What is immunity?
The body's ability to protect itself from itself as well as from viruses, bacteria, and other disease-causing entities
What is innate immunity?
Nonspecific, generalized defenses that are present at birth prior to contact with infective agents or other products. Responds quickly to invading pathogens, but does not adapt or 'learn'.
What is the acquired or adaptive immunity?
Highly specific defenses that adapt over time as the body encounters infective agents. A robust, highly effective defense that "learns" and "remembers" to respond more quickly each time a specific pathogen invades.
What is the humoral response?
Involves the production of antibodies by B lymphocyte and is highly effective against toxins, bacteria and extracellular viruses.
One function of the immune system is to recognize and remove abnormal self-cells. Why is this important?
It provides a effective defense against cancers that can be life threatening if left unchecked.
What is a pathogen?
An infectious agent that causes disease or illness to its host.
Complete this sentence: Bacterial are rod-shaped cells that contain ____________ DNA.
circular
Do human cells have cell walls?
No. Our cells are only protected by their membrane. Only plant and bacterial cells have cell walls.
Complete this sentence: Bacteria are protected by a cell wall and sometimes by a _____________________ layer.
lipopolysaccharide
Bacterial infections are treated by:
Antibiotics
Can bacteria survive outside their host?
Yes. In fact most bacteria live their entire life-cycle outside of a host. Many live in a host without causing illness. Relatively few of them cause disease.
Can a virus survive outside its host?
Viruses can exist as spores and sometimes survive that way for years, but they must have a host to replicate.
Viruses contain a ________ or __________ core surrounded by a protein coat.
DNA, RNA
The protein coat surrounding viral RNA or DNA is called a:
Capsid
Sometimes a virus contains an additional __________________ coat, which protects the protein capsid and RNA or DNA viral core.
Phospholipid
Virus lack the transcription/translational machinery necessary to produce viral proteins, so how do they replicate?
Viruses infect cells and use the cells' transcription and translational machinery. In other words, the DNA polymerase, RNA polymerase, and ribosomes of the cell are used to make viral proteins instead of cellular proteins.
Our first line of defense against invasion is our physical and chemical barriers such as:
skin, mucus, and stomach acid
What is lysozyme?
An enzyme in sweat, saliva, tears, and mucus that is capable of destroying certain kinds of bacteria
Leukocytes include:
Mast cells, basophiles, neutrophiles, eosinophiles, and monocytes (which become macrophages)
Lymphocytes include:
Natural Killer Cells (NK cells), B cells, and T cells
Mast cells and basophiles release ________________, which makes capillaries more leaky to allow white blood cells to migrate into the tissues where an infection has occurred.
histamine
Eosinophiles specialize in killing:
parasites
Neutrophiles and Macrophages are the primary ________________ of the immune system.
phagocytes
Cells of the innate immune system recognize __________________________________ (four words) found on the surface of invading pathogens.
Pathogen Associated Molecular Patterns (PAMPs)
What are Pathogen Associated Molecular Patterns?
They are proteins found on the surface of invading pathogens. They are not specific to any one strain of pathogen, but instead are common to many different strains.
What are Pattern Recognition Receptors?
Receptors found on cells of the innate immune system. They are not selective and bind to a variety of proteins (PAMPs) found on the surface of many pathogens.
What are opsonins?
Proteins produced by the liver or antibodies produce by B-cells that coat pathogens to make them easier for the innate immune system to detect.
Monocytes are the precursor cells for:
Macrophages
What is phagocytosis?
The ingestion of bacteria or other material by cells.
What are phagocytes?
White blood cells that ingest pathogens like bacteria.
What are Perforins and Granzymes?
Enzymes that attack and destroy cell membranes
What are cytokines?
Chemical messengers that are released by damaged/infected tissue, cells in the immune system, and by the kidneys that stimulate the differentiation and development of blood cells and recruit white blood cells to injured or infected tissue. These chemical
What are colony stimulating factors?
A family of signaling molecules that stimulates the differentiation of stem cells into specific WBCs, and promotes clonal expansion.
What are Interleukins?
