Understanding the Nervous System: Structure, Function, and Health

The Nervous System: An Overview

The nervous system’s basic units are neurons, responsible for receiving sensory information and transmitting responses. A neuron consists of a cell body, short branching extensions called dendrites, and an extension called an axon. Glial cells, including astrocytes, microglia, and Schwann cells, also play crucial roles.

Functions of the Nervous System

The nervous system’s function relies on connections between neurons. Sensory neurons transmit impulses from organs to the spinal cord and brain. Motor neurons transmit impulses from the brain and spinal cord to effectors. Interneurons connect neurons to each other.

Voluntary and Reflex Actions

Voluntary actions involve receiving information from vision and touch, which is transmitted to the brain. Reflex actions involve information from stimuli like heat reaching the spinal cord, triggering a motor response to effectors.

Major Diseases of the Nervous System

Degenerative diseases cause nerve tissue damage. Abnormal nervous system development can lead to irreversible paralysis. Injuries, such as strokes, can also damage the nervous system. Psychological disorders, like mood swings, can sometimes stem from organic problems.

Risk Factors and Prevention

• Use of addictive substances: Alcohol and drugs can cause irreversible damage. Prevention involves strong social pressure against substance use.
• Reckless conduct: Activities like cycling or driving increase the risk of trauma. Prevention includes using protective gear and responsible behavior.
• Noisy environments: Can cause hearing disorders. Avoid noisy places or use ear protection.
• Exposure to bright light: Can cause eye injury. Wear sunglasses.
• Prolonged screen use or low-light reading: Can lead to refractive anomalies. Limit screen time.
• Vitamin A deficiency: Can cause vision problems.

Central Nervous System

The central nervous system coordinates responses and is divided into the brain and spinal cord.

Brain

The brain contains the cerebrum, divided into two hemispheres with lobes and convolutions, which interprets sensory information, controls voluntary movement, and develops advanced functions. The cerebellum, also divided into two hemispheres, and the brainstem, which connects the brain to the spinal cord, are also key components.

Spinal Cord

The spinal cord is a thick nerve cord with two functions: a communication path for stimuli to and from the brain, and the development of simple responses.

Peripheral Nervous System

The peripheral nervous system is made up of nerves, including cranial nerves (12 pairs from the brain) and spinal nerves (31 pairs from the spinal cord).

Somatic and Autonomic Nervous Systems

The somatic nervous system connects the central nervous system to skeletal muscles and skin receptors. The autonomic nervous system connects to internal organs and has sympathetic and parasympathetic components.

Vision Anomalies

• Myopia: Abnormal eyeball enlargement causing images to focus in front of the retina.
• Hypermetropia: Abnormal eyeball shortening causing images to focus behind the retina.