The Integumentary and Immune Systems

36–3 The Integumentary System The Skin 1. Epidermis 2. Dermis Section Outline Section 36-3 36–3 The Integumentary System The Skin 1. Epidermis 2. Dermis 3. Skin Cancer

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

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

Concept Map Skin Section 36-3 functions as a is made up of the Barrier to infection Regulator of body temperature Remover of waste products Protector against UV radiation Epidermis Dermis which is the which is the Outer layer Inner layer

Figure 36-13 The Structure of Skin Section 36-3

Disorder of the Integumentary System Skin cancer Excessive exposure to UV radiation can lead to an abnormal growth of cells in the skin

A. Nonspecific Defenses 1. First Line of Defense Section Outline Section 40-2 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 Passive Immunity D. Diseases of the Immune System

The body’s primary defense mechanism 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

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.

Figure 40–7 The Inflammatory Response Section 40-2 Wound Skin Phagocytes move into the area and engulf the bacteria and cell debris Bacteria enter the wound 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

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

Primary and Secondary Immune Responses Section 40-2 Interval between exposures Antibody Concentration First exposure Second exposure Time

Figure 40–9 Humoral Immunity Section 40-2

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

Figure 40–10 Cell-Mediated Immune Response Section 40-2 Helper T cell activates killer T cells and B cells Macrophage T cell binds to activated macrophage Helper T Cell Killer T Cell T Cell T cell, activated by macrophage, becomes a helper T cell Antigens are displayed on surface of macrophage Infected Cell Killer T cells bind to infected cells, disrupting their cell membranes and destroying them

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

40–3 Immune System Disorders A. Allergies Autoimmune Diseases Section Outline Section 40-3 40–3 Immune System Disorders A. Allergies Autoimmune Diseases HIV and AIDS

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

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

AIDS is an autoimmune disease that results from infection with HIV 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

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