Innate Immunity Flashcards
Describe the physical and mechanical barriers to infection
Skin: physical barrier to invasion
Two layers
Epidermis: tightly packed layers of dead skin cells, shedding stop pathogens
Epidermal dendritic cells phagocytize pathogens
Dermis: collagen fibers help skin resist abrasions that could allow entry of pathogens
Skin Chemicals:
Perspiration by sweat glands: salt inhibits growth, lysozyme destroys bacterial cell walls, other antimicrobial peptides
Sebum: helps keep skin pliable and less easy to break, lowers pH to inhibitory level
Mucous Membranes: Line all body cavities open to the environment, creates protective covering, bathed in antimicrobial secretions
Two layers
Epithelium: thin outer covering of living, tightly packed cells preventing entry of pathogens. Constant shedding carries away microorganisms
Deeper CT layer that supports the epithelium
Respiratory System
Air flow deposits microbes onto mucosal surfaces
Mucociliary blanket: mucous secretions that trap microbes
Once trapped, microbes are transported away from lungs through coughing, sneezing, and washing into the stomach (mucociliary escalator)
Alveolar macrophages: phagocytic cells in alveoli of lungs
Lacrimal Apparatus- eyeball
Produces and drains tears
Blinking spreads tears, washing the surface of the eye.
Lysozyme in tears kills bacteria
Antimicrobial peptides
Present in skin, mucous membranes; act against a variety of microbes
GI tract
Gastric acid in stomach
Intestines contain pancreatic enzymes, bile, intestinal enzymes, GALT, peristalsis, shedding of columnar epithelial cells, secretory IgA, normal microbiota, paneth cells
Genitourinary Tract
Flushing with urine and mucous
Distance barrier of male urethra
Unfavorable environment (low pH of urine/vagina, toxicity of urine, hypertonic kidney medulla, normal microbiota)
Role of Normal Microbiota
Normal microbiota compete with potential pathogens for nutrients
Help stimulate the bodies second line of defense
Promote overall health by giving vitamins to host
List and describe protective chemicals in the body
Lysozyme: hydrolyzes bond connecting sugars in peptidoglycan
Lactoferrin: secreted by activated macrophages and PMNs- sequesters iron from plasma
Lactoperoxidase: produces superoxide radicals
List the cells of the innate response and describe their specific roles
basophils: white blood cells that functions in inflammatory events and allergies
non-phagocytic cells found in the blood (where they travel to inflamed tissues) where they regulate inflammation through the release of vasoactive mediators(such as histamine, prostaglandins, serotonin, and leukotrienes from granules)
also play a role in allergic response and the development of allergies and hypersensitivities
eosinophils: are phagocytic (in a secondary way) cells that are found in the blood and rapidly traffic to inflamed tissue. MAY play a role in allergic reactions. they defend against protozoan and helminth parasites by…
being eukaryotic receptors on antibodies
recognizing Fc receptors on antibodies
releasing cationic proteins and reactivating oxygen metabolites
neutrophils: circulate in blood tissues then migrate to sites of tissue damage. they are HIGHLY phagocytic and kill ingested microbes with lytic enzymes and reactive oxygen metabolites contained in primary and secondary granules
dendritic cells: are a heterogeneous group of cells with neuron-like appendages, they are present in small numbers in blood, skin, and mucus membranes of the noses/lungs/intestines. they also…
express pattern recognition receptors
contact phagocytose and process antigens
display foreign antigens on their surfaces (antigen presentation)
mast cells: are non-phagocytic, residential cells (meaning they are vascularized tissues throughout the body and prominently found in mucosal tissues that interface the external environment) they regulate inflammation through the release of vasoactive mediators (such as histamine, prostaglandins, serotonins, and leukotriene from granules). they also aid allergic response by playing an important role in development of allergies and hypersensitivities
macrophages: are highly phagocytic, larger than monocytes and reside in specific tissues, and have a variety of surface receptors including pattern recognition receptors (which recognize pathogen associated molecular patterns PAMPs)
Define phagocytosis and explain the process
Phagocytosis is the engulfing of a solid particle (usually bacteria)
6 stages
1. Chemotaxis of phagocyte to microbe
2. Adherence to cell
3. Ingestion of microbes by phagocytes
4. maturation/fusion of a series of vesicles, including lysosomes
5. Killing of microbes by enzymes/chemicals
6. Elimination from cell (exocytosis)
Discuss the complement system and its role in host defense
Complement: set of serum peptides designated numerically according to their discovery
Complement activation results in lysis of the foreign cell
Can be activated in 3 ways
Classical pathway- antibody dependent
Alternate pathway- antibody independent
Lectin pathway- lectin ligand
C1 becomes activated upon binding with antibody-antigen complex. C1 enzyme creates “complement cascade” of each C enzyme helping to form the next, finally creating the Membrane attack complex (MAC). the MAC drills a hole in of antigen cytoplasmic membrane, lysing the cell
Explain the process of inflammation and the importance. List the major signs.
Inflammation is a nonspecific response to tissue damage (various causes)
Major signs: redness, heat, swelling, pain, loss of function
Two types
Acute inflammation: develops quickly, is short lived. Usually beneficial- helps in second line of defense (increased permeability of blood vessels, migration of phagocytosis, tissue repair)
Chronic inflammation: develops slowly, can cause damage to body, can cause disease
Discuss the importance of fever
Fever: body temp over 37 C
Results when pyrogens trigger hypothalamus to increase body temperature
Pyrogens- include bacterial toxins, cytoplasmic contents of bacteria, antibody-antigen complexes
Benefits
- inflammation
- inhibits growth of microorganisms
- enhance phagocytosis
- tissue repair
-specific immunity
