Neural Control and Coordination

Why Study Neural Control and Coordination?

Neural Control and Coordination explains how the nervous system receives information, processes the stimulus and coordinates responses throughout the body. Along with this, it also helps understand sensory perception, reflex actions, voluntary movements, memory, learning, etc.

Important Topics of Neural Control and Coordination

This chapter highlights major regions of the nervous system. The Central Nervous System (CNS), which includes the brain and spinal cord, is the primary command centre for information processing. The Peripheral Nervous System (PNS) links the CNS to the rest of the body via nerves. The Autonomic Nervous System regulates involuntary functions such as heartbeat and digestion through its sympathetic and parasympathetic divisions. The other notable concepts are reflex actions, reflex arc, synapses, and neurotransmission, which describe how the body reacts rapidly to stimuli. Hence, the important topics are:

• Central Nervous System (CNS)

• Peripheral Nervous System (PNS)

• Autonomic Nervous System

• Important Concepts - Reflex Actions, Reflex Arc, Synapses and Neurotransmission

What is Neural Control and Coordination?

Coordination is the mechanism by which two or more organs collaborate to help one another's function. For example, when physical exercise is undertaken, the oxygen and energy requirements of the body are increased by increased muscle activity. In the same way, the heart beats more rapidly, lungs labour more, and kidneys modify fluid balance, all coordinated by the nervous and endocrine systems. When the activity is over, these systems restore the body to regular functioning. This smooth adjustment explains how various organs collaborate through nerve impulses and hormones to keep the interior balanced and react effectively to shifting demands.

• The nervous system facilitates fast communication through a point-to-point electrical signalling system.
• The nervous system allows for quick responses through a point-to-point electrical signalling system.
• Both systems cooperate and help in maintaining homeostasis and proper body coordination.
• Functions such as exercise, stress reaction, and growth need to have close cooperation between nerves and hormones.

The Nervous System

The Nervous System is a very rapid point-to-point communication network. Communication in the endocrine system, through the synthesis and release of hormones, is much slower. Combined, they form a highly complex network that controls and coordinates bodily functions.

Components of the Nervous System

There are two broad categories of the nervous system. Both of them are discussed below in the table:

Divisions of the Autonomic Nervous System

The autonomic nervous system (ANS) is an important component of the peripheral nervous system that governs involuntary activities like heart rate, digestion, and breathing rate. It is categorised into two primary divisions: the sympathetic nervous system and the parasympathetic nervous system. These two operate in tandem to keep internal equilibrium and react correctly to varying situations. Whereas the sympathetic system readies the body for coping with stress or emergencies, the parasympathetic system helps in restoring tranquillity and conserving energy during resting conditions. The comparison table for both of them is discussed below:

Neuron Structure

A neuron is the structural and functional unit of the nervous system, specialised for receiving, processing, and transmitting nerve impulses. It is composed of three components: the cell body (soma), which houses the nucleus and cytoplasm and performs metabolic activities, dendrites, which are branched projections that receive messages from other neurons and a sole axon, a lengthy fiber that transmits impulses away from the cell body to other neurons or effector organs.

In most neurons, the axon is sheathed with a myelin sheath that insulates the axon and accelerates signal transmission. The axon terminates in axon terminals or synaptic knobs, which secrete neurotransmitters in synapses to transmit signals to the following cell. The parts of neurons are discussed below:

All parts of neurons are discussed below:

• Cell Body (Soma): Houses the nucleus and organelles; is where metabolic processes and processing of arriving signals occur.

• Dendrites: Short, branch-like extensions that are receptive to signals from other neurons and direct them towards the cell body.

• Axon: A single, long fibre that conducts nerve impulses away from the cell body to effectors or other neurons.

• Axon Hillock: The cone-shaped region of the cell body where the axon begins is where the action potential is triggered.

• Myelin Sheath: Fatty insulating layer enveloping the axon (in myelinated neurons), which enhances the velocity of nerve impulse transmission.

• Nodes of Ranvier: Tiny gaps between segments of the myelin sheath facilitate saltatory conduction of impulses.

