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Section 36-3
Section Outline
36 –3 The Integumentary
System
The Skin
1.Epidermis
2.Dermis
3.Skin Cancer
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•The skin or integumentary system has four roles
– It acts as a barrier against infection and injury
– It helps to regulate body temperature
– It removes waste products from the body
– Provides protection against UV radiation from the sun
•It also serves as a way through which sensations are transmitted to the nervous system
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•Made of two main layers
– Epidermis – outer layer
• The outer layer consists of dead skin cells
• The inner layer is made of living cells
– These undergo rapid mitosis, constantly making new cells and pushing older cells to the surface
– Also contains melanin (pigment)
– Dermis – contains collagen fibers, blood vessels, nerve endings, glands, smooth muscle and hair follicles
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Concept Map
Section 36-3
Skin
Barrier to infection functions as a
Regulator of body temperature
Remover of waste products
Protector against UV radiation
Epidermis which is the is made up of the
Outer layer
Dermis which is the
Inner layer
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Section 36-3
Figure 36-13 The Structure of Skin
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•Skin cancer
– Excessive exposure to UV radiation can lead to an abnormal growth of cells in the skin
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Section 40-2
Section Outline
40 –2 The Immune System
A.
Nonspecific Defenses
1.
First Line of Defense
2.
Second Line of Defense
B.
Specific Defenses
1.
Humoral Immunity
2.
Cell-Mediated Immunity
C.
Acquired Immunity
1.
Active Immunity
2.
Passive Immunity
D. Diseases of the Immune System
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The Immune System
•The body’s primary defense mechanism
•May destroy invaders by engulfing them by special cells or by chemically marking them for destruction and elimination
•Functions by being able to recognize proteins on the surface of cells
•It can distinguish between self and non-self
– The non-self, or invading foreign proteins are referred to as antigens
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Nonspecific vs. Specific
•Two types of defense mechanisms
– Non-specific – physical and chemical barriers
• 1 st line of defense - Keep pathogens out of your body
– Done by skin, mucous, sweat and tears
» The secretions contain lysozyme, and enzyme which breaks down the cell walls of bacteria
• 2nd line of defense – inflammatory response
– If pathogens do enter your body, phagocytic white blood cells move into the area to destroy the bacteria
– The immune system also releases a chemical that increases your body temperature
» The fever kills the bacteria because they can only exist in a narrow temperature range.
» The fever also increases heart rate so wbc can get to the infection site faster.
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Section 40-2
Figure 40–7 The Inflammatory Response
Skin
Wound
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Bacteria enter the wound
Phagocytes move into the area and engulf the bacteria and cell debris
Capillary

Specific Defense
•A specific defense against a pathogen is called an immune response
– Pathogens that trigger this response are called antigens
• These may be viruses, bacteria or other pathogens such as fungi, parasites, etc.
•The immune response attacks the particular disease-causing agent with a response especially for that pathogen
•There are two types of wbc’s that recognize specific antigens
– B cells – humoral immunity – pathogens and antigens in body fluids
– T cells – cell-mediated immunity – pathogens and antigens inside living cells
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Humoral Immunity
•When a pathogen enters the body, B cells recognize the foreign invader
– They grow and divide rapidly, producing plasma cells and memory B cells
• Plasma cells release antibodies
– Proteins that recognize and bind to antigens (lock and key), and are carried in the blood to attack the pathogen
– When the pathogen is killed the plasma cells die out
• Memory B cells remain capable of producing antibodies to that specific pathogen
– If the pathogen enters the body again, a secondary response occurs and new plasma cells are formed to create antibodies to kill the pathogens
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Section 40-2
Primary and Secondary Immune Responses
First exposure
Interval between exposures
Second exposure
Time
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Section 40-2
Figure 40–9 Humoral Immunity
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Cell-Mediated Immunity
•When viruses or other pathogens get inside living cells, antibodies alone can not destroy them
•Special cells, T cells, divide into 4 types of T cells
– Helper T cells – activated by a macrophage and activates killer T cells
– Killer T cells – bind to infected cells, destroying the cell membrane and killing them
– Memory T cells – will cause a secondary response if they encounter that antigen again
– Suppressor T cells – shut down killer T cells once the pathogens are brought under control
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Section 40-2
Figure 40–10 Cell-Mediated Immune Response
Macrophage
T cell binds to activated macrophage
Helper T cell activates killer T cells and B cells
Helper
T Cell
Killer
T Cell
Antigens are displayed on surface of macrophage
T Cell
T cell, activated by macrophage, becomes a helper T cell
Infected Cell
Killer T cells bind to infected cells, disrupting their cell membranes and destroying them
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Acquired Immunity
•Two types of acquired immunity
– Active – appears after exposure to an antigen
• May be natural (the body fights an infection)
• May be artificial (through vaccination)
– Vaccine – injection of a weakened form of an antigen to produce an immune response
– Passive – receiving antibodies to fight off an infection – only lasts a short time because the body will eventually destroy the foreign antibodies
• May be natural – antibodies are passed to a baby through the placenta and through breast milk
• May be artificial – vaccines may contain antibodies to protect and prevent disease
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Section 40-3
Section Outline
40 –3 Immune System Disorders
A. Allergies
B. Autoimmune Diseases
C. HIV and AIDS
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Allergies
•An overreaction of the immune system
– Allergy causing antigens enter the body and attach themselves to mast cells
• Mast cells initiate the inflammatory response
– Produce chemicals called histamines
» Increase the flow of blood and fluids to surrounding areas, and increase mucous production
– Asthma – a chronic respiratory disease where the air passages become narrower than normal, causing wheezing, coughing and difficulty breathing
• May be treated with medications that relieve the symptoms of asthma
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Autoimmune Disorders
•The immune system has the ability to recognize self and non-self
– When the immune system makes a mistake and attacks its own cells, it produces and autoimmune disease
• Examples
– Type I diabetes – insulin-producing cells of the pancreas are destroyed
– Multiple sclerosis – antibodies destroy the functions of the neurons in the brain and spinal cord
– Lupus – attacks normal connective tissue, leading to inflammation and pain in the joints
– some of the autoimmune diseases may be treated with immune suppressing drugs
• However, this therapy is not used often or must be monitored carefully
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HIV and AIDS
•AIDS is an autoimmune disease that results from infection with HIV
– Normally healthy patients die from microorganisms that don’t normally cause disease, from extremely rare forms of cancers and pneumonia and from pathogens that healthy people can normally fight off
•HIV – a retrovirus – it carries its genetic information in RNA, not DNA
– It can evade the defenses of the immune system and attacks key cells in the immune system
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Transmission and Prevention of HIV
•Transmitted through bodily fluids such as blood, semen, vaginal secretions and breast milk
– Through any form of sexual intercourse
– Through shared needles that are contaminated with infected blood
– Through contact with blood or blood products
– From infected mother to child, through pregnancy, birth and/or breast feeding
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