PHYSIOLOGY INTRO:The Integumentary System

Honors BiologyUnit 8 – Powerpoint #1Chapter 35 /36

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 •Muscular •Circulatory•Respiratory•Digestive •Nervous

•Reproductive •Excretory•Lymphatic/Immune •Endocrine• Integumentary

Today: Integumentary System•Structures: skin, hair, nails, sweat glands and oil glands.

•Functions:• Barrier against infection and injury (including UV protection)

• Helps regulate body temperature• Prevents H2O loss• Waste excretion• Vitamin D synthesis

Fun Facts• Where is your thinnest skin located? Thickest?

• Eye lids (thinnest) soles of feet (thickest)• How many skin cells do you shed in a minute?

• About 30,000-50,000 dead cells• How many pounds of skin do you loose per year?

• 8-10 lbs• How much of the dust in your home is dead skin cells?

• 50% (Globally, dead skin accounts for about a billion tons of dust in the atmosphere)

• Does sweat smell?• No, it’s the bacteria

• How much bacteria is on your body?• 1,000 different species AND 1,000,000,000,000 individual

bacteria

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) Epidermis2) DermisBelow the dermis is subcutaneous fat (hypodermis) that insulates body

Skin: The Layers

Epidermis: First layerStructure• Outer layer are flattened, dead cells, inner layer living

• As lower cells do mitosis they move and push others to surface of skin

• As move up, become flattened and make keratin (tough, fibrous protein)

• Takes 30-45 days for new cells to reach the top• Contain nerve endings but no blood vessels

Epidermis

Epidermis: First layerFunction

1) Water resistance (keratin filled dead cells)2) Protective layer against biological/ chemical assault3) Contains MELANOCYTES (Produce pigment MELANIN which protects from UV) (will talk more about later)

4) Contains Merkel cells – attached to nerves and detect touch5) Contains Langerhans cells –guard against toxins, microbes and other pathogens that penetrate the skin. If detected, alerts immune system

Epidermis

Skin: DermisFound beneath the

Epidermis

Dermis: Second layerStructure

Made of strong, flexible connective tissueContains:

CollagenNervesBlood vesselsLymph vesselsHair folliclesSweat glandsMuscles (attached to hair follicles)

Function1) Contains Sweat glands (3000/ in2) these: -maintain homeostasis- regulates body temp

-Release various wastes from 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 waterproof3) Contains many sensory cells 4) Gives skin its elasticity and strength (collagen)

Dermis: Second layer

Skin color• Skin color is due mainly to the pigment MELANIN (made by melanocytes in the epidermis)

• 2 types of melanin• Eumelanin (comes in

brown and black)• Phomelanin (pinkish-

red)

Skin Color• Darker skin is due to kind and amount of melanin produced (everyone has relatively similar numbers of melanocytes)

• UV rays stimulate melanocytes to make more melanin (causing tanning)

• Melanin protects skin cells under it from harmful UV B rays

Melanoctyes

Skin MarkingsSkin Markings:Freckles: Flat, melanized patches Varies with heredity or sun exposure

Moles: Elevated patches of melanized skin, with hair

This is your hair, and yes that is bacteria

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 (red, brown, black) and amount of melanin

• Hair Texture • Related to difference in shape of hair• Straight = round, Wavy = oval, Tightly curly = flat

Hair differences• Scanning electron

micrograph of a hair fiber from a Caucasian blonde female (above) and an Asian male (below). The overlapping cells of the cuticle are readily apparent on both fibers.

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• Skin Cancer• Basal Cell Carcinoma

• Most Common – 99% fully cured

• 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

What not to do:

Burns: 1st Degree

• Inflamed, red skin – surface of epidermis is shed

2nd Degree• Blisters form as fluid builds beneath epidermis• Burns epidermis and part of dermis

3rd Degree• Epidermis & Dermis is destroyed

• Catastrophic loss of fluids (dehydration)

• Highly susceptible to infection

• Look up photos online if you would like (they can be pretty graphic)

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

Interesting Websites on Integumentary system

• Interesting Facts• http://visual.ly/50-incredible-facts-about-skin

• Skin Anatomy and Effects of Aging• http://science.nationalgeographic.com/science/health-and-human-b

ody/human-body/skin-article/

• Skin Cancer Investigation• http://sciencenetlinks.com/interactives/skindeep/interactive/

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