WPS Office Suite Overview

WPS Office Overview

• WPS Office is a complete office suite that includes a PDF editor
• It offers a desktop application for both Mac and PC users
• Users can download WPS Office from the official website: https://www.wps.com/d/?from=ios

Skin Structure and Function

• Skin is the largest organ in the body, weighing about 16% of the body weight and covering an area of 22 square feet.
• It is continuous with the mucous membrane at the mucocutaneous junction, seen at the orifices of the body, such as lips, anus, and eyelids.
• The skin shows regional variations, being thin in the eyelids and thick in palms, soles, and scalp.

Types of Skin

• There are two types of skin: thick skin and thin skin.
• Thick skin covers the back of the body, palms, and soles, and is hairless.
• Thin skin is present on the rest of the body and is hairy.

Functions of Skin

• Protective: protects from chemicals, ultraviolet rays, microorganisms, and injury, and acts as a barrier in preventing water absorption.
• Temperature Regulation: helps regulate body temperature.
• Sensory: perceives pain, temperature, touch, pressure, and vibration sensations.
• Excretory: excretes urea.
• Metabolic Function: performs metabolic functions.
• Sexual signaling: plays a role in sexual signaling.

Layers of Skin

• Epidermis: the surface layer of epithelium.
• Dermis: the middle connective tissue layer.
• Hypodermis: the deeper loose connective tissue layer.

Appendages of Skin

• Nails
• Hairs and hair follicles
• Sebaceous glands
• Sweat glands

Nerve Endings in Skin

• Free nerve endings
• Meissner’s corpuscles
• Ruffini’s corpuscles
• Pacinian corpuscles

Microscopic Structure of Skin

• Epidermis: the surface layer in contact with the external environment, lined by stratified squamous keratinized epithelium.
• Consists of epithelial cells arranged in two zones: germinative zone and horny zone.
• Epithelial cells produce keratin, which protects the skin.

Epithelial Cells

• The epithelium is stratified squamous keratinized type.
• Nearly 90% of epithelial cells in the epidermis are called keratinocytes.
• The arrangement of layers in the epithelium includes:
  • Stratum basale/basal layer: consists of a single layer of cuboidal or low columnar cells with oblong, dark heterochromatic nuclei.
  • Stratum spinosum/prickle cell layer: contains several layers of polyhedral cells with pale staining euchromatic nuclei.
  • Stratum granulosum/granular layer: consists of two or three layers of fusiform cells, which contains numerous granules.
  • Stratum Lucidum/clear layer: an amorphous homogenous layer seen in thick skin only.
  • Stratum corneum/keratin layer: more prominent in palms and soles, consists of several layers of horny epithelial cells.