Human Nervous System: Description, Development, Structure, Function, Diagram

What Is The Nervous System?

The nervous system utilises a complicated web of nerves and cells that convey messages to and from the brain and spinal cord down to various parts of the body. It is responsible for nearly every operation going on in the human body and the maintenance of homeostasis by its reactions to internal and external stimuli.

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This Story also Contains

1. What Is The Nervous System?
2. Structure Of The Nervous System
3. Neurons
4. Functions Of The Nervous System
5. Disorders Of The Nervous System
6. Recommended Video on ‘Human Nervous System’

Structure Of The Nervous System

The nervous system is foremost divided into the Central Nervous System and the Peripheral Nervous System.

Central Nervous System (CNS)

The parts of CNS include:

Brain

The brain is that part of the nervous system which forms the central organ controlling various functions and processes as a whole.

Lobes Of The Cerebrum

• Frontal Lobe: It is related to decision-making, problem-solving, and planning.

• Parietal Lobe: It processes sensory information like touch, temperature, pain, etc.

• Temporal Lobe: concerned with hearing processing and memory.

• Occipital Lobe: It controls such visual processing.

Role And Importance

• Each lobe has some special roles in the process of cognition, sensory processing, and motor control.

• It regulates any vital life process: the brainstem controls heartbeat, breathing rate, sleeping, and waking up.

Cerebellum: Coordination And Equilibrium

• It provides for smooth, coordinated muscle action; it maintains balance.

Spinal Cord

The spinal cord is another major component of the CNS and acts as a connecting link between the brain and the rest of the body. Moreover, it enables reflex actions to take place.

Structure Of The Spinal Cord

• Nerve fibres ensure that there are signals both toward and away from the brain.

• A reflex arc includes sensory neurons, interneurons, and motor neurons that give rise to quick, involuntary responses to stimuli.

Peripheral Nervous System (PNS)

It is divided into two parts:

Somatic Nervous System

Controls voluntary movements by transmitting signals to skeletal muscles.

The PNS relays information between the CNS and limbs/organ systems, so it's indispensable for the body's functioning and movements.

Structure And Function Of Nerves

• Nerves are bundles of axons that transmit signals between the CNS and the body.

Cranial Nerves

• Twelve pairs of nerves arise directly from the brain, each with specific sensory or motor functions.

Spinal Nerves

• Thirty-one pairs of nerves emerge from the spinal cord, transmitting signals to and from the body.

Autonomic Nervous System (ANS)

The ANS controls involuntary body functions, which it regulates with necessary physiological processes.

Sympathetic vs. Parasympathetic Systems

• Sympathetic Nervous System: A help system that turns on your body when under stress or during an emergency.

• Parasympathetic Nervous System: Calms the body and saves energy after stress.

Functions And Effects On The Body

• The sympathetic nervous system accelerates this rate of the heartbeat, dilates pupils, and inhibits digestion.

• The parasympathetic nervous system will slow the heart rate, constrict the pupils, and prompt digestion.

Diagram: Human Nervous System

Neurons

They are the basic units of the nervous system that convey information throughout the body.

Structure Of Neurons

• Cell Body (Soma): It contains a nucleus surrounded by usual organelles.

• Dendrites: The far ends of the dendrites receive signals from other neurons and conduct these towards the cell body.

• Axon: The axon conducts electrical impulses away from the cell body.

• Myelin Sheath: The sheath covering the axon that insulates it and increases the speed of transmission of the signal.

Classification Of Neurons

• Sensory Neurons: They carry information from sensory receptors to the CNS.

• Motor Neurons: They carry commands from the CNS to muscles and glands.

• Interneurons: These connect the sensory and motor neurons within the CNS.

Synapse And Neurotransmitters

• Synapse: This is the junction between two neurons.

• The ending of one neuron releases neurotransmitters, which carry the signal.

Diagram: Structure Of Neuron

Functions Of The Nervous System

The nervous system has important functions, including:

Sensory Input

• Sense changes in the environment with the help of sensory receptors.

Integration

• Process and interpret sensory information to make decisions.

Motor Output

• Generate responses by activating muscles and glands.

Disorders Of The Nervous System

Several disorders may occur within the nervous system and may trigger critical health concerns.

Alzheimer's Disease

• Memory loss, confusion, and cognitive decline.

• Deposits of amyloid plaques and neurofibrillary tangles within the brain.

• Medications to alleviate symptoms, and supportive care.

Parkinson's Disease

• Tremors, rigidity, and problems with balance and coordination

• Prospective loss of dopamine-producing neurons in the brain

• Medications aimed at increasing dopamine levels; physical therapy.

Epilepsy

• Recurrent seizures of variable intensity and type

• Abnormal electrical activity within the brain.

• Anti-seizure medications; surgery in some cases.

Multiple Sclerosis

• Fatigue, muscle weakness, coordination and balance difficulty

• Immune system attacking the myelin sheath of neurons.

• Immunosuppressive drugs, physical therapy.

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