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NOTES: The Lymphatic / Immune System (UNIT 10 part 1)
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The lymphatic system is closely associated with the cardiovascular system.
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Functions of the Lymphatic System:
● transports excess fluid to the bloodstream ● absorbs fats (lacteal inside villi) ● helps defend the body against disease-causing agents (pathogens)
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LYMPHATIC PATHWAYS Lymphatic capillaries ● microscopic, closed-end
tubes that extend into intercellular spaces ● receive LYMPH through their thin walls (LYMPH = the fluid of the lymphatic system; contains water and dissolves substances that leaked out of blood capillaries.) ● lymphatic capillary networks parallel blood capillary networks
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Lymphatic vessels: ● have walls similar to those
of veins, but thinner, and have valves to prevent backflow of lymph ● become larger as vessels merge; lead to LYMPH NODES and then merge, merge, merge before returning to circulatory system.
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Organs of the Lymphatic System
Lymphatic vessels: transport lymph Lymph nodes: “hang out spot” for immune system cells Spleen: filters blood (immune cells detect germs) Thymus: mature T cells (1 type of immune system cell) Tonsils: lymphoid tissue that “samples” bacteria & viruses as you swallow
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Lymphatic System Condition:
Lymphedema: swelling (edema) due to accumulated lymph Causes: Surgical removal of lymph nodes (i.e. cancer treatment) Some medicines Damage to lymph nodes
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NOTES: The Immune System (UNIT 10 part 2)
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• PATHOGEN: a disease-causing agent; causes infection
-pathogens include: viruses fungi bacteria protozoans
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Background Pathogen Info: Bacteria vs.Virus
*Alive (1 celled organism) take ANTIBIOTICS to slow their growth *Not alive, therefore no antibiotics *Viruses “hijack” cells & use the cells’ machinery in order to reproduce (use cells’ ribosomes. ATP, amino acids, etc.) * 2 types: 1. hijacker (cold) 2. hijacker & infiltrator (HIV) *VACCINES prepare your immune system in case you are exposed to that virus later (can be difficult to develop due to high # of virus mutations)
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Examples of bacteria that cause infection:
E. coli Salmonella Staphylococcus Examples of viruses that cause infection : Papovavirus – papilloma (warts) Adenovirus – respiratory diseases Herpes virus – herpes Poxvirus – smallpox Parvovirus – roseola Picornavirus – polio Rhinovirus – common cold
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The body has nonspecific and specific defenses against infection.
Why don’t YOU have mold on your skin???
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Nonspecific Defenses:
• general defense • provide protection against many different pathogens • involve physical and chemical barriers, fever, inflammation, phagocytosis
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Specific Defenses: • very precise • target certain pathogens
• also known as ACQUIRED IMMUNITY • involve specialized lymphocytes (T cells and B cells) that recognize and respond to specific pathogens **nonspecific defenses are quick to respond; specific defenses are slower to respond
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NONSPECIFIC DEFENSES 1) Species Resistance
• each species is resistant to certain diseases that may affect other species • examples: measles, mumps, gonorrhea, and syphilis infect humans but not other animal species • one species may be resistant to a disease that affects another species because its tissues somehow fail to provide a suitable environment for the pathogen (temperature, chemical environment, etc.)
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2) Mechanical Barriers = FIRST LINE OF DEFENSE (keep out!)
● mechanical barriers / physical barriers include: -skin (and associated hairs) -mucous membranes -fluid (sweat and mucus) ● as long as they remain intact, they can keep out many pathogens
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**all other “nonspecific defenses” are considered the SECOND LINE OF DEFENSE (pathogen inside…. destroy!)
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3) Phagocytosis – removes foreign particles from the lymph and blood
• the most active phagocytes in blood are NEUTROPHILS and MONOCYTES • Monocytes give rise to MACROPHAGES
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• MACROPHAGES are found in the linings of blood vessels in the:
-bone marrow -liver -spleen -lungs -lymph nodes
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4) Chemical Barriers • gastric juice: contains hydrochloric acid (HCl) and enzymes (e.g. pepsin) that are lethal to pathogens • tears: contain the enzyme LYSOZYME (which has antibacterial action) • the salt in perspiration accumulates on the skin and kills bacteria on the skin
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4) Chemical Barriers (cont.)
• INTERFERONS: chemicals released by virus-infected cells; they bind to receptors on uninfected cells; block virus replication
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5) Fever • higher body temperature increases the rate of phagocytic cells • also lowers iron levels in the blood (bacteria and fungi require iron, so this slows their growth)
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6) Inflammation • a tissue response to injury or infection
• histamine & other chemicals released by damaged tissues attract WBCs to the site • histamine dilates capillaries & other chemicals make capillaries more permeable so WBC’s can slip out • produces: localized redness, swelling, heat and pain the mass of WBCs, bacterial cells, and damaged tissue forms a thick fluid called PUS
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CLICKER QUESTION: Which of the following is NOT a nonspecific defense? A) Gastric juice B) Lysozyme found in tears C) fever D) Macrophages (phagocytic cell) E) Skin F) All of nonspecific defenses
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CLICKER QUESTION: Which of the following is NOT part of the 1st line of nonspecific defense? Gastric juice Skin Sweat Mucus membranes
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CLICKER QUESTION: TRUE or FALSE: Interferons are a chemical defense (part of 2nd line of defense) and they are released by virus- infected cells.
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CLICKER QUESTION: How do antibiotics work?
By interfering with a bacteria’s ability to divide or survive. By interfering with a virus’ ability to divide or survive. By increasing the number of “good cells” in your body. A and B All of the above
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CLICKER QUESTION: What causes inflammation? A tissue injury
Broken/damaged lymph capillaries Infection A and C All of the above
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