MICROPARA (15): Nonspecific Host Defense Mechanisms in Microbiology

Ability to ward off disease

Capacity of an organism to defend itself against a disease/withstand the

effects of a harmful environmental agent.

Resistance

non specific defense mechanisms

first line of defense and second line of defense

first line of defense

- skin

- mucous membranes

- secretion of skin and mucous membranes

second line of defense

- phagocytic white blood cells

- antimicrobial proteins

- the inflammatory response

specific defense mechanisms (immune system)

third line of defense

- lymphocytes

- antibodies

Defenses that protect against all

pathogens.

Non specific Defense Mechanisms

Protection against specific

pathogens.

Specific Defense Mechanisms

Vulnerability or lack of resistance. The state of being predisposed to, sensitive to, or of lacking the ability to resist a pathogen, familial disease, or a drug.

Susceptibility

Non-specific natural barriers which restrict entry of pathogen.

First Line of Defense

skin and mucous membranes

Innate non-specific immune defense provide rapid local response to pathogen after it has entered host.

Second Line of Defense

Ex: Fever, phagocytes (macrophages

and neutrophils), inflammation, and

interferon.

Antigen specific immune responses, specifically target and attack invaders that get past first two lines of defense.

Third Line of Defense

Ex: Antibodies and Lymphocytes.

Proteins produced by the immune system to identify and neutralize pathogens.

Antibodies

A type of white blood cell that is part of the immune system.

Lymphocytes

Thin outer layer of epithelial tissue that contains Langerhans cells, dead cells, and keratin (waterproof).

Epidermis

Thick inner layer of connective tissue where infections are rare in intact skin.

Dermis

"skin loving" fungi

dermatophytes

Line gastrointestinal, genitourinary, and respiratory tracts.

Mucous Membranes

secretes mucus which maintains moist surfaces.

epithelial layer

virus that cause HPV

papillomavirus

a microaerophilic, gram-negative, spirochaete bacterium with subspecies that cause the diseases syphilis, bejel, and yaws.

treponema pallidum

Continual washing and blinking prevents microbes from settling on the surface.

Lacrimal Apparatus

Washes microbes from teeth and mouth mucous membranes.

Saliva

Thick secretion that traps many microbes.

Mucus

Coated with mucus to filter dust, pollen, and microbes.

Nose Hair

Cilia on mucous membranes of lower respiratory tract move upwards towards throat at 1-3 cm/hour.

Ciliary Escalator

Expel foreign objects.

Coughing and Sneezing

Covers larynx during swallowing, protecting the respiratory system from infections.

Epiglottis

mechanical defense

1. Skin

2. Mucous membrane

3. Lacrimal Apparatus

4. Saliva

5. Mucus

6. Nose hair

7. Ciliary Escalator

8. Coughing and Sneezing

9. Epiglottis

Chemical Defense

1. Sebum

2. pH

3. Perspiration

4. Lysozyme

Oily substance produced by sebaceous glands that forms a protective layer over skin.

Sebum

sebum contains these that help inhibit growth of certain pathogenic bacteria and fungi

unsaturated fatty acids

Low, skin pH usually between 3 and 5, caused by lactic acid and fatty acids.

pH

Produced by sweat glands and contains lysozyme and acids.

Perspiration

Enzyme that breaks down gram-positive cell walls, found in nasal secretions, saliva, and tears.

Lysozyme

Derived from the Greek words 'Eat and cell'.

Phagocytosis

> macrophages

> occasionally eosinophils

> neutrophils

Phagocytic cells that originated from monocytes that leave blood and enter infected tissue.

Macrophages

White blood cells that predominate early in infection.

Neutrophils

Occasionally involved in phagocytosis.

Eosinophils

stages of phagocytosis

1. Chemotaxis

2. Adherence

3. Ingestion

4. Digestion

Phagocytes are chemically attracted to the site of infection.

Chemotaxis

Phagocytes' plasma membrane attaches to the surface of pathogen or foreign material.

Adherence

Coating process with opsonins that facilitates attachment.

Opsonization

Includes antibodies and complement proteins.

Opsonin

Plasma membrane of phagocytes extends projections (pseudopods) which engulf the microbe.

Ingestion

The sac in which a microbe is enclosed during phagocytosis.

Phagosome

Inside the cell, phagosome fuses with lysosome to form a phagolysosome.

Digestion

The structure formed when a phagosome fuses with a lysosome.

Phagolysosome

Kill most bacteria within 30 minutes.

Lysosomal enzymes

after digestion, these undigestible material are discharged

residual body

Triggered by tissue damage due to infection, heat, wound, etc.

Inflammation

Function of Inflammation

1.Destroy and remove pathogens.

2. If destruction is not possible, to limit

effects by confining the pathogen and its

products.

3. Repair and replace tissue damaged by

pathogen and its products.

Characterized by major symptoms such as redness, pain, heat, swelling, and loss of function.

Acute Inflammation

major symptoms of inflammation

local manifestation:

systematic manifestaton:

local manifestation:

1. redness

2. pain

3. heat

4. swelling

5. loss of function

systematic manifestation:

1. fever

2. chills

3. myalgia

4. malaise

A type of inflammation that produces a serum-like exudate.

Serous Inflammation

Inflammation of mucous membranes in an airway or cavity of the body.

Catarrhal Inflammation

a type of inflammation that occurs when fibrinogen escapes from an injury and is converted to fibrin.

Fibrinous Inflammation

a type of inflammation that is characterized by a large number of erythrocytes in the exudate.

Hemorrhagic Inflammation

When pus is produced as a result of inflammation.

Suppurative Inflammation

A serious condition that occurs when pus builds up in a body cavity.

Emyema

A chronic inflammatory bowel disease that causes inflammation in the large intestine and rectum.

Ulcerative Colitis

Can occur in a variety of internal organs, including the gallbladder, bile duct, pancreas, lungs, kidneys, and eyeballs.

Gangrenous Inflammation

A severe inflammation of the large intestine's inner lining caused by an overgrowth of Clostridioides difficile.

Pseudomembranous Colitis