Upload
alexander-hamilton
View
222
Download
1
Tags:
Embed Size (px)
Citation preview
Chapter 43 ~
The Immune System
The 3 R’s- Reconnaissance,
Recognition and Response
Types of Immunity
Innate Defense – nonspecific barriers (skin, mucus) and chemical defenses
phagocytic cells Acquired Defense- highly
specific, only after exposure to the pathogen
Specific immunity includes lymphocytes and antibodies
Macrophage filled with pathogens
Lines of Defense- Nonspecific or Specific
Non-specific patrolling cells attack pathogens, but
don’t “remember” for next time leukocytes
phagocytic white blood cells macrophages, neutrophils,
natural killer cells, dendritic cells
Antimicrobial proteins Complement system Interferons
inflammatory response increase in body temp. increase capillary permeability attract macrophages/neutrophils
yeast
macrophage
bacteria
Specific defense Antigens illicit a response
of B or T cells Lymphocytes recognize a
small portion of the antigen called an epitope
After initial response- possible illness
Selected B cells clone themselves to become antibodies
Some B cell clones develop into memory cells
The Inflammatory Response 1- Tissue injury causes release of chemical signals 2. Histamine causes dilation and increased permeability of capillaries 3. Increased blood flow causes heat and swelling cytokines secreted by blood vessel endothelial cells initiate phagocytic migration of WBCs 4- Phagocytosis of pathogens occurs by WBCs
Acquired or Specific Immunity Terms B Cells- WBCs made in bone
marrow T Cells WBC stored in thymus Antigen: a foreign molecule that
elicits a response by lymphocytes Antibodies: antigen-binding
immunoglobulin, produced by B cells
Antigen receptors: plasma membrane receptors on B and T cells
Memory cells: cloned lymphocytes
Major Histocompatability Complex MHC
body cell surface antigens coded by a family of genes Allows cells to recognize each other as SELF Different antigens will be considered FOREIGN
Cell-mediated Response: T cells Cytotoxic T cells Destroy cells infected by intracellular pathogens and
cancer cells by cell lysis by the chemical perforin
Humoral response: B cells Occurs outside the
cell Helper T cell aids
macrophage with CD4 protein
Activated T cell secretes cytokines that activate B cell
B cell differentiates into memory and plasma cells (antibodies)
Helper T lymphocytes Function in both humoral & cell-mediated immunity Stimulated by antigens Clones itself and produces memory cells
How Antibodies work1. antibody binds to and blocks antigen activity
2. Agglutination: antigen clumping
3. Precipitation: cross-linking of soluble antigens
4. Complement fixation: activation of 20 serum proteins, that lyse viruses and pathogenic cells
Primary and Secondary Immune Responses
Primary Secondary -lag time of 10 days -no lag time
to 14 days as body - antibodies already makes antibodies made
- response is
immediate
Immunity in Health & Disease Active immunity:
natural: recovering from disease
artificial: immunization
Passive immunity:
natural: mother to fetus; breast milk
• artificial: rabies antibodies
Active Immunity Get exposed to pathogen!
Naturally – get sick Artificially – get a vaccination
Both methods cause memory cells to be made for future exposures.
Rapid response to
second exposure. You
don’t even know you
were exposed!
Naturally obtaining antibodies from mother
antibodies pass from mother to baby across placenta or in mother’s milk
Artificially injection of antibodies Ex: anti-venom serum short-term immunity
Passive immunity
Tissue Graft and Organ Transplantation
Can be a problem due to MHC
Antirejection drugs are used to prevent tissue or organ rejection
Identical twins have identical MHC but can have different antibodies (they aren’t always in the same place)
In 2013 a 3 year old has a 5 organ transplant- liver, stomach, pancreas small and large intestine
Abnormal immune functions
Allergies hypersensitive responses to environmental antigens (allergens);
Autoimmune disease (generate antibodies against own cells):
-multiple sclerosis (myelin sheath of nerve cells)
-lupus (variety of cells)
-rheumatoid arthritis (joints)
-insulin-dependent diabetes mellitus (pancreatic cells)
Immunodeficiency diseases:
- inborn -SCIDS (bubble-boy)
- acquired -AIDS
Acquired ImmunoDeficiency Syndrome
Immune system is susceptible to opportunistic infections ( a fungal pneumonia, Kaposi’s sarcoma)
Loss of helper T cells HIV is highly mutable Transmission requires
transfer of body fluids (semen and blood)
How Do Vaccines Work?
Vaccines imitate an infection
Immune system will respond by producing T cells and antibodies