12 The Lymphatic and Immune Systems Lesson 12

12 The Lymphatic and Immune Systems Lesson 12. 1: The Lymphatic System Lesson 12. 2: Nonspecific Defenses Lesson 12. 3: Specific Defenses Lesson 12. 4: Disorders and Diseases of the Immune System

Chapter 12: The Lymphatic and Immune Systems Lesson 12. 1 The Lymphatic System

The Lymphatic System • Organization of the lymphatic system – lymph formation and flow – lymph drainage • Lymphatic cells, tissues, and organs – lymphatic cells – lymphatic tissues – lymphatic organs © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Organization of the Lymphatic System © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymph • What is lymph? – Straw-colored fluid, similar to plasma • It is fluid that has leaked out of the blood vessel capillaries and gathered in the spaces between cells • Know as interstitial fluid – Composed of H 2 O, lymphocytes, O 2, digested nutrients, cellular waste (no RBCs or proteins) – Enters the lymphatic capillaries to be returned to the circulatory system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymph Formation and Flow • Fluid (plasma) leaks out of blood vessel capillaries – about 4 liters per day • Enters lymphatic capillaries – Fluid is now called lymph • Returns to circulatory system through lymphatic trunks © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymph Vessels - Pathway • Transport excess fluid back into the circulatory system – Lymph capillaries, collecting vessels, trunks, ducts • Closely parallel veins – Also contain valves like veins do to prevent backflow – Also rely on skeletal muscle action and organ movement to move the fluid as there is no pump for lymph vessels • Located in almost all tissues that have blood vessels • Pathway: – Lymph enters capillaries, which join together to form collecting vessels – Collecting vessels link together to form larger vessels called lymphatic trunks (named by location/part they drain) – Lymphatic trunks drain into ducts, which ultimately drain into the subclavian veins © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymph Drainage • Thoracic duct (largest) – Carries lymph superiorly from cisterna chyli • Enlarged lymph chamber in abdomen; receive lymph from inferior lymph trunks – drains legs, abdominopelvic area, left arm, and left side of the head and thorax • Right lymphatic duct – drains right arm, right side of head, and right side of the thorax © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymph Drainage © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Cells • Lymphocytes – 20 -30 % of WBCs • Created in bone marrow – T lymphocytes mature in thymus • Cell-mediated immunity • Recognize, respond to, and remember antigens – Helper T cells direct and regulate, and signal other immune cells to assist macrophages – Cytotoxic T cells are able to kill targeted cells on contact – B lymphocytes mature in bone marrow • B cells – antibody-mediated immunity • Produce antibodies (proteins) • Can’t penetrate cells, so must rely on cytotoxic T cells to attack © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Cells • Natural killer cells – Another type of lymphocyte that matures in the bone marrow – Nonspecific defense system – Recognize and destroy virus-infected cells and cancer cells » Release perforins and granzymes » Perforins make holes in the cell, and granzymes enter the holes to induce apoptosis » In viruses this is very important, as lysing the cell would release virions; apoptosis kills the cell » NK cells contain the viral infection while the adaptive immune system makes specific cytotoxic T cells to clear the infection © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Cells • Macrophages – Body’s first line of defense – Begin as monocytes; leave lymphatic tissue to enter surrounding tissue and become macrophages – Phagocytizes foreign cells and substances – Help activate T lymphocytes © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Tissues • Loose connective tissue with many lymphocytes • Present in mucous membranes and certain organs • Include: – Mucosa-associated lymphatic tissue • Tonsils – Pharyngeal (aka adenoid): upper throat – Palatine: back of mouth – Lingual: either side of the base of the tongue – Lymphatic nodules • Clusters of dense lymph tissue • Develop in areas often exposed to foreign microorganisms (axilla, intestine) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Organs • • Lymph nodes Small; vary in size Often grouped along lymphatic vessels Dual purpose – Cleanses lymph • Traps bacteria, viruses, and harmful substances • These are destroyed by WBCs – Immune response may trigger production of more lymphocytes, causing swelling – store and produce T and B cells © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Organs • Spleen – Scans and cleans blood – Activates the immune response when infectious agents are detected, causing lymphocytes to multiply – Stores RBCs for release at times of blood loss – Destroys or removes pathogens, old platelets, and old RBCs © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Lymphatic Organs • Thymus – Incubates young T cells – Does not store them – Steadily shrinks as we age © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Review and Assessment Match these words with 1– 4 below: right lymphatic duct, thoracic duct, tonsil, spleen. 1. drains left side of head 2. scan and clean blood 3. drains right side of head 4. palatine © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Chapter 12: The Lymphatic and Immune Systems Lesson 12. 2 Nonspecific Defenses

