Download Brett Dougherty and Jan Carlos Camacho

Immune System Notes
1. What Causes Infectious Diseases?
A. Causes of infectious diseases
1) Pathogens
a. Small microscopic organisms
b. Most pathogens are parasites
1} Parasites- organisms that live in or on another organism, and derive
nourishment from it.
a) Bacteria
1/ A bacteria is a single-celled organism
2/ They can live almost anywhere, including air, soil and water
3/ Some bacteria are harmful to human cells and if enough
bacteria grow, a disease can result
4/ Bacteria enter the body and grows at a rapid rate because of
cell division
5/ After just 15 1/2 hours one bacterium can multiply into more
then 4 billion bacteria, but it needs perfect conditions.
6/ In a healthy individual, the body’s immune system destroys the
bacteria
b) Viruses
1/ the smallest known type of infectious agent
2/ HIV-Deadliest virus known that causes AIDS
3/ Host- when a virus enters the body it attaches itself to a cell
and injects its genetic material into the cell
4/ viruses aren’t living cells
a/ entirely depend on living cells for survival and
reproduction
5/ invades forms of life such as mammals, birds, reptiles, insects,
plants and even bacteria
6/ viruses can make copies of itself by using materials in the host
cell
7/ after they run their course they are killed by the immune
system
c) Rickettsias
1/ Rickettsias= an organism that resembles small bacteria, but like
viruses, are able to multiply only by invading the cells of
another life form.
2/ Most are found in the intestinal tracts of insects and animals,
such as:
a/ Fleas
b/ Mice
c/ Ticks
d/ Mites
3/ Transmitted through bites and feces deposited on the skin
4/ Rickettsias cause diseases such as:
a/ Typhus
b/ Rocky Mountain spotted fever
d) Protozoans
1/ Protozoans= single celled organisms that are larger than
bacteria and have a more complex cell structure.
2/ Most are harmless.
3/ About 30 different types cause diseases in humans
4/ Disease producing protozoans are most common in tropical
areas with poor sanitation.
e) Fungi
1/ Fungi = simple organisms that cannot make their own food.
2/ Many are saphrophytes, which are organisms that feed off of
dead animals, insects, and leaves
3/ They prefer a dark, damp environment.
4/ Most disease causing fungi invade deep tissues of hair, nails,
and the skin.
5/ Causing things such as ringworm, and athletes foot.
2. How Infectious Diseases are Spread
A. Several Well defined means of transmission or spread of infectious pathogens
1) Direct contact with an infected person, animal, or object.
2) Some are free in the environment.
a. People
1} Many infectious diseases are spread as a result of direct or indirect
contact with infected persons
a) Direct Contact
1/ When an uninfected person comes into physical contact with
infected person.
a/ STD’s are spread this way.
2/ The human bite is another, and especially dangerous, made of
transmission.
3/ A pregnant woman may also transmit an infection to her
unborn child.
b) Indirect Contact
1/ Bacteria and Viruses can enter the body through the lungs. If
droplets- exhaled, coughed, or sneezed out by an infected
person-are inhaled.
a/ The common cold, influenza, and tuberculosis are spread
this way.
b. Animals
1} Animals, including insects may spread infectious diseases.
a) The bite of an infected dog or other animal can spread rabies, a
disease that can be fatal.
b) Blood sucking insects, such as a mosquito ingests blood from an
infected person or animal.
1/ The insect may take pathogens into it’s own body.
2/ The insect later takes blood from an uninfected person, injects
the pathogens into its body- thus spreading the disease.
3/ Malaria : A dengue fever, infectious disease common to
tropical regions are spread.
c. Contaminated Objects
1} Pathogens are spread when an uninfected person touches objects that
an infected one touched.
2} Forks and Knives
3} Glasses
4} Toothbrushes
5} Pens and Pencils
d. Environment
1} They also are spread through food, water, soil, and the air we breathe.
2} Some infectious diseases are results of human errors.
a) Throwing away hospital waste
b) Toxic dumping
3} Poor handling of food
a) When food is handled wrong this results into food poisoning.
3. Immune Response
A. Pathogens
1) in the air you breathe
2) clings to the surfaces you touch
3) multiply
4) the body constantly fights them
5) Innate Immune system
a. nonspecific resistance
6) Adaptive Immune system
a. specific adaptive
7) Nonspecific Resistance
a. nonspecific/“general” defenses
b. Physical Barriers
1} first line defense in skin
2} Mucous Membrane
a) Soft, skin like lining in mouth, nose, and bronchial tubes
b) Cilia: tiny hairs that trap pathogens
c. Chemical Barriers
1} Enzymes that are found in tears and saliva
2} Can destroy bacteria
3} Acidic digestive juices in stomach are also chemical barriers
d. Body cells
1} Phagocytes – destroy pathogens
2} phagocytosis-the process by which phagocytes engulf & destroy
pathogens
3} neutrophils – the chief phagocyte involved in the process of
phagocytosis
e. Inflammatory response
1} Inflammatory response – “red alert” pathogens break outermost barrier
body goes into this stage.
2} inflammation – heat, redness, swelling
8) Specific Resistance
a. lymphocytes – white blood cells that protect the body against pathogens
b. Lymphocytes
1} Type of white blood cell that fights pathogens.
2} Travels through blood & lymph vessels, which are a part of your
lymphatic system.
3} Types:
a) B cells
1/ When B cells encounter pathogens they are stimulated to
enlarge and multiply.
2/ Turns into plasma cells which produce antibodies (proteins that
destroy or neutralize invading pathogens)
3/ These antibodies for a particular pathogen remain in your
blood to become active if you encounter the pathogen again.
b) T cells
1/ Killer T cells are stimulated to multiply by the presence of
body cells. They attach to these cells and release toxin that help
destroy them.
