What are commonly used to attach to surfaces, including host cells?
fimbriae and capsules
What are biofilms formed?
if cells produce enough capsule slime
What is biofilm?
a thick layer of slime inhabited by numerous slime-producing and non-slime-producing cells
What is an example of a biofilm?
slime on spoiled food or slime that develops on dirty dishes soaking in the sink
What is dental plaque considered?
What do biofilms do for cells?
has a protective effect on cells
What are exotoxins?
toxins that are released from the cell - always proteins
What are the genes that code for exotoxins?
What are endotoxins? Example?
held in or on the cell and are released only when the cell dies or breaks apart - lipopolysaccharide in the outer membrane of gram-negative bacteria
What is the biologically active component of LPS?
What do endotoxins caused in low amounts? High amounts?
fever and chills - shock and death
How does LPS cause fever?
1) phagocytes engulf and digest gram-negative cells
2) digestion breaks the cells apart which releases the LPS
3) LPS stimulates the phagocyte to produce IL-1 (interleukin-1)
4) IL-1 travels through the bloodstream and stimulates the hypothalamus to produce prostaglandins
5) prostoglandins stimulate the hypothalamus to re-set the body temperature to a higher level
6) fever develops and continues as lonas as the level of prostaglandins remains high in the hypothalamus
How do aspirin, acetaminophen, and inbuprofen reduce fever?
block the production of prostaglandins
What is shock?
life-threatening drop in blood pressure
What happens if blood pressure drops too low?
blood flow to various organs decreases or even stops, which results in organ failure followed by death if the condition isn't corrected
What is septic shock caused by?
the presence of bacteria in the blood and the complex toxic condition that occurs as a result
What is the term for having bacteria in the blood?
What is the complex toxic condition that can result from having bacteria in the blood?
What are the symptoms of sepsis cause of?
chemicals our immune system produce during the fight against the bacteria in the blood
How does LPS cause septic shock?
1) phagocytes engulf and digest the gram-negative bacteria
2) digestion breaks the cells apart which releases the LPS
3) LPS stimulates the phagocyte to produce TNF (tumor necrosis factor)
4) a series of events initiated by TNF results in damage to capillaries
5) the damaged capillaries leak excessive fluid from the circulatory ystem
6) the loss of fluid caues blood pressure to drop
How can you raise blood pressure?
fluid replacement and epinephrine
How does epinephrine raise blood pressure?
causes blood vessels to constrict
What two major branches can the immune system be divided into?
the innate immune system and the adaptive immune system
When are the components of the innate immun system functional?
at birth or soon after
When are the components of the adaptive immune system functional?
as we are exposed to more microbes throughout our lives
What are some physical microbe barriers?
skin, mucous membranes, ciliary escalator, peristalsis, fluid flow in various locations
What is skin a physical barrier?
the major protein of skin is keratin, few microbes produce enzymes that can break down keratin so as long as the skin is not damaged microbes can't go through it
How are mucous membranes physical barriers?
they line the respiratory, digestive, and genitourinary tracts, the membranes trap invading cells and prevent contact with host cells
How is the ciliary escalator a physical barrier?
the cilia on the cells in the respiratory tract move mucus (and microbes trapped in it) out of the lungs and into the throat
How is peristalsis a physical barrier?
rhythmic contractions that move materials along the digestive tract
How is fluid flow a physical barrier?
fluids flowing across the surfaces of the mouth (saliva), urinary tract (urine), and eyes (tears) rinse away microbes
What are some chemical microbe barriers?
low pH, lysozyme, digestive enzymes, and transferrins
How is low pH a chemical barrier?
the pH of the skin is often around 3-5, which is low enough to inhibit microorganisms, the pH of the stomach is about 2, and the pH of the vagina is very low
Why is the pH of our skin so low?
due to fatty acids in sebum as well as acids produced by bacteria on our skin
Why is the pH of the vagina so low?
acids produced by a species of Lactobacillus
How is lysozyme a chemical barrier?
an enzyme produced in tears, sweat, and saliva that breaks down peptidoglycan and ruining that peptidoglycan layer make the cell vulnerable to damage and death
How are digestive enzymes chemical barriers?
enzymes in our saliva, stomach, small intestine, and pancreas break down the carbohydrates, proteins, and lipids in bacterial cells as easily as the food we eat
How are transferrins chemical barriers?
iron-binding proteins in the blood, saliva, milk, and tears work by preventing iron from floating free in our fluids which prevent nutrients for microbes
If transferrins take away iron in body fluids, how do some microbes get nutrients in our body?
they produce their own iron-binding proteis called siderophores that help them grab available iron
What are included in transient microbiota?
bacteria we pick up and drop off during the day when we come into contact with dust and other things
Where is the vast majority of our normal microbiota?
in the colon
What do our normal microbiota contribute to?
innate immune system
How do our normal microbiota contribute to our innate immune system?
crowd out pathogens and produce acids
What is a common microorganism in the colon?
