IHD 1 Flashcards
What is the concept of self and non-self in immunology?
The immune system distinguishes self (body’s own cells) from non-self (foreign invaders). Self-antigens promote immune tolerance, while non-self antigens trigger an immune response.
What is an antigen?
Any substance recognized by the immune system, including proteins, peptides, polysaccharides, lipids, or nucleic acids. Antigens can be self (from the host) or non-self (foreign invaders).
What is the Human Leukocyte Antigen (HLA) complex?
A group of cell surface proteins coded by polymorphic genes that present antigens to the immune system. HLA proteins are unique to each individual and play a key role in organ transplantation.
Why does the HLA complex cause organ transplant rejection?
Each individual has a unique set of HLA proteins. If a donated organ has different HLA proteins from the recipient, the immune system recognizes it as non-self and attacks it.
What happens when pathogens invade tissues?
They trigger an inflammatory response where damaged cells release histamine, serotonin, and other chemicals that increase blood flow and attract immune cells to fight infection.
What are the four classic signs of inflammation?
- Tumor (swelling) 2. Calor (heat) 3. Dolor (pain) 4. Rubor (redness).
How does fever (pyrexia) contribute to the immune response?
Fever is caused by neutrophils and macrophages releasing pyrogens like IL-1 and prostaglandins. These reset the hypothalamus to a higher temperature, enhancing immune efficiency and slowing pathogen replication.
What immune cells are involved in the inflammatory response?
Macrophages, neutrophils, and monocytes migrate to the infection site to destroy pathogens and clear debris.
What is the difference between specific and non-specific immune responses?
The non-specific (innate) response is the first line of defense, reacting quickly to general threats. The specific (adaptive) response is slower but highly targeted, involving T and B lymphocytes.
What are examples of non-specific defense mechanisms?
- Physical barriers: Skin, mucous membranes. 2. Chemical defenses: Stomach acid, lysozymes. 3. Cellular defenses: Phagocytosis by neutrophils and macrophages. 4. Inflammatory response.
How does the skin function as a non-specific immune defense?
The skin acts as a physical barrier and secretes antimicrobial substances like lysozyme to destroy pathogens.
What are cytokines?
Proteins secreted by immune cells that regulate immune responses. They include interferons (antiviral response) and interleukins (immune cell communication).
What is the role of interferons?
They are cytokines released in response to viral infections, signaling nearby cells to produce antiviral proteins and enhancing immune response.
What is the complement system?
A group of >20 plasma proteins that form a non-specific defense mechanism against microbes, helping antibodies and forming Membrane Attack Complex (MAC) to lyse bacterial cells.
What are the three pathways of complement activation?
- Classical (activated by antigen-antibody binding). 2. Lectin (activated by microbial surfaces like mannose). 3. Alternative (spontaneous activation on foreign surfaces).
What is phagocytosis?
The process where immune cells engulf and destroy pathogens. Key phagocytes include monocytes/macrophages, dendritic cells, and neutrophils.
How do Natural Killer (NK) cells function in innate immunity?
NK cells attack virus-infected and cancerous cells without needing antigen presentation. They release perforin (creates pores in target cells) and granzyme (induces apoptosis).
What are the main phagocytic immune cells?
Macrophages, neutrophils, and dendritic cells. They engulf and destroy pathogens and present antigens to activate adaptive immunity.
