Mention the functions of the epidermis
Answers
What is epidermis
The epidermis is a keratinized stratified squamous epithelium. That is, the epidermis outermost layer consists of dead cells packed with the tough protein keratin. Like other epithelia, the epidermis lacks blood vessels and depends on the diffusion of nutrients from the underlying connective tissue. It has sparse nerve endings for touch and pain, but most sensations of the skin are due to nerve endings in the dermis.
Epidermis function
1)The skin is much more than a container for the body. It has a variety of very important functions that go well beyond appearance, as you shall see here.
2)Resistance to trauma and infection. The skin suffers the most physical injuries to the body, but it resists and recovers from trauma better than other organs do. The epidermal cells are packed with the tough protein keratin and linked by strong desmosomes that give this epithelium its durability. Few infectious organisms can penetrate the intact skin. Bacteria and fungi colonize the surface, but their numbers are kept in check by its relative dryness, its slight acidity (pH 4–6), and defensive antimicrobial peptides called dermcidin and defensins. The protective acidic film is called the acid mantle.
3)Other barrier functions. The skin is important as a barrier to water. It prevents the body from absorbing excess water when you are swimming or bathing, but even more importantly, it prevents the body from losing excess water. The epidermis is also a barrier to ultraviolet (UV) rays, blocking much of this cancer causing radiation from reaching deeper tissue layers; and it is a barrier to many potentially harmful chemicals. It is, however, permeable to several drugs and poisons.
4)Vitamin D synthesis. The skin carries out the first step in the synthesis of vitamin D, which is needed for bone development and maintenance. The liver and kidneys complete the process.
5)Sensation. The skin is our most extensive sense organ. It is equipped with a variety of nerve endings that react to heat, cold, touch, texture, pressure, vibration, and tissue injury. These sensory receptors are especially abundant on the face, palms, fingers, soles, nipples, and genitals. There are relatively few on the back and in skin overlying joints such as the knees and elbows.
6)Thermoregulation. The skin receives 10 times as much blood flow as it needs for its own maintenance, and is richly supplied with nerve endings called thermoreceptors, which monitor the body surface temperature. All of this relates to its great importance in regulating body temperature. In response to chilling, the body retains heat by constricting blood vessels of the dermis (cutaneous vasoconstriction), keeping warm blood deeper in the body. In response to overheating, it loses excess heat by dilating those vessels (cutaneous vasodilation), allowing more blood to flow close to the surface and lose heat through the skin. If this is insufficient to restore normal temperature, sweat glands secrete perspiration. The evaporation of sweat can have a powerful cooling effect. Thus, the skin plays roles in both warming and cooling the body.
7)Nonverbal communication. The skin is an important means of nonverbal communication. Humans, like most other primates, have much more expressive faces than other mammals. Complex skeletal muscles insert in the dermis and pull on the skin to create subtle and varied facial expressions. The general appearance of the skin, hair, and nails is also important to social acceptance and to a person’s self-image and emotional state—whether the ravages of adolescent acne, the presence of a birthmark or scar, or just a “bad hair day.”
Answer:
two function of lower epidermis are
exchange of gases
prevent the loss of water.
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Explanation: