Pathogens and Disease Flashcards
What is a microorganism?
Any organism too small to e seen without a microscope
What is a pathogen?
Any organism that causes diseases
How can pathogens spread?
Direct physical contact, indirect contact through air, indirect contact through objects and disease vectors
What is direct physical contact?
Pathogens spread through infected skin, bodily fluids, touching or sexual activity
What is indirect physical contact through air?
Pathogens spread through droplets in the air when an infected person coughs or sneezes
What is indirect contact by objects?
Pathogens spread by inanimate objects called fomites such as door handles or counter tops
What are disease vectors?
Pathogens spread by living organisms such as mosquitoes that carry them to other living organisms
How do pathogens cause diseases?
Rapid multiplication, toxins, cell destruction and competition
What is rapid multiplication?
When pathogens multiply so rapidly and crowed or kill healthy cells and tissues
What are toxins?
Pathogens produce toxins that interfere with normal cellular activities
What is cell destruction?
When the pathogen takes over the cells to replicate itself, destroying the cells
What is pathogen competition?
When the pathogen competes with the body for nutrients, thus causing malnutrition
How can pathogens enter the body?
Through open cuts/wounds, inhaling airborne droplets, drinking contaminated water, eating contaminated food, direct physical contact and sexual activity
What are the 4 main types of pathogens?
Viruses, bacteria, fungi and potozoa
What is bacteria?
single-celled microbes without a nucleus that multiply rapidly and can destroy cells directly or by releasing toxins
What pathogen can be killed by antibiotics?
Bacteria
What is a virus?
A non-living particle that can only reproduce inside living cells, they are much smaller than bacteria and spread by bodily fluids including blood and mucus
What pathogen cannot be killed by antibiotics?
Viruses
What is a fungi?
A simple organism like mushrooms, yeasts an molds that grow as single cells or threadlike filaments
What pathogen is treated with antifungals?
Fungi
What is protozoa?
A single celled animal that is more complex than bacteria and is found in decaying matter and contaminated water that may have a threadlike flagellum to move
What is an infection?
Occurs when a pathogen successfully enters the hosts body an begins to multiply
What is a disease?
Occurs when a hosts cells are damaged as a result of infection, crating symptoms
What are the types of infection?
Pathogenic, opportunistic, exogenous, endogenous and HAI
What is a pathogenic infection?
Infection due to a disease-causing organism
What is a opportunistic infection?
infection occurring when the immune system is weak
What is a exogenous infection?
Infection that originates outside of the body
What is a endogenous infection?
infection that originates inside the body
What is a HAI infection
a hospital acquired infection
What is a communicable disease?
the diseases is caused by an infectious agent that is capable of being spread from one person to another by direct or indirect mechanisms
What is a contagious disease?
that disease is easily spread from one person to another
What are signs?
Conditions of a disease that are objective and can be directly measured by a doctor
What are symptoms?
conditions of a disease that are subjective and cannot be directly measured by a doctor
What are the 5 stages of illness?
incubation period, prodromal period, period of illness, period of decline and period of convalescence
What is the incubation period?
the period after entry into the host, pathogens start to multiply inside the host, signs and symptoms are not present
What is the prodromal period?
The period where the immune system is activated, the pathogen continues to multiple, signs and symptoms are mild and generalized
What is the period of illness?
The period where symptoms can be recognized, pathogens are multiplying actively and signs and symptoms are most severe
What is the period of decline?
The period were the immune system fights pathogens, pathogen numbers begin to decline, signs and symptoms are less severe
What is the period of convalescence?
The period where the host recovers from the infection, pathogen numbers are very small or zero, signs and symptoms are not present
What are the levels of disease?
Sporadic, endemic, epidemic and pandemic
What is a sporadic disease?
a disease that occurs infrequently or irregularly in a population
What is an endemic?
A constant or baseline presence of a disease in a population within a certain area with low spreading
What is a epidemic?
a sudden increase in the number of cases in a wide area, such as a province or region
What is a pandemic?
an epidemic that has spread over several countries or continents and affects many more people
What is the first line of defense?
Barriers of the body that prevent pathogens from entering the body
What are non-specific barriers?
does not distinguish one pathogen from another
What are physical barriers?
Skin, hair and mucous membranes
What are chemical barriers?
tears, saliva. sweat and gastric juices
What triggers the immune system?
Pathogens that get past the barriers
What is the immune system?
a group of cells, tissues and organs that protect the body from infection
What is the primary immune system organs?
thymus, bone marrow
What are the secondary immune system organs?
tonsils, spleen, liver, appendix, lymph nodes
What are the phagocyte cells?
macrophages and neutrophils
What are the lymphocyte cells?
B-cells and T-cells
What are the 2 types of white blood cells?
phagocytes and lymphocytes
What are phagocytes?
a non-specific response that destroys pathogens by ingesting them through phagocytosis, attracted by chemicals released by cells
What are the 2 types of phagocytes?
Neutrophils and macrophages
What do neutrophils do?
they ingest and destroy pathogens but die in the process
What do macrophages do?
they ingest and destroy pathogens, dead neutrophils and debris
What are lymphocytes?
a specific response that destroys pathogens by producing antibodies that can distinguish between body cells and foreign cells
What are the 2 types of lymphocytes?
