Learning Goals:

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

IntegumentarySystem

Skin, glands, hair & nails

Chapter 4

Learning Goals:

Turn to page 95 in textbook

Write down each objective on green learning goal paper. Each objective gets its own box.

Body Membranes

Cover surfaces & line cavitiesForm protective & lubricating sheet around organs

2 categories:1. epithelial2. connective

Epithelial Membranes

Named inaccurately – actually a simple organ because is made of epithelial & connective tissues

3 types:1. mucous2. serous3. cutaneous

Mucous Membranes

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

Serous membranes

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

Cutaneous Membrane

Skin

Function - protection & temperature control

Includes hair, nails, sweat & oil glands, sensory receptors

a “dry” membrane exposed to air

Synovial Membranes

Locations: 1. surrounds joints2. surrounds bursae

(small sacs of tissue)3. surrounds tendons

Functions:1. provide a smooth surface2. secrete lubricating fluid3. cushion organs during

movement

LG 4c: 8 Functions of

1. Forms body covering2. Waterproof barrier3. Insulates & cushions deeper organs4. Protective barrier against:

- mechanical, chemical, thermal, UV, bacteria

5. Regulates heat loss6. Secretes sweat & oil7. Makes proteins & vitamin D8. Provides sensory information

- touch, pressure, temp., pain

LG 4D: Integumentary System

Made of: 1. skin2. sweat &

oil glands3. hair4. nails5. sensory

receptors

Structures of Skin

Composed of 2 layers1. Epidermis – outermost layer

- made of stratified squamous - ability to keratinize – become

hard & tough2. 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.

Layers of the Epidermis

Melanin- 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

Keratin - protein made in the epidermis

- made from cells called keratinocytes

- makes our skin waterproof- the main component of hair & nails

Layers of the Dermis

Varies in thickness –

depends on location-palms & soles: thick - eyelids: very thin

2 layers:- papillary- reticular

Papillary Layer

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!

Reticular Layer 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.

Cutaneous Glands

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 bacteriaDuring puberty – becomes very active..

Leads to oily skin & increase acne.

Sebaceous Gland

Sudoriferous Glands (Sweat)

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

bodyAprocrine – 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!!

Eccrine & Apocrine Sweat Glands

Subcutaneous Layer (Hypodermis)

Composed of adipose tissue Not considered part of skin Anchors the skin to underlying organsFunctions:

1. shock absorber2. insulates from extreme

temperature changes outside the body

3. responsible for the differences between the man & woman body structure.

Subcutaneous/Hypodermis

Hair

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

Structure of Hair

Hair ….. continued

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

Hair…. conclusion

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

Nails

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.