Nonspecific Defenses • • Physical barriers Cellular and chemical defenses Inflammatory response Fever © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Physical Barriers • Skin – Keratin is hard to penetrate – Cuts and burns leave you prone to infection • Hair – Protection against chafing, sunburn, insect bites • Acidic secretions from sebaceous/sweat glands – Toxic to certain bacteria • Mucous membranes – Secreted mucus forms a sticky trap for microorganisms (pollens, bacterium, etc. ) – MALT destroys what gets trapped © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Cellular and Chemical Defenses • Phagocytosis – Phagocytes engulf foreign cells and debris • Neutrophils & macrophages • Phagocytes enclose invader in a vesicle; lysosome fuses with vesicle and releases digestive enzymes; invader is destroyed; debris is released from cell through exocytosis • Natural killer cells – Recognize and destroy abnormal body cells • Virus-infected and cancer cells attract NK cells (unusual protein/lack of protein) – NK cells bind to abnormal cells and release perforins to perforate (create holes in) the cells; and granzymes to cause apoptosis of abnormal cell © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Cellular and Chemical Defenses • Complement system – Set of 11 proteins that circulate in the blood plasma and work to destroy foreign substances • Classical pathway – Complement protein recognizes an antibody bound to a target and activates the rest of the system • Alternative pathway – Complement protein recognizes foreign material • Both pathways result in opsonization – Proteins (opsonins) stick to target cells and make them more attractive to phagocytes – Other complement proteins then stimulate mast cells to release histamine to initiate the inflammatory response – Additional proteins form an MAC by inserting themselves into bacterial cell membrane and causing a large hole » Similar to perforin molecules in NK cells © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

The Complement System © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Cellular and Chemical Defenses • Interferons – Protein released by virus infected cells to interfere with viral replication and spreading – Virus – bundle of nucleic acids that can enter a cell and take over its machinery, copy itself, and spread – Help block protein synthesis, which also hinders cell growth and division, including rapid growth and division of cancer cells – Different types: • Alpha interferons: produced by virus-infected leukocytes • Beta interferons: produced by virus-infected fibroblasts • Gamma interferons: produced by NK cells and T-cells © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Inflammatory Response • Response to tissue injury caused by bacteria, toxins, trauma, etc. • Promotes repair of damaged tissue • Cells damaged = release of histamines and prostaglandins – These attract phagocytes and lymphocytes to consume cellular debris and pathogens • Symptoms include heat, redness, swelling, and pain © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

The Development of Inflammation • Tissue damage occurs • Intracellular contents are released from damaged cells into interstitial fluid, triggering: • Mast cells in interstitial space to release histamine and other inflammatory chemicals; this makes: • Blood vessels dilate (heat), blood flow increase (redness), capillary permeability increase (leaking and swelling/pain), leading to: • Clot formation (temp repair); metabolic increase: • Scar tissue forms, replacement cells grow = healing © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Fever • Maintenance of higher than normal body temperature • Activation of leukocytes and macrophages causes release of pyrogens, which raise the set-point temp of the neurons in the hypothalamus • Hypothalamus raises body temperature, causing a fever – The increase in temp boosts the rate of biochemical rxns in cells by 10% for every 1º C (1. 8ºF) rise in temp – Severe temps can be life-threatening © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Review and Assessment True or False? 1. Interferon is released by virus infected cells. 2. Pyrogens cause fever. 3. Neutrophils are not phagocytes. 4. Mucous membranes are a physical barrier. 5. Perforins engulf cells. © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Chapter 12: The Lymphatic and Immune Systems Lesson 12. 3 Specific Defenses

