Transcript skin and immune system

The Integumentary and
Immune Systems
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Section:
Section Outline
Section 36-3
36–3 The Integumentary
System
The Skin
1.Epidermis
2.Dermis
3.Skin Cancer
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Section:
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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Section:
Concept Map
Section 36-3
Skin
functions
as a
Barrier to
infection
Regulator of
body
temperature
is made
up of the
Remover of
waste products
Protector
against UV
radiation
Epidermis
which
is the
Outer layer
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Dermis
which
is the
Inner layer
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
Section 40-2
40–2
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Section:
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
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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Figure 40–7 The Inflammatory Response
Section 40-2
Skin
Wound
Phagocytes move into the
area and engulf the bacteria
and cell debris
Bacteria enter
the wound
Capillary
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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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Section:
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:
Primary and Secondary Immune Responses
Antibody Concentration
Section 40-2
Interval
between
exposures
First
exposure
Second
exposure
Time
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Figure 40–9 Humoral Immunity
Section 40-2
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Section:
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:
Figure 40–10 Cell-Mediated Immune Response
Section 40-2
Macrophage
Helper T cell activates
killer T cells and B cells
T cell binds to
activated
macrophage
Helper
T Cell
Killer
T Cell
T Cell
Antigens are displayed on
surface of macrophage
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 Outline
Section 40-3
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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