• What is a pathogen?
• What is a virus?
• What are some ways diseases can be spread?
• What is happening in the body when an infection is present in a living organism?
• What is a vaccines• How do they work?
Any disease that is caused by an agent that has invaded the body
Can be passed from one person to another person, from food or water, from animals, or from something in the environment
Examples:Colds, flu, tuberculosis, MRSA, Ebola
Infectious (Communicable) Diseases
PATHOGENSAny agent that causes disease
Bacteria, viruses, fungi, protists, parasites
All infectious diseases are caused by:
Bacteria: Tiny, single-celled organisms that live almost everywhere
on Earth Most bacteria are harmless and help with bodily functions Bacteria in mouth, intestines
Harmful bacteria make you sick when they grow on or in your body
Example: Some give off poisons (tetanus/toxins) that damage cells Sinus infections
Most harmful bacteria are killed by our immune system, others need antibiotics to treat and cure infections
Pathogens
Viruses:Smaller than bacteriaDisease-causing particles made up of
genetic material surrounded by a coat of protein
the virus finds a living “host cell” and forces it to reproduce and “attack” more cellsColds, flu, measles, AIDS
Pathogens
Fungi (fungus) Organisms that absorb and use nutrients from other living or dead
organisms Mushrooms Athlete’s foot, ringworm
Protists Larger and more complex than bacteria
Malaria
Parasites Animals—get their energy and nutrients by feeding on other living
organisms Lice, tape worms, etc.
Rickettsia Pathogens that resemble bacteria
Invade cells of other organisms Enter humans through bites from fleas, ticks, or lice
typhus
Pathogens
Person to person Airborne (sneezing, coughing, touching anything drops landed on)
kissing, drinking from same glass, direct contact (tetanus)
Dirty Hands Suck
Food and water Contaminated food (from humans, from infected animal)
Examples? Water from streams or lakes, sewage,
Typhoid, cholera, dysentery
Environment Pathogens are all around you—few can cause disease
Tetanus present in soil
Animals Pathogens live on/in animals Ringworm from pets, mosquitos carry malaria, yellow fever,
encephalitis, ticks carry Lyme disease
How are they transmitted (spread)?
Bacterial diseases Antibiotics-medicines used to kill or slow the growth of bacteria
Penicillin CANNOT be used to treat colds or viral diseases
Antibiotic resistance: bacteria are no longer killed by a particular antibiotic
Improper use=build up of antibiotic resistant bacteria
Viral Diseases Not much is known, so most concentrate on relieving symptoms and
stopping production of viruses inside cells
Fungal Infections Over-the-counter or prescription medicine
Protistan, parasitic Infections Prevention—good hygiene, sanitation
How to treat…
Immune System- general and specific
Network of cells, tissues, organs, and chemicals that fight off pathogens
Physical and Chemical BarriersFirst line of defensePhysical—skin (sweat and oil) and mucous
membranes (mucus and cilia)block pathogens from entering the body
Chemical—enzymes (stomach acid, tears)
Protection Against Diseasesread pgs. 638-644
Inflammatory Response-2nd line of defense A reaction to tissue damage caused by injury or
infections Prevents further tissue injury and stops invading
pathogens
Immune System- general
Made up of different types of blood cells and proteins called antibodies-(act against a specific pathogen)
Cells move through bloodstream and lymphatic system
A network of vessels that carry a clear fluid called lymph throughout the body—pick up bacteria and viruses and delivers them to the lymph nodes
Collection of WBCs in lymph nodes while fighting infection
Protection
Antigen-a substance capable of triggering an immune response Found on the surface of pathogens and in toxins
Immune System White Blood Cells
Primary job=defend against disease
Phagocytes (to eat) A specific white blood cell that attacks invading pathogens Engulfs pathogens and then destroys them with chemicals (enzymes) Creates pus
A collection of dead white blood cells and damaged tissue—may collect at the site of inflammation as a response to harmful bacteria
Macrophages-a type of phagocyte that destroys pathogens by making antigens (recognized my WBCs) to trigger an immune response
Result=IMMUNITY The stat of being protected against a particular disease
Protection- specific
LymphocyteA specialized white blood cell that coordinates and performs
many of the functions of specific immunity
T cells, B cells, NK cellsRecognize antigens not made by the body (non-self)
B cells- produce antibodies to neutralize the pathogen
T cells- produce powerful enzymes to kill the infecting pathogenHelper T cells trigger production of B cells and NK cellsNK Cells- attack and destroy infected cells
**attack only infected cell—NOT pathogen
Protection- specific
VaccinesSubstances made of killed or weakened
pathogens or from genetic material introduced into the body to create immunity
The body begins to make WBCs called memory cells
If the specific pathogen enters the body , the memory cells and their antibodies fight the pathogen before it can cause disease
May need boosters for vaccinesFlu?
