The Senses of Hearing and Health of Sense Organs
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The Senses of Hearing
5) THE SENSES OF HEARING: 
6) THE HEALTH OF THE SENSE ORGAN:
Short-sightedness (myopia): distant objects appear out of focus because the eyeball is too long, so images are focused in front of the retina. Concave lenses or surgery can correct the problem.
Long-sightedness (hypermetropia): close objects appear out of focus because the eyeball is too short. This causes images to be focused behind the retina. Convex lenses or surgery can correct the problem.
Astigmatism: objects appear distorted or blurred. It is caused by an irregularly shaped cornea. Lens or surgery can correct the problem.
Cataracts: the crystalline lens loses its transparency until it becomes opaque. This causes progressive loss of vision and possible blindness.
Conjunctivitis: an inflammation of the conjunctiva. It is usually caused by an infection or allergy. 
Typical Disorders of the Skin, Ear, and Nasal Passages
TYPICAL DISORDERS OF THE SKIN, EAR AND NASAL PASSAGES |
Organ | Disorders | Description and Causes |
Skin | Urticaria (hives) | A rash or welt caused by an allergic reaction to food or medicine. |
Psoriasis | A chronic condition that produces thick red skin with silver scales. | |
Ear | Otitis | An acute or chronic inflammation usually caused by inflammation. |
Deafness | Hearing loss. It may be genetic or caused by diseases or trauma. | |
Nasal Cavities | Rhinitis | Inflammation of the nasal respiratory membrane often caused by allergies. It causes nasal congestion, sneezing, etc. |
Health Habits for the Sense Organs
Eat a healthy diet. Avoid the use of harmful substances. Have routine examinations. Maintain good hygiene and avoid injuries.
7) COMPONENTS OF THE NERVOUS SYSTEM:
The neurons function: Sensory neurons, Motor neuron, and Relay neurons.
Transmission of Nerve Impulse:
The presynaptic neuron transmits the impulse, it goes through the axon, the postsynaptic neuron receives the impulse and it sends it to the axon terminals.
Synapse: Neurotransmitters, Synaptic cleft, Receptors (postsynaptic neuron)
8) RESPONSES OF THE SOMATIC NERVOUS SYSTEM:
Voluntary response: 1) The stimulus is detected by a receptor, 2) The stimulus is transmitted by the optic nerve to the brain, 3) The brain interprets the stimulus and responds, 4) The response is transmitted as a nerve impulse from the brain through a motor nerve to the muscles, 5) The muscles carry out the response.
Involuntary response: 1) The stimulus is detected by a receptor, 2) Sensory neurons transmit nerve impulses to the spinal cord, 3) A relay neuron in the spinal cord connects the sensory neuron to the motor neuron, 4) The motor neuron carries the response to a muscle, 5) The muscle carries out the response.
9) THE HEALTH OF THE NERVOUS SYSTEM: Infectious diseases, Cerebrovascular events, Physical trauma, progressive neurodegenerative diseases (multiple sclerosis (MS), Alzheimer's, Parkinson's)
10) MENTAL HEALTH: Phobias - A disorder due to a persistent, irrational fear; for example, fear of small places. Dementia - A disease characterized by declining brain function. Symptoms include problems with memory, language, and identity. Causes are varied: injury, disease, aging, etc. Depression - A mood disorder that interferes with daily life. Symptoms vary: sadness, low self-esteem, negative and suicidal thoughts. Schizophrenia - A brain disorder that appears in adolescence or adulthood. Symptoms include hallucinations and drastic changes in behavior.
11) HEALTHY HABITS FOR THE NERVOUS SYSTEM: Maintain an orderly life. Exercise. Develop social relationships. Perform intellectual activities regularly. Take proactive measures to prevent injury. Avoid smoking, drinking alcohol, or using drugs (Drugs and Health) - Stimulants, Depressants, Mind-altering, Tolerance, Dependence.