1. 4. Skin and body membranes

2. DID YOU KNOW?!?: We have a totally “new” epidermis every 25 to 45 days
Moles and freckles are seen where melanin is concentrated in one spot
Melanin is the natural sunscreen, but excessive sun exposure damages skin causing the elastic fibers to clump  leathery skin
Excessive sun exposure weakens the immune system
You can lose up to 7L of body water by sweating on a hot day.
You have more than 2.5 million sweat glands!

3. Objectives:
List the general functions of each membrane type and give locations
Compare tissue makeup of the major membrane types
Describe functions of the integumentary system
Recognize and label skin diagram as; epidermis, dermis, hair follicle, sebaceous gland, & sweat gland
Describe the layers of the epidermis
Describe the function of melanin
Recognize the importance of the “rule of nines”
Summarize the distinctions between skin cancers
List examples of integumentary aging

4. Body membranes
Body membranes cover surfaces, line body cavities, form protective (lubricating) sheets around organs
Two categories
Epithelial membranes- Cutaneous, mucous, and serous
Connective tissue membranes- synovial

5. Epithelial membranes are simple organs
Cutaneous- skin, its superficial epidermis is made up of keratinizing stratified squamous epithelium.
A dry membrane that is exposed to air
Mucous (mucosa)- lines all body cavites that open to the exterior such as those hollow organs of the respiratory, digestive, urinary, and reproductive tracts. Comprised of stratified squamous ephethelium (mouth) or simple columnar epithelium (rest of digestive tract).
These are wet or moist mucosa and are surrounded in secretions

6. These membranes occur in pairs:
Serous (serosa)- composed of a layer of simple squamous epithelium resting on a thin layer of areolar connective tissue. Lines body cavities that are closed to the exterior (except for the dorsal body cavity and joint cavities)
These membranes occur in pairs:
The parietal layer lines a specific portion of the wall of the ventral body cavity. It folds in on itself to form the visceral layer which cover the outside of the organs in that cavity
These layers are separated by a tiny amount of thin, clear fluid , serous fluid, which allows organs to slide easily across the cavity walls w/o friction

8. Naming serous membranes depends on LOCATION, LOCATON, LOCATION
Peritoneum- serosa lining the abdominal cavity and covering it’s organs
Pleura- lining around the lungs
Pericardium-lining that encloses the heart

9. Connective Tissue Membranes
Synovial membranes- cushions organs and structures as they move as a result of skeletal/muscular movement
Found at the ends of
the fibrous capsules of
joints where they provide
a smooth surface that
secretes a lubricating
fluid, synovial fluid, to reduce
friction of tendons moving
across bone etc…

10. Integumentary “covering” System (skin, sweat glands, oil glands, hair, and nails)
Functions to protect deeper tissue from:
Mechanical damage detected by cutaneous sensory receptors
Chemical damage prevented by keratinized cells
Bacterial damage prevented by acid secretions of skin
UV damage (melanin produced)
Thermal damage detected by thermal receptors
Drying out prevented by waterproofing keratin and glycolipids
Aids in temperature regulation
Aids in excretion of urea and uric acid
Synthesizes vitamin D from cholesterols (solar powered)

12. Epidermis- the outer portion is comprised of stratified squamous epithelium that is capable of keratinizing (becoming hard and tough)
Dermis- the underlying layer mostly made up of dense connective tissue
Blister the result of interstitial
fluid getting in between and
separating the dermis from the
epidermis (caused by rubbing)

13. Subcutaneous tissue (hypodermis)- deep below the dermis it is comprised of adipose tissue. It anchors the skin to the underlying organs. Acts as a shock absorber and insulator, and is responsible for curves of the body.

14. Strata of the epidermis
From the inside out:
Stratum basale- receives nourishment from dermis via diffusion. Cells constantly dividing million/day
Stratum Spinosum- daughter cells movin on up!
Stratum Granulosum-daughter cells movin on up!
Stratum Lucidum – daughter cells that are full of keratin, flat,clear, and dead!
Stratum corneum- skin region that occurs only where the skin is hairless and extra thick cells thick!
Epidermis is avascular (good thing )
Most epidermal cells are keratinocytes (produce protein keratin)

15. Melanin- a pigment tht ranges in color from yellow to brown to black and is produced by melanocytes that are located primarily in the stratum basale
When sunlight stimulates the melanocytes to produce more of the melanin pigment, tanning occurs.
The stratum basale cells phagocytize (eat) the pigment and it accumulates within them.
Melanin forms a protective pigment umbrella over the superficial side of their nuclei that shields their genetic material from the UV damage

16. Dermis = “hide”
This dense fibrous connective tissue layer is comprised of two parts:
Papillary layer- the upper layer dermal region, uneven with fingerlike projections (dermal papillae) which indent the epidermis. Contain capillary loops, pain receptors (free nerve endings), touch receptors ( Meissner’s corpuscles), produce ridges of the palms and soles (increase friction)
Reticular layer- deepest skin layer containing blood vessels, sweat and oil glands, deep pressure receptors (Pacinian corpuscles)
Found throughout the dermis are: phagocytes to destroy bacteria, collagen fibers for skin toughness and keep skin hydrated, elastic fibers provide the elasticity of young skin.

