Lecture 04: The Lymphatic and Immune Systems PDF

8/08/2024 Lecture 04: The Lymphatic and Immune Systems Human Systems Physiology 2 – NATS3054 Dr Kayte Jenkin (Subject coordinator) [email protected] 1 Lecture Overview  Immune System Overview  What is immun...

8/08/2024 Lecture 04: The Lymphatic and Immune Systems Human Systems Physiology 2 – NATS3054 Dr Kayte Jenkin (Subject coordinator) [email protected] 1 Lecture Overview  Immune System Overview  What is immunity?  Targets of the immune system  Function and composition of the immune system  Blood  Composition of blood, and types of blood cells  Blood testing  The Lymphatic System  Function and composition of the lymphatic system  The lymphatic system and fluid balance  Lymphatic organs and tissues PAGE 2 2 Immune System Overview PAGE 3 Figure: A macrophage engulfing bacteria 3 1  8/08/2024 Introduction to Lymphatic and Immune  Immune and lymphatic systems function together in what is broadly called immunity  Immunity is a set of diverse processes which protects the body from both cellular injury and disease‐causing cells and molecules (pathogens)  The immune and lymphatic systems work to defend body against internal and external threats Figure 1.5 The organ systems of the human body. 4 What is the Immune System?  The immune system is a functional system, rather than an organ‐ based system  It provides defence against foreign material, bacteria, viruses, cancer, damaged tissue, cellular debris etc.  The two main branches of the immune response is the innate and adaptive immune response Figure: A cluster of CD8 Killer T‐cells defending the body against a cancer cell https://columbian.gwu.edu/new‐research‐targets‐immune‐system‐vulnerabilities 5 Components of the Immune System  Leukocytes: white blood cells  Chemicals and proteins: antimicrobial chemicals, antibodies, platelets  Lymphoid tissues and organs: lymph nodes, spleen, thymus, bone marrow, and MALT Immune cells are generated and mature, residing in lymphoid organs/tissues  Processes: Inflammation, fever, phagocytosis and apoptosis Figure 20.4: Microscopic structure of lymphoid organs. 6 2  8/08/2024 Targets of an Immune Response What types of things is our immune and lymphatic systems trying to protect us from? Pathogens: Bacteria, viruses, fungi, parasites Other biological material: Transplanted tissue and organs, animal and plant material (food, pollen), foreign particles and chemicals (smoke, pollution) Our own tissue: Damaged tissue from trauma or injury, necrotic tissue, cancerous cells or cells with genetic mutations, even healthy tissue (!) Figure: https://www.coursehero.com/sg/microbiology/classification-of-microbes/ 7 Composition of the Immune System  The immune system is made up of Barriers: inhibit entry of pathogens and foreign material into the body (skin, mucous membranes, chemical barriers, physical mechanisms) Internal defences: cells, chemicals, and processes which act in a non‐specific manner that provide innate immunity (antimicrobial proteins, phagocytes, inflammation) Adaptive defence: Cells and proteins which act in a manner which is particular to specific pathogens, providing adaptive immunity (T cells, B cells, antibodies) 8 Blood: Cells of the Immune System Figure: https://eugraph.com/histology/cardiova/index.html 9 3  8/08/2024 Function of Blood  Exchanging gases: Oxygen and carbon dioxide are Covered in HSP1 transported in blood  Distributing solutes: Plasma transports ions, Water: The universal nutrients, hormones, and wastes, and plays role solvent (Lecture 01) in regulating ion concentrations in tissues  Immune functions: Both leukocytes and proteins Examined in more detail in with immune functions are transported Lectures 05 and 06 throughout body via blood Figure 19.1: The three visible layers of blood. 10 Composition of Blood  Even though only 1% of our blood is composed of leukocytes (white blood cells) and platelets, these cells have a huge role to play in ensuring our body is protected from pathogens or damaged tissue! 45% 55% 1% Figure: Composition of blood Silverthorn, 2019, Human Physiology: An Integrated Approach 11 Leukocytes (White Blood Cells)  Generally WBC’s don’t function within the blood uses blood as transport to locations where needed, acting as the body's defence against disease  Leukocytes have the ability to leave blood capillaries and travel to damaged/infected tissues via a process called diapedesis  Are recruited to damaged or infected tissues by chemical messengers  The body can speed up the production rate of leukocytes in response to infection Figure: Morikis & Simon, 2018, ‘Neutrophil mechanosignaling promotes integrin engagement with endothelial cells & motility within inflamed vessels’, Frontiers in Immunology, vol. 9, DOI: 10.3389/fimmu.2018.02774 12 4  8/08/2024 Types of Leukocytes (White Blood Cells)  Leukocytes can be divided into two basic categories:  Granulocytes: Contain cytoplasmic granules that are released when activated. Neutrophils, eosinophils, basophils and mast cells.  Agranulocytes: Lack visible granules. Lymphocytes (B and T cells, NK cells), monocytes (macrophages) Figure 19.8: Classes of leukocytes. 13 Cells of the Immune System  Leukocytes can be grouped histologically, or they also be categorised based on their role in immune function:  Cells of innate immunity: Dendritic cells (DC), macrophages, monocytes, neutrophils, basophils, eosinophils, mast cells, Natural Killer cells (NK)  Cells of adaptive immunity: B and T cells. These can mature into helper T‐ cells, T‐cytotoxic cells, plasma B‐cells, and memory cells (B or T) Figure: researchgate.net/publication/325820677_Tailoring_inorganic_nanoadjuvants_towards_next‐generation_vaccines/figures?lo=1 14 Visual Appearance of Leukocytes  Each type of leukocyte has a distinctive appearance. Can you distinguish between them? Figure: https://quizlet.com/ca/241397127/blood‐histology‐diagram/ 15 5  8/08/2024 Blood Tests  Blood tests can indicate the presence of infection, particularly when the differential breakdown of leukocytes is examined. Lecture 05 (next week) we will look at the roles of different leukocytes in more detail Figure: Types and relative percentage of leukocytes in normal blood. Marieb & Hoehn, 2013, Human Anatomy and Physiology 16 Blood Tests  Typical results from blood tests examining red and white blood cells Test Males Females Hematocrit: is the percentage of total blood volume that is occupied 40–54% 37–47% by packed (centrifuged) red blood cells. Haemoglobin (g Hb/dL*): Reflects the oxygen‐carrying capacity of 14–17 12–16 red blood cells. (*dL = deciliter = 100 mL) Red Cell Count (cells/mL): A machine counts erythrocytes as they 4.5 – 6.5 X 106 3.9 – 5.6 X 106 stream through a beam of light. Total White Count (cells/mL): Includes all types of leukocytes but 5 – 10 X 106 4.5 – 11 X 106 does not distinguish between them. Neutrophils 50 – 70% Eosinophils 1–4% Basophils