MID 2 - Lecture 13 Flashcards
Immune system
widely distributed cells, tissue and organs, recognizes foreign substances or microbes and acts to destroy them
Immunology
study of immune responses and how they protect host
innate immunity
first line of defense, resistance to microbe or foreign material (skin, mucusm, lysozyme), doesn’t remember and act the same way
Adaptive immune response
Activated by cells and chemicals of innate immunity, resistance tailored to specifc foreign agent, memory
Barriers in innate resistance
Skin, mucous membrane, resp system, gastro tract, genitourinary tract
Skin (barrier)
stratified, cornified epithelial cells, mechanical barrier, microbiota defend invaders (outer skin sheds continuously)
Mucous membrane (specialized cells)
Resists penetration, traps invaders, gastro, genit, resp tracts, consist of epithelial cells and specialized cells
-goblet (mucus), paneth (antimicrobial peptides and enzyme lysozyme)
Resp system (alveolar macrophages)
air flow deposits microbes onto mucosal surfaces (mucociliary blanket, and hairs and cilia in nasal cavity) and away from lungs
AMs - phagocytic cells in alveoli of lungs, ingest and kill microbes inhaled
Gastrointestinal tract (stomach and intestines)
stomach: HCL, proteolytic enzymes, mucus
Intestines: pancreatic enzymes, bile, intestinal enzymes, GALT, peristalsis, shedding of epithelial cells
Genitourinary tract (male vs female)
Unfavourable environment for microbes
-low pH of urine, flushing, urea and metabolic products, distance barrier - male, Innate defense - vagina
Chemical mediators in innate resistance
lysozyme - hydrolyzes bond connecting sugars in peptidoglycan
Lactoferrin- breast milk, mucous secretions
Cationic peptides - release can damage microbial membranes
Complement system (3 activities) and opsonization
- inflammatory response (recruitment of white blood cells)
- Penetrate microbial cell membranes (cell lysis)
- defend against microbial invasion (phagocytosis) through opsonization
opsonin: molecule marks antigen for phagocytosis
Alternative complement pathway (C3, C5b, C6, C7, C8, C9)
-nonspecific defenses (bacteria, fungi), initiated response to molecules with repetitive structure
activation of C3, production of C5b, recruitment of rest), formation of attack complex
Lectin complement pathway
lectin binds and activation of C3, dependent on interaction of MBP with pathogen surfaces
Classical complement pathway
dependent on antigen-antibody interactions, activated when pathogens persist (2nd invasion)
Opsonization
microbes coated by serum components for recognition of phagocytic cells, complements proteins first to be made, vital role in phagocytic removal of microbes
Cells of immune system
leukocytes, granulocytes, agranulocytes, mast cells, innate lymphoid cells
-arise from bone marrow, specialized role
Phagocytosis (R-I-K), dependent and independent
phagocytic cells recognize, ingest, and kill microbes
Opsonin-dep: complement and/or antibody opzonizes pathogen
Opsonin-ind: Phagocytes recognize phagocytose pathogen
Granulocytes and 3 types (B-E-N)
ireg shaped nuclei (2-5) lobes, cytoplasm has granules with reactive substances that kill microbes (inflammation)
ex. basophils, eosinophils, neutrophils
Neutrophils
3-5 lobes, highly phagocytic, circulate in blood to tissue damage, kill ingested microbes (hydrolytic enzymes and reactive O2
Agranulocytes (monocytes and macrophages)
monocytes - bone marrow and enter blood, circulate and mature into macrophage
Macrophage - Larger, specifc tissue, highly phagocytic, chemical alarm when invaded
Dendritic cells
skin, mucous (nose), lungs, intestines
-detect and phagocytose pathogens, display foreign antigens on surfaces, share info about lymphocytes about invaders and respond
Innate lymphoid cells
Lymphoid progenitor cells give rise to: ILCs, Lymphoblasts (give rise to T and B cells) , natural killer cells (NK)
