Micro Exam 3

Holobiont

A human plus all of its resident microbiota.

Human Microbiome Project

A project of the National Institutes of Health to identify microbial inhabitants of the human body and their role in health and disease.

Microbial antagonism

A relationship in which microorganisms compete for survival in a common environment by taking actions that inhibit or destroy another organism.

Endogenous

Originating or produced within an organism or one of its parts.

Opportunistic

Ordinarily non-pathogenic or weakly pathogenic microbes that cause disease primarily in an immunologically compromised host.

Virulence

The relative capacity of a pathogen to invade and harm host cells.

Virulence factor

A microbe's structures or capabilities that allow it to establish itself in a host and cause damage.

Infectious dose

The minimum number of organisms required to cause an infection.

Portal of entry

The route of entry for an infectious agent; typically a cutaneous or membranous route.

Polymicrobial

Infections caused by more than one microbe.

Exogenous

Originating outside the body. (opposite of endogenous)

STEP 1: Types of Portals of Entry

1. Skin - through abrasion, broke skin, or bites

2. Gastrointestinal - by contaminated food, drink, ingested substance

3. Respiratory tract - oral and nasal cavities

4. Urogenital - contracted by sexual means

Pathogens that infect during birth

T - toxoplasmosis

O - other diseases

R - rubella

C - cytomegalovirus

H - Herpes

STEP 2: Attaching to the host and interacting with microbiome

Adhesion

The process where microbes gain a more stable foothold on host tissues.

• Bacteria, fungi, and protozoal pathogens attach by fimbriae, surface proteins, adhesive slimes and capsules

• Viruses attach by specialized spikes and glycoproteins

• Helminths attach by suckers, hookers, and barbs

Step 3: Surviving Host Defense

Phagocytes

A class of white blood cells capable of engulfing other cells and particles.

STEP 3: Leukocidin

A heat-labile substance formed by some pyogenic cocci that impairs and sometimes lyses leukocytes.

STEP 3: Epigenetic

Referring to changes in the way DNA is transcribed, not actual changes in the DNA sequence.

STEP 4: Causing Disease

The three ways microbes can cause disease to the host are

1. By secreting proteins (enzymes or toxins) that directly damage host cells

2. causing an overreaction by the body’s defense and those defenses causes host damage

3. altering the host cell genome or transcription process through epigenetic changes

1. Direct damage via enzyme and toxins

Exoenzymes

break down and inflict damage on tissues, extracellular enzyme

Examples of exoenzymes - Mucinas and Keratinase

Hyaluronidase

digest hyaluronic acid

Toxigenicity

the power to produce toxins

Toxinoses

diseases whose adverse effects are primarily due to the production and release of toxins

Toxemia

condition in which a toxin is spread throughout the bloodstream

Intoxications

poisoning that results from the introduction of a toxin into body tissues through ingestion or injection

Types of Toxins

• Neurotoxins - act on the nervous system

• Enterotoxins - acts on the intestine

• Hemotoxins - act on red blood cells

• Nephrotoxins - damage the kidneys

Exotoxin

A toxin that is secreted by a living bacterial cell into infected tissues *causes more harm than endotoxin*

Endotoxin

a toxin that is not actively secreted but is shed from the outer membrane

• found on all gram-negative bacteria

• lipopolysaccharide

Hemolysins

class of bacterial exotoxin that disrupts the cell membrane of red blood cells

Localized infection

The microbe enters the body and remains confined to a specific tissue.

Systematic infection

Infection that spreads to several sites and tissues, usually in the bloodstream.

Focal infection

Infectious agent breaks loose from a local infection and is carried into other tissues.

Leukocytosis

An increase in white blood cells.

Leukopenia

A decrease in white blood cells.

Types of Portals of Exit

1. Respiratory and Salivary Portals - mucus, sputum, and nasal discharge

2. Skin Scales - shed skin and scalp

3. Fecal matter

4. Urogenital Tract - vaginal discharge or semen and urine

5. removal of blood or bleeding - blood removed or released from a puncture

Latency

The state of being inactive.

4 phases of infection and disease

1. incubation period - from time of contact of disease to first symptoms

2. Prodrome Stage - start of mild symptoms indicating the onset of disease

3. Acute period - disease becomes well established and multiples

4. convalescent Period - immune system responds and you start to get better

Passive carrier

A person who mechanically transfers a pathogen without ever being infected by it.

Horizontal pattern of transmission

Disease is spread through a population from one infected individual to another.

Vertical pattern of transmission

Transmission from parent to offspring via ovum, sperm, placenta, or milk.

Vehicle

an inanimate material that serves as a transmission agent for pathogens

Fomite

An inanimate object that harbors or transmits pathogens.

Koch's Postulates

A series of criteria to establish a causative relationship between a microbe and a disease.

Florence Nightingale

The first to collect and use health, disease, and death statistics to improve public health.

John Snow

The first to use a map to identify the cause of a disease outbreak.

