EXAM 4: Innate

Question 1

Immunology

Answer 1

The study of the body’s natural defense against disease

Question 2

Immunity

Answer 2

Ability of host to resist a particular disease or infection

Question 3

Antigen

Answer 3

Foreign substance that induces an immune response in the body

Question 4

Hematopoesis

Answer 4

Development of white blood cells in bone marrow of mammals

Question 5

Phagocytosis

Answer 5

the process of engulfing a solid particle

Question 6

Pyrogen

Answer 6

a substance, typically produced by a bacterium, that produces fever when introduced or released into the blood

Question 7

Lysozyme

Answer 7

an enzyme that catalyzes the destruction of the cell walls of certain bacteria

Question 8

Lactoferrin

Answer 8

A secretion with bactericidal and iron-binding properties

Question 9

Mast cells

Answer 9

Specialized tissue cells that trigger local inflammatory responses

Question 10

Basophils

Answer 10

White blood cell that functions in inflammatory events and allergies

Question 11

Eosinophils

Answer 11

White blood cells that are active in worm and fungal infections, allergy, and inflammation

Question 12

Neutrophils

Answer 12

Blood phagocytes, very effective at chemotaxis, and engulfing/killing bacteria

Question 13

Monocytes

Answer 13

Blood phagocytes that rapidly leave the circulation and mature into macrophages and dendritic cells

Question 14

Macrophages

Answer 14

Large phagocyte that specializes in ingesting and killing foreign cells
* critical to specific immune responses

Question 15

Dendritic cells

Answer 15

Heterogeneous population of cells that reside throughout the tissues and are responsible for processing an antigen and presenting it to lymphocytes

Question 16

Describe the physical and mechanical barriers to infection

Answer 16

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

Question 17

List and describe protective chemicals in the body

Answer 17

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

Question 18

List the cells of the innate response and describe their specific roles

Answer 18

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

Question 19

Define phagocytosis and explain the process

Answer 19

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)

Question 20

Discuss the complement system and its role in host defense

Answer 20

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

Question 21

Explain the process of inflammation and the importance. List the major signs.

Answer 21

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

Question 22

Discuss the importance of fever

Answer 22

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

Question 23

Elevated Eosinophils is often indicative of a ?????

Degranulated Mast cells indicate ?????

Bacterial diseases often show increase in ????

Viral infections show increase in ????

Answer 23

– helminth infestation

– allergic response

– leukocytes and neutrophils

– lymphocytes