Where is E. coli commonly found?
What is the most common microbiota of the skin?
What are other common microbiota of the skin?
What is Propionibacterium acnes?
major contributor to the acidity of the skin
What is Brevibacterium linens?
major contributor to foot and body oder due to sulfer compounds it produces (methanethiol)
What are probiotics?
live microbes consumed for a benficial effect
What are some microbiota that are considered probiotics?
lactobacillus (Lactobacillus acidophilus or Bifidobacterium - colon)
What does consuming probiotics ensure?
a good population of normal microbiota will always be present in the intestinal tract
What do leukocytes include?
neutrophils, basophils, eosinophils, monocytes, natural killer cells, B cells, and T cells
What is the most common leukocyte?
What are the major functions of neutrophils?
phagocytic, first responder
What do basophils contain?
What do basophils play a role in?
allergic and inflammatory responses
What do eosinophils defend against?
What do monocytes differentiate into?
macrophages (which are phagocytic)
What do natural killer cells do?
attack infected cells
What are neutrophils also known as?
PMNs (polymorphonuclear leukocytes)
Basophils are important in what? Why?
anaphylactic shock - they histamine they release when stimulated cause capillaries to expand and become leaky all over the body - the loss of fluid from the blood is shock (anaphylactic bc of the things that enter the blood)
Where are mast cells located?
they live under skin and mucous membranes
What do mast cells contain? What do mast cells cause?
vesicles of histamine - basic allergic reactions that affect they eyes and respiratory passages where their histamine cause a more local reaction that involves redness and swelling
Are mast cells leukocytes? Why?
No, they don't live in the blood
How do eosinophils kill helminths?
releasing toxins and reactive oxygen species (like peroxide)
Monocytes are inactive, but how do they work?
they leave the circulatory system when stimulated and mature into macrophages
What do monocytes do at sites of infection?
they come second (after neutrophils) and act as clean up crew
Where do wandering macrophages exist?
they wander through our tissues and respond to infection where they find it
Where do fixed macrophages exist? What is an example of a fixed macrophage?
a specific organ - Kupffer cells, microglial cells, and alveolar macrophages
What are Kupffer cells?
macrophages found in blood vessels of the liver where they kill bacteria that flow by
What are microglial cells?
macrophages found in the central nervous system (spinal cord, brain) where they migrate around and kill bacteria they find
Where are alveolar macrophages found?
passageways and alveoli of the lungs where they digest bacteria or particles that enter
How do natural killer cells kill the cells?
they release perforin and granzymes - the perforin creates pores in the cell membrane which allows granzymes to enter then stimulate cell suicide
What is cell suicide called scientifically?
Natural killer cells do not kill microbes inside the host cell, but instead do what?
kill the host cell and then phagocytes (neutrophils and macrophages) kill any bacteria/viruses released
Any chemical that stimulates or regulates immune cells.
How does most communication in the cell occur?
The ingestion of microbes or particles by an immune cell.
What are the three steps to killing microbes by phagocytosis?
phagocytosis, fusion of the vesicle with a lysozome, and digestion
Describe the step of phagocytosis.
initial ingestion of an invader, after the microbe is contained in a vesicle inside the cell
Describe the step of fusion.
the vesicle merges with a lysozome (another vesicle filled with digestive enzymes)
Describe the step of digestion.
various digestive enzymes begin breaking down all parts of the microbe (proteins, lipids, DNA, carbs) and other enzymes produce acids, hypochlorite, and an oxidative burst
What is an oxidative burst?
the sudden production of various toxic forms of oxygen (ROS) - cause numerous undesirable reactions and interfere with all cell functions
What are the interferons alpha-INF and beta-INF produced by?
How do interferons work to prevent infection?
the stimulate neighboring cells antiviral proteins (hopefully before it becomes infected), these proteins prevent viral biosynthesis and limit the spread of infection
How are interferons used medically?
therapeutically in combination with other drugs to treat chronic viral infections and some types of cancer
What is complement?
a set of proteins found in the blood, when damage or inflammation occur they enter the affected area and activate
How do complement proteins work?
form pores in the cell membrane of invading cells, resulting of the death of the invader
When does fever occur?
when the level of prostaglandins increase in the hypothalamus, which causes the hypothalamus to reset the body temp to a higher temp
What is the increase in prostaglandins usually caused by?
