BIOL 1202 Chapter : Immune System
Document Summary
Three lines of defense: nonspeci c external barriers innate defense skin: is an inhospitable environment for growth; dry, dead cells at surface. Sweat/sebaceous glands secreting acids and natural antibiotics like lactic acid mucous membranes: of respiratory and digestive tracts well-de ned. Low-grade (100-102: are bene cial slows down microbial reproduction enhances immune system, speci c immune response acquired immunity trained to recognize the intruder without infecting the organism (vaccine) lymphocytes b cells (bone) and t cells (thymus) B cells and t cells originate in the same place bone marrow. Variation is determined by which genes are turned on and o . B cell receptors antibodies (can exist in 100 million di erent versions) proteins that embed themselves in the b cell membrane to recognize invaders antigens. Immune response b cells and t cells: recognize the invader. B cells who can recognize own proteins, will undergo apoptosis (programmed cell death)
