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Why are cells seen as desirable by bacteria?
Cells are sacs full of nutrients and energy.
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Name 3 External Defenses (nonspecific) to invading microbes:
Skin, mucous membranes, and secretions
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Name four internal defenses against invading microbes:
Phagocytic cells, antimicrobial proteins, inflammatory response, and natural killer cells
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The skin and mucous membranes act as a barrier for the body, but also provides chemical defenses. How so?
Saliva, tears, and mucus provide washing action. Secretions contain antimicrobial proteins, and stomach pH is low due to large amounts of pepsin, making it an undesirable place for bacteria.
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How do cilia and mucus work?
Cilia sweeps pathogens (ie: dust, pollen, etc.) upwards, and it catches in mucus. The mucus is then also swept upwards by the cilia.
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What do pseudopodia do?
They trap pathogens by forming a vacuole around them.
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What is the purpose of the vacuole in phagocytosis?
The vacuole holds the microbes (pathogens) inside of the macrophage.
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What does the lysosome do in phagocytosis?
It fastens itself to vacuoles and breaks down the microbes inside.
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Phagocytosis
When macrophages engulf bacteria, sends them into lysosomes, and kills them.
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Name two ways lysosomes can kill microbes:
They can use superoxide anions and nitric oxide to tear apart any sort of molecule, or they can use lysosomal enzymes to break down the peptidoglycan in cell walls.
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Some microbes evade phagocytosis. How do they do this?
They enter cells in a way which allows them to be far away from macrophages, escape macrophages before lysosomal attachment to the vacuole by increasing the pH, or overwhelm the system.
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Where do phagocytic cells "catch" their prey?
They travel around in areas with lots of capillary beds, or are fixed in the lymph nodes.
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Neutrophils
60-70% of all leukocytes, these cells are attracted towards chemical signals and self-destruct when they destroy invading microbes.
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Monocytes
5% of all leukocytes, these cells migrate into tissues and develop into macrophages. They are long-lived.
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Eosinophils
1.5% of all leukocytes, these cells defend against larger pathogens by discharging destructive enzymes from cytoplasmic granules and destroying bacteria from the outside.
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Basophils
Migrating leukocytes that release chemical signals which help initiate inflammatory response.
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Mast Cells
They stay in one place and signal for inflammatory response to begin and to recruit destroyers to come to area of infection.
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What is localized inflammatory response triggered by?
It is triggered by damage to tissue or by the entry of microorganisms.
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First step of the localized inflammatory response:
Basophils and mast cells release histamine and prostaglandins.
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Second step of the localized inflammatory response:
Capillary dilation and increased permeability allow blood clotting elements to be released (fluid, red, and hot).
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Third step of the localized inflammatory response:
Chemokines from bacteria and tissue attract leukocytes.
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Fourth step of the localized inflammatory response:
Macrophils carry out phagocytosis and neutrophils heal the affected area.
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Antimicrobial Proteins
Proteins involved in nonspecific defense. They attack microbes directly or inhibit their production.
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Complement System
About 20 serum proteins stringed together that carry out processes which LEAD to lysis.
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Interferons
Made by virus-infected cells, they help prevent spread of viral infection and give short-term nonspecific resistance to other viruses.
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Fever
A nonspecific response to infection which is triggered by toxins from pathogens or by pyrogens released from leukocytes.
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What do pyrogens do?
They reset the body's temperature to something higher.
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Septic Shock
Occurs when a fever is too high for the body's own good. Is a systemic inflammatory response and is characterized by high fever and low blood pressure.
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Natural Killer Cells
Attack abnormal body cells and virus-infected cells. They cause lysis.
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First line of defense for the body
skin and mucous membranes
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Second line of defense for the body
Phagocytes, natural killer cells, inflammation, antimicrobial proteins, and fever
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Chemokynes
Chemicals which create a response from cells. They create signals.
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What are the two main types of lymphocytes?
B lymphocytes (B cells) and T lymphocytes (T cells).
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Where are lymph cells concentrated?
The spleen, lymph nodes, and in other lymphatic tissue.
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Where do T cells develop?
In the thymus.
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Where do B cells develop?
In bone marrow.
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B cells give rise to ___________ immunity.
Humoral
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T cells give rise to ___________ immunity.
Cellular
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Antigen
A foreign molecule that binds specifically to antibodies or antigen receptors.
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Antibody
Produced and secreted by B cells that are stimulated by a particular antigen.
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B cells who have antibodies attached to them can become two different things. Name them.
They can become long-lived memory cells to help fight off disease later or they can become short-lived and fight off infection now.
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A shot makes it so you get a __________ immune response when infected.
Secondary
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How do antibodies help protect the body from foreign cells and pathogens?
The binding of antibodies to antigens marks (tags) foreign cells and molecules for destruction by phagocytosis or causes cell lysis.
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To activate complement fixation, you need:
Two antibodies near each other.
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Helper T Cells
Help stimulate B-cells to make antibodies.
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Cytotoxic T-cells
Destroy abnormal body cells and infected body cells.
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Do helper t-cells and cytotoxic t-cells recognize antigens made by MHC molecules?
Yes.
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MHC molecules do two things. What are they?
They mark body cells as belonging to yourself and they present antigens to T-cells.
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T Dependent Antigens
Antigens which trigger antibody production only with the participation of helper T cells.
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T Independent Antigens
Antigens which trigger antibody pruduction without helper T cells.
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Active immunity depends on what?
The person's own immune system.
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Passive immunity depends on what?
Antibodies transferred from another individual to the person.
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List four autoimmune diseases:
Rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and insulin-dependent dibetes mellitus.
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List three immunodeficiency diseases:
Hodgkin's disease, severe combined immunodeficiency, and acquired immune deficiency syndrome.
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