Immune System

• DUCUSIN is the Special Science Teacher and Team Lead for Biology at the Philippine Science High School – Ilocos Region Campus.
• The subject code for this lesson is Bio 1 Fundamentals of Biology 1, focusing on the subject of Immunity, specifically on Non-specific Defenses of the Human Body (Innate Immunity).
• The learning guide code for this lesson is 4.0, focusing on the subject of Immunity, specifically on Non-specific Defenses of the Human Body (Innate Immunity).
• The lesson code for this lesson is 4.2, focusing on the subject of Immunity, specifically on Non-specific Defenses of the Human Body (Innate Immunity).
• The time frame for completing this lesson is 30 minutes, divided into one session.
• To complete this lesson, you need a pen, paper, phone/tablet/laptop, Moodle app, Moodle (PSHS Knowledge Hub) account, stable internet connection, and the textbook "Biology: A global Approach by Campbell et al" (2015).
• After completing this lesson, you are expected to compare nonspecific and specific defenses, explain how the various nonspecific defenses function in defending the body, and discuss the cellular elements of blood (basophils, lymphocytes, eosinophils, neutrophils, monocytes, platelets) that function in defense.
• The immune system or defense system is the body system which defends the body against any foreign molecule and aims to limit if not prevent many infections.
• Animals utilize a variety of strategies in order to protect themselves from the threats of the external environment.
• There are two types of immunity found in animals: innate immunity and adaptive immunity.
• Complement system is a type which eliminates dead cell wastes, and augments adaptive immunity.
• Lymph is a fluid which carries liquid and pathogens which have leaked from the interstitial fluid of the cell and the blood.
• Cellular innate defenses usually circulate throughout the body and detect any possible infection.
• Drugs can effectively eliminate these pathogens.
• Underlying medical conditions can be deduced from a CBC report.
• Lymph is distributed throughout the body by a network known as the lymphatic system.
• Natural killer cells act against virus-stricken and cancerous cells not by engulfing them or phagocytosis but by releasing chemicals which lead to cell death.
• Streptococcus pneumoniae, the causative agent of pneumonia, possesses a capsule which made it hard for innate defenses to recognize them.
• Interferons are proteins which interfere with viral infections.
• Natural killer cells circulate throughout the body and can easily recognize whether a cell is healthy or cancerous or infected by a virus.
• The response cells involved in cellular innate defenses usually reside in the lymph nodes, a structure which contains lymph.
• There are substances which directly kill pathogens and impede their reproduction, known as antimicrobial peptides and proteins.
• At the lymph nodes, the response cells act against the pathogen.
• Complete blood count is a blood test which determines the amount of several cellular components of the blood which include the red blood cells, white blood cells, lymphocytes, platelets and hematocrit (the proportion of red blood cells in relation to the plasma).
• Vertebrates possess both immunity and in this module, we will be focusing on the nonspecific defenses of vertebrates and how each structure protects a vertebrate's body.
• The innate immunity of vertebrates can be classified as either barrier defense or cellular innate defense.
• Barrier defense is the first line of defense and protects against any outside invaders while cellular innate defense is the second line of defense composed of immune cells dedicated to detect, devour, and destroy pathogens which have breached the barrier defense.
• The urethra in females and males are orange extensions of the bladder and ureter.
• Saliva, produced by salivary glands, contains lysozymes and antibody IgA.
• Urine is very acidic due to ions (with a pH of 6 – 7), adding another layer of protection to the urinary tract.
• Cellular innate defenses often rely on Toll-like receptors (TLRs), a mammalian recognition protein similar to the Toll proteins of insects.
• Earwax, produced by ceruminous glands in the ear, traps dirt and germs which enter the ear canal.
• Lysozymes are enzymes which break down bacterial cell walls.
• Tears, produced by lacrimal glands of eyes, contain lysozymes, phagocytes and IgA antibodies, which protect the eyes from the entry of dirt and pathogens.
• The skin is also acidic (with a pH of 3 - 5) due to sebum, an oil produced by the sebaceous gland in the dermal layer of the skin.
• Some body organs and bodily secretions have an acidic environment, which is unfavorable for the growth of bacteria since acidity has a bactericidal effect.
• The internal environment of the vagina is also acidic (pH: 3 – 4) as maintained by Lactobacillus.
• Lactobacillus, a friendly bacterium seen in the micrograph below, usually grows in the vagina and large intestine.
• Phagocytes are cells which engulf foreign materials and pathogens.
• IgA antibodies, immunoglobulin A, protect the body from infections.