What does higher body temp do to us?
increases our metabolism and effectiveness of immune cells (the high temp does not kill pathogens)
What are the four classic symptoms of inflammation? What is a fifth that may occur?
What is the inflammatory response?
injury causes mast cells to release histamine, prostaglandins, and other materials
histamine increases vasodilation, vascular permeability, and phagocyte chemtaxis
damage, sweeling, and prostaglandins all stimulate pain nerves
What is vasodilation?
expansion of the blood vessels
What does vasodilation do?
increases blood flow to the area which results in heat and redness
What does increased permeability do for blood vessels during inflammation?
allows fluids, phagocytes, complement, and antibodies to escape from capillaries - the accumulation of these fluids causes swelling
How is pus formed?
phagocytes flowing in the bloodstream sense histamine and other cytokines and they migrate to the damaged area
Macrophages phagocytize bacteria just like neutrophils, but they're big enough to also do what?
phagocytize dead neutrophils and damaged host cells
Aspiring, ibuprofen, etc reduce pain by blocking the production of prostaglandins. Why?
prostaglandins sensitize pain nerves
How does the adaptive immune system differ from the innate immune system?
the adaptive immune system improves throughout the life as each person is exposed to more microorganisms
What are B and T cells called? Why?
lymphocytes - they spend most of their time in the lymph system and the lymphoid tissues (but are also considered leukocytes because they spend part of their time in the blood)
What do the vessels of the lymph system do?
collect fluids that leave the circulatory system and return them to the circulatory system near the heart
Where do lymphocytes congregate?
near lymphoid tissues
What are some lymphoid tissues?
lymph nodes, tonsils, Peyer's patches, spleen
What are lymph nodes?
enlarged pockets that occur along the vessel of the lymph system
What do lymph nodes contain?
numerous lymphocytes that detect invaders that flow by in the lymph fluid
How do lymph nodes become swollen?
they fill up with large numbers of reproducing lymphocytes during infection
What do cells on surface of the tonsils and peyer's patches do?
constantly sample materials on the surface and present the material to the immune cells under the surface which allows immune cells to respond to pathogens before they have time to penetrate the body
Where are peyer's patches located?
the small intestine
What is one function of the spleen?
trap and destroy damaged red blood cells
What are Helper T Cells called?
What is CD4?
a molecule on the surface of helper t cell's that is important to their function
What are Helper T Cell's?
ringleaders of the immune system, they stimulate and regulate oher immune cells with the cytokines they release
What are helper t cell's activited by?
antigens displayed on the surface of other immune cells, once stimulated they release cytokines that stimulate the immune cell
What are every B cell coated with?
antibodies - each are identical and grab the same antigen
What are events are required for the stimulation of B cells?
initial stimulation by an antigen and then stimulation by a helper t cell
What do most B cells turn into? What do the rest turn into?
plasma cells, memory cells
What do plasma cells do?
release large quantities of antibodies, all of which are identical and bind to the antigen that stimulated its production
What do memory cells do?
they wait and multipy and release antibodies when we become infected again with the same pathogen, these cells help us react more quickly the second time
The first time we are exposed to an antigen, how long does it take to produce antibodies?
What is the first type of antibody produced during an infection? What does large amounts of this antibody indicate?
IgM - first stages of infection
What is produced after IgM?
When a second exposure occurs what are IgM and IgG amounts in the body?
they are both produced but IgG are much higher
What is the purpose of vaccinating individuals?
to mimic the initial infection of a pathogen and stimulate the adaptive immune response (without causing sickness) so that the immune system can respond faster and stronger when exposed to the actual pathogen
What are antibodies?
proteins produced by plasma cells in response to an antigen and able to bind to the antigen
What is another term for antibody?
What is an antigen?
any molecule that stimulates the production of antibodies
What are antigens usually?
proteins or polysaccharides on the surface of a pathogen
What is the shape of an antibody?
What are the three antibodies we need to know?
IgG, IgM, IgA
What does Ig stand for?
What is IgG?
What is the most common antibody in the blood?
What is the most abundant antibody produced during an infection?
What does IgG do during pregnancy?
crosses the placenta and protects the fetus
What is IgM?
What is the first antibody produced during infection?
What is IgM especially good at?
What is IgA?
What antibody is secreted into fluids like mucus, saliva, tears, and breast milk?
What antibody protects our moist surfaces?
This provides protection for breast-fed infants.
What are three ways antibodies increase the effectiveness of the immune system?
enhanced immune cell grip
What is agglutination?
antibody binding causes clumps of the pathogen to form
How does agglutination destroy pathogens?
immobilizes them until immune cells can destroy them
Cytotoxic T Cells are also called what?
What is CD8?
molecule of the surface of cytotoxic t cell's that is important to their function
What do cytotoxic t cells kill?