B-cells and T-cells
What do T-cells do?
cytotoxic t-cells destroy germs
What do helper t-cells do?
they stimulate b-cells to mature and make antibodies
What do b-cells do?
they create Y-shaped antibodies for specific pathogens to lock on and mark them for destruction
What are the 3 parts of the second line of defense?
WBC’s. inflammatory response and specialized proteins
What can phagocytes do?
they can identify proteins on the surface of pathogens called antigens and determine if they are self or non-self
What does the natural killer (NK) cells do?
they kill body cells that have become infected with a virus or have become cancerous
What do alarm chemicals trigger?
the inflammatory response
What are the 4 features of the inflammatory response?
- Injured cells/ tissues release alarm chemicals (histamines)
- Blood vessels expand to allow greater blood flow to the area
- Blood vessels become porous to let WBC’s pass through easily
- Phagocytes move into the area in large numbers to kill pathogens
What does the inflammatory response localize?
heat, redness, pain and swelling
What do specialized proteins do?
they attack pathogens directly or block their replication
What is the third line of defense?
specific immunity which recognizes and targets particular pathogens (more affective but takes more time)
What are the 2 types of third line responses?
B-cells and T-cells
What do all antibodies have?
antigen binding sites at the tip of each arm that fit a certain antigen molecule
Where can antibodies be found?
on the surface of b-cells or free floating in the blood
What do B-cells carry?
1 type of antibody on their cell membrane to make it a specialist for 1 particular foreign antigen
When do B-cells become activated?
When it finds a matching antigen to its antibody
What do highly-active plasma B-cells do?
fight the pathogen immediately
What do memory B-cells do?
help mount a faster immune response if the antigen were to return later
How do plasma B-cells work?
they travel through the entire body and bind to any matching antigen they encounter and mark it for destruction
What 3 ways do antibodies help kill pathogens?
Neutralization, agglutination and signaling
What does neutralization do?
the antibodies block binding sites on viruses and bacterial toxins to prevent them from attaching and entering body cells and tissues
What does agglutination do?
antibodies cause pathogens to clump together in groups so phagocytes can find and engulf them at once
What does signaling do?
antibodies activate other immune signaling chemicals to the site to engulf the clumped pathogens
What do T-cells target?
body cells that have already been infected by a pathogen or have become cancerous
How do T-cells recognize infected cells?
The same as b-cells
What do cytotoxic t-cells do?
They bind to an infected cells membrane and release specialized enzymes that poke holes in the cell membrane
How do infected cells die by cytotoxic t-cells?
infected cells leak fluid, breaks open and dies
What is apoptosis?
When a cell dies due to being broken open and leaking out
how are helper t-cells activated?
by other cells displaying foreign antigens
What cells do helper t-cells recognize?
macrophages from the 2nd lines inflammatory response
How are t-cells activated?
with processed pieces of the pathogen on the membrane of the macrophages binds to the helper t-cells
what do effector t-cells do?
release chemicals that sound the alarm to activate other b and t cells
how do effector t-cells sound the alarm?
they release molecules called cytokines that activate both plasma b-cells and cytotoxic t-cells
What is immunity?
the ability of the body to resist an attack of a disease-causing pathogen
What are the 2 primary forms of immunity?
Active immunity and passive immunity
What is active immunity?
antibody production by the body itself and transfer to memory cells
What is natural active immunity?
normal infection by an actual pathogen
What is artificial active immunity?
a weak pathogen in an active vaccine
What is passive immunity?
receiving antibodies from an outside source, no memory cells
What is natural passive immunity?
natural antibodies from a mother to her infant
what is artificial passive immunity?
artificial antibodies in a passive vaccine
What do active vaccines contain?
weakened or deactivated pathogens to trigger an immune response
What do antigens from the pathogen stimulate?
antibody production and memory cell formation to fight future infections
What is a autoimmune disease?
A disease the immune system cannot distinguish between self and non-self
When do autoimmune disease occur?
when the immune system mistakenly attacks the body itself
What are the common symptoms of autoimmune diseases?
fatigue, joint pain and swelling, skin problems, digestive problems, swollen glands, recurring fever
What are some common autoimmune diseases?
multiple sclerosis, lupus, Crohn’s, rheumatoid arthritis, vitiligo
What are the 6 links of the chain of infection?
Infectious agent, reservoir, portal of exit, transmission, portal of entry, susceptible host
What is the infectious agent?
the microbe or pathogen itself that can cause an infection
What is the reservoir?
where the infectious agent normally lives, grows and multiplies (living or non-living)
What does an infectious agent depend on for its survival?
the reservoir
What is the portal of exit?
how the pathogen leaves its reservoir
What is the mode of transmission?
how an infectious agent is transmitted to a host
What is direct transmission?
physical contact and airborne droplets
What is indirect transmission?
inanimate objects such as door knobs and vectors such as mosquitoes
What is the portal of entry?
how an infectious agent enters a susceptible host
What are some portal of entry?
broken skin, mucous membranes, blood, respiratory, digestive or reproductive tracts
What is a susceptible host?
A person at risk of infection
How to break the chain of infection?
controlling transmission, protecting portals of entry and increasing host defenses
What is herd immunity?
when enough people are vaccinated or have antibodies from a prior infection to interrupt the chain of infection
What is the herd immunity threshold?
the percent age of the population that must be immune to ensure that a pathogen will not cause a large outbreak