Point Source

infectious agent came from one course and everyone that was exposed, was exposed of the same source at the same time.

Common Source

Outbreak resulting from common exposure to a single source of infection that can occur over a period of time

Propagated Epidemic

results from an infectious agent that is communicable from person to person and is therefore sustained over time in a population

Healthcare associated infection

any infections acquired as a direct results of a patients presence in a hospital or healthcare setting

Herd immunity

The collective acquired immunity in a population reducing the likelihood of infection.

White Blood cell: Granulocytes

a mature leukocyte that contains noticeable granules in a wright stain

Neutrophils, eosinophils, and basophils

Agranulocytes

One from a leukocytes having globular, non lobed nuclei and lacking prominent cytoplasmic granules

Cytokines

Chemical substances by white blood cells that regulate development, inflammation, and immunity.

• B cells mature in red bone marrow, and T cells mature in the thymus

Lysozyme

An enzyme found in sweat, tears, and saliva that breaks down bacterial peptidoglycan.

Rubor - Red

Calor - warmth

Tumor - swelling

Dolor - pain

Diapedesis

The migration of intact blood cells between endothelial cells of a blood vessel.

Interferon

A small protein produced by certain white blood and tissue cells that acts as a cytokine.

Natural killer cells

A type of lymphocyte related to T cells that lack specificity for antigens.

Dendritic cells

A type of phagocyte that boosts immune responses by presenting antigens.

Antimicrobial peptides

short protein molecules found in epithelial cells, have the ability to kill bacteria

Immunogens

Any substance that induces a state of sensitivity or resistance after processing by the immune system.

B cells

type of lymphocyte or white blood cell, produce antibodies and neutralize pathogens

T cells

type of lymphocyte or white blood cell, destroy infected or cancerous cells

Major Histocompatibility Complex (MHC)

a set in mammals that produces molecules on surface of cells that differentiate among different individuals in the species

Epitope

The primary signal that a molecule is foreign.

Haptens

Partial antigens that cannot stimulate a full immune response.

Superantigens

Bacterial toxins that are potent stimuli for T cells.

Classes of Antibodies

Different types of antibodies including IgG, IgA, IgM, IgD, and IgE, each with distinct functions.

Active Immunity

Immunity that occurs when an individual receives an immune stimulus activating B and T cells.

Passive Immunity

Immunity that occurs when an individual receives immune substances produced actively in another body.

The immune system is responsible for…

• Surveillance of the body

• recognition of foreign material

• Destruction of anything foreign

Antigen

any cell that induces a specific immune response by B cells or T cells and can stimulate resistance to an infection or toxin

Pathogen-associated molecular patterns (PAMP)

molecules on the surface of many types of microbes that are not present on host cells that mark the microbes as foreign

Pattern recognition receptors (PRR)

molecules on the surface of host defense cells that recognize pathogens associated molecular patterns on microbes

Mononuclear Phagocyte system

a collection of monocytes and macrophages scattered throughout the extracellular spaces that function to engulf and degrade foreign molecules.

Lymph

A plasma like fluid carried by the lymphatic circulation

Skin-associated lymphoid tissue (SALT)

discrete bundle of lymphatic tissue located just under the surface of the skin

Mucosa-associated Lymphoid Tissue (MALT)

small patches of lymphoid tissue situated in and on mucosal surface, containing T cells, B cells, phagocytes, and other immune cells

Gut-associated lymphoid Tissue (GALT)

A collection of lymphoid tissue in the gastrointestinal tract that includes the appendix, the lacteals, and Peyer’s patches.

Whole Blood

a liquid connective tissue consisting of blood cells suspended in plasma

Pluripotential Stem cell

a primary precursor of new blood cells, is a pool of undifferentiated cells

Clone

a group of genetically identical cells

IgA

a monomer of immunoglobulin, it is the most prevalent antibody, and neutralizes toxins. The only antibody capable of crossing the placenta

IgA

coats the surface of membranes and is found in saliva, tears, colostrum, and mucus

IgM

composed of five monomers, binds antigens, circulates mainly in the blood

IgD

found in miniscule amounts, main function is that it is the receptors for antigen on B cells

IgE

its role is to stimulate an inflammatory response, can lead to asthma and certain other allergies

How B cells respond to antigens

• A B cell divides giving rise to plasma that releases the five classes of antibodies

• Regulatory B cells regulate the degree of response from T cell

Characteristic of Good antigens

• chemical composition

• context

• size

3 different cells that can serve as Antigen-presenting cells: APC

1. Macrophages

2. B cells

3. Dendritic Cells

First line of defense

includes any barriers that block invasion at the portal of entry, and limits access to the internal tissues of the body

skin, hair follicles, and skin glands

Second line of defense

internalized system of protective cells and fluids and includes inflammation, phagocytosis, fever, and antimicrobial products

three main types of phagocytes - neutrophils, monocytes, macrophages

Third line of defense

acquired on an individual basis as each foreign substance is encountered by white blood cells lymphocytes