Defence mechanisms Phagocytosis Flashcards
What is the definition of immune response?
the reaction of the cells and fluids of the body to the presence of a substance that is not recognized as a constituent of the body itself, known as the antigen.
What is the purpose of the antigen signature on the cell surface?
: The antigen signature, which consists of characteristic cell surface proteins, helps the body distinguish between its own cells (self) and foreign cells (non-self)
Question: What happens if a cell’s antigen signature is recognized as non-self?
Answer: If a cell’s antigen signature is not recognized as self, it is considered non-self, leading to the generation of an immune response.
Question: Which cells carry out the process of recognizing self versus non-self antigens?
Answer: Lymphocytes are responsible for carrying out the process of distinguishing between self and non-self antigens.
Question: Why is it important that lymphocytes do not “attack” their own cells?
Answer: Lymphocytes must not “attack” their own cells to prevent autoimmune reactions and maintain the integrity of the body’s tissues and organs.
Question: What are some barriers to disease in the human body?
Answer: Some barriers to disease in the human body include:
The epidermis of the skin, consists of layers of dead cells preventing invasion.
Mucus membranes, which secrete a protective mucus layer trapping invaders, such as in the nasal passages.
Ciliated epithelia, which sweep invaders away for removal, as seen in the lung’s bronchi and bronchioles.
Hydrochloric acid in the stomach, with its low pH denaturing pathogens’ enzymes.
Ears, where wax in the ear canal traps pathogens.
Eyes, where tears containing lysozyme wash the surface, draining via the nasal passage into the throat.
Question: What are some examples of pathogens that can penetrate the body’s barriers?
:
Malaria, caused by Plasmodium, which passes through the skin when a mosquito bites.
Bubonic plague, which enters the skin through flea bites.
Influenza virus and coronavirus, which pass through the lining of the trachea and lungs.
Question: What is phagocytosis, and what is its role in the immune response?
Answer: Phagocytosis is the process by which pathogens that have breached barriers are engulfed and destroyed by white blood cells. These white blood cells, known as phagocytes, are continuously produced from stem cells in the bone marrow. They are stored in the bone marrow and released into the blood to engulf and digest foreign bodies.
Question: What are the two types of phagocytes, and what are their characteristics?
Answer: The two types of phagocytes are neutrophils and macrophages. Neutrophils are characterized by their lobed nucleus, while macrophages originate from monocytes, which are immature macrophages. Both neutrophils and macrophages play crucial roles in the immune response by engulfing and digesting pathogens.
Question: How do neutrophils contribute to the innate immune response?
Answer: Neutrophils, a type of phagocyte, contribute to the innate immune response by entering tissues via diapedesis and defending against pathogens through phagocytosis. They also participate in the exocytosis of residues from cells for recycling.
Question: What are the key characteristics of the innate immune system?
Answer: The innate immune system is a defense mechanism that is present at birth and does not require previous exposure to potentially harmful agents.
Question: What role do macrophages play in the innate immune system?
Answer: Macrophages, another type of phagocyte, defend against pathogens through phagocytosis in the innate immune system. Additionally, they perform antigen presentation, where they present a fragment of a microbe on their cell surface. This interaction with “T” cells helps coordinate the immune response.
Question: What is diapedesis, and how does it relate to the immune response?
Answer: Diapedesis refers to the passage of blood cells through the intact walls of capillaries, typically accompanying inflammation. Neutrophils utilize diapedesis to enter tissues and contribute to the immune response by engaging pathogens directly.
Question: What are some characteristics of neutrophils regarding their lifespan and capability to deal with pathogens?
Answer: Neutrophils are relatively short-lived cells, typically surviving for 3 to 5 days. Due to their small size, they can only deal with small numbers of pathogens. However, they are the first to respond to an infection.
Question: How do macrophages compare to neutrophils in terms of size, lifespan, and capability to handle pathogens?
Answer: Macrophages are much larger compared to neutrophils and can engulf many more pathogens. They are relatively long-lived cells and take over the work following the initial response by neutrophils.
