Sensory Receptors: Understanding the Human Body's Senses

1. Sensory Receptors

Sensory receptors are responsible for perceiving information, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces feeling.

1.1. Types of Sensory Receptors

Sensory receptors can be classified according to the stimuli that they can receive, or by where they are located.

1.1.1. According to the Stimuli

• Photoreceptors: They detect light stimuli and are located in the eye.
• Mechanoreceptors: They are stimulated by mechanical changes such as pressure, contact, or sound waves.
• Chemoreceptors: They respond to chemical changes.
• Thermoreceptors: They detect temperature changes.

1.1.2. According to Their Location

• Internal receptors: They are located in the internal organs where they collect information about them.
• External receptors: They are located on the surface of the body and are responsible for collecting information about the external environment.

2. The Eye

The eye is the organ where the sense of sight is located.

2.1. Anatomy of the Eye

• Globe:
• Accessory organs:

2.2. How the Eye Works

When light hits the retina, special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.

3. The Ear

The ears are the sensory organs located inside the cavities of the temporal bones.

3.1. Anatomy of the Ear

• The outer ear: Formed by the eardrum.
• The middle ear: Formed by the oval window and round window, hammer, anvil, and stirrup.
• The inner ear: Formed by the membranous labyrinth, bony labyrinth, perilymph, and endolymph.

3.2. How the Ear Works

Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes.

3.2.2. Balance

• Knowledge of the body's position or perception of static balance.
• Detecting movement or perception of dynamic balance.

4. The Skin

The skin is an organ that has sensory receptors that perceive very diverse stimuli through touch.

Sensations:

• The shape and texture.
• The pressure.
• The heat and cold.
• The pain.

Other structures of skin:

• Melanocytes.
• Adipose tissue.
• Sweat glands.
• Hair.
• Sebaceous glands.

5. Taste

Taste allows us to detect chemical substances from foods as they dissolve in our saliva.

6. Smell

Our sense of smell allows us to perceive gas molecules that reach our nose.