1. The Integumentary System Biology Unit 8 – Powerpoint #1 Chapter 35 /36
Physiology:
The Integumentary System
Biology
Unit 8 – Powerpoint #1
Chapter 35 /36

2. Warm Up: Anticipation Guide
Complete questions #1-10 by circling agree, disagree.

3. What is Physiology?
Physiology is the study of the functions of living organisms and their parts

4. What is Homeostasis
The ability to maintain a constant internal environment

5. Eleven Organ Systems
For example the Skeletal System which includes your bones, cartilage, ligaments and tendons. Try to think of as many organ systems as you can. Write them on the lines provided.

6. The Eleven Organ Systems
Skeletal
Muscular
Circulatory
Respiratory
Digestive
Nervous
Reproductive
Excretory
Lymphatic/Immune
Endocrine
Integumentary

7. Today: Integumentary System
Structures: skin, hair, nails, sweat glands and oil glands.
Functions:
Barrier against infection and injury
Helps regulate body temperature
Provides protection from UV light from the sun
Waste excretion
Vitamin D synthesis

8. The Largest Organ Skin is 12-15% of body weight
15-20 sq. ft ( sq. meters)
Some organisms, such as insects, and some amphibians, use the integumentary system for respiration

9. Epidermis Dermis 2 Layers The skin is made of 2 main layers
Below the dermis is subcutaneous fat (known as adipose tissue)

10. Skin: The Layers

11. Epidermis: First layer
Structure
Top is made of squamous epithelium cells:
Top layer is filled with keratin. Keratin is a fibrous, waterproof protein.
Top cells are flattened and dead, cells below are pushing upward, and not fully keratinized.
Cells at the bottom of the epidermis undergo mitosis
Top cells are replaced every days

12. Epidermis: First layer
Function
1) Water resistance
2) Protection against biological/ chemical assault
3) Contains MELANOCYTES
Produce pigment MELANIN
4) Contains Merkel cells – attached to nerves and detect touch
5) Contains Langerhans cells – these cells guard against toxins, microbes and other pathogens that penetrate the skin. If detected, alert the immune system

13. Epidermis has 5 cell layers
Stratum corneum
Stratum luciderm
Stratum granulosum
Stratum spinosum
Stratum basale
Come, Let’s Get Sun Burned!

14. Skin: Dermis
Found beneath the Epidermis

15. Dermis: Second layer Structure
Made of strong, flexible connective tissue
Contains:
Collagen
Nerves
Blood vessels
Lymph vessels
Hair follicles
Sweat glands
Muscles (attached to hair follicles)

16. Dermis: Second layer Function
1) Contains Sweat glands (3000 in2) these:
-Release sweat to maintain homeostasis
-Release various wastes collected by the bloodstream
-Mammary glands and ear wax glands are modified sweat glands
2) Contains Sebaceous (oil) glands (2 per hair)
These glands release SEBUM keeping the epidermis and hair flexible and waterproof
3) Contains many sensory cells
4) Site of hair follicles
5) Gives skin its elasticity and strength

17. Skin color Skin Markings:
Skin color is due mainly to the pigment MELANIN
Melanin may be a yellow, rust, brown or black pigment
Darker skin is due to kind and amount of melanin
Amount of melanin can vary with exposure to sunlight
Skin Markings:
Freckles: Flat, melanized patches. Varies with heredity or sun exposure
Moles: Elevated patches of melanized skin, with hair

18. Melanocytes

19. Hair Made of Keratin Hair covers almost every exposed surface.
Hair growth is determined by hormones
You are born with as many hair follicles as you will ever have
Hair is used for protection. From the sun, or dirt
Hair color
Depends on kind (yellow, rust, brown, black) and amount of melanin
Hair Texture
Related to difference in shape of hair
Straight = round, Wavy = oval, Tightly curly = flat

20. Nails Scale-like modification of the epidermis
Made of thin, dead, scaly cells, packed together
Protect the ends of the fingers and toes
Produced by the nail root: an area of rapid mitosis
Fingernails grow 1mm/week, toenails slower

21. Disorders Genetic disorders Allergies: poison ivy
Viral infection: herpes simplex
Fungal infection: athletes foot
Bacterial infection: inflammation of hair follicle/sebaceous glands
Genetic disorders
Psoriasis: Dry and scaly skin.
Skin cell production is 2X-3X normal
Hypertrichosis: Dense hair growth on face and
upper body.

22. Disorders Skin Cancer Basal Cell Carcinoma Squamous Cell Carcinoma
Most Common – 99% fully cured
Inability to form keratin
Strikes between epidermis and dermis
Squamous Cell Carcinoma
Lower layer of epidermis
Induced by the sun
Malignant Melanoma
Cancer of pigment cells = melanocytes
Rare – 1% of skin cancers
Poor chance of cure
Often begins with moles

23. Burns 1st Degree Inflamed, red skin – surface of epidermis is shed
2nd Degree
Blisters form as fluid builds beneath epidermis
3rd Degree
Epidermis & Dermis is destroyed
Catastrophic loss of fluids
Highly susceptible to infection

24. Aging Hair Thin and gray as melanocytes die, and mitosis slows
Oil Glands
Sebaceous glands atrophy (shrink) = Skin and hair become drier
Skin Layers
Mitosis slows, Collagen lost from dermis = Skin becomes thin and translucent
Loose and sagging as elastic fibers are lost in dermis
Fewer blood vessels = More bruising, slower healing
Age Spots – accumulation of pigment cells