Immune System • AKA specific immune system or adaptive immune system • Highly specific in its responses to foreign substances – Can recognize new challenges, adapt to them, and remember what it learned • “Immunity” comes from the interaction between the cells and chemicals of the immune system – It is the body’s ability to resist bacterial invasion and disease (natural and acquired) – Not well understood © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Specific Defenses • • • Antigens Immune system cells Humoral immunity Primary and secondary immune responses Cellular immunity © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Antigens • On the surface of cells – Are large molecules such as proteins, polysaccharides, glycolipids, or nucleic acids • Help body to determine “self” from “nonself” cells to i. d. foreign cells and respond – Presence of foreign antigens causes the immune system to produce antibodies that bind to and mark foreign cells for destruction • A single complex antigen molecule can have multiple antigenic determinants (epitopes) – The more a. d. s a molecule has, the more likely it is to trigger an immune response © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immune System Cells • Consist of lymphocytes and antigen-presenting cells (APCs) – APCs include macrophages, dendritic cells, and certain B lymphocytes • Lymphocytes – Coded to recognize only one antigen (very specific) – Clonal selection – occurs when a lymphocyte meets its antigen • Lymphocyte makes exact copies (clones) of itself • Clones act as effector cells and fight the invader – Memory cells – left over clones that live in lymph tissue and become active if the same antigen reinvades © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immune System Cells • For immune response initiation, antigens must be presented in a particular way • Antigens are displayed on the surfaces of cells by major histocompatibility complex glycoproteins (MHC proteins) – Class I – found on surface of ALL cells that contain nuclei; deal with endogenous antigens synthesized in a cell (viruses or malignancies) – Class II – found only on the surfaces of APCs; deal with exogenous antigens from foreign bodies (bacterium, allergens) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immune System Cells • Class I MHC proteins – Found on cell surfaces – Display fragments of the proteins found in the cell • Normal body cells display normal protein fragments (selfantigen) on the surface – Passing lymphocytes ignore the self-antigens • Abnormal cells display abnormal, undesirable proteins that are inside the cell (parts of infectious agents or cancerrelated proteins) • Cytotoxic T cell lymphocytes monitor cells, “see” the unfamiliar antigen, and attack it – Immune system’s way of dealing with pathogens arising from normal body cells © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immune System Cells • Class II MHC proteins – Found on APC (macrophages, dendritic cells, and certain B lymphocytes) surfaces – APCs look for pathogens • Engulf them, phagocytize them, and then bind the pathogen’s peptide fragments to class II MHC proteins • The MHC II proteins take the pathogen’s peptide fragments to the membrane of the cell to display • Helper T lymphocytes detect the foreign peptides and bind to the MHC II proteins on the APC membrane – On macrophages & dendritic cells - Release lymphokines to attract other cells to the area to contain and kill the infection – On B lymphocytes – stimulates the cloning of antibody producing cells to fight the pathogen Permission granted to reproduce for educational use only. © Goodheart-Willcox Co. , Inc.

