Nail is basically a modified form of skin. Nails are the hard coverings that protect the fingers and the toes. They are composed of keratin and are made by the epidermal cells. The parts of a nail are: free end, main nail plate, lunula, nail fold, cuticle and nail root. The nail is a dead […]
Hair is a type of modified epidermal layer. The hair follicles are embedded deep in the dermis layer of the skin, from where hair growth takes place. Hair falling and growth is a continuous process. Hair is composed of dead cells which contain the protein keratin. The parts of the hair are: tip, shaft, root
Gland The skin layers have various glands, the sweat gland and fat/sebaceous glands, found throughout the body, except a few areas like, the palms of the hands and soles of the feet. The sweat glands secrete mostly a concentrated salty sweat into the gland tube that lowers the body temperature, especially in summer season. The
Dermis Dermis is the thicker middle layer of the skin. It is composed of fibrous connective tissues. This layer has several microstructures, such as: blood vessels, hair follicles and glands that produce sweat, hair follicles and nail. These microstructures are supplied by arteries and veins. This layer also acts as a base for several sensory
Skin Skin is the outer covering of the body; it is one of the largest organs of the human body. It is the sense organ of touch, but plays certain crucial roles such as: regulation of body temperature and waste excretion. Skin along with hair and nails form the integumentary system. They provide external protection
The taste pores are envelope-shaped structures that house taste buds, supporting cells and nerve endings of taste nerves. The taste sensations are transmitted to the taste nerves through the taste pores. The tongue is connected with the V, VII and IX cranial nerves that are responsible for the overall taste sensation perception. The taste centre
Taste buds are the taste receptors present on the tongue; they are the tiny sensory structures. They are located around the base of the papillae. There are numerous taste buds on the circumvallate and the fungiform papillae. There are four types of taste buds according to the tastes–bitter sensing buds are located at the back,
Tongue The tongue is the sense organ for taste. It is made up of several muscle elements and is a flexible part. It has two types of muscles, one of the muscles that performs delicate movements and the other that performs larger movements (mastication and swallowing). The tongue is attached to the throat and is
Teeth are the hard, bony structures that are fixed in deep sockets in the jawbone. These sockets are attached to the jawbone with the help of strong periodontal fibres and cementum. A human being possesses two sets of teeth during the entire lifetime, the temporary set and the permanent set. An infant has 20 temporary
Mouth The mouth is a hollow oral cavity located below the nose and works in close coordination with the nose. It serves several purposes, such as ingestion of food, detection of taste and digestion. The mouth cavity has many organs inside it: it starts with lips and inside it, it contains other organs, like the
The auditory nerves transmit the sound wave from the ear-drum to the auditory centre in the brain. These auditory nerves (VIII cranial nerve) are made by the association of vestibular nerve and the cochlear nerve.
The human ear is a hearing organ designed to collect sound vibrations, and then pass those vibrations to the brain through auditory nerves. The main part of the ear is located inside the skull. The ear has a complex structure; it has several small bones intricately arranged inside it. It has the smallest bone of
The olfactory portion of the nose is exclusively involved in the sensation of smell. The olfactory portion of the nose consists of: the olfactory epithelium, olfactory nerves and olfactory bulb. The olfactory epithelium is a soft patch on the roof of the nasal cavity. This epithelium has several olfactory hair cells connected to the olfactory
The nose has an internal air-filled chamber called the nasal cavity. Septum divides the nasal cavity into two sections. The septum walls consist of two skull bones: the ethmoid above and the nasal concha (below). Nasal cavity is connected with the throat. On the upper wall or the roof of the nasal cavity, the olfactory
The nose is the sense organ for smell. It is connected with the olfactory nerves of the brain. The nose helps a person to smell and carry out one of the most important functions called the respiration. It works in coordination with the sense of taste. The main parts of the nose are: the two