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PHYSIOLOGY:
The Integumentary System
Biology
Unit 8 – Powerpoint #1
Chapter 35 /36
Warm Up: Anticipation Guide
• Complete questions #1-10 by circling agree, disagree.
What is Physiology?
• Physiology is the study of the functions of living
organisms and their parts
What is Homeostasis
• The ability to maintain a constant internal environment
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.
The Eleven Organ Systems
• Skeletal
• Reproductive
• Muscular
• Excretory
• Circulatory
• Lymphatic/Immune
• Respiratory
• Endocrine
• Digestive
• Integumentary
• Nervous
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
The Largest Organ
• Skin is 12-15% of body weight
• 15-20 sq. ft ( 1.5-2.0 sq. meters)
• Some organisms, such as insects,
and some amphibians, use the
integumentary system for respiration
2 Layers
• The skin is made of 2 main layers
1) Epidermis
2) Dermis
Below the dermis is subcutaneous fat
(known as adipose tissue)
Skin:
The Layers
Epidermis: First layer
Structure
Top is made of squamous epithelium cells:
•
•
•
•
Top layer is filled with keratin. Keratin is a
fibrous, waterproof protein.
Top 20-30 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 30-45 days
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
Skin: Dermis
Found beneath the Epidermis
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)
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
Skin color
• 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
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
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
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.
Disorders
• Skin Cancer
• Basal 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
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
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