Human Infection and Response Year 9 Flashcards
What is a pathogen
Microorganism that causes disease
What is a microorganism?
Organisms that can only be seen by a microscope?
Name four types of pathogens
Bacteria, virus, protist, fungi
What is bacteria?
A single-celled microorganism
What is a virus?
Non-cellular organism that replicates in cell of living host
What is a protist?
Eukaryotic single-celled organism
What is fungi?
Large group of microorganisms with single-celled yeasts, mould and mushrooms
Name types of transmission that pathogens spread in
Infected water, contaminated food, air droplets, direct contact, body fluids, animal vectors
How does bacteria reproduce?
Binary fission, every 20 minutes
How does a virus infect a human?
Attaches to cell, injects DNA into cell, DNA takes over cell and starts replicating, viruses begin to infect new cell
What is a toxin?
Poison released by bacteria when it enters the cell, making victim feel ill
What are measles?
Very infectious viral disease that shows skin rash and fever as symptoms?
How does measles spread?
Air droplets from sneezes, coughs or breathing
What is HIV(Human Immunodeficiency Virus)?
Virus that attacks immunity system
When do symptoms of HIV start to surface?
2-4 weeks after exposure
What are antiretrovial drugs?
Drugs used to stop virus replicating in body
How is HIV transmitted?
Sexual contact or bodily fluids
Life cycle of HIV
Unless successfully controlled by drugs, virus enters lymph nodes and attacks immune system. Months/years later, untreated HIV becomes AIDS and body can’t defend itself against other diseases.
What is salmonella?
A bacteria that spreads food poisoning
What are the symptoms of salmonella?
Fever, abdominal cramps, vomiting, diarrhoea
How is salmonella transmitted?
Ingestion of contaminated food
What is gonorrhoea?
Sexually transmitted disease caused by bacteria
What are the symptoms of gonorrhoea?
Thick yellow/green discharge from penis or vagina and pain while urinating
What is penicillin?
Antibiotic that treats gonorrhoea
How is gonorrhoea spread?
Sexual conduct
How is gonorrhoea prevented?
Using a condom during sex
What is an antibiotic?
A medicine used to cure bacterial disease by killing infective bacteria
What is malaria?
A disease caused by protist pathogens
Life cycle of malaria
Mosquitos carrying Plasmodium protist infect people by biting them. The saliva of mosquito passes through victim’s skin and into their bloodstream. Saliva carries a parasite that circulates in blood, then settles in liver where it multiplies. Days later, the liver cells, now containing thousands of parasites, ruptures and parasites move to red blood cells, where they then release toxins.
What are symptoms of malaria?
Recurrent episodes of fever
Name defence systems of body against pathogens
Skin, nose, trachea and bronchi, stomach
How does skin defend body?
Produces antimicrobial secretions that help prevent pathogen’s growth
How does nose defend body?
Traps particles that may contain pathogens
How does trachea and bronchi defend body?
It secretes mucus that traps pathogens, and cilia wafts mucus to back of the throat, where it is swallowed
How does stomach defend body?
It produces hydrochloric acid that kills majority of pathogens that enter via the mouth
What is phagocytosis?
Process that engulfs and destroys pathