 3J: Analyze the life cycle of cells in the body and describe the effects of aging of cells and tissues  3K: Evaluate possible causes of cancer and describe the process of cancer growth

Chapter 4

 Turn to page 95 in textbook  Write down each objective on green learning goal paper. Each objective gets its own box.

 Cover surfaces & line cavities  Form protective & lubricating sheet around organs  2 categories: 1. epithelial 2. connective

 Named inaccurately – actually a simple organ because is made of epithelial & connective tissues  3 types: 1. mucous 2. serous 3. cutaneous

 Description: - Considered a “wet” or moist membrane - continuous secretions  Locations: all body cavities that open to the outside of body  Functions: absorption and/or secretion

 Line body cavities that are closed to the outside  Function :protective barrier over organs allows movement without friction-  SEROUS FLUID - allows organs to slide w/o friction

 Skin  Function - protection & temperature control  Includes hair, nails, sweat & oil glands, sensory receptors  a “dry” membrane exposed to air

 Locations: 1. surrounds joints 2. surrounds bursae (small sacs of tissue) 3. surrounds tendons  Functions: 1. provide a smooth surface 2. secrete lubricating fluid 3. cushion organs during movement

1. Forms body covering 2. Waterproof barrier 3. Insulates & cushions deeper organs 4. Protective barrier against: - mechanical, chemical, thermal, UV, bacteria 5. Regulates heat loss 6. Secretes sweat & oil 7. Makes proteins & vitamin D 8. Provides sensory information - touch, pressure, temp., pain

 Made of: 1. skin 2. sweat & oil glands 3. hair 4. nails 5. sensory receptors

 Composed of 2 layers 1. Epidermis – outermost layer - made of stratified squamous - ability to keratinize – become hard & tough 2. Dermis – underlying the epidermis - made of connective tissue ***Both are tightly connected together ***However, a burn or friction can separate them resulting in a blister.

- protein found the epidermis - made by cells called melanocytes - same amount of these cells in all people - darker skin = more active - lighter skin = less active - natural sunscreen (protects from UV rays

- protein made in the epidermis - made from cells called keratinocytes - makes our skin waterproof - the main component of hair & nails

 Varies in thickness –  depends on location -palms & soles: thick - eyelids: very thin  2 layers: - papillary - reticular

 upper layer  Includes: - free nerve endings – pain - Meissner’s corpuscles – touch  Fingerprints – whorls & ridges - fingers & feet -increase friction & gripping -formed in the womb - all are unique…. Even in identical twins!

 Deepest skin layer  Contains: - blood vessels, sweat & oil glands - Pacinian corpuscles – deep pressure - phagocytes –destroy bacteria  Made of - collagen – keeps skin hydrated - elastin – gives skin elasticity - with age, it decrease and creates wrinkles & begins to sag.

 Sebaceous Glands (oil glands) - found everywhere, except palm & soles - excrete SEBUM into the follicle or surface of skin - SEBUM – keeps skin soft & moist & prevents hair from becoming brittle - contains chemicals to kill bacteria  During puberty – becomes very active.. Leads to oily skin & increase acne.

 Eccrine – most numbrous, found all over body - produce sweat – clear fluid, primarly water & salts, wastes & lactic acid. - released through pores - critical in temperature regulation of body  Aprocrine – axillary & genital areas only - excrete into hair follicles - produce sweat that is yellow & can be cloudy - odorless until bacteria living on skin uses it as food, then it becomes stinky!!

 Composed of adipose tissue  Not considered part of skin  Anchors the skin to underlying organs  Functions: 1. shock absorber 2. insulates from extreme temperature changes outside the body 3. responsible for the differences between the man & woman body structure.

 Millions of hairs are scattered all over the body, except palms, soles, nipples, & lips  Functions: - guarding the head from UV rays and bumps - shielding the eyes - helps keep particles out of respiratory tract  Hair has lost much of its usefulness….  Hair for Early humans provided insulation in cold weather. Now we have clothes

 Flexible epithelial structure  Dead, keratinized cells  Different colors – made by varying amounts of melanin.  Variety of sizes and shapes: - eyebrows: short & stiff - hair of head: long & flexible  Shape of hair shaft determines what texture your hair will be… oval = smooth & silky; flat= curly; round = straight & coarse

 Humans are born with as many hair follicles as they will ever have  Among the fastest growing tissues in the body  Hormones control hair growth  By age 50, number of hair follicle drop to 1/3 and continue to decline.  Results in hair thinning and different degrees of baldness  Gray hair – results from the absence of melanin

 Hardened skin cells – mostly nonliving  Transparent and nearly colorless  Look pink because of blood supply  Lunula – white crescent area where nail grows  When blood supply is low, nail appears to be blue (cyanotic) tint.