of point-to-point connections for quick coordination and the endocrine system is the requirement for a chemical integration through hormones. In this article, we will discuss the human neural system and the mechanisms of neural coordination.
All the following topics are well covered in Neural control and coordination NCERT books for class 11.
Neural System
Highly specialised cells known as neurons that have the role to detect, receive and transmit various kinds of stimuli are present in the neural system of all animals. In lower vertebrates such as Hydra, the nervous system organisation is very simple with a network of neurons. In insects, it is better organised where the brain consists of numerous ganglia and neural tissues. Ganglia is the collection of cell bodies outside the central nervous system. On the other hand, vertebrates have a more developed nervous system.
Human Neural System
Neurons can be unipolar, bipolar and multipolar.
Central nervous system includes the brain and the spinal cord. Also referred as CNS, it is the site for processing information and control.
Brain comprises cerebrum, cerebellum, medulla oblongata, midbrain and brainstem. Brainstem performs vital functions like regulation of temperature and helps hypothalamus in functioning. Cerebrum helps in memory and cerebellum functions in regulation.
Peripheral nervous system includes autonomic nervous system (involuntary) and somatic system (voluntary). It comprises the two kinds of nerve fibers associated with CNS, namely, afferent fibres and efferent fibres.
The somatic neural system (SNS) transmits impulses from the CNS to skeletal muscles and the autonomic neural system (ANS) relays impulses from the CNS to involuntary organs and smooth muscles of the body. ANS is further divided into sympathetic nervous system and parasympathetic nervous system. The former one works during fight, fright and flight (3F) conditions. The latter works during rest or digest conditions.
Neuron: Structural and Functional Unit of Neural System
A neuron is the microscopic structure that consists of three important structures which are the cell body, dendrites and axon.
Cell Body: It contains cytoplasm with typical cell organelles as well as certain granular bodies called Nissl’s granules.
Dendrites: These are the short fibres containing Nissl’s granules that project out of the cell body. Dendrites are responsible to transmit impulses towards the cell body.
Axon: It is a long fibre and its distal end is branched. Each of its branches terminates as a bulb-like structure called synaptic knob that possess synaptic vesicles that have chemicals called neurotransmitters that follow unidirectional flow. The two types of axons are myelinated and non-myelinated nerve fibres; the myelinated one are enveloped with Schwann cells forming a myelin sheath around the axon and found in spinal and cranial nerves. Nodes of Ranvier is the term given to the gaps between two adjacent myelin sheaths. Non-myelinated nerve fibre doesn’t form a myelin sheath around the axon but contains Schwann cells, and is found commonly in ANS and SNS.
The role of axons is to transmit nerve impulses away from the cell body to a synapse or to a neuro-muscular junction.
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Depending on the number of axons and dendrites, the neurons can be classified into three types which are as follows:
Multipolar Neurons: it consists of one axon and 2 or more dendrites and is found in the cerebral cortex.
Bipolar Neurons: It consists of one axon and one dendrite and is found in the retina of the eye.
Unipolar Neurons: It is the cell body with only one axon and is found in the embryonic stage.
Generation and Conduction of Nerve Impulse
This topic is very elaborately explained in the neural coordination chapter in the NCERT books for class 11. Here, we understand a bit of it which can be included in neural control and coordination notes.
Neurons are excitable cells and are called so because they conduct electricity.
Their membranes are polarised and different types of ion channels are present in the neural membrane called axolemma. These ions are selectively permeable to different ions.
Resting membrane potential is the resting state when a neuron is not conducting any impulse. The axonal membrane is more permeable to Potassium ions (K+) and nearly impermeable to sodium ions (Na+).
FAQs on Neural Control and Coordination
1. What is meant by neural control and coordination in the human body?
Neural control and coordination refers to the process by which the nervous system regulates and integrates the activities of different organs and organ systems in the body. It allows the body to respond quickly and appropriately to internal and external stimuli, ensuring all parts work together in a synchronized manner to maintain homeostasis and carry out complex behaviours.
2. What are the fundamental parts of a neuron and what role does each part play?
A neuron, or nerve cell, is the structural and functional unit of the nervous system. Its main parts are:
- Dendrites: These are branched, tree-like extensions that receive signals from other neurons and transmit them towards the cell body.
- Cell Body (Soma): This contains the nucleus and other organelles. It processes the incoming signals and generates a nerve impulse if the stimulation is strong enough.
- Axon: This is a long, slender projection that carries the nerve impulse away from the cell body to other neurons, muscles, or glands.
- Axon Terminal: Located at the end of the axon, these branches release neurotransmitters to pass the signal across a synapse to the next cell.
3. How is a nerve impulse, or action potential, generated and transmitted along a neuron?
A nerve impulse is an electrical signal that travels along a neuron's membrane. It is generated when a stimulus causes a rapid change in the neuron's membrane potential. Initially, the membrane is in a resting state (resting potential). Upon stimulation, ion channels open, allowing an influx of positive ions (like Na+) which depolarises the membrane, creating an action potential. This wave of depolarisation then propagates along the axon, moving from one point to the next until it reaches the axon terminal.
4. What is a synapse, and what are the key differences between a chemical and an electrical synapse?
A synapse is the specialised junction where a signal is transmitted from one neuron to another cell. The two main types differ significantly:
- Chemical Synapse: The neurons are separated by a fluid-filled space called the synaptic cleft. The signal is transmitted by chemical messengers called neurotransmitters. This process is slower but allows for more complex signal modulation.
- Electrical Synapse: The membranes of the pre- and post-synaptic neurons are in very close proximity, connected by gap junctions. The electrical current flows directly from one neuron to the next. This transmission is extremely fast but less versatile than a chemical synapse.
5. What are the main divisions of the human nervous system?
The human nervous system is broadly divided into two main parts:
- The Central Nervous System (CNS), which consists of the brain and the spinal cord. It acts as the primary processing and control centre.
- The Peripheral Nervous System (PNS), which includes all the nerves that branch out from the CNS to the rest of the body. The PNS is further divided into the somatic nervous system (controls voluntary actions) and the autonomic nervous system (controls involuntary actions).
6. Explain the path of a reflex action using the concept of a reflex arc.
A reflex action is a rapid, involuntary response to a stimulus. The neural pathway it follows is called the reflex arc. The typical path involves five components:
- A receptor detects the stimulus (e.g., heat on the skin).
- An afferent neuron (sensory neuron) transmits the signal from the receptor to the spinal cord.
- An interneuron in the spinal cord processes the signal and relays it.
- An efferent neuron (motor neuron) carries the command from the spinal cord.
- An effector (e.g., a muscle) responds by contracting, pulling the hand away from the heat.
7. What are the major parts of the human brain and their primary functions?
The human brain is the command centre of the nervous system and is divided into three main parts:
- Forebrain: Consists of the cerebrum, thalamus, and hypothalamus. The cerebrum is the centre for thought, memory, intelligence, and voluntary actions. The hypothalamus controls body temperature, hunger, and thirst.
- Midbrain: It is located between the forebrain and hindbrain and is involved in processing visual and auditory information, as well as controlling eye movement.
- Hindbrain: Comprises the pons, cerebellum, and medulla oblongata. The cerebellum coordinates motor control and balance, while the medulla controls essential involuntary functions like breathing and heart rate.
8. Why is the myelin sheath essential for the efficient functioning of the nervous system?
The myelin sheath is a fatty, insulating layer that surrounds the axons of many neurons. Its importance lies in its ability to dramatically increase the speed of nerve impulse transmission. It prevents the electrical signal from leaking out of the axon and forces the action potential to "jump" from one unmyelinated gap (Node of Ranvier) to the next. This process, known as saltatory conduction, is much faster and more energy-efficient than conduction along an unmyelinated axon.
9. How does the human eye perceive an image, and what are the roles of rods and cones?
The human eye functions like a camera. Light enters through the cornea, is focused by the lens, and forms an inverted, real image on the retina. The retina contains two types of photoreceptor cells that convert light into neural signals:
- Rods: These cells are highly sensitive to low light levels and are responsible for vision in dim light (scotopic vision). They do not detect colour.
- Cones: These cells function in bright light (photopic vision) and are responsible for colour vision and high-acuity detail. There are three types of cones, each sensitive to different wavelengths of light (red, green, and blue).
10. What is the functional difference between the sympathetic and parasympathetic nervous systems in our daily life?
The sympathetic and parasympathetic systems are two divisions of the autonomic nervous system that have opposing effects to maintain bodily balance (homeostasis).
- The Sympathetic Nervous System prepares the body for "fight-or-flight" responses during times of stress, danger, or excitement. It increases heart rate, dilates pupils, and diverts blood flow to muscles.
- The Parasympathetic Nervous System promotes "rest-and-digest" functions when the body is calm. It slows the heart rate, constricts pupils, and stimulates digestion and other metabolic processes.
