Four Types of Membranes 1 Serous membranes line

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 - 1 st line of defense, prevents water loss, waterproofs the body Hair - insulates the body, receptor for touch Nails - protects distal phalanx (fingers /toes) Sebaceous glands - lubricates the skin, discourages growth of bacteria Sweat glands - temperature regulation

The Skin A. The largest organ of the body and vital in 
maintaining homeostasis B. Two distinct layers, some say three  . Epidermis  . most superficial layer  . 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

 . 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  ) 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  ) skin color is due to the amount of 
melanin produced but color is also influenced 
by environmental and physiological factors

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

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

Hair Follicles A. 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 surface a. this is dead cells b. process of keratinization 3. sebaceous glands usually are attached to hair follicles 4. hair color

Nails A. unguis, onych B. protective covering at the ends of fingers and toes C. consist of keratinized stratified squamous cells with very hard keratin D. 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 Glands A. aka oil glands B. usually attached to hair follicles C. 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 Glands A. aka sudoriferous glands B. 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 ballshaped coil in the deeper dermis or superficial subcutaneous layer D. fluid (sweat) is carried away in a duct, which opens at the surface as a pore E. sweat is mostly water, but it also contains small quantities of salt and wastes (urea, uric acid)

Regulation of Body Temperature Healing of Wounds