EXAM 4: Innate Flashcards
Immunology
The study of the body’s natural defense against disease
Immunity
Ability of host to resist a particular disease or infection
Antigen
Foreign substance that induces an immune response in the body
Hematopoesis
Development of white blood cells in bone marrow of mammals
Phagocytosis
the process of engulfing a solid particle
Pyrogen
a substance, typically produced by a bacterium, that produces fever when introduced or released into the blood
Lysozyme
an enzyme that catalyzes the destruction of the cell walls of certain bacteria
Lactoferrin
A secretion with bactericidal and iron-binding properties
Mast cells
Specialized tissue cells that trigger local inflammatory responses
Basophils
White blood cell that functions in inflammatory events and allergies
Eosinophils
White blood cells that are active in worm and fungal infections, allergy, and inflammation
Neutrophils
Blood phagocytes, very effective at chemotaxis, and engulfing/killing bacteria
Monocytes
Blood phagocytes that rapidly leave the circulation and mature into macrophages and dendritic cells
Macrophages
Large phagocyte that specializes in ingesting and killing foreign cells
* critical to specific immune responses
Dendritic cells
Heterogeneous population of cells that reside throughout the tissues and are responsible for processing an antigen and presenting it to lymphocytes
Describe the physical and mechanical barriers to infection
Skin
First line of defense
Two major layers:
Epidermis
* tightly packed dead skin cells layers, shedding removes microorganisms
* Epidermal dendritic cells phagocytize pathogens
Dermis
* Collagen fibers help skin resist abrasions that could introduce microorganisms
Skin chemicals
1. Perspiration by sweat glands: salt inhibits growth, lysozyme destroys bacterial cell walls, antimicrobial peptides act
against microorganisms
2. Sebum by sebaceous glands: helps keep skin pliable and less easy to break, lowers skin pH to an 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 MM w/ tightly packed living epithelial cells preventing infection, constant shedding removes microorganisms
Deeper conn. layer supports the epithelium
Respiratory System:
* Air flow deposits microbes onto mucosal surfaces
* Mucociliary escalator: Microbes transported away from lungs through coughing, sneezing, etc.
* Mucociliary blanket: mucous secretions that trap microbes
* Alveolar macrophages: phagocytic cells in alveoli of lungs
Lacrimal Apparatus:
* eyeball, produces and drains tears
* blinking spreads tears
* 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 enzymes, GALT, lgA, paneth cells
Genitourinary Tract
* Flushing with urine and mucous
* Distance barrier of male urethra
* Unfavorable environment (low pH, urine toxicity, etc)
Role of Normal Microbiota
* Microbial antagonism: compete with potential pathogens for nutrients
* Help stimulate 2nd line of body defense
List and describe protective chemicals in the body
Lysozyme: hydrolyzes bond connecting sugars in peptidoglycan, tears are also related
Lactoferrin: secreted by activated macrophages and PMNs- sequesters iron from plasma
Lactoperoxidase: produces superoxide radicals
Perspiration: changes the salt concentration on the skin making it hard for microbes to survive
List the cells of the innate response and describe their specific roles
WBC play major role in innate and specific responses
hematopoiesis
mature WBC: respond to all antigens
not fully func WBC: become part of adaptive immune sys
Granulocytes
* Irregularly-shaped nuclei w/ 2-5 lobes
* Cytoplasm has granules with reactive substances
4 Types:
Basophils
* Functions in inflammatory events and allergies
* Non phagocytic
* Found in blood
* Regulate inflammation thru release of vasoactive mediators
* Play role in allergic response & development
Mast cells
* Specialized tissue cells that trigger local inflammatory responses
* Non-phagocytic
* Residential cells: vascularized tissues throughout the body, prominent in mucosal tissues
* Regulate inflammation thru vasoactive mediators (repeat)
* Play role in allergic response & development
Eosinophils
* Active in worm and fungal infections, allergy, and inflammation
* Defend against eukaryotic pathogens, helminths and protozoan parasites
* Phagocytic
* Found in the blood
* May play role in allergic reactions
Neutrophils
* Very effective at chemotaxis, and engulfing/killing bacteria
* Circulate in blood then migrate to sites of tissue damage
* Phagocytic: kill ingested microbes w/ lytic enzymes & reactive oxygen metabolites
Agranulocytes
* no visible granules under light microscopy, visible under electron microscopy
Macrophages:
* Large phagocyte that specializes in ingesting and killing foreign cells
* Highly phagocytic, larger than monocytes
* Reside in specific tissues
* Recognize Pathogen Associated Molecular Patterns (PAMPS)
Dendritic Cells:
* heterogeneous group of cells with neuron appendages
* Small #’s in blood, skin, mucous membranes of nose, lungs and intestines
* Express pattern recognition receptors
* Display antigen presentation on surface of cell
Define phagocytosis and explain the process
The engulfing of a solid particle (typically bacteria)
- cells capable of phagocytosis are known as phagocytes
6 stages
1. chemotaxis
2. adherence
3. ingestion
4. maturation
5. killing (by enzymes and other chemicals)
6. elimination (exocytosis)
Discuss the complement system and its role in host defense
A form of nonspecific chemical defenses against pathogens
* activation results in lysis of the foreign cell (leads to opsonization, inflammation and MAC)
Complement activated in 3 different ways:
1. classical pathway- antibody dependent
2. alternate pathway- antibody independent
3. lectin pathway- lectin ligand
Inactivation of Complement
* Body’s own cells withstand complement cascade
* Proteins on many cells bind and break down activated complement proteins
Explain the process of inflammation and the importance. List the major signs.
Nonspecific response in tissues due to damage from various causes.
Has migration of phagocytes, dilation and increased vascular permeability.
2 types:
1. chronic inflammation: develops slowly and can cause damage to body or lead to disease
2. acute inflammation: develops quickly and is short lived, it is typically beneficial and an important part of the second line of defense
MAJOR SIGNS: by redness, heat, swelling, pain, and loss of function
Discuss the importance of fever
Fever: body temp over 37 C
results from pyrogens triggering the hypothalamus is beneficial because:
- benefits inflammation
- encourages tissue repair
- enhances phagocytosis
- inhibits growth of some microorganisms
- specific immunity
Various types of pyrogens, for example: bacterial toxins
Elevated Eosinophils is often indicative of a ?????
Degranulated Mast cells indicate ?????
Bacterial diseases often show increase in ????
Viral infections show increase in ????
– helminth infestation
– allergic response
– leukocytes and neutrophils
– lymphocytes