A very large family of signaling molecules. Mostly produced by macrophages, helper T-cells and endothelial cells (cells in the lumen of blood vessels and lymph vessels). Stimulates differentiation of stem cells and production of T cells, B cells, macropha
What are Stem Cell Factors?
A family of signaling molecules that maintains hematopoietic stem cell colonies, promoting their growth when additional blood cells are needed.
What are chemotaxins?
Cytokines that promote cell migration.
What are pyrogens?
Cytokines that cause fever.
What are acute phase proteins?
Proteins that are synthesized by the liver in response to infection, illness, and tissue injury. The proteins enhance the inflammatory response, and aid the innate immune system in defense against pathogens. The include opsonins (not antibodies- those are
What are complement proteins?
A group of plasma proteins released by the liver that can be activated by both the innate and acquired immune systems. They are activated in the complement cascade, that terminates with the activation of membrane attack complex proteins, which create a po
What are antigen presenting cells?
Macrophages and other cells that engulf pathogens, and present proteins and proteins fragments (antigens) from the pathogens on their cell surface. The antigens are displayed on MHC molecules. The antigens are detected by T and B cells and activate the ce
What are antigens?
Proteins or peptide fragments that can mobilize the immune system by activating T and B cells and by promoting antibody production. The only T and B cells that are activated are the T and B cells that have a highly specific receptor for the protein/peptid
What are MHC molecules?
Self-recognition proteins found on the cell surface of most cells in the body. They present peptide fragments from cellular proteins, viral proteins, or in the case of antigen presenting cells, proteins from ingested phagocytes.
Where would I find class I MHC molecules and what do they do?
On most nucleated cells of the body. They present self-peptides generated by normal protein turnover (all proteins wear out and are destroyed and recycled. Some of those protein bits make it to the surface on MHC molecules). Self-peptides are sometimes ca
Where are MHC class II molecules found and what do they do?
They are found on Antigen Presenting Cells such as macrophages, some lymphocytes, some endothelial cells, and in the epithelium of thymus. They presents antigens generated from the phagocytosis and destruction of bacteria and other engulfed pathogens.
How are T-cells activated?
By cell-to-cell contact only. They must make contact with an MHC molecule AND a specific antigen that matches their receptor.
How are B-cells activated?
By cell-to-cell contact with Helper T-cells, and by direct contact with a pathogen. Cell-to-cell contact and pathogen activation is very selective; the B-cell must express a receptor that matches a specific antigen detected by the Helper T-cells, or it mu
How do Helper T-cells aid the immune system?
They are activated by specific antigens displayed by antigen presenting cells. They then activate the B-cell that matches the antigen. The B-cell is activated by direct cell-to-cell contact. The cells also release cytokines that activate T-cells and macro
Cytotoxic T-cells can kill using two different methods. What are they?
They release perforins and granzymes to destroy the cell membrane of an infected cell, or they can activate 'death receptors' on the cell and cause the cell to undergo apoptosis.
During embryonic development T and B cells are created with receptors for an estimated 250,000,000 antigens. The receptors are created by random combination of several gene segments (via alternative splicing). By chance, some of those combinations will re
The embryonic T and B cells that recognize self-antigens are deleted (destroyed). Without these embryonic cells, the immune system is 'blind' to self-antigens.
Where are T-cells educated?
In the thymus
How are T-cells educated?
Embryonic T-cells migrate to the thymus where they encounter MHC molecules and self-antigens. The cells must detect MHC molecules so that they can recognize 'self'. If they detect the MHC molecule adequately, they receive a survival signal. This is called
What happens to B-cells once they are activated?
They undergo rapid clonal expansion. Some develop into plasma cells and secrete antibodies. Some develop into memory cells to prepare for a possible future invasion.
What are antibodies?
Also called immunoglobulins. They are proteins secreted by B-cells that are highly selective for specific antigens. When they encounter the antigen, they bind strongly to it, and they can cause the pathogens to clump together. They help the innate immune
B-cells that produce a specific type of antibody are called:
Clones
How do memory cells enhance our immune response?
Memory cells stay dormant in the lymph system until they encounter their specific antigen, at which point they are activated and rapidly begin producing antibodies. Their response is faster and stronger than the response of a naive B-cell that encounters