Answer
There are four main types of membranes: these are mucous membranes, serous membranes, cutaneous membrane and synovial membranes.
1. Mucous membranes consist of epithelium over areolar connective tissues: they line cavities that open to the exterior Thus mucous membranes are found lining the respiratory tract, the digestive(GI) tract, the reproductive tract, and portions of the urinary tract. Probably, the principal function of mucous membranes is to secrete mucous fluid that provides lubrication. The slipperiness of mucous fluid facilitates the movement of food through the digestive tract, but the relative viscoscity of respiratory tract mucous aids in the trapping and elimination of microbes ,and particles from bronchi and trachea Mucous membranes also secrete digestive enzymes, and speed up the absorption of nutrients. Fluid from blood vessels in connective tissue layers help to maintain hydration, and transport gases, electrolytes and nutrients; in the case of stomach, membranes protect against abrasion.
2. Serosa is the second type of membranes. This kind of membrane lines the body cavities that do not open to the exterior, and covers the surface of organs within those cavities. Thus the pericardium lines the mediastinum and covers the heart; the pleura lines the thoracic cavity and covers the lungs, and the peritoneum lines the abdominopelvic cavity and covers the viscera within it.
Serous fluid is a mixture of serous secretion and fluid from the capillaries of the areolar connective tissue layer of this kind of membrane. While not as thick as mucous secretion, serous fluid is slippery and provides lubrication that lessens or eliminates friction as organs slide against cavity walls, or over each other.Serous membranes also connect organs and provide routes for blood vessels .
Work Step by Step
The body has one cutaneous membrane and it is the skin. The skin is usually thought of as having an outer waterproof epidermis of four layers keratinized cells and an inner dermis of connective tissue with blood vessels, hair follicles sweat and sebaceous glands hair follicles collagen fibers, fibroblasts and macrophages and sensory cells and nerve endings. However a third lowest hypodermal layer is often proposed. The hypodermis is is considered to consist the mainly of adipocytes with some collagen fibers and blood vessels. The cutaneous membrane covers the entire outer surface of the body .
The most obvious function of the skin is the provision of protection from physical injury, including that inducible by infra-red radiation.. But the cutaneous membrane has several other very vital functions. There is also the protection from chemical injury, and from microbial infections, and from excessive water loss, that is, from dehydration. Normal body temperature is essential to the maintainace of comfort , good health, and life itself. Through the action of sweat glands, the skin helps to cool us down when we tend to get too hot. The latent heat of vaporization is high, and so sweating is an effective method of combating the heating effects of vigorous muscular activity, or over-exposure to sunlight or other forms of radiant energy. The hypodermis functions as a kind of cushion against physical shocks, and it also serves as insulation against too abrupt body temperature changes. In addition, its adipocytes store triglycerides that may be accessed to supply the body with heat and energy in cold environments
4. Synovial membranes. Finally we come to synovial membranes. This kind of membrane consists of loose connective tissue, and is devoid of an epithelial layer. It is to be found in diarthroses joints, for example, ball and socket joints of the hip and shoulder; hinge joints; pivot joints ( atlas and axis vertebrae); the inter phalangeal joints; and knee, and, elbow joints.. Synovicytes secrete synovial fluid which provides lubrication, and facilitates movement in diarthroses.
