THE SKIN; ANATOMICAL,PHYSIOLOGICAL AND CLINICAL EPLANATION WITH WELL LABELLED AND CLEAR DIAGRAMS

1. Openings of sweat ducts
2. Epidermis
3. Dermis
4. Subcutaneous tissue
5. Pacinian corpuscle
6. Sweat gland
7. Cutaneous nerve
8. Hair bulb
9. Hair follicle
10. Hair root
11. Arrector pili muscle
12. Sebaceous gland
13. Unencapsulated Meissner’s
corpuscle (tactile)
14. Dermal papilla
15. Basal layer
16. Cornified layer
17. Shaft of hai
Comments
Anatomical: The skin is the largest organ in the body, with a surface area of up
to 2 m2
. It is made up of the epidermis, the dermis and the subcutaneous tissue.
The epidermis is superficial and consists of a germinal basal layer and a thick
keratinising layer. It contains no blood vessels or nerve endings. It is traversed
by hairs, the secretory products of the sebaceous glands and the excretory ducts
of the sweat glands. The papillae, which are upward projections of the dermis,
come close to the surface. The dermis is made up of connective tissue containing
collagen and elastic fibres responsible for its ability to be both strong and flexible.
It contains blood vessels and lymphatics, nerve endings, sweat glands, sebaceous
glands and hairs with their arrector pili muscles.
Physiological: The cells are produced in the basal layer and move up to the
cornified layer. The basal layer has melanocytes, which secrete melanin when
exposed to the sun. The dermal papillae allow the transfer of nutrients. The functions
of the skin include protection of the body, control of body temperature, vitamin
D synthesis, provision of sensory input and wound healing.
Clinical: A yellowish discolouration of the skin is due to the presence of blood-derived
bile pigments or carotenoids in the subcutaneous fat. Stretch marks result from
the stretching and subsequent rupture of the elastic fibres in cases of obesity or
pregnancy. Skin lesions include macules, papules, vesicles, bullae, pustules, ulcers
and nodules