BIOL 220 Lecture Notes - Lecture 18: Macrophage, Antibody, Phagosome
Lecture 18
BIO 220
Immune System
Immune System
oThe immune system is an integrated system of organs, tissues, cells and cell products
oIt differentiates self for nonself and neutralizes potentially pathogenic organisms or
substances
oIt is capable of responding to nearly any foreign molecular structure
Our Microbial Residents
oOur bodies carry about ten times as many bacterial cells as nucleated human cells
oThe consortium of colonizing microbes has been dubbed the human microbiota or
microbiome
oAn immunocompromised host is at risk due to opportunistic pathogens
oThe human body teams with microbial hitchhikers
Most are harmless
Some are beneficial to their host
oThe human body is also under constant attack from microbial invaders
Fortunately, we have barriers
Nonspecific defenses
Adaptive and nonadaptive immune defenses
Where do they come from?
oMicrobiome develops before birth
The source of those microbes may be the placenta
Oral and Nasal Cavities
oThe oral microbiota are normally harmless, but they can cause disease
oDental procedures, for instance, will often cause these organisms to enter the blood
stream, producing what is called bacteremia
Respiratory Tract
oThe lungs and trachea are usually sterile
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oThe ciliated mucous lining og the trachea, bronchi and bronchioles makes up the
mucociliary escalator
Sweeps foreign particles up and out of the lung
The Stomach
oHas very high acidity so very few microbes can survive
oDecreased stomach acidity=hypochlorydia
Caused by malnourishment
Intestinal Tract Microbiome
oThe intestine contains 10^11 bacteria/gm of feces
Microbiomes and Disturbance
oEmotional stress, a change in diet, or antibiotic therapy can alter gut microbiome
balance
oThe resultant dysbiosis can lead to poor digestion or inflammatory bowel disease
oProbiotics are living microbes that are ingested to restore the natural microbial balance
Hygiene and Microbiomes
oFor millennia, human microbiota were shaped by an intimate contact with natural
environments composed of animals, caves, dirt, poop, and bugs
oToday we are an indoor species spending most of o9ur time inside closed buildings,
segregated from nature
Use of soaps, antibiotics, disinfectants has severely restricted our access to
microbes
oAs a result our microbiota is less diverse than those of a long time ago
Types of Pathogens
oPrimary pathogens
Cause disease in healthy hosts
oOpportunistic pathogens
Cause disease only in immunocompromised patients
oThe term pathogenicity refers to an organisms ability to cause disease
Virulence
oA measure of the degree or severity of a disease
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find more resources at oneclass.com
Document Summary
Some are beneficial to their host: the human body is also under constant attack from microbial invaders. Where do they come from: microbiome develops before birth. The source of those microbes may be the placenta. Oral and nasal cavities: the oral microbiota are normally harmless, but they can cause disease, dental procedures, for instance, will often cause these organisms to enter the blood stream, producing what is called bacteremia. Respiratory tract: the lungs and trachea are usually sterile, the ciliated mucous lining og the trachea, bronchi and bronchioles makes up the mucociliary escalator. Sweeps foreign particles up and out of the lung. The stomach: has very high acidity so very few microbes can survive, decreased stomach acidity=hypochlorydia. Intestinal tract microbiome: the intestine contains 10^11 bacteria/gm of feces. Use of soaps, antibiotics, disinfectants has severely restricted our access to microbes: as a result our microbiota is less diverse than those of a long time ago.