17. Age process
As we age the number of collagen and elastic fibers decrease, and the subcutaneous tissue loses fat
The result: skin loses elasticity and begins to sag and wrinkle 

18. Dermis & temp regulation homeostasis
When body temp is high, the capillaries of the dermis become engorged with heated blood and the skin becomes reddened and warm. This allows body heat to radiate from the skin surface
If the environment is cool and body heat must be conserved, blood bypasses the dermis capillaries temporarily, allowing internal body temperature to stay high

19. Skin color Three pigments and their amounts contribute to skin color:
Melanin (yellow, reddish brown, or black)
Carotene (orange/yellow)
Oxygen rich hemoglobin (pigment in red blood cells)
People who produce a lot of melanin have brown-toned skin. In light-skinned people, the crimson color of the oxygen-rich hemoglobin in the dermal blood supply flushes through the transparent cell layers above

20. Redness (erythema)- blushing, fever, hypertension, inflammation, allergy
pallor- pale color due to emotional stress, anemia, low blood pressure, reduced blood flow
Jaundice- abnormal yellow skin tone due to liver disorders in which excess bile pigments are absorbed by the blood and deposited
Bruises- reveal sites where blood has clotted in tissue spaces (hematoma) frequent bruising may indicate a vitamin C deficiency or hemophilia

21. Skin appendages: cutaneous glands, hair, hair follicles, and nails
Cutaneous glands- exocrine glands that release their secretions to the skin surface via ducts.
Two types:
Sebaceous glands
Sweat glands

22. Sebaceous glands (oil)- found all over skin (except palms and soles) secrete sebum. This is a mixture of oily substances and fragmented cells. Sebum is a lubricant that keeps skin soft, moist, and prevents hair from becoming brittle. Sebum contains bacteria killing chemicals. These glands are very active when male sex hormones are produced in high amounts

23. Sweat glands-sudoriferous glands are widely distributed is skin ~2
Sweat glands-sudoriferous glands are widely distributed is skin ~2.5 million /person
Two types
Eccrine-numerous and everywhere. They produce sweat- a clear secretion that is primarily water, salts, vitamin C, metabolic wastes, lactic acid. Has a slightly acidic pH to prevent bacterial growth. They are supplied with nerve endings to detect high temperature. Sweating through pores is a cooling process due to evaporation.
Apocrine- found in the axillary and genital areas. Larger than eccrine glands and ducts empty into hair follicles. Secretions contain fatty acids and proteins and may be milky or yellowish in appearance. The secretion is odorless however as bacteria on the skin use its proteins and fats, it takes on a musky odor.
These glands begin to function at puberty under the influence of androgens (male sex hormones)

24. Hair and Hair Follicles
Functions:
Minor protection
Shields eyes
Prevents foreign particle from entering respiratory tract
Minimal insulation
Hair follicles produce hair. It is formed by the division of the stratum basale epethial cells in the matrix (growth zone) of the hair bulb at the inferior end of the follicle. As daughter cells are pushed further from the growth zone, they become keratinized and die. Therefore hair is dead cells and is mostly protein.

26. Small bands of smooth muscle-arrector pili- connect each side of the hair follicle to the dermal tissue.
When these muscles contract (cold, fear) the hair is pulled upright, dimpling the skin surface with “goose bumps”
This action allows insulation by trapping air in the fur
Hair pigment is made by melanocytes (yellow, rust, brown, and black)
Hair shaft shape determines hair type and texture

27. Nail
A scale-like modification of the epidermis that corresponds to the hoof or claw of other animals
Comprised of non living material as the daughter cells produced by the matrix become heavily keratinized

28. Go to the dermatologist
skin disorders resul from:
Allergies- contact dermatitis
Bacterial infections-carbuncles, impetigo
Viral infections-cold sores
Fungal infections-athletes’s foot
Autoimmune-psoriasis

30. Burns-1st, 2nd, 3rd, degree
(rule of 9s)- volume of
fluid loss is determined by
the body surface area that
had been burned. Infection is
the cause of death in burn
victims. Skin is sterile for 24
hours after burn but then
bacteria infest the decaying
skin matter and thrive. The
immune
system is suppressed and
dehydration, electrolyte loss
and protein loss can contribute to
circulatory shock

31. ABCD Rule for recognizing melanoma

32. Causes of premature gray hair/hair loss
Genetics- permanent
Emotional crisis
Anxiety
Protein-deficient diets
Chemotherapy
Radiation
Excessive vitamin A
Fungal disease (round worm)

33. review
Systems in sync pg 125 to understand homeostatic relationships between the integumentary system and the other body systems
Read summary pg
Complete all review questions pg 127
Going further/bonus
complete at the clinic responses