Our ears are the sense organs that provide us with hearing and balance. Just like the waves created by a stone thrown into the water, sound waves exist in the air. These sound waves are perceived by the sensory receptors in our ears.
The ear consists of three sections: the outer ear, the middle ear, and the inner ear.
Parts of the Ear
a) Outer Ear: Consists of the auricle (pinna) and the ear canal. The eardrum (tympanic membrane) is located at the end of the ear canal. The auricle has a cartilaginous structure. The ear canal is a passage connecting the auricle to the middle ear. Our ear secretes a fluid called earwax (cerumen). This fluid, along with the hairs in the ear canal, prevents dust and similar substances from reaching the eardrum.
b) Middle Ear: The middle ear contains the malleus (hammer), incus (anvil), stapes (stirrup) ossicles, the Eustachian tube, and the oval window. The stapes is the smallest bone in our body. The malleus contacts the eardrum, and the stapes contacts the oval window in the inner ear. With these features, the ear ossicles form a bridge connecting the eardrum to the inner ear. The Eustachian tube opens from the middle ear to the pharynx (throat). By doing so, it balances the pressure difference between the middle ear and the outside of the body, preventing the eardrum from rupturing.
c) Inner Ear: Consists of the vestibule, the cochlea, and the semicircular canals. The vestibule transmits sound waves coming from the oval window to the cochlea. The cochlea contains auditory nerves, and the incoming sound waves are transmitted to the brain via these nerves. The semicircular canals, located in the upper part of the cochlea, are responsible for informing the cerebellum whether the body’s balance has been disturbed.
Important NOTE:
The semicircular canals in the inner ear play an important role in maintaining the body’s balance. When the body’s position changes, messages sent from here to the brain cause the brain to adjust the body’s position and maintain balance.
How Do We Hear?
1. Sound waves collected by the auricle travel through the ear canal to the eardrum and cause the membrane to vibrate.
2. Along with the vibration of the eardrum, the malleus, incus, and stapes ossicles also vibrate, and this vibration is transmitted to the oval window.
3. The stapes ensures the transmission of sound vibrations from the oval window to the vestibule in the inner ear. The vestibule sends the sound waves coming from the oval window to the semicircular canals in the cochlea.
4. The sound is perceived by the auditory receptors in the semicircular canals and transmitted to the auditory center in the brain via the auditory nerves. Thus, the event of hearing occurs.
Hearing Impairments and Their Treatment Methods
Are there people with hearing impairments around you? What could be the cause of hearing impairments? Hearing impairments have many causes. Some of these can lead to hearing loss, and some to deafness, meaning no hearing at all. Hearing impairments can be congenital (present from birth) or acquired later. Hardening of the eardrum, fusion of bones in the middle ear, and damage to the inner ear can be congenital. Sometimes, an illness or high-intensity sounds can damage the ear and cause hearing loss. If hearing loss occurs, a hearing aid must be used.
Hearing Aids: These are small electronic devices that amplify the intensity of external sounds, bringing them to a level that the ear can hear. They are generally used for hearing loss related to the inner ear but can sometimes be used for middle ear problems as well. A hearing aid amplifies sound but does not correct the hearing loss itself. They consist of some basic parts like a microphone, battery, and earpiece. Hearing aids can be used by people of all ages with hearing impairment.
Wireless Technology: This is a new technology that provides wireless transmission from the non-hearing ear to the hearing or partially hearing ear. With this device, the patient hears sounds better.
Our Organ of Touch: The Skin
The skin is our largest sense organ and completely covers the outside of our body. It also regulates body temperature, aids in respiration and excretion, and protects the body from external factors. The skin contains receptors that perceive senses such as touch, pressure, pain, heat, cold, etc.
Let’s learn about the layers of the skin by examining the figure below.
The skin consists of two layers: the epidermis (upper skin) and the dermis (lower skin).
Layers of the Skin
a) Epidermis (Upper Skin): This is the layer that protects the underlying parts of the skin. This layer does not contain blood vessels or nerves. The outermost part of the epidermis is made up of dead cells. Below this section is a layer composed of living cells. This layer protects the skin from harmful rays from the sun. The epidermis also contains cells that determine skin color.
b) Dermis (Lower Skin): The dermis is thicker than the epidermis and is composed of living cells. The dermis contains blood vessels, arrector pili muscles, nerves, sweat glands, sebaceous glands, hair follicles, and sensory receptors. The layer at the very bottom of this section is the fatty layer. The fatty layer protects the body against bumps and blows and prevents the body from losing heat. The sweat glands located here aid in excretion through sweating.
How do we feel with our skin?
Sensory receptors in the dermis perceive senses such as hot, cold, pressure, hardness, and softness. The sensations received by the sensory receptors are transmitted to the brain via nerves, where they are processed and perceived. Sensory receptors are not evenly distributed across the skin. Therefore, the sense of perception is not the same in every region of our skin. Perception is higher in areas such as fingertips and lips.
Skin Diseases and Their Treatment Methods
Skin diseases can be caused by physical factors (like sharp, crushing objects, or chemical substances) as well as by parasites. Some of these include fungal diseases and skin disorders resulting from bites by parasites like fleas and ticks. Certain microorganisms that cause skin inflammation can easily settle on any wound on the skin. Allergic skin diseases include urticaria (hives) and eczema. A device called a dermatoscope is used in the diagnosis of some skin diseases.
Dermatoscope: Sunspots and moles on the bodies of individuals with fair skin and numerous moles, as well as those whose family members have previously had skin cancer, are examined with a dermatoscope. Based on the examination with the dermatoscope, individuals determined to be at risk are either given medication or undergo surgical intervention.
Important NOTE:
The skin is our largest sense organ, covering the entire exterior of the body.
The function of the skin is to regulate body temperature, assist in respiration and excretion, and protect the body from external factors.
The skin has receptors that perceive senses such as touch, pressure, pain, heat, etc.
The nose is our organ for smell and respiration. This organ ensures that the inhaled air is cleaned, warmed, humidified, and its scent is perceived. If the same odor is inhaled for a period, it is no longer sensed after a while. However, when a different scent enters the environment, this new scent is noticed. Let’s examine the structure of the nose, its sections, and the surrounding sinuses on the figure below.
The nose is an organ supported by bone and cartilage. The wall of the nasal cavity is covered with cells that produce mucus secretion. This mucus-producing layer is called the mucosa. The mucosa keeps the inside of the nose moist. Olfactory receptors are located in the upper part of the nasal cavity. The region where the olfactory receptors are concentrated is called the yellow spot (olfactory region).
How Do We Perceive Scent?
1. Particles that evaporate from odorous objects and mix with the air dissolve in the mucus fluid in the yellow spot, stimulating the olfactory receptors.
2. The stimuli are transmitted to the brain’s olfactory center. Thus, the sense of smell is perceived.
Some Nasal Diseases
Sinusitis: Inflammation of the sinuses is called sinusitis. It can be treated with medication recommended by a doctor.
Hay fever: Hay fever is an allergy. During spring and summer, pollen is carried by the winds and spreads over wide areas. Pollen that settles in our nose with the air we breathe causes the nose to secrete a watery discharge, accompanied by severe sneezing. It can be treated with medications or by vaccination.
Runny nose (Rhinorrhea): A runny nose can occur due to a cold, hay fever, sinusitis, allergic rhinitis, or something having entered the nose. A runny nose is also seen at the onset of measles.
Nosebleeds (Epistaxis): Nosebleeds can be seen during adolescence due to growth. In middle age, nosebleeds caused by high blood pressure may occur. First aid to stop nosebleeds is to immediately sit the patient down, tilt their head slightly forward, press the bleeding nostril for about ten minutes, and instruct them to breathe through their mouth and avoid swallowing during this time.
Important NOTE:
The nose, which is the organ of smell and respiration, plays a role in cleaning, warming, humidifying, and perceiving the scent of the inhaled air.
How Do We Taste?
We like the taste of some foods, but not others. Do you know how we distinguish that pepper is hot, lemon is sour, and chocolate is sweet? Does our tongue, which is responsible for perceiving these different tastes, have other functions? Our tongue has functions such as tasting, chewing, swallowing, and aiding speech. For substances to be tasted, they must dissolve in saliva. Let’s examine the structure of the tongue and the taste regions on the figure below.
Taste buds are located on the tip, sides, and back of the tongue. Taste buds contain receptors for perceiving tastes. Every region of our tongue can perceive every taste. However, taste buds that perceive certain tastes are more concentrated in some areas of our tongue. The tip of our tongue perceives sweet tastes more, the back perceives bitter tastes more, the front sides perceive salty tastes more, and the back sides perceive sour tastes more.
1. Substances dissolved in saliva stimulate the receptors in the taste buds.
2. The receptors transmit the stimuli they receive to the taste nerves.
3. The taste nerves stimulate the taste center in the brain, and the sense of taste is perceived.
Some Tongue Diseases
Taste Blindness (Ageusia): Some people cannot taste certain substances. This hereditary condition is called taste blindness.
Glossitis (Tongue Inflammation): This is a type of disease that can be seen in people with rotten teeth, gingivitis, smokers, or those who have made eating very hot or very cold things a habit.
Tongue Sores: Redness around the tongue and small water-filled blisters are symptoms of tongue sores. This condition can stem from indigestion or the flu.
Hearing-impaired people use sign language to communicate with their environment.
This sign language relies on symbolic gestures that use only the hands to express letters or words. Although this language does not completely replace hearing and speaking, it largely solves the communication problem for the hearing-impaired.
The Braille Alphabet, used for the visually impaired, uses characters composed of raised dots. The visually impaired can read texts written with this alphabet by using the tips of their fingers.
Important NOTE:
The tongue aids in tasting, swallowing, and speaking.
For substances to be tasted, they must dissolve in saliva.
Taste buds, which perceive tastes, are located on the tip, sides, and back of the tongue.
Taste buds contain receptors for perceiving tastes.
Metabolism: The entirety of the constructive and destructive events that occur in living organisms.
For our Eye Health:
• We must keep our eyes clean. We should not use towels or glasses belonging to others.
• We should not watch television for long periods or from close range.
• We must ensure the distance between our eyes and the book is 20–35 cm during reading.
• We must protect our eyes from excessive light.
• We should eat foods containing Vitamin A to enhance our eyesight.
For our Ear Health:
• We must keep our ears clean.
• We must protect our ears from the cold.
• We must not probe our ears with hard objects.
• We must protect our ears from external impacts.
• We must avoid loud environments.
• In environments with loud noises like explosions, we must open our mouths to prevent the pressure from damaging our eardrum.
For our Nose Health:
• We must not pluck our nasal hairs.
• We must not pick our nose.
• We must not smoke.
• We must not smell substances whose identity we do not know or those with sharp odors.
For our Skin Health:
• We must protect our skin from crushing, cuts, and burns.
• We must prevent microbes from breeding on the skin by keeping our bodies clean. For this, we must remove dirt and dead cells from our skin by washing frequently.
For our Tongue Health:
• We must prioritize oral hygiene.
• We must avoid very hot or very cold foods and drinks.
• We must not consume alcohol or tobacco and should stay away from certain chemical substances that could harm our tongue.
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