When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.

In humans, the photoreceptor cells of the eye and sensory hair cells of the ear lack stem cells. These cells are thus unrenewable and cannot be replaced when they are damaged or destroyed.
Photoreceptors
The retina is composed of several layers and contains specialized cells called photoreceptors. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. There are two types of photoreceptors—rods and cones—which differ in the shape of...

Restorative care is provided once a patient has been discharged from a healthcare facility and requires additional services. The additional services include home care, rehabilitation programs, and extended care. Restorative care centers help the patient regain their previous level of functioning or acquire a new level of functioning due to the incapacitating effects of a disease or a disability. It aims to assist patients in enhancing their quality of life by encouraging independence,...

Specialized care settings or centers are situated in convenient locations within the community and offer care to a specific group or population. They consist of daycare facilities, mental health facilities, rural health facilities, educational institutions, industries, shelters for the homeless, and rehabilitation facilities.
Daycare centers
They provide several functions. Some facilities care for healthy newborns and children whose parents work, while others are medically focused and care for...

Rural Health Centers
Rural health centers are specialized care facilities in remote locations with very few medical personnel. The primary care providers who run the centers are mostly Registered Nurse Practitioners. Here, emergency treatment is provided to critically ill or injured patients before they are transferred to the closest hospital. Fortunately, due to advancement in technology, many rural healthcare facilities and professionals have easy access to diagnostic and treatment...

Auditory sensation, commonly called hearing, involves the transformation of sonic waves into neural impulses facilitated by the structures of the auditory organ. The prominent, flesh-like structure on the side of the head, called the auricle, directs sound waves towards the auditory canal. The auricle is often mislabeled as the pinna, a term more aligned with mobile structures like a feline's external ear. The auditory canal penetrates the cranium via the external auditory meatus of the...