Download Animals and Immune Systems

During the Quarter Quell, Katniss Everdeen searches for
water in the arena. Before she found it, she began to
become dehydrated. What would happen because of this
in terms of ADH? How would this help her condition?
HW:
-Read 35.1
Turn in:
-Nothing
• Animals are the only organisms with major immune systems
• Help defend against pathogens= disease-causing agents
• Ex. Bacteria, fungi, protists, viruses
• 2 major components
• Innate immunity
• Adaptive immunity
• Response to specific pathogens
• Both ways require molecular
recognition
• Found in all animals and plants
• Invertebrates
• Hard exoskeleton in insects
• Immune cells- phagocytosis
• Barrier Defenses (external)
• Skin
• Mucous membranes
• Other body secretions
• Ex. Lysozyme
• Acidic environment of stomach
• Ciliated epithelia
• Cellular Innate
Defenses (internal)
• Phagocytic cells
• Macrophages
• Natural killer cells
• Release chemicals
• Lymphatic system
helps
• Pathogen presence triggers polypeptide and protein production
1. Interferons- proteins that help with viral infections
2. Complement System
-Proteins in plasma that can lead to lysis of invading cells
• Inflammatory response
• Signaling molecules released upon injury or infection
• Swelling and pain
• Molecules (cytokines and histamine) to increase blood flow to
site of injury or infection
*Fever
What is one example of innate immunity?
HW:
-Read 35.2
Turn in:
-Nothing
• Pathogen-specific recognition
• Relies on T cells and B cells
• White blood cells known as lymphocytes
• Anything that brings about response from the cells is known as an
antigen
• Usually proteins or polysaccharides
• Pathogen recognition is done by an antigen receptor on T and B cells
• B cells have membrane-bound antigen receptors
• Antibodies- proteins secreted by cells rather than
membrane-bound
• T cells bind only to fragments of antigens
• MHC molecule- protein on cell that displays fragment of
antigen
• Immense diversity of lymphocytes and receptors
• Allow your body to respond to pathogens that have never
been encountered
• Self-tolerance
• Not attack self
• Cell proliferation triggered by activation
• Increases number of B and T cells specific for an antigen
• Stronger and more rapid response to an antigen encountered
previously
• Immunological memory
• 1 million different B cell receptors, 10 million T
cell
• Only 20,000 protein-coding genes
• How can this happen?
• How does body know self?
• Lymphocytes are tested for self-reactivity
during development
• If have antigen receptors for body, the cell is
destroyed
• Binding of an antigen receptor to an epitope
starts events
• Activates B cell or T cell
• Once activated, begin cellular divisions
•Clones are effector cells
• B cells= plasma cells which secrete
antibodies
• T cells= helper T cells and cytotoxic T cells
• Memory cells= give rise to effector cells if
same antigen is encountered later
• Primary Immune Response
• Production of effector cells during first exposure to
antigen
• Secondary Immune Response
• Later exposure
• Much faster response (2 days)
• Prolonged response
• Adaptive!!!
What is the difference between B cells
and T cells?
HW:
-Read 35.3
• Humoral
• Occurs in body fluids
• Antibodies eliminate pathogens and toxins
• Cell-mediated
• T cells destroy infected host cells
***Both can have a primary and secondary immune
response
***Both use helper T cells
• Trigger both humoral and cell-mediated responses
• Release signals that lead to production of antibodies
and activate cytotoxic T cells
• 2 requirements for helper T cell to activate either
response
1. Foreign molecule must bind to antigen receptor of
T cell
2. Antigen must be displayed on surface of antigenpresenting cell
-Ex. B cell or macrophage
• Two classes of MHC molecules
• Most cells have only MHC I
• Antigen presenting have MHC I and II
• Class II provides the correct molecular signature by which
a cell is recognized
• Activated helper T cells can activate cytotoxic T cells
• Use toxic proteins (enzymes) to disrupt membrane and
trigger cell death
• B cells secrete antibodies in the humoral response
• Activation occurs by helper T cells
• B cell divides, becoming plasma cells and memory B
cells
• Antibodies do not kill pathogen directly but marks
them and can also inactivate the pathogen
• Ex. Virus inactivation
• Active immunity: defenses that arise when a pathogen infects the
body
• Passive immunity: Antibodies in recipient are produced by another
individual
• Ex. Fetus and mother
• Breast milk and infant
• Vaccination/immunization
• Allergies
• Allergens
• Trigger release of histamines and inflammatory chemicals
• Attack against certain molecules of the body
• Ex. Lupus
• Antibodies that tag histones and DNA
• Ex. Rheumatoid arthritis
• More females affected than males
• Unknown why this is….