2/ Helper T cells helps B & killer T cells. and control other
aspects of the bodies immune system.
4. Respiratory Infections
A. Common cold
a. A viral infection, inflammation of the mucous membrane, lining nose &
throat.
b. Symptoms; runny nose, sneezing, headache, sore throat.
c. Diagnosed by hand to hand contact, or by a person who has a cold
d. Clear up within a week, there is no cure; the best cure would just be rest.
B. Influenza
a. Viral infection of respiratory tract
b. Symptoms are chills, fever, headache, muscle aches, and weakness.
c. Outbreaks usually occur during the winter
d. Best cure would be rest, proper nutrition, and drinking plenty of fluids.
e. Can develop into pneumonia which is a serious inflammation if the lungs.
C. Tuberculosis
a. Highly contagious, bacterial infection that most likely is found in lungs.
b. Caused by airborne droplets
c. Your body can stop the process, but if spread it can go to your
bloodstream.
d. Symptoms, coughing, chest pains, shortness of breath, fever, sweating,
poor appetite & weight loss.
e. Usually major cause of death
D. Strep Throat
a. Bacterial infection of throat
b. Symptoms, sore throat, fever, general feeling of sickness & enlarged
lymph nodes in the neck.
c. Can be cured by antibiotics
5. Inf Disease of Nervous system
A. Encephalitis
1) Inflammation of the brain
2) Caused by virus transmitted by Mosquitoes
a. Starts as headache and fever
b. Progresses to
1} Hallucinations
2} Confusion
3} Paralysis
c. Gradual loss of consciousness progressing to possible coma
d. When caused by most viruses no treatment
B. Meningitis
1) Inflammation of the meninges
a. Membranes that cover CNS
b. Viral
1} Relatively mild
2} Symptoms - resemble flu
c. Bacterial
1} Life threatening
2} Symptoms
a) Headache
b) Fever
c) Stiff neck
d) Sensitivity to light
3} Treated with antibiotics
C. Poliomyelitis (Polio)
1) infectious disease of central nervous system caused by virus
2) may lead to extensive paralysis
a. paralysis of muscles used in breathing
b. death
3) mid- 1950’s researchers Jonas Salk and Albert Sabin developed a polio
vaccine
6. Measles
A. highly contagious viral disease
B. affects children but can occur at any age
C. symptoms
1) fever, runny nose, sore eyes, and cough
2) 3-4 days red rash that covers entire body
3) ear and chest infections
7. Mononucleosis / Mono - “kissing disease”
A. viral infection, common among young teens
B. symptoms
1) chills, fever, sore throat, fatigue, and swollen lymph nodes
C. treatment
1) bed rest
2) can take up to 3-6 weeks
8. Hepatitis
A. inflammation of the liver
B. toxic hepatitis
1) caused by certain drugs , chemical , or poisons
C. most frequent: caused by viral infection
D. symptoms
1) juandice - yellowing of skin and whites of eyes
2) fever , nausea , loss of appetite , pain in abdomen , aching muscles , joint pain
3) if serious , liver damage
4) appears 4 weeks after exposure and last 2-6 weeks
E. 3 main types of viral hepatitis
1) Hepatitis A
a. results from eating food or drinking water that has been contaminated with
the virus from an infected person’s feces
b. many cases occur among people who traveled to areas where standards of
hygiene are low
2) Hepatitis B
a. found in all body fluids of an infected person , especially blood
b. used to be spread mainly by contaminated blood transfusions and blood
products
1} main ways Hepatitis B is spread :
a) contaminated medical instruments
b) hypodermic needles shared by infected needles shared by drug
users
c) sexual contact with an infected person
c. more serious than Hepatitis A
d. may lead to chronic infection and eventually to liver damage
3) Hepatitis C
a. spread through infected blood
b. discovered in 1989 , hepatitis C can cause liver cancer
c. can be detected in the blood
1} blood is now screened before transfusion
4) there is no cure for hepatitis although there is a vaccine for hepatitis B
5) treatment for hepatitis is rest, proper nutrition and ingesting plenty of fluids
9. Immunity
A. Immunity is the body’s natural resistant to many pathogens
1) Active Immunity
a. the immune system gives the body long-term protection immunity against
many infectious diseases
b. active immunity is the immunity your body develops to protect you from
diseases
2) Passive Immunity
a. passive immunity is a temporary immunity that an infant acquires from its
mother
b. lasts for a few months until the baby can produce antibodies of its own
B. Active Immunization
1) Commonly called vaccinations and vaccines are strong enough to force the
body to make antibodies but not strong enough to cause the disease to die.
2) There are 3 major types of vaccines
a. Live virus vaccines:
1} These are weakened viruses designed by scientists to allow the body to
create anti bodies and won’t cause diseases.
b. Killed virus vaccines
1} Contains viruses that have been killed then put into the body to create
antibodies to kill disease. It is not as powerful as a live virus vaccine.
It is needed to be followed up with booster shots
c. Toxoids
1} They are chemically treated bacteria that causes production of
antibodies and established active immunity
10. Preventing Infectious Diseases
A. Immunization for All
1) In most states, students cannot enter kindergarten without up-to-date
immunizations
2) In most states teenagers are prevented from attending school without complete
immunization
3) Immunization gives control over or can even eradicate certain diseases
4) Immunization is essential to prevent plagues and pestilences from wiping out
populations
B. Common Sense Measures
1) Guidelines
a. Keep your body healthy
1} Good Nutrition
2} Regular Exercise
3} Adequate Sleep
4} Health Care
b. Bathe or shower everyday
c. Avoid sharing eating/drinking utensils
d. Store and prepare food safely
e. Wash hands after contamination
f. When sick avoid others
g. Avoid people who are sick