Immune System Flashcards
Identify the two lines of defense against pathogens. Innate (Non-specific) system and Adaptive (Specific) system.
The Innate Defense System will react to all foreign substances in body. There are 2 barricades; the Surfaces Barriers (Skin and Mucosae) and the Internal Defenses (antimicrobial proteins, phagocytes, and other cells to inhibit the spread of infection).
The Adaptive Defense System only reacts to specific pathogens. It uses Humoral Immunity (B cells) and Cellular Immunity (T cells).
Identify the external parts of the Innate Defense System and what makes them excellent for defending against pathogens.
Skin: Produces Keratin which is waterproof and protects against microorganisms, weak acids and bases, bacterial enzymes and toxins. The skin has antimicrobial chemicals called Defensis that are made by Neutrophils and help control bacterial and fungal colonization in exposed areas. Defensis make holes in the membrane of infectious cells and destroy them from the inside. The Lactic Acid on the skin has a pH of 3-5. Lysosomes break down the cell membranes of the bacteria.
Mucous Membrane: Lines the parts of the body that are exposed to the external environment. The Respiratory Tract, Digestive Tract, Urinary Tract, and Reproductive Tract. These membranes help to trap pathogens.
Identify the Non-specific cells of the body. Neutrophils, Macrophages , and Lymphocytes.
Neutrophils: Perform phagocytosis. The most abundant white blood cell.
Macrophages: Derived from Monocytes. They are mobile and free-moving. Free moving Macrophages move freely through tissue spaces. There are “fixed” macrophages that only reside in particular organs such as Microglial Cells and Dendritic Cells. Macrophages participate in phagocytosis.
Lymphocytes: These are Natural Killer Cells. When a “self-cell” becomes abnormal or there is a transplanted cell, they will monitor them using Immune Surveillance. When they attack a foreign cell they secrete Perforin which binds to the cell membrane and makes holes. It then secretes Granzymes into the holes and causes the cell to Apoptosis (cell suicide).
Define Chemotaxis.
When inflammatory chemicals act on chemotactic agents, neutrophils will migrate up the gradient of the agents to the site of the injury.
Define Diapedesis.
Chemical signals prompt neutrophils to pass and squeeze through the walls of capillaries.
What is respiratory burst of neutrophils?
Helper T cells release chemicals that tell the neutrophils that phagocytosis isn’t going to work. The neutrophils then release free radicals in the tissue causing cells to convert oxygen into hydrogen peroxide instead. Neutrophils destroy themselves in this process.
What are Natural Killer cells?
Natural Killer cells attack and destroy cancerous and infected cells. They kill the target cell by causing it to undergo apoptosis(cell suicide).
What is Immunological Surveillance?
Theory that the immune system patrols the body to recognize an destroy pathogens including cancerous “host” cells.
How does perforin work?
A chemical secreted by Killer Cells. It binds to the membrane to the infectious cell and makes a hole in the membrane.
Define Inflammation.
Localized, protective response to tissue injury of any kind.
What are the goals of inflammation?
To limit the spread of pathogens, Remove debris from tissue, alert adaptive immune system, and sets stages for tissue for repair.
Identify the three stages of inflammation: Inflammatory Chemical Release, Vasodilation and increase vascular permeability, and Tissue Clean up and Repair.
Inflammatory Chemical Release by the damaged tissue (Histamine, Bradykinin, Heparin). These cause localized vasodilation and capillaries to become leakier.
Vasodilation and Increased Vascular Permeability causes Exudate (fluid containing clotting factors and antibodies) to seep from blood to the damaged tissue. This rush of fluids causes the foreign materials to go to the Lymphatic System. Clotting factors then form a fibrin mesh for a scaffolding for repair.
Tissue Clean UP; this is an increased number of Leukocytes to the area of repair. Macrophages act as Antigen Presenting Cells, Pus forms, Platelets release Platelet Derived Growth Factors (PDGF) which stimulate fibroblasts to make collagen fibers.
Identify the two types of Antimicrobial Proteins the provide short term non-specific resistance to pathogens. (Interferons and The Complement System)
Interferons: Made by virus infected cells. They move to uninfected cells which cause them to make antivirual proteins which will interfere with the virus’ ability to infect that cell. They also activate natural killer cells.
The Complement System: A group of 20+ beta globulin proteins that supplement the action of the other immune responses such as Phagocytosis, Inflammation, and Infected Cell Lysis.
What are the three pathways the complement system can undergo? (Classical Pathway, Lectin Pathway, and Alternative Pathway)
Classical Pathway: Involves antibodies that the adaptive immune system produces to fend off foreign invaders. When these antibodies bind to the pathogen, they can also bind to complement components. This is called Complement Fixation.
Lectin Pathway: Involves Lectins that the innate immune system produces to recognize foreign invaders. When they bind specific surgars on the surface of microorganisms, they can bind and activate complement.
Alternative Pathway: Triggered by spontaneously activated C3 and other complement factors interacting on the surface of microorganisms. They lack the complement activation inhibitors allow the process to continue.
Define Fever.
Fever: Abnormal increase in body temperature. System wide response to pathogens. Macrophages/Neutrophils appear and release Pyrogens (Fever producing cells that are sent to the hypothalamus to increase body temperature).
