General Biology 2: Immune System PDF

Republic of the Philippines Department of Education Region VIII Division of Catbalogan City **EASTERN VISAYAS REGIONAL SCIENCE HIGH SCHOOL** Catbalogan City LEARNING SHEET IN GENERAL BIOLOGY 2 Learning Competency: - Compare and contrast the following processes in plant...

Republic of the Philippines Department of Education Region VIII Division of Catbalogan City **EASTERN VISAYAS REGIONAL SCIENCE HIGH SCHOOL** Catbalogan City LEARNING SHEET IN GENERAL BIOLOGY 2 Learning Competency: - Compare and contrast the following processes in plants and animals: reproduction, development, nutrition, gas exchange, transport/ circulation, regulation of body fluids, chemical and nervous control, immune systems, and sensory and motor mechanisms. (STEM\_BIO11/12-IVa-h-1) Objective/s: - Explain the differences between innate and adaptive immunity, including their unique functions and characteristics. - Describe the types of cells involved in both innate and adaptive immune responses and their specific roles in fighting pathogens. - Develop a deeper understanding of the importance of immunity and healthy practices in everyday life. **LESSON: Immune System (Animals)** Have you ever experienced common diseases like common colds, diarrhea, influenza, etc.? Have you ever wondered the reasons of getting sick despite following healthy precautions? If yes, let us explore this topic and discover the science which is involved in it. ***Immunity*** is the ability to resist damage from pathogens such as microorganisms and harmful chemicals. These microorganisms release toxins and internal threats such as cancer cells which are not good for the body. This mechanism is being covered in the further study of the Lymphatic System's defense function that cites two fully integrated systems in the body such as: - ***Innate immunity***- It is described as fast-acting defense mechanism as it is the first immunity to respond in an infection. However, its responses never change from exposure to exposure because specific (the ability to recognize a certain substance) and memory (the ability to remember previous encounters with a certain substance) features are not present. - ***Adaptive Immunity***- It is characterized for having slower responses in the beginning of an infection. However, it can engage a faster response during the second exposure to the same bacteria as it exhibits memory and specific features. Therefore, pathogens are being destroyed before the development of any symptoms that makes a person immune. **INNATE IMMUNE SYSTEM** The innate immunity gives the rest of immune system a signal to eliminate some threats in the body. This innate response cannot be activated by an adaptive immune response as it is being accomplished by: - **Barrier defenses**- these are the body's most basic defense mechanisms that prevent pathogens and any chemicals from entering. Some of its common examples are: a. skin/ other ectodermal derivatives (epithelial surfaces as first line of defense against any infection) and mucous membranes, and b. secretions like tears, saliva, and urine wash. - **Internal defenses**- these are the body's defense systems that consist of *chemical mediators* (*antimicrobial proteins like interferons and complement system*); *white blood cells* (*phagocytic cells and natural killer cells*) -see Table 1; and *inflammatory response* which stimulate the release of chemical mediators once the bacteria infect the tissues. *Inflammation* is characterized by fever, redness, swelling, pain and loss of function in infected area. -- -- -- -- **ADAPTIVE IMMUNE SYSTEM** The adaptive immunity is an acquired immune system that involves the recognition of traits to certain substance or antigen. **Antigen** is substance / part of pathogen that generates an immune response. It is divided into two: *foreign antigen* (introduced from outside the body like bacteria, viruses and chemicals); and *self- antigens* (molecules that the body produces to stimulate immune system response). The adaptive immune response is made possible because of: I. **Humoral response**- production and secretion of antibodies (a protein produced or immunoglobulins by immune system to specifically bind a target against specific antigens. These antibodies are being produced by B-cells. B-cells are: - white blood cells that develop and mature in bone marrow (see figure 2), - activated when they encounter antigen in the lymph nodes, and - produced an antibody which recognizes only one kind of antigen (specificity). +-----------------------------------+-----------------------------------+ | **Type of Antibody** | **Function** | +===================================+===================================+ | *IgM* | It coats the pathogen and | | | promotes endocytosis by | | (first antibody to appear in the | macrophages. | | response to initial exposure to | | | an antigen) | | +-----------------------------------+-----------------------------------+ | *IgG* | It activates the other parts of | | | the immune response and leads to | | (major antibody produced) | neutralization and destruction of | | | pathogen. It also provides immune | | | protection to the fetus and | | | newborn. | +-----------------------------------+-----------------------------------+ | *IgA* | It prevents pathogens from | | | crossing the epithelium and | | (the important antibody for the | entering the blood stream. | | mucosal immune response) | | +-----------------------------------+-----------------------------------+ | *IgE* | It activates mast cells and leads | | | to the production of histamine | | (associated with allergic | | | reactions) | | +-----------------------------------+-----------------------------------+ | *IgD* | Antigen-binding receptor on B | | | cells | +-----------------------------------+-----------------------------------+ II. **Cell mediated response** is an immune response that occurs when cytotoxic cells defend the body against the microorganisms that live inside the body cells. It focuses on handling pathogens that are not easily accessible for antibodies produced by B-cells like some pathogens found inside cells such as viruses. This is due to the production of T-cells. T-cells are: - the white blood cells that are produced in the bone marrow and mature in the **thymus** (see figure 3); - activated when they encounter antigens in the lymph nodes, and - needed to recognize an antigen in the context of self-molecules, unlike B cells, called **major histocompatibility complex (MHC)** molecules (glycoproteins that have binding sites for antigens). There are 3 major types of T cells: 1. **Cytotoxic T-cells** -- recognize virus-infected cells and kill them. 2. **Helper T-cells** -- secrete proteins that help other immune cells (B cells, macrophages, etc.) survive and perform their function. 3. **Regulatory T-cells** -- control the immune response by turning it off. They prevent the immune system from harming the body. These are very important as the loss of function can lead to autoimmune disease. **\-\-\-\-\-\-- E N D \-\-\-\-\-\--** **ACTIVITY:** **The Immune System and Me: A Short Essay** - In a 1 whole sheet of yellow paper, explain, in your own words, why a healthy immune system is essential and how you can protect it through everyday practices. - Prompt Questions that can be used in writing your essay: *(1) Why is the immune system important for overall health? (2) What specific actions can I take daily to help strengthen my immune system?* 3. *How can maintaining a strong immune system impact my future health?*