Four Types of Membranes

1. Serous membranes - line body cavities that do not open to the

outside- layer of simple squamous epithelium and layer

of loose connective tissue-secretes serous fluid which lubricates

2. Mucous membranes-line cavities and tubes that open to the outside

of the body-epithelium overlying a layer of connective-secrete mucus

3. Synovial membranes-form the inner linings of the joint cavities

between the ends of bones (freely moveable joints)-fibrous connective tissue overlying loose

connective tissue-cells secrete a thick, colorless synovial fluid

into the joint cavity which lubricates the ends of the bones

4. Cutaneous membrane- The skin (how many layers?)

The Integumentary System

Skin - 1st line of defense, prevents water loss, waterproofs the bodyHair - insulates the body, receptor for touchNails - protects distal phalanx (fingers /toes)Sebaceous glands - lubricates the skin, discourages growth of bacteriaSweat glands - temperature regulation

The SkinA. The largest organ of the body and vital in maintaining homeostasisB. Two distinct layers, some say three 1. Epidermis  a. most superficial layer b. half the thickness of a piece of paper c. varies in thickness

(eyelids and sole of foot) d. avascular, it is nourished by the blood vessels in the dermis 

 e. keratinization is when the older cells harden, the cytoplasm of the skin cell fills with the protein keratin f. specialized cells known as melanocytes produce melanin  1) melanin is a dark pigment in the deeper layers of the epidermis that absorbs light energy and so protects the deeper cells from UV light 2) skin color is due to the amount of melanin produced but color is also influenced by environmental and physiological factors  

 2. Dermis a. binds the epidermis to underlying tissue (basement membrane) b. gives skin its strength and elasticity c. vascular which supply nutrients to all skin cells d. nerve fibers are scattered throughout as well as sensory receptors (touch, pressure, heat, pain) 

3. Subcutaneous layer a. aka Hypodermis b. adipose tissue which insulates (conserves body heat and keeps out outside heat) c. vascular that supplies skin and adipose tissue

Hair FolliclesA. Hair is present on all skin surfaces except...B. hair develops from a group of skin cells at the base of a tube called a hair follicle

1. follicle extends from the dermis to the surface and contains the hair root (bulb)

a. a bundle of smooth muscle cells form the arrector pili muscle that is attached to each follicle

b. the hair stands on end when the muscle contracts

2. hair shaft extends away from the surfacea. this is dead cellsb. process of keratinization

3. sebaceous glands usually are attached to hair follicles4. hair color

NailsA. unguis, onychB. protective covering at the ends of fingers and toesC. consist of keratinized stratified squamous cells with very hard keratinD. form by cell division in the nail root

1. whitish half-moon-shaped area at the base of the nail is the lunula and is the growing region

2. skin at base is the eponychium (cuticle)

3. as the nail develops it slides forward over a layer of epithelium called the nail bed (matrix)

Sebaceous GlandsA. aka oil glandsB. usually attached to hair folliclesC. they are holocrine glands

1. secrete an oily mixture called sebum through small ducts into the hair follicle

2. Sebum helps keep the hair and skin soft, pliable, and waterproof, discourages bacteria

Sweat GlandsA. aka sudoriferous glandsB. exocrine glands that are widespread in the skin but are most numerous in the ____ C. each gland consists of a tiny tube that originates as a ball-shaped coil in the deeper dermis or superficial subcutaneous layerD. fluid (sweat) is carried away in a duct, which opens at the surface as a poreE. sweat is mostly water, but it also contains small quantities of salt and wastes (urea, uric acid)

Regulation of Body Temperature

Healing of Wounds