Human Nervous System and Neuron Functionality

Organization of the Nervous System

The nervous system is organized into two main parts. The Central Nervous System (CNS) consists of the brain and the spinal cord. It is protected by a membrane called the meninges.

Structure of the Central Nervous System

The brain is housed within the cranial cavity. It includes the cerebrum, the cerebellum, and the medulla oblongata. The medulla connects the brain with the top of the spinal cord.

• Cerebrum: It is divided into two parts. The surface features protrusions called convolutions and indentations called sulci or fissures.
• Cerebellum: Located below the brain, the cerebellum's role is to coordinate movements.
• Spinal Cord: Located inside the vertebral column, it is a neural pathway and acts as the source of the "boss's orders."

The Peripheral Nervous System (PNS)

The Peripheral Nervous System consists of the spinal nerves and cranial nerves. Based on their function, they can be classified as:

• Sensory Nerves: These carry information from the sense organs and guts to the Central Nervous System.
• Motor Nerves: These carry orders from the Central Nervous System to the muscles and organs responsible for carrying out the response.

The Neuron: Structure and Function

Neurons are highly specialized cells that transmit nerve impulses.

Structure of the Neuron

A neuron consists of the cell body or soma, which contains the nucleus and most of the cytoplasm, and two types of prolongations:

• Dendrites: Short and highly branching extensions.
• Axon: A long and unbranched prolongation, except at its very end.

Neuron Function and Synapses

To transmit nerve impulses, connections called synapses are established between neurons. In a synapse, there is no physical contact; impulse transmission occurs via chemicals called neurotransmitters.

Nervous System Disorders and Hormones

Nervous Disorders

Disorders of the nervous system include:

• Organic Disorders: Physical abnormalities in the organs of the nervous system. These include shock, obstruction, infectious diseases, and meningitis.
• Degenerative Diseases: Such as Alzheimer's disease.
• Psychiatric Illnesses: Such as anxiety or depression.

Hormonal Influence

The system is also influenced by hormones:

• Thyroid: Produces thyroxine, which stimulates the chemical activity of the cell.
• Adrenal: Produces adrenaline, which stimulates the heart rate and breathing.