Neural control and coordination refer to the coordinated action of the nervous system and endocrine system to regulate the internal environment of the body and maintain it. The nervous system facilitates rapid communication through neurons, which convey electrical impulses to coordinate both voluntary and involuntary movements. A neuron can carry impulses up to 120 m/s. These impulses are transferred through synapses, specialised contacts via chemical neurotransmitters such as acetylcholine and dopamine. Reflexes, or rapid automatic reactions to stimuli, function through a reflex arc that is normally composed of sensory neurons, spinal interneurons, and motor neurons.
This chapter also discusses the organisation of the peripheral and central nervous systems. The central nervous system (CNS), brain, and spinal cord receive information and send out orders. The peripheral nervous system (PNS) consists of all tissues outside the CNS and is divided into the somatic and autonomic systems. The autonomic nervous system (ANS) is subdivided into sympathetic and parasympathetic divisions that act in opposition to uphold internal stability. Collectively, these systems provide coordinated responses to internal stimuli as well as environmental alterations and assist the body in maintaining homeostasis.
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
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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 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.
There are two broad categories of the nervous system. Both of them are discussed below in the table:
Feature | Central Nervous System (CNS) | Peripheral Nervous System (PNS) |
---|---|---|
Components | Brain and spinal cord | All neural tissues outside the CNS (nerves and ganglia) |
Location | Within the skull and vertebral column | Outside the skull and vertebral column |
Function | Processing and integrating information control centre | Transmission of signals between the CNS and the rest of the body |
Protection | Enclosed by bones (skull and vertebrae) and meninges | Not enclosed in bone less protected |
Type of Neurons | Interneurons (mainly) | Sensory (afferent) and motor (efferent) neurons |
Subdivision | No further divisions | Divided into the Somatic Nervous System and the Autonomic Nervous System |
Regeneration Ability | Very limited or none | Some regeneration is possible in peripheral nerves |
Control Type | Controls both voluntary and involuntary functions | Acts as a communication relay for both voluntary and involuntary functions |
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:
Features | Sympathetic Nervous System | Parasympathetic Nervous System |
---|---|---|
Function | "Fight or flight" response | "Rest and digest" response |
Effect on Heart Rate | Increases heart rate | Decreases heart rate |
Effect on Pupil | Dilates pupils | Constricts pupils |
Effect on Digestive Activity | Inhibits digestion | Stimulates digestion |
Effect on Respiratory Rate | Increases breathing rate | Decreases breathing rate |
Effect on the Urinary Bladder | Relaxes bladder | Contracts bladder |
Neurotransmitters Involved | Norepinephrine (primarily) | Acetylcholine |
Energy Usage | Consumes energy (catabolic) | Conserves energy (anabolic) |
Origin of Nerves | The thoracic and lumbar regions of the spinal cord | Brainstem and sacral region of the spinal cord |
Overall Role | Prepares the body for action in stressful situations | Restores the body to a calm, restful state |
The neuron is the functional and structural building block of the nervous system, nerve impulses transmitting, as a specialisation. It is composed of three components: the cell body (soma), which houses the nucleus and cytoplasm and performs metabolic activities in 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:
All three types of Neurons are discussed below:
Type of Neuron | Structure | Location | Function |
---|---|---|---|
Unipolar Neuron | One axon, no dendrites | Early embryonic stages | Primitive signal transmission |
Bipolar Neuron | One axon and one dendrite | Sensory organs (e.g., retina, olfactory epithelium) | Sensory signal transmission |
Multipolar Neuron | One axon and multiple dendrites | Brain and spinal cord (e.g., cerebral cortex) | Integration and processing of information |
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.
Feature | Myelinated Axons | Non-myelinated Axons |
---|---|---|
Myelin Sheath | Present | Absent |
Conduction Speed | Fast (due to saltatory conduction) | Slow (continuous conduction) |
Appearance | White (due to fatty myelin) | Grey |
Location | Brain, spinal cord, and peripheral nerves | Autonomic Nervous System (ANS) |
Node of Ranvier | Present; impulses jump from node to node | Absent; impulse travels along the entire axon |
Energy Efficiency | More energy-efficient | Less energy-efficient |
The different organs of the nervous system are described below-
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.
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.
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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 (amplifies sound via small bones) and the inner ear ( contains the cochlea for hearing and semicircular canals for balance). Sound waves are converted into nerve impulses, which are then sent to the brain for interpretation.
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.
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.
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.
The control and coordination by the brain involve directing and regulating body functions as well as channelling sensory input, sending out signals for voluntary and involuntary actions. The brain works with the spinal cord and the peripheral nervous system to control all physiological processes in an organism.
The brain and the spinal cord are included in the central nervous system. Brain is an organ of our body that serves as the center of command and control. It is safe as it is protected by a skull and is divided into three main parts, namely, forebrain, midbrain and hindbrain. The brain regulates voluntary movement, the function of unwanted vital organs, and aids in balance.
Cranium - 8 cranial bones form a hard outer layer of the Meninges of the brain - The brain is covered with three layers called meninges. Pia mater, arachnoid membrane, and dura mater Cerebrospinal fluid - It is located in the gaps between the meninges and absorbs shock.
The various organs have sensory nerves that sense surroundings and send them across brain connections like a computer input device. The human brain can be compared to a Central Processing Unit (CPU). The data collected by sensory neurons is processed by the brain that continues to instruct a particular organ to function in harmony. Finally, the message is captured by motor neurons similar to output devices.
It can lead to cognitive impairment or physical dysfunction. In addition, it can also cause emotional or behavioural disorders. Injury to the cervix can lead to tetraplegia.
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