TECHNICAL UNIVERSITY OF MACHALASCHOOL OF MEDICNE

SPEAKERS:•Jhonny Freire•Guillermo Morocho•Kevin Salazar

TOPIC: HAIR AND NAILS

HAIR

HAIRHair is a filamentous biomaterial, that grows

from follicles found in the dermis. Hair is one of the defining characteristics of mammals.

The especial funtions of hair include :

1. retencion of body heat

2. the magnification of the sense of touch.

• the removal of hair from hiary spots in the skin is know to reduce their sensitivity to touch.

The parts of a single hair include: SHAFTextending upward from a pint in or near the surface of epidermisROOT embedded in the corium and surrounded by an epidermal downgrowth HAIR FOLLICLE HAIR BULB; the expanded base of the root into which from underneat a DERMAL PAPILLA (conective tissue) nerves capillaries projects.

A single hair has three layers of cells: the external layer, or cuticle the horny porcion, or cortex (actuallly consisting of several layers) and central row of cells the medulla (not present in the some hair). Hair cells contain a pigment responsible for variation – in hair coloring; if the

pigmentation is inadequeate, the air between the cells reflects ligth tha makes the hair appear silvery or gray.

• In the bulb of the hair root are the live germinating cells wich multiply and cause the shaft to rise upward to be replaced by younger cells

• Scalp hais grow at the rate of about five inches per year during their life period of two to five years,eyebrows and eyelashes can grow for several months at most, before replacement.

• Sex hormones have a pronunce effect on the extent and location of hair growth, as seen in the faces of males and in the pubic and axillary region of males and females

• The hair follicle, surrounding the root , has an inner, epithelial sheath and an outer, conective tissue sheath.

• The inner sheath consists of three layers of cells:

the horny cuticle, huxley´s layers of flat cells, and henle´s layer of tube-shaped cells and an outer layer merging with the deep stratum geminativum of the epidermis.

• The outer connective tissue sheath, growing out of the corium, surround the inner sheath

NAILS

On the dorsal surfaces of the digits and toes are the nails, horny plates cosisting of the following parts: a visible portion attached to the digit or toe, which it protects; a free edge in the distal portion: and a root, the covered portionembedded in the skin.

NAILS

NAILS• The nails bed is the skin

under the nail; the nail wall is the skin covering the root and sides of the nail.

• The lunula is the white portion at the base of the nail.

• Cells in the stratum germinativum near the nail root fuse with the root cells and push the older cells away so that the nail grows.