Protection
With a partner, answer questions #1 and #3 on page 644
Then, write a story with a phagocyte as the main character.
This story should be an imaginative description of a phagocyte joining the inflammatory response to stop invading pathogens after some kind of injury to the body. Your stories can be funny or sad, but all should accurately describe the strategy against disease.
Questions
Tetanus Symptoms- Severe muscle spasms
Transmission- Tetanus causing bacteria found in soil Prevention- vaccine and boosters
Treatment- antibiotics
Strep Throat Symptoms- sore throat, fever, yellow or white specks on tonsils
Transmission- contact with mucus from infected person Prevention- avoid contact
Treatment- antibiotics
Meningitis-inflammation of membranes covering brain and spinal chord
Symptoms- severe headache, fever, stiff neck, sensitivity to light, nausea Transmission- contact with saliva or mucus from infected person
Prevention- vaccine, avoid contact Treatment- antibiotics—if caught early enough
Common Infectious DiseasesBacterial
Sinus Infection Symptoms- headache, tenderness of sinuses, thick
greenish mucus, pressure in head Transmission- contact with mucus Prevention- avoid contact and allergens Treatment- ??
Salmonellosis- an infection of the digestive system Symptoms- headache, cramps, diarrhea, nausea, vomiting Transmission- eating contaminated food Prevention- thorough cooking, hand washing,
refrigeration Treatment- OTC meds for symptoms, sometimes
antibiotics
Bacterial cont.
Flu Symptoms- headache, sore muscles and throat, fever, vomiting, ect.
Transmission- contact with saliva or mucus Prevention- vaccine and avoid contact
Treatment- rest, fluids
Cold Symptoms- sore throat, sneezing, runny nose, mild cough
Transmission- contact with saliva or mucus Prevention- wash hands, avoid contact
Treatment- rest, fluids
Mumps Symptoms- pain and swelling of glands in throat, fever, headache
Transmission- contact with infected airborne droplets and infected person
Prevention- vaccine Treatment- see doc. Rest, fluids
Common Infectious DiseasesViral
Measles Symptoms- fatigue, runny nose, cough, fever, small white dots in
mouth, rash on body Transmission- contact with saliva or mucus
Prevention- vaccine Treatment- see doc. Rest, fluids
Mononucleosis Symptoms- fever, swollen lymph nodes, sore throat, weakness
Transmission- contact with saliva or mucus Prevention- avoid eating/drinking after infected person
Treatment- see doc. Rest, fluids
Hepatitis Symptoms- inflammation of liver, jaundice, fever, darkening of urine
Transmission- contact with bodily fluids, contaminated food or water Prevention- vaccine for A and B, wash hands, avoid contact
Treatment- see doc. Rest, meds, no cure for Hep. B and C
Viral cont.
You are a scientist for the CDC and have just discovered a recent outbreak of a new disease. As the head scientist, it is now you responsibility to describe this disease, how it is spread, and how to prevent it.
The following must be provided in your document:
• Name of disease
• Cause of disease
• Symptoms of disease
• Transmission of disease
• Prevention methods
• Treatment
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