Lecture 9: Lymphatic and Immune Systems PDF

BIOL 101 Life Processes Lecture 9 Chapter 7: The Lymphatic and Immune Systems  Chapter 7.1: Lymphatic System Lymphatic system – consists of lymphatic vessels and lymphatic organs  Chapter 7.1: Lymphatic System Lymphatic system – consists of lymphatic ve...

BIOL 101 Life Processes Lecture 9 Chapter 7: The Lymphatic and Immune Systems  Chapter 7.1: Lymphatic System Lymphatic system – consists of lymphatic vessels and lymphatic organs  Chapter 7.1: Lymphatic System Lymphatic system – consists of lymphatic vessels and lymphatic organs Homeostasis Functions: Lymphatic capillaries absorb excess interstitial fluid Lymphatic capillaries absorb fats from the digestive tract and transport them to the bloodstream Lymphoid organs help defend the body against disease  Chapter 7.1: Lymphatic System Lymphatic vessels – form a one-way system of vessels that move fluid from tissues to the cardiovascular system Chapter 7.1: Lymphatic System  Chapter 7.1: Lymphatic System Interstitial fluid – the primary component of lymph; mostly water, but also contains solutes (nutrients, electrolytes, and oxygen) derived from blood plasma. Additionally, interstitial fluid contains cellular products (hormones, enzymes, and cellular waste).  Chapter 7.1: Lymphatic System Lymphatic organs – divided into primary and secondary lymphatic organs Primary lymphatic organs are the red bone marrow and the thymus Secondary lymphatic organs are the lymph nodes and the spleen Chapter 7.1: Lymphatic System  Chapter 7.1: Lymphatic System Primary Lymphatic Organs: Red bone marrow – produces all types of blood cells Children have red bone marrow in most bones  Chapter 7.1: Lymphatic System Primary Lymphatic Organs: Red bone marrow – produces all types of blood cells Adults have red bone marrow in: The sternum Pelvic girdle Vertebrae Humerus Ribs Femur  Chapter 7.1: Lymphatic System Red bone marrow produces red blood cells and five types of white blood cells: Neutrophils Eosinophils Basophils Lymphocytes Monocytes  Chapter 7.1: Lymphatic System Red bone marrow produces red blood cells and five types of white blood cells: Neutrophils Eosinophils Basophils Lymphocytes – divided into B cells and T cells Monocytes  Chapter 7.1: Lymphatic System B cells (B lymphocytes) mature in the bone marrow Any B cell that reacts to body cells is destroyed in the bone marrow and does not enter circulation to prevent autoimmune disorders T cells (T lymphocytes) mature in the thymus **We will return to Lymphocytes later in this chapter to discuss their function**  Chapter 7.1: Lymphatic System Thymus – soft-bodied and bilobed organ located in the cavity between the trachea and the sternum which decreases in size as children grow into adulthood Thymus functions: Produce hormones (like thymosin – aids in the maturation of T lymphocytes) Maturation site of T lymphocytes  Chapter 7.1: Lymphatic System Thymus functions: Maturation site of T lymphocytes – only ~5% of these cells ever leave the thymus To leave the thymus, T cells have to demonstrate that they can attack a pathogen and that they will not attack body cells  Chapter 7.1: Lymphatic System Thymus functions: Maturation site of T lymphocytes – only ~5% of these cells ever leave the thymus To leave the thymus, T cells have to demonstrate that they can attack a pathogen and that they will not attack body cells Without mature T cells, the body cannot adequately respond to specific infections  Chapter 7.1: Lymphatic System Secondary Lymphatic Organs: Spleen – filters blood; largest lymphatic organ, located in the upper left part of the abdominal cavity Within the spleen, macrophages engulf pathogens and debris  Chapter 7.1: Lymphatic System Secondary Lymphatic Organs: Lymph nodes – occur along lymphatic vessels; each of their multiple compartments are filled with lymph, and lymphocytes and macrophages (which attack pathogens and cancer cells) Chapter 7.2: Innate Immune Defenses  Chapter 7.2: Innate Immune Defenses Immunity – the capability of killing or removing foreign substances, pathogens, and cancer cells  Chapter 7.2: Innate Immune Defenses Immunity – the capability of killing or removing foreign substances, pathogens, and cancer cells  Innate (non-specific) immunity  Adaptive immunity Chapter 7.2: Innate Immune Defenses  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Physical and Chemical Barriers  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Physical and Chemical Barriers  Skin – prevents the entry of microbes  Mucous membranes – trap invading pathogens  Perspiration, saliva, and tears – contain Lysozyme (antibacterial enzyme)  Acidic pH – stomach and vagina  Microbiome – beneficial bacteria in our systems  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Physical and Chemical Barriers  Inflammatory Response – employs neutrophils and macrophages to surround and kill invading pathogens  Symptoms of IR: Redness, heat, swelling, pain Chapter 7.2: Innate Immune Defenses Chapter 7.2: Innate Immune Defenses Chapter 7.2: Innate Immune Defenses  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Physical and Chemical Barriers  Inflammatory Response  Histamine – a chemical mediator released by damaged tissue cells and mast cells which cause the capillaries to dilate and become more permeable  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Excess fluid from leaky capillaries cause swelling (which presses on nerves) and pain  These conditions summon white blood cells to the region  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Excess fluid from leaky capillaries cause swelling (which presses on nerves) and pain  These conditions summon white blood cells to the region  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Neutrophils are the first WBCs to arrive, and they phagocytize (eat) debris, dead cells, and bacteria  If neutrophils are overwhelmed, they release Cytokines  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Cytokines – proteins that attract more WBCs, including monocytes  Monocytes are longer-lived cells that become Macrophages  Macrophages are more powerful phagocytes than neutrophils  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Complement system – composed by a number of blood plasma proteins that increase the immune response of one or more specific immune responses  Chapter 7.2: Innate Immune Defenses Innate (non-specific) immunity  Inflammatory Response  Complement proteins can:  Trigger mast cells to release histamine  Attract phagocytes to a specific location  Bind directly to bacteria can cause them to burst Chapter 7.2: Innate Immune Defenses  Chapter 7.2: Innate Immune Defenses Inflammatory Response Phase I -  Chapter 7.2: Innate Immune Defenses Interferons – proteins produced by virus-infected cells that cause uninfected cells to prepare for viral infection by producing substances that interfere with viral replication  Chapter 7.3: Adaptive Immune Defenses Antigen – a large protein structure that the immune system recognizes as a foreign body Fragments of: Bacteria Viruses Molds Parasitic worms  Chapter 7.3: Adaptive Immune Defenses Adaptive defenses primarily depend on B and T cells (B and T lymphocytes)  Chapter 7.3: Adaptive Immune Defenses Adaptive defenses primarily depend on B and T cells (B and T lymphocytes) Each lymphocyte has a single kind of receptor to combine with a specific antigen (like a lock and key)  Chapter 7.3: Adaptive Immune Defenses Adaptive Immunity Pathways Cell-mediated immunity Antibody-mediated (humoral) immunity  Chapter 7.3: Adaptive Immune Defenses Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen  Chapter 7.3: Adaptive Immune Defenses Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen  Helper T cells may come into contact with an antigen and release cytokines to call Cytotoxic T cells to the area  Chapter 7.3: Adaptive Immune Defenses Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen  Helper T cells may come into contact with an antigen and release cytokines to call Cytotoxic T cells to the area  Cytotoxic T cells either phagocytize or trigger apoptosis in infected cells Chapter 7.3: Adaptive Immune Defenses  Chapter 7.3: Adaptive Immune Defenses Adaptive Immunity Pathways Cell-mediated immunity Antibody-mediated (humoral) immunity  Chapter 7.3: Adaptive Immune Defenses Antibody-mediated (humoral) immunity  An antigen binds with a B cell’s receptor  Chapter 7.3: Adaptive Immune Defenses Antibody-mediated (humoral) immunity  An antigen binds with a B cell’s receptor  The B cell then undergoes rapid clonal expansion, creating B memory cells, and plasma cells  The plasma cells created secrete antibodies for the original antigen Chapter 7.3: Adaptive Immune Defenses  Chapter 7.3: Adaptive Immune Defenses Antibody-mediated (humoral) immunity  Only the B cells that have receptors that fit the antigen undergo clonal expansion  Most cloned B cells become plasma cells, which circulate in the blood and lymph and constantly excrete antibodies keyed to the original antigen  Chapter 7.3: Adaptive Immune Defenses Antibody-mediated (humoral) immunity  A minority of the cloned B cells become B memory cells, which have a long life and have the same receptors  Once the infection has passed, any remaining plasma cells undergo apoptosis (programmed cell death)  Chapter 7.3: Adaptive Immune Defenses Antibody Structure  Y – shaped with two antigen binding sites  Chapter 7.3: Adaptive Immune Defenses Antibody Function  Many antibodies will bind with the antigens, covering the offending molecule so that it can’t bind  Antibodies then call for other white blood cells  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgG  IgM  IgA  IgD  IgE  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgG  Main antibody type in circulation  Crosses the placenta from mother to fetus  Binds to pathogens  Activates compliments  Enhances phagocytosis by WBCs  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgM  Found in circulation  Largest antibody  First antibody formed by newborns  First antibody formed in any new infection  Activates compliment and clumps cells  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgA  Main antibody in saliva and breast milk  Prevents pathogens from attaching to epithelial cells in the digestive and respiratory tracts  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgD  Antibody found on the surface of immature B cells  Signifies readiness of B cells  Chapter 7.3: Adaptive Immune Defenses Antibody Classes  IgE  Antibody found as antigen receptors on mast cells  Responsible for immediate allergic response and protection against certain parasitic worms Chapter 7.3: Adaptive Immune Defenses  Chapter 7.3: Adaptive Immune Defenses Cytotoxic T cells – specialized T lymphocytes with storage vacuoles that contain perforins and storage vacuoles that contain granzymes (an enzyme that causes apoptosis) Chapter 7.3: Adaptive Immune Defenses  Chapter 7.3: Adaptive Immune Defenses Helper T cells – specialized T lymphocytes that regulate immunity by secreting cytokines  B lymphocytes cannot be activated without T cell help  HIV (which causes AIDS) attacks T cells, which leaves patients vulnerable to opportunistic infections, which may eventually cause death  Chapter 7.3: Adaptive Immune Defenses Memory T cells – remain within the body and can jump-start an immune response to an antigen previously present in the body  Chapter 7.4: Acquired Immunity Active immunity – occurs when an individual produces antibodies against an antigen Passive immunity – occurs when an individual is given prepared antibodies via an injection  Chapter 7.4: Acquired Immunity Active immunity  Develops naturally after a person is infected with a pathogen  Can be artificially developed by exposure to the antigen  Chapter 7.4: Acquired Immunity Active immunity Immunization – involves the use of vaccines to expose the immune system to the antigen Vaccine – substances that contain an antigen to which the immune system responds  Chapter 7.4: Acquired Immunity Active immunity – Vaccines Vaccines have traditionally been composed of either the pathogen itself or their products that have been treated to no longer be virulent (able to cause the disease) Today, we can use genetic engineering to make bacteria mass produce a protein from the pathogen to make a vaccine (Hep B and Malaria)  Chapter 7.4: Acquired Immunity Active immunity – Vaccines Initially, vaccines typically illicit an immune response that peaks around 14 days after injection A second dose of vaccine (Booster) will typically illicit a much faster and higher concentration of antibodies, because memory B and T lymphocytes are already present Chapter 7.4: Acquired Immunity  Chapter 7.4: Acquired Immunity Passive immunity – occurs when an individual is given prepared antibodies via an injection (or via other means) Because the infected individual’s body (Plasma cells) is not responsible for making the antibodies, the immunity is temporary  Chapter 7.4: Acquired Immunity Passive immunity is commonly achieved in infants from IgG antibodies that have crossed the placenta from their mother. Within a few months, these antibodies will disappear, and the infant will be susceptible to infection  Chapter 7.4: Acquired Immunity Even though passive immunity does not last, it is sometimes used to prevent illness in a patient who has unexpectedly been exposed to an infectious disease. This can be done by injecting the patient with gamma globulin of serum that contains antibodies (sometimes taken from individuals who have recovered from the disease) Chapter 7.4: Acquired Immunity  