The adaptive immune system can be divided into what two parts?
humoral immunity and cell-mediated immunity
What is humoral immunity?
immunity provided by antibodies
What is humoral immunity active against?
What is cell-mediated immunity?
immunity provided by cytotoxic t cells
What is cell-mediated immunity active against?
What is immunology?
the study of the immune system
What are vaccines?
preparations designed to induce adaptie immunity
What are three types of vaccines?
whole agent vaccines
What do whole-agent vaccines contain?
whole cells or whole virions, but these may be weakened or killed
What do subunit vaccines contain?
antigenic pieces of a pathogen, usually proteins or polysaccharides rom a cell membrane or viral capsid
What are subunit vaccines usually safer?
they only contain necessary cell parts, so they're less likely to cause disease or have side effects
What do toxoid vaccines contain?
Why do attenuated whole-agent vaccines provide the longest-lasting immunity?
they reproduce in the host and mimic an actual infection
What is the goal of immunizing a community?
establish herd immunity and prevent outbreaks - if a large enough population is immune the risk is reduced because the chances of susceptible people coming into contact with someone infected is decreased
What is herd immunity usually reached?
85-90% of population becomes vaccinated
What do antitoxins contain?
antibodies against a toxin
Antitoxins are used when?
after exposure to a toxin (like a snake bite) in order to provide immediate relief by neutralizing the toxin
What are some antitoxins available for bacterial toxins?
toxins that cause botulism or tetanus
Tests that use antibodies to determine the results.
What are serological tests useful for?
indentifying bacteria or diagnosing disease
What are some examples of serological tests?
agglutination and immunofluorescence
What indicates a positive result during an agglutination test?
What can be used in agglutination tests?
microscopic latex beads - they can be coated with antibodies - latex agglutination
When clumping involves red blood cells, what is it called?
What is an example of hemagglutination?
Immunofluorescence uses antibodies that have been treated how?
bonded with fluorescent dye
What type of microbe that causes infection would you use an immunofluorescence test on?
Mycobacterium tuberculosis and Treponema pallidum (causes syphillus)
What is an immunodeficiency?
an inability to produce a normal immune response
What is an example of an immunodeficiency?
AIDS (acquired immunodeficiency), SCID (severe combined immunodeficiency syndrome)
What is HIV?
an enveloped retrovirus
What does HIV mostly infect?
CD4 cells - a protein in the envelope called gp120 attaches to the CD4 cells
How can the progression of HIV be described?
the first stage is usually asymptomatic
as infection progresses, cell numbers drop, and susceptibility increases
when tH cell count reaches 200/mm3 the CDC diagnoses AIDS
What are some common indications of a failing immune system?
persistent yeast infections (oral in males, vaginal in females)
What is the normal tH cell count?
What is the average period of time from initial infection to the development of AIDS
What are some diseases associated with AIDS?
Candida albicans (yeast infections that can spread to esophagus and lungs), Pneumocystis jiroveci (yeast that causes severe pnuemonia), and humans herpesvirus (causes Kaposi's sarcoma, a skin cancer)
What region has the most HIV-infected persons in the world?
How was HIV probably first transmitted?
contact with the blood of monkeys killed or food
What are the most common drugs used to fight HIV infection?
reverse transcriptase inhibitors, usually in combination with other drugs
Substances produced by one microorganism that inhibits or kill another microorganism.
What was the first antibiotic?
Who discovered the first antibiotic and when?
Alexander Fleming - 1928
When was the first widespread use of antibiotics?
World War II
What are half of the antibiotics used in the US each year used for?
in animal feeds to encourage weight gain
What are half of all antibiotics produced by?
species of Streptomyces
What are other antibiotics produced by?
molds or species of Bacillus
What do the species that produce antibiotics all have in common?
they are soil microbes, and their antibiotics are useful in eliminating competition in the crowded soil environment
The range of microbes an antibiotic is effective against.
Spectrum of Action
What is an example of a broad spectrum antibiotic?
What is tetracycline effective against?
gram-postive, gram-negative, and obligate intracellular bacteria
What is an example of a narrow spectrum antibiotic?
What is penicillin effective against?
only gram-positive bacteria
When are broad spectrum antibiotics useful? But, what are they most likely to kill?
when the agent is unknown - normal microbiota
When are narrow spectrum antibiotics useful?
when the agent is known so the antibiotic can be targeted against a specific pathogen in the location of infection
The ability to inhibit a microbe without harming the host.
Why is selective toxicity important?
we don't want to harm the host when we're trying to heal them
Finding selective toxicity agents is easiest for what pathogens? Harder for who? Hardest for who?