Immunology-1 Lecture Notes PDF

Immunology-1 Bio-207 Introduction to Immune System Dr. Manal Abouelwafa Badr University in Assiut Biotechnology Department [email protected] Lecture-1  Immunology-1 Content ❑Unit-1 Introduction to immune system ❑Unit-2 Immune types and complementary system ❑Unit...

Immunology-1 Bio-207 Introduction to Immune System Dr. Manal Abouelwafa Badr University in Assiut Biotechnology Department [email protected] Lecture-1  Immunology-1 Content ❑Unit-1 Introduction to immune system ❑Unit-2 Immune types and complementary system ❑Unit-3 Immune response to pathogen ❑Unit-4 Antibody and antigen ❑Unit-5 Immune diseases Basic Terminology What is Immunology? The study of how our body fight against diseases and infections Immunity It is the capability of the body to fight or resist foreign particles like bacteria, viruses, toxins, etc. Immune system failing: Mainly to identify any foreign particle and to eliminate harmful substances like viruses, bacteria, toxins that are not part of our body Housekeeping: Removal of debris/dead cells Protection: against pathogens Communication: By sending chemical messages as an alarm, Antigen presentation by antigen-presenting cells, and memory  Concept of Immunity The word Immunology, which comes from Latin = immunis = “exempt;” English = protection from diseases (resistance). So, Immunology is the study of the way in which body defends itself from infectious agents. Immunity: The ability of an organism to recognize and defend itself against specific pathogens or antigens. The cells and molecules responsible for immunity constitute the immune system, and their collective and coordinated response to foreign substances is called the immune response.  What is the Immune System? The Immune system is a biological structure and processes within an organism that protects against disease by identifying and killing pathogen and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism’s own healthy cells and tissues in order to function properly. Structure of the Immune System: The immune system has a multilayered architecture with defenses provided at many levels The immune system is a complex network security system of chemicals, cells, tissues and organs that work together to protect the body. The function of the Immune System: Without an immune system, a human being would be an exposed to the harmful influence of pathogens or other substances from the outside environment to inside the body Your immune system works hard to keep you healthy. It does this by: Keeping invaders (like germs) out of your body. Destroying invaders. Limiting how much harm the invaders can do if they’re inside your body. Healing damage to your body. Adapting to new challenges and threats. Invaders your immune system protects you against include: Bacteria. Viruses. Fungi that can cause infections. Parasites. Cancer cells.  How does the immune system work? 1. Tells the difference between cells that are yours and those that don’t belong in your body. 2. Activates and mobilizes to kill germs that may harm you. 3. Ends an attack once the threat is gone. 4. Learns about germs after you’ve had contact with them and develops antibodies against them. 5. Sends out antibodies to destroy germs that try to enter your body in the future. But things don’t always go this smoothly. Sometimes, your immune system doesn’t work properly. For example, it may be too weak to fight off invaders, or it may launch too strong of a response. Weak immune system Many different conditions can weaken your immune system and make you more susceptible to infection. Conditions at birth are less common than those that develop later in life, like Type 2 diabetes and cancer. Overactive immune system At the other end of the spectrum, your immune system may react too strongly to invaders (real or perceived). It may mount an attack when there’s no invader. Or it may keep attacking after getting rid of an invader. An overactive immune system can lead to problems like autoimmune diseases or allergic reactions. Immune system soldiers  Innate Natural Immunity Getting Acquired with life Innate Immune System ▪ Begins with the physical barriers that prevent pathogens from entering the body ▪ Destroy them after they enter ▪ Flush them out before they can establish themselves in the hospitable environment of the body’s soft tissues ▪ Protect the body from different types of pathogens Acquired Immune system ▪ Highly specialized cells and processes that eliminate specific pathogens and tumor cells ▪ Highly specific to a particular pathogen (or its antigen) ▪ Create immunological memory ▪ It allows a faster, stronger response on subsequent encounters with the same pathogen usually before the pathogen can cause symptoms of illness.  Lymphocytes are the main cells of the adaptive immune system They are leukocytes that arise and mature in organs of the lymphatic system including the bone marrow and thymus The human body normally has about 2 trillion lymphocytes, which constitute about a third of all leukocytes. Most of the lymphocytes are normally sequestered within tissue fluid or organs of the lymphatic system, including the tonsils, spleen, and lymph nodes. There are two main types of lymphocytes involved in adaptive immune responses, called T cells and B cells.