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The Integumentary and Immune Systems

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36–3 The Integumentary SystemThe Skin

1.Epidermis2.Dermis3.Skin Cancer

Section Outline

Section 36-3

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Roles of the Skin

•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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Layers of the Skin

•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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Skin

Barrier to infection

Regulator of body

temperature

Remover of waste products

Protector against UV radiation

Epidermis Dermis

Outer layer Inner layer

functions as a

is made up of the

which is the

which is the

Concept Map

Section 36-3

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Figure 36-13 The Structure of Skin

Section 36-3

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Disorder of the Integumentary System

•Skin cancer

– Excessive exposure to UV radiation can lead to an abnormal growth of cells in the skin

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Section Outline

40–2 The Immune System A. Nonspecific Defenses

1. First Line of Defense2. Second Line of Defense

B. Specific Defenses1. Humoral Immunity2. Cell-Mediated Immunity

C. Acquired Immunity1. Active Immunity2. Passive Immunity

D. Diseases of the Immune System

Section 40-2

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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• 1st 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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SkinWound

Bacteria enter the wound

Phagocytes move into the area and engulf the bacteria and cell debris

Capillary

Section 40-2

Figure 40–7 The Inflammatory Response

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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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Interval between exposures

First exposure

Second exposure

Time

Ant

ibod

y C

once

ntra

tion

Section 40-2

Primary and Secondary Immune Responses

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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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Macrophage

T Cell

Helper T Cell

Killer T Cell

Infected CellAntigens are displayed on surface of macrophage

T cell binds to activated macrophage

T cell, activated by macrophage, becomes a helper T cell

Helper T cell activates killer T cells and B cells

Killer T cells bind to infected cells, disrupting their cell membranes and destroying them

Section 40-2

Figure 40–10 Cell-Mediated Immune Response

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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 Outline

40–3 Immune System DisordersA. AllergiesB. Autoimmune DiseasesC. HIV and AIDS

Section 40-3

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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