Chapter 10 <3

• Ecology

  is the systematic study of the interrelationships that exist between organisms and their environment.
• Microbial ecology

  is the study of the numerous interrelationships between microbes and the world around them—how microbes interact with other microbes, how microbes interact with organisms other than microbes, and how microbes interact with the nonliving world around them.
• symbiosis or symbiotic relationship


  Is defined as the living together or close association of two dissimilar organisms
• Symbionts


  The organisms that live together in a symbiotic relationship
• Neutralism


  Used to describe a symbiotic relationship in which neither symbiont is affected by the relationship
• Commensalism


  Symbiotic relationship that is beneficial to one symbiont and of no consequence to the other
• Host


  Defined as a living organism that harbors another living organism
• Demodex


  Tiny mite which lives in the hair follicle and sebaceous glands, especially those of the eyelashes and eyebrows
• Mutualism


  A symbiotic relationship that is beneficial to both symbionts
• Escherichia coli


  An intestinal bacterium which obtains nutrients from food materials ingested by the host and produces vitamins (such as vitamin K) that are used by the host
• Vitamin K


  A blood-clotting factor that is essential to humans
• Parasitism


  A symbiotic relationship that is beneficial to one symbiont and detrimental to the other symbiont
• Trypanosoma brucei gambiense


  is one of the parasites that causes African sleeping sickness, a human disease that often cause death to the host
• Dysbiosis


  Is a disruption in the normal indigenous microbiota
• Microbiota


  Refers to the microorganisms that make up our indigenous microflora
• Microbiome


  Consists of not only the microorganisms but also the genes they posses and their effect on the local environment within the body
• Bacterial proteins genes are 360 times more abundant than human genes
• human virome

  consists of viruses that infect human cells and become latent such as the Herpes viruses, pieces of ancient viral nucleic acids that have become part of the genetic makeup of our own cells, as well as bacteriophages that infect the bacteria of the microbiome.
• A person's indigenous microbiota includes all of the microbes (bacteria, fungi, protozoa, and viruses) that reside on and within that person
• It has been estimated that our bodies are composed of about 10 trillion cells (including nerve cells, muscle cells, and epithelial cells), and that we have at least that many microbes that live on and within our bodies.
• it has been estimated that our indigenous microbiota is composed of as many as 10,000 different species, although
• A fetus has no indigenous microbiota although there is now evidence that a few microorganisms are present in the infant GI tract at birth, likely acquired
• Areas of the body where most indigenous microbiota resides:


  Ears and eyes, mouth and upper respiratory tract, skin, Gastrointestinal tract, Genitourinary tract, scalp, axilla
• Parts of the body that are free from microorganisms:

  Blood, lymph, spinal fluid, most internal tissues and organs
• Transient microbes


  Take up temporary residence on and within humans
• Diarrhea


  usually the result of such an imbalance, which, in turn, leaves the body more susceptible to secondary invaders
• Candida albican


  An opportunists usually found in small numbers near openings which in the absence of sufficient numbers of other resident microbiota
• Candida albicans


  May grow unchecked in the mouth, vagina, or lower intestine
• Candidiasis


  A disease caused by Candida albicans
• Superinfection


  An overgrowth or population explosion of an organism that is usually present In low numbers
• The resident microbiota of the skin consists primarily of bacteria and fungi -as many as 300 different species, depending on the anatomic location.
• The most common bacteria on the skin:

  Staphylococcus spp., Corynebacterium spp., Propionibacterium spp.
• Factors microorganism in the skin depends on:

  Anatomic location, amount of moisture present, pH, temperature, salinity, presence of chemical wastes, presence of other microbes
• Coagulase 


  an enzyme that causes clot formation
• Sebum


  sebaceous gland secretions
• Middle and inner ear are usually sterile, whereas the outer ear and the auditory canal contain the same type of microbes found on the skin.
• The external surface of the eye is lubricated, cleansed, and protected by tears, mucus, and sebum.
• Lysozyme


  an enzyme or antimicrobial substance found in tears
• The nasal and throat have an abundant and varied population of microbes.
• Upper respiratory tract


  consists of nasal passages and the throat