Humoral Immunity • Aka antibody-mediated immunity • Effective against extracellular pathogens (viruses, bacterial toxins) – Begins when B lymphocytes encounter their foreign antigen and bind to it, which triggers clonal selection – Strengthened when the B cell, with the antigen bound to it, presents the antigen to a helper T lymphocyte with the same antigen receptor – The T lymphocyte responds by releasing interleukins • Chemicals that stimulate the immune response by fully activating the B lymphocytes © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Humoral Immunity • Plasma cells (B lymphocyte effector cells) – produce large amounts of antibodies – Created by B cell clonal selection – Some clones become memory B cells, and some become plasma cells • Plasma cells contain a large rough ER • Large quantities of antibodies are made in the RER and secreted into the interstitial fluid – These antibodies recognize and bind to the specific antigen that stimulated the original B lymphocyte – Works like a clone army © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Humoral Immunity • Antibodies • Y-shaped proteins (4 polypeptide chains) that recognize very specific antigens – Also called immunoglobulins – Recognize, bind to, and mark specific antigens for destruction • Bind at the tips of the Y • Interfere with antigen function – Eliminate antigen threat through multiple mechanisms © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Antibody Classes © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Primary and Secondary Immune Responses • When the body encounters an antigen for the first time, the response is not optimal (primary immune response) – Memory cells don’t exist yet • The second time that antigen enters the body, the response is much more rapid and thorough thanks to memory cells (secondary immune response) © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immunity Types • Natural – at birth, inherited, and permanent – Unbroken skin, mucus, tears, blood phagocytes, and local inflammation • Acquired – developed by body’s rxn to invaders – Passive acquired – artificially acquired by injecting antibodies to protect from a specific disease – Immediate immunity – Lasts 3 -5 weeks – Used when exposed to things like rabies, tetanus, and infectious hepatitis • Mother provides newborn with some passive immunity © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Immunity Types • Active acquired immunity; last longer, 2 types – Natural acquired • Result of having had the disease and recovering from it (measles) – Artificial acquired • Comes from being vaccinated • Immunization – artificial resistance to a particular infection by artificial means – Injection of antigen is your primary infection – As the body is fighting the antigen, it learns – The next time that pathogen enters the body, it initiates a secondary infection © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Cellular Immunity © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Review and Assessment Fill in the blanks with: antibodies, antigen, memory cells, or vaccination. 1. A(n) ________ is passive immunity. 2. ________ are also called immunoglobulins. 3. Lymphocytes recognize only one ________. 4. ________ are part of the secondary immune response. © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Chapter 12: The Lymphatic and Immune Systems Lesson 12. 4 Disorders and Diseases of the Immune System

Disorders and Diseases of the Immune System • • Cancer and lymph nodes Allergies Autoimmune disorders HIV and AIDS © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Cancer and Lymph Nodes • Rapid, unregulated cell growth – too fast, and without limit • Sometimes cancerous cells break free of original tumor and migrate to other areas of the body – Called metastasizing; metastatic cancer • Metastatic cells can spread by entering the lymph vessels • Often get stuck in the lymph nodes and keep growing – Normal for lymph nodes in the area of cancer growth to be biopsied to look for the presence of cancer cells – If cancer is found in a lymph node, more nodes will be removed to reduce risk of further metastisis – Disrupts normal lymph drainage, which can lead to swelling in the interstitial spaces; known as lymphedema © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Allergies • Inappropriately strong immune response to a harmless environmental antigen – The antibodies (Ig. E) formed irritate certain body cells (mast cells and basophils) – Each exposure to the allergen causes release of histamine from mast cells and basophils • Histamine causes the inflammatory response, which leads to allergy symptoms – runny nose, itchy eyes, anaphylaxis © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Allergies • Severe allergies (bees, peanuts) can lead to release of large amounts of histamine, which can lead to anaphylaxis – Severe swelling of airways, pulmonary edema, low blood pressure • Allergies can be treated with immunotherapy (allergy shots) – Escalating amounts of the allergen are injected under the skin, helping to build up a tolerance of the antigen, thereby reducing the allergic response © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Allergies © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Autoimmune Disorders • Similar to allergies in that the immune system overreacts to an antigen that typically isn’t a threat • Difference is the antigen is part of the body’s tissue (a self-antigen) • Immune system attacks own body • Cause unclear • Examples – Rheumatoid arthritis – i. s. attacks synovial membrane – Multiple sclerosis – i. s. attacks myelin sheath – Type I diabetes – i. s. attacks insulin-producing cells in the pancreas © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

HIV and AIDS • HIV – Infects and kills helper T cells, meaning neither humoral nor cellular immune response can take place • AIDS – Helper T cell count falls below 200/mm 3 – Immune system seriously weakened – Patient is susceptible to opportunistic infection • Never seen in someone with a healthy immune system © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.

Review and Assessment Match these words with 1– 4 below: metastasis, autoimmune disorder, HIV, cancer. 1. rapid, unregulated cell growth 2. cancerous cells move within the body 3. rheumatoid arthritis 4. infects and kills T cells © Goodheart-Willcox Co. , Inc. Permission granted to reproduce for educational use only.