Maintaining Healthy Sense Organs and Nervous System

Healthy Habits for Sense Organs

Provide multidirectional protection. Eat a healthy diet, avoid harmful substances, have routine examinations, maintain good hygiene, and avoid injuries.

Specific Preventive Measures

Eyes

• Use sunglasses to prevent overexposure to intense light.
• Read or do precision work in bright light.
• Do not rub your eyes when they itch.
• Rest your eyes periodically; look into the distance regularly when working at the computer.

Ears

• Remove excessive earwax by washing the outer ear; do not insert anything into the auditory canal.
• Avoid loud noise; use headphones at a moderate volume to prevent hearing loss.

Skin

• Shower or wash daily.
• Avoid UV radiation, which causes severe sunburn and skin cancer.
• Cover your body or use sunscreen during the hottest hours.

Mouth

• Brush your teeth after every meal.
• Gently brush your tongue to keep the taste buds clean.

The Nervous System

Detects and interprets external and internal stimuli. It then produces the necessary responses for the body to function and transmits them to the effectors. Neural tissue is made up of two cells:

Neurons

Generate and transmit nerve impulses. They have three parts: cell body, dendrite, and axon (which divides into branches).

Neurons Classified by Function

• Sensory neurons: Send information from receptors to the CNS.
• Motor neurons: Send responses from the CNS to effectors, causing muscle contractions or gland secretions.
• Relay neurons: Connect sensory and motor neurons.

Glial Cells

Surround neurons, providing support and protection. Main types:

• Astrocytes: Star-shaped cells that transport nutrients to neurons.
• Microglia: Remove cellular waste and protect against microorganisms like bacteria.
• Oligodendrocytes and Schwann cells: Produce the myelin cover found on some axons, which helps to transmit nerve impulses.

Transmission of Nerve Impulses

Neurons transmit information as electrical signals. These impulses travel along the neuron, always in the same direction, and exit through the axon terminal. Transmission occurs at a synapse between a presynaptic and postsynaptic neuron.

Synapse

Neurons are not physically connected. There is a gap called the synaptic cleft. The axon terminal of the presynaptic neuron releases chemical messengers called neurotransmitters.

The Nervous System's Role

Controls the internal environment (homeostasis) and enables the body to interact with the external environment. Consists of the central nervous system and peripheral nervous system.

Central Nervous System

The brain and spinal cord. Surrounded by three membranes called meninges and by cerebrospinal fluid.

Brain

Protected by the skull.

• Cerebrum: Interprets the information sent by the sense organs. Controls voluntary actions and emotional and intellectual processes like thinking and speech.
• Cerebellum: Under the brain. Controls posture and balance. Coordinates complex voluntary movements like walking.
• Brain stem: Connects the brain to the spinal cord. Controls involuntary functions such as heartbeat, breathing, and sleeping.

Spinal Cord

A column of nerve tissue about 1 cm in diameter. Protected by the spinal column. Connects the brain to the PNS.

Peripheral Nervous System

Connects the CNS with organs, limbs, and skin.

• Peripheral nerves: Composed of axons grouped in bundles.
• Cranial nerves: Emerge from the brain.
• Spinal nerves: Emerge from the spinal cord.
• Sensory nerves: Transmit information from receptors to the CNS.
• Motor nerves: Transmit information from the CNS to effectors.