Pathophysiology of Otitis Externa: Otitis externa is an inflammatory or infectious condition of the external auditory canal, commonly known as “swimmer’s ear.” It occurs when the protective mechanisms of the ear canal are disrupted, allowing microorganisms to multiply and cause inflammation. The most common bacterial cause is Pseudomonas aeruginosa, although other bacteria and fungi may…
Pathophysiology of Myopia: Myopia (short-sightedness) is a refractive error in which a person can see nearby objects clearly, but distant objects appear blurred. In myopia, light rays from a distant object are focused in front of the retina rather than directly on the retina. Step 1: Normal Refraction of Light Normally, light entering the eye…
Pathophysiology of Cataract: Cataract is a condition in which the normally transparent crystalline lens of the eye becomes progressively opaque, resulting in reduced transmission of light to the retina and causing blurred or decreased vision. Cataract develops because of structural and biochemical changes in lens proteins, particularly crystallins, along with oxidative stress, disruption of lens…
Pathophysiology of Glaucoma: Glaucoma is a group of progressive eye disorders characterized by damage to the optic nerve, particularly the retinal ganglion cell axons, leading to characteristic visual field loss. The major risk factor is often increased intraocular pressure (IOP), although glaucoma can also develop with IOP within the statistically normal range. The disease is…
The Peripheral Nervous System (PNS) is the part of the nervous system that lies outside the brain and spinal cord. It forms an important communication network between the central nervous system (CNS) and the rest of the body. The PNS carries sensory information from receptors in the body to the CNS and transmits motor commands…
Structure and Functions of the Nose: The nose is a facial organ and sensory structure that serves primarily as the organ of smell (olfaction) and is also involved in functions related to breathing and the sense of taste. It is located centrally on the face, typically protruding above the mouth, and consists of two nostrils…
Structure and Functions of the Ear: The ear is a complex organ responsible for hearing and balance. It consists of three main parts: the outer ear, the middle ear, and the inner ear, each with distinct structures and functions. Structure and Functions of the Ear 1. Outer Ear The outer ear is the external portion…
Structure and Function of the Eye: The human eye stands as a vital organ crucial for the sense of sight or vision, as it actively engages with light. Within the eye, two distinct types of cells, rods and cones, play integral roles. These cells carry out conscious light perception, facilitate color differentiation, and enable depth…
Spinal and Cranial Nerves: The nervous system is a highly complex and organized network responsible for transmitting signals throughout the body, coordinating voluntary and involuntary actions, and maintaining homeostasis. Two essential components of the peripheral nervous system (PNS) are the spinal nerves and cranial nerves. These nerves originate from the spinal cord and brain, respectively,…