• Axon Terminals (Synaptic Knobs): Branched terminals of an axon that secrete neurotransmitters to pass the signal to the subsequent cell.

All three types of Neurons are discussed below:

Types and Functions of Axons

Axons are long extensions of neurons that carry electrical impulses to target cells. They are categorised as myelinated or non-myelinated axons depending on whether they have a myelin sheath or not, a fatty insulating structure. Myelinated axons allow for more and quicker conduction of nerve signals through saltatory conduction, which is mainly observed in the spinal cord and brain.

At the same time, non-myelinated axons do not possess this sheath and thus conduct impulses more slowly and are present primarily in the autonomic nervous system. This difference in structure significantly influences the speed and effectiveness with which the nervous system transmits.

Organs of the Nervous System

The different organs of the nervous system are described below-

Human Brain

The human brain is the main control centre of the body, protected by the skull and three membranes called the meninges. It is divided into three major parts: forebrain (controls thinking and emotions), midbrain (controls reflexes) and hindbrain (regulates balance and vital functions like breathing and heartbeat). The brain processes information from the sense organs and coordinates all voluntary and involuntary actions.

Major Parts of the Human Brain

Human Eye

The human eye is a light-sensitive organ that allows us to see. Its key parts include the cornea, lens. Iris, retina and optic nerve. Light enters through the cornea and lens, focusing the image on the retina, where photoreceptor cells convert light into nerve signals. These signals are sent to the brain via the optic nerve, which helps us with vision.

Functions of Important Parts of the Eye

Human Ear

The human ear is responsible for both hearing and balance. It is divided into three parts: the outer ear (collects sound), the middle ear and the inner ear. Sound waves are converted into nerve impulses, which are then sent to the brain for interpretation.

The middle ear contains three small bones called the malleus, incus, and stapes, which are used to amplify sound vibrations.

Functions of Important Parts of the Ear

Reflex Action

Reflex action is a quick, automatic and involuntary response to a stimulus which protects the body from harm. For example, pulling your hand away when you touch something hot. Reflexes are controlled by the spinal cord and occur without conscious thinking. The pathway taken by nerve impulses in a reflex is called a reflex arc, which includes receptors, sensory nerves, the spinal cord, motor nerves, and effectors like muscles. This fast reaction helps the body respond instantly to danger.

Difference Between Reflex Action and Voluntary Action

Reflex actions are fast, automatic responses that occur without conscious thought and help protect the body from harm. Voluntary actions are deliberate responses that are performed under conscious control. Here are a few important differences between reflex action and voluntary action.

Neuronal Communication and Signal Conduction

Neurons transmit signals by generating electrical impulses along their membranes, which are in a polarised state at rest. This resting condition is called the resting membrane potential, where the neuron has high permeability to potassium and low permeability to sodium ions, creating a negative charge inside the cell. The plasmalemma, or the neuron's membrane, contains ion channels that open and close to regulate the movement of ions. These channels help maintain the resting state and allow the neuron to generate and conduct impulses when stimulated.

Synapse and Signal Transmission

Synapses are junctions where neurons communicate. The signal transmission occurs via electrical or chemical synapses. Chemical synapses release neurotransmitters to relay information, which is fundamental in neural control and coordination questions and answers. The synaptic mechanism underpins critical concepts that appear in neural control and coordination, NEET PYQ.

Types of Synapses

Synapses are classified into two major types on the basis of the mode of signal transmission.

Chemical Synapse

Chemical synapses transmit signals through neurotransmitters released into the synaptic cleft.

Electrical Synapse

Nerve impulses pass directly from one neuron to another through gap junctions without the use of neurotransmitters.

Neural Control and Coordination Revision Notes

• CNS consists of the brain and spinal cord.

• PNS connects the CNS with the body organs.

• ANS controls involuntary activities.

• Neurons transmit electrical impulses.

• Synapses allow communication between neurons.

• Myelin sheath increases conduction speed.

• Reflex actions are rapid and involuntary.

• The cerebellum maintains posture and balance.

• The retina contains photoreceptor cells.

• Cochlea is responsible for hearing.

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