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Our senses: Touch and sound

How does human’s hear?

  1. Sound waves enter the outer ear through the ear canal to the eardrum
  2. The eardrum will vibrate from the incoming sound waves, these vibrations occurs in the middle ear with bones called the malleus, incus, and stapes, which amplifies or increase, the sound vibrations and send them to the inner ear.
  3. The vibrations cause the fluid to form traveling waves along the basilar membrane.
  4. Which moves to the hair cells near the wide end of the snail-shaped cochlea detect higher-pitched sounds, such as an infant crying. Those closer to the center detect lower-pitched sounds, such as a large dog barking.
  5. As the hair cells move up and down, it will bump against an overlying structure and bend. Bending causes pore-like channels, to open up and creates an electrical signal to the brain

Here is a video to explain everything above!

How does human’s feel?

Our sense of touch is controlled by a huge network of nerve endings and touch receptors in the skin known as the somatosensory system. This system is responsible for all sensing cold, heat, smooth, rough, pressure, tickle, itch, pain, vibrations, and more. Within the somatosensory system, there are four main types of receptors:

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Mechanoreceptors: Pressure, vibrations, and texture

Thermoreceptors: Found in the dermis layer of the skin, it contains two categories of  hot and cold receptors.

(Cold receptors start to perceive cold sensations when the surface of the skin drops below 35° . They are most stimulated when the surface of the skin is at 25 °  and are no longer stimulated when the surface of the skin drops below 25° .)

(Hot receptors start to perceive hot sensations when the surface of the skin rises above 30 °  and are most stimulated at 45 ° beyond this, pain receptors take over to avoid damage being done to the skin and underlying tissues.

Pain receptors: These receptors detect pain or stimuli that can or does cause damage to the skin and other tissues of the body. There are over three million pain receptors throughout the body, found in skin, muscles, bones, blood vessels, and some organs. They can detect pain that is caused by a cut or scrape, or thermal stimuli (burn), or chemical stimuli (poison from an insect sting).

Proprioceptors: It senses the position of the different parts of the body in relation to each other and the surrounding environment. Proprioceptors are found in tendons, muscles, and joint capsules. This location in the body allows these special cells to detect changes in muscle length and muscle tension. Without proprioceptors, we would not be able to do fundamental things such as feeding or playing sports.

 

What is the similarity between the frog and humans?

Hearing:

  1. Frogs, like humans have tympanum

The tympanum are part of an ear structure
– However for the frog, it is located behind its eye and is used to transmit sound waves into the inner ear. Its unique structure also allows protection and to keep it hearing while it is submerged, which is an ability humans lack as we have an outer ear structure.

2. Neuromuscular junctions

Frogs and humans also both have neuromuscular junctions that transmit motor impulses from the nervous system to muscles.

*Interesting fact! Frogs can only detect high-pitched sounds with their ears; low-pitched sounds are detected through the skin.