Chapter 7.5: Disorders of the Immune System Acquired immunodeficiency syndrome (AIDS) – inability of the acquired immune system to respond to opportunistic pathogens because of a low helper T cell count; caused by HIV Human immunodeficiency virus (HIV) – virus that infects and destroys T helper cells and macrophages; causes AIDS if untreated  Chapter 7.5: Disorders of the Immune System Opportunistic infection – an infection that can only occur because the patient’s immune system is compromised Chapter 7.5: Disorders of the Immune System  Chapter 7.5: Disorders of the Immune System Allergies – a hypersensitivity to a substance, like pollen, food, animal hair, or mold, that would ordinarily do no harm to the body Allergen – an antigen that elicits an allergic response Immediate allergic response – response within seconds to be exposed to an allergen; caused by IgE antibodies attached to receptors on mast cells and basophils  Chapter 7.5: Disorders of the Immune System Anaphylactic shock – an immediate allergic response that occurs when an antigen enters the bloodstream; characterized by a life-threatening sudden drop in blood pressure due to the increased permeability of capillaries in response to a flood of histamine. Often treated with epinephrine.  Chapter 7.5: Disorders of the Immune System Delayed allergic response – immune response initiated by T cells at the site where an allergen contacts the body  Used to test for tuberculosis (TB): when the antigen is injected under the skin, the site will become red and hardened if the patient has previously been exposed to TB  Contact dermatitis occurs at the point where skin is exposed to the antigen; common examples include poison ivy, jewelry, cosmetics, latex, etc.  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Organ Rejection Many human organs could easily be transplanted between patients if not for the immune system recognizing the new tissue as “not self” (MHC antigens) Immunosuppressive drugs can be administered to prevent the production of certain T cell cytokines  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Severe Combined Immunodeficiency Disease (SCID)  Characterized by both the antibody and cell-mediated immune responses being either inadequate or lacking  Has been successfully treated with bone marrow transplant and/or gene therapy Chapter 7.5: Disorders of the Immune System  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Disease  Occurs when cytotoxic T cells or antibodies attack the body’s own tissues  Exact cause is unknown, but it appears to have both genetic and environmental components  Women more likely to develop autoimmune disorders than men https://healthmatch.io/blog/the-hygiene-hypothesis-does-being-too-clean-increase-your-risk-of-developing https://healthmatch.io/blog/the-hygiene-hypothesis-does-being-too-clean-increase-your-risk-of-developing  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Disease – The Hygiene Hypothesis  Living in anthropogenic (human-made) environments limits our contact with a variety of pathogenic worms and bacteria  Our immune systems may require irregular contact with these pathogens to maintain an understanding of what is “self” and “not self”  Modern pollutants and antibiotics may also be contributing to the confusion of our immune systems https://healthmatch.io/blog/the-hygiene-hypothesis-does-being-too-clean-increase-your-risk-of-developing  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Diseases that Follow Infections  Rheumatic fever – antibodies introduced into throat to fight the streptococcal infection also react with the heart muscle  Causes an inflammatory response in the heart that damages the heart muscle and valves  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Diseases Rheumatoid arthritis – causes chronically inflamed joints  Antibodies, compliments, neutrophils, activated T cells, and macrophages all attack the cartilage of the joints  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Diseases Systemic lupus erythematosus (SLE) – various symptoms including facial rash, fever, and joint pain  Patients produce high levels of anti-DNA antibodies, which interferes with tissues throughout the body  Damage to the central nervous system, heart, and kidneys can be fatal Chapter 7.5: Disorders of the Immune System  Chapter 7.5: Disorders of the Immune System Other Immune System Disorders Autoimmune Diseases Myasthenia gravis – antibodies attach to muscle cells  Causes muscle weakness and eventual death from respiratory failure