Integumentary System

Topics: Skin, Epidermis, Epithelium Pages: 12 (1847 words) Published: August 8, 2014
INTEGUMENTARY SYSTEM

The integumentary system consists of the skin and accessory structures, such as hair, nails, sudorifenous gland (sweat gland) and sebaceous gland (oil gland). Integument means covering, and the integumentary system is familiar to most people because it covers the outside of the body and is easily observed.

FUNCTIONS OF THE INTEGUMENTARY SYSTEM

1. Protection
The skin provides protection against abrasion and ultraviolet light. It prevents the entry of microorganisms and dehydration by reducing water loss from the body. 2. Sensation
The integumentary system has sensory receptors that can detect heat, cold, touch, pressure and pain. 3. Vitamin D production
Ultraviolet light stimulates the production of precursor molecule in the skin that is modified by the liver and kidneys into vitamin D. Vitamin D increases calcium uptake in the intestines.
4. Temperature regulation
Through dilation and constriction of blood vessels, the skin controls heat loss from the body. Evaporation of sweat cools the body.
5. Excretion
Small amounts of waste products are lost through skin and in gland secretions. TYPES OF MEMBRANES

1. Serous Membrane lines the sealed, internal cavities of the body. There are three such membranes with each consisting of a simple epithelium supported by loose connective tissue: the pleura lines the pleural cavities and covers the lungs

the peritoneum lines the peritoneal cavity and covers the surfaces of enclosed organs such as the liver and stomach the pericardium lines the pericardial cavity and covers the heart.

2. Mucous Membrane is a membrane lining bodily cavities and canals that lead to the outside, chiefly the respiratory, digestive, and urogenital tracts. Mucous membranes line many tracts and structures of the body, including the mouth, nose, eyelids, windpipe and lungs, stomach and intestines, and the ureters, urethra, and urinary bladder.

3. Synovial Membrane produce synovial fluid which helps lubricate joints permitting smooth movement. The synovial membrane consists mainly of loose connective tissue with the epithelial layer being incomplete.

4. Cutaneous Membrane of the skin covers the surface of the body. They consist of stratified squamous epithelium and the underlying connective tissues. Cutaneous membranes are thick, relatively waterproof, and dry.

Hypodermis

The hypodermis, which is not part of the skin, is sometimes called subcutaneous tissue. It is essentially composed of a type of cells specialized in accumulating and storing fats, known as adipocytes. These cells are grouped together in lobules separated by connective tissue. Subcutaneous tissue acts both as an insu­lator, conserving body heat, and as a shock absorber, protecting in­ternal organs from injury. It also stores fat as an energy reserve in the event extra calories are needed to power the body. The blood vessels, nerves, lymph vessels, and hair follicles also cross through this layer.

SKIN

2 Major Tissue Layers:

1. Dermis
The dense collagenous connective tissue that makes up the dermis contains fibroblasts, fat cells, and macrophages. 10 to 20 times thicker than the epidermis
Responsible for most of the structural strength
Nerves, hair follicles, smooth muscles. Glands, and lymphatic vessels extend into the dermis

2 sub layers of Dermis:

a. Papillary Layer is the upper layer that supplies nutrients to select layers of the epidermis and regulates temperature. Constriction and expansion control the amount of blood that flows through the skin and dictate whether body heat is dispelled when the skin is hot or conserved when it is cold.

b. Reticular Layer is the lower layer that is thicker and made of thick collagen fibers that are arranged in parallel to the surface of the skin. This layer is denser than the papillary dermis, and it strengthens the skin, providing structure and elasticity. It also supports other components of the skin, such as hair...
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