Anatomy And Physiology

Anatomy Physiology

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The ear is the organ which detect sound. It is also responsible for maintaining balance and body position. The ear is a transducer which converts sound waves into mechanical energy and then into nerve impulses that are then transmitted to the brain. This highly complex process allows humans and all other vertebrates to interpret the pitch of sounds by detecting the various frequency which makes up sound waves.

The ear consists of three separate part, responsible for a specific function in the hearing process. The outer ear known as the Pinna which is a funnel-like structure, sometimes also referred to as the auricle. It is the most visible part of the ear, attached on either side of the head constructed mostly of cartilage covered with skin. It has a canal leading to the middle ear, which is approximately 2cm long with an earflap which provides protection of the inner workings of the middle ear and eardrum.

The Pinna gathers the sounds which it directs to the middle ear. The middle ear is an air-filled cavity which consists of an eardrum and three of the smallest bones in the human body, known as the hammer (malleus), anvil (incus) and stirrup (stapes). The eardrum is a tightly stretched and durable membrane connected to the hammer and vibrates as the incoming pressurized sound waves connects with it and in so doing sets in motion the anvil and stirrup.

The middle ear transforms the collected sound waves into internal vibrations which activate the three small bony structures located in the middle ear. This in turn transforms the vibrations into compressional waves in the inner ear. The inner ear then transforms the energy or vibrations of compressional waves within the inner ear into nerve impulses that are then transmitted to the brain for interpretation.

The inner ear consists of the cochlea, which is a small snail-like circular shaped structure, filled with a water-like fluid, which if uncoiled is able to stretch to approximately 3cm. It is lined with 20,000 hair-like nerve endings which provides a series of critical roles in our ability to hear and also plays an active part in the mechanism, which serves to detect movement and maintain balance.

The nerve cells vary in length and has different levels of resilience to the water-like fluid that passes over them. The small hair-like nerve cells becomes activated and has a natural sensitivity to a particular frequency or vibration. The increased vibrational amplitude stimulates the cells to release electrical impulses along the auditory nerves leading to the brain, which has the capacity to recognize and interpret the quality of the sounds it receives.

There is an inextricable link between the ability to hear and speak. It is through hearing sounds that humans are able to replicate them through speech and it is for this reason that individuals who are born deaf and have never heard sounds have difficult speaking normally, although there is nothing wrong with their vocal cords.

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