Integumentary System

Chapter 3

Integumentary System

Introduction

• The surface area of skin in an adult is approximately about 01.5-02 m2; however it may vary according to the individual; age and other factors. Skin has normally two layers, epidermis and dermis and below the dermis there is a fatty layer, called as subcutaneous layer

The Epidermis

• Epidermis is made up of stratified epithelium and thickness of the layer varies according to the site or position of the body. The soles of feet and palms of hands are little thicker than the rest of the body. Blood vessels are absent in this area and the inner part has interstitial fluid, coming from the dermis. This layer provides nutrients and oxygen. The stratum corneum is constantly replaced by deep layers, because the stratum corneum is constantly cast-off and is replaced by deeper layer, this change in replacement takes place in about approximately 40-45 days. The neat and healthy surface of skin is essential, but it depends upon several factors, such as cell division or Keratinization or cells etc. The various structures enter through epidermis, the sweat duct, sebaceous gland secretion, and the hair etc.

Dermi

• It is the inner layer below the epidermis and made of elastic tissues. This layer is composed of collagen fires forming network with elastic fibers. If the skin is overstretched, the elastic fibers may rupture; such overstretching of skin is observed in pregnancy condition. The collagen fires bind with water but as age advances water binding ability decreases: the skin shows wrinkling. In the deepest layer there are areolar tissue and fat bodies. The structure of dermis contains various other structures, such as lymph vessels, blood vessels, sensory nerve endings; sweat glands, sweat duct, hair roots; hair follicle, hair bulb, and hair, the involuntary muscles such as erector pullorum and sebaceous glands. The lymphatic system provides lymph vessels which form network throughout the dermis region.

Skin Functions Exercise

• It is the main protective organ of the body. Mostly deeper organs are protected. It prevents the invasion of pathogenic organisms and entrance of harmful chemicals. The skin forms a waterproof layer, so dehydration is prevented. The skin contains nerve endings, so it can feel thus preventing the body from harm by its stimulus reaction.

1. Temperature Regulation in the Body 

• The normal temperature of the body is about 36.S°C. In healthy person, there is slight variation in temperature say about 0.5—0.75°C. During certain changes in physiological condition, such as exercise, just before ovulation and in the evening, there is slight rise in temperature besides change in the metabolic rate; either temperature decreases or increases. During the metabolism of fats, carbohydrates or protein food, some energy is produced in the form of heat and also due to contraction of voluntary muscles, maximum heat is produced.

• 2. Blood reservoir: The dermis houses an extensive network of blood vessels that carry 8-10% of the total blood flow in resting adult. For this reason, the skin acts as a blood reservoir.

• 3. Protection: The skin provides protection to the body in various ways.

• (i) Keratin protects underlying tissues from microbes, abrasion, heat and chemicals and tightly interlocked keratinocytes resist invasion by microbes.