infectious disease and the immune system. viruses viruses are non- living. only characteristic of...
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Infectious Disease Infectious Disease and the Immune and the Immune
SystemSystem
Viruses
• Viruses are non-living.
• Only characteristic of living organisms is ability to reproduce.
• Obligate intracellular parasites.
• Viruses are composed of;– a nucleic acid- can
be dna OR rna. – Protein coat called
a capsid which can be different shapes; helical, polyhedral
– Some viruses have an envelope of lipids that surround the capsid when they leave a host cell
Viruses
• Virus types:– DNA viruses.– RNA viruses.
Viruses
• Retroviruses– RNA core.– Must contain an
enzyme called reverse transcriptase.
– RNA + reverse transcriptase--DNA—inserts into host cell’s DNA—host cells ribsomes make mRNA—Proteins are part of new viruses
Viruses
• Viroids:– Naked RNA that
can replicate.• Prions:
– Infectious proteins.
– Disrupt the cells activities.
Viroids & Prions
Polio virus Influenza Virus
EbolaRabies
Bacteria
• Prokaryotic cells.• Always single cell.• Composed of:
– Cell wall– Cell membrane– Cytoplasm.– DNA that is a
single closed loop– NO membrane
bound organelles
Plasmids
• Some bacteria have a secondary genome called a plasmid.
• Small self replicating DNA that cause disease or make the bacteria resistant to antibiotics
• Some bacteria have a capsule.– Composed of
polysaccharides.– Protects bacteria
from WBCs.
• Bacteria have short hair like structures called pili for connecting to each other and to hosts.
Bacteria
Nonspecific Defenses
Nonspecific Defenses
• Pathogens are disease causing agents.
• Resistance is your bodies ability to defend against pathogens.
• Your immune system gives you resistance.
Koch’s Postulates
• Pathogen must occur in body of organism with the disease.
• Pathogen should be isolated and grown in culture.
• Inoculated animal should develop the disease.
• Same pathogen should be grown in culture.
Identifying Pathogens
Physical Barriers to Disease
• Nonspecific defense.– Sweat, oils, & waxes.– Mucous membranes.– HCL of stomach.
Fever
• Pathogens that attack human body like 98.6 f. best.
• Hypothalamus raising temperature of body increases effectiveness of WBC’s.
• Decreases effectiveness of pathogen.
Proteins
• Interferons– Chemical released by
cells infected by viruses.
– Causes surrounding cells to resist infection.
• Complement Proteins– Circulate in your blood
and become active when they encounter certain pathogens
Inflammatory Response
• Inflammatory response occurs when pathogen penetrates the skin.
• Nonspecific- any pathogen causes an inflammatory response if your skin is broken
Inflammatory Response
• Symptoms:– Redness– Heat– Swelling
pain
Inflammatory Response
• What occurs:– Damaged cells
release histamines.– Causes increase in
permeability.– Causes
vasodialation (swelling)
– Allows phagocytes to digest and destroy foreign matter.
– Phagocytes are drawn towards histamine
Non specific Cellular Defense
• Neutrophils– Most common
phagocyte– Kill pathogens
using phagocytosis.– Circulate in blood
stream.– Migrate towards
site of infection. (chemotaxis)
– Move out of the blood stream (emmigration)
Non specific Cellular Defense
• Macrophages- another type of phagocyte– Stationed in
certain tissues.– Destroy by
phagocytosis.– Rid the body of
debris and damaged cells.
Non specific Cellular Defense
• Natural Killer CellsCytotoxic T Cells
–Attack cells which have been infected by pathogen.–Kills cancer cells.–Kills by puncturing cell membrane.
Day 3
Immune system and recognition of pathogens
How WBCs Recognize Pathogens
• All of your cells are marked as “self” by proteins in your cell membrane.
• Nonspecific WBCs recognize your proteins.
• They leave these cells alone.
• Any cell that does not have “self” markers are attacked.
Summary of Immune System To Date:
• Body has different “lines of defense”.– Barriers
• Skin, mucous membranes, secretions.
– Non specific defenses.• Macrophages, neutrophils, natural killer
cells.• Interferon, compliment proteins.
– Specific defenses.
Specific Defenses
• If pathogens enter the body, the immune system responds.
• Response is to specific pathogens. (Single type)
RBC of different blood type has RBC of different blood type has antigensantigens
Immune System Organs
• Thymus gland• Spleen• Bone marrow• Lymph nodes• Lymphocytes
– B cells– T cells (helper,
cytotoxic)
Immune Responsehow antigens are 1st
recognized by lymphocytes- cell mediated response
• Pathogen has proteins (antigens) on its surface.
• Macrophages destroy pathogen.
• Macrophages present parts of the pathogen (antigen) to helper T cells.
• Macrophages release interleukins
• Interleukins cause– Cytotoxic Killer T cells to
destroy infected cell– Creation of B cells
How Antigens are Recognized
• Lymphocytes then remember the antigen.
• Attack and destroy if in body.
• Cell mediated immune response.
• Antibody and cell mediated immune response are happening at the same time in the body.
Cell Mediated Immune System
• Macrophages present portion of pathogen to B Lymphocyte cells.
• B cells learn pathogen structure and divide into plasma cells and memory cells
• Antibodies are madeBacteria adhering to T lymphocyte.
Antibody Mediated Immune System
• Plasma cells produce proteins called antibodies.
• Antibodies recognize and attach to pathogen.
• Antibodies are Y-shaped proteins.
Antibody Mediated Immune System
• The two arms of the antibody are identical.
• • Antibodies match
proteins of pathogen.
• Actions of antibodies.
Antibody Mediated Immune System
• Primary response occurs the first time exposure to pathogen occurs.
• Secondary response occurs when pathogen invades again.– Faster reaction.– Stronger reaction.– Memory B cells.
Immunity & Vaccination• Naturally acquired active immunity.
– Your are exposed to pathogen in everyday life.
• Naturally acquired passive immunity.– Breast milk.– Mom’s antibodies prior to to birth.
• Artificially acquired active immunity.– Vaccination.
• Artificially acquired passive immunity.– You are given a shot of antibodies.
Brain Pop
• http://glencoe.mcgraw-hill.com/sites/dl/free/0078695104/161752/00051106.html
• Immune System ↑
• http://glencoe.mcgraw-hill.com/sites/dl/free/0078695104/164155/00044676.html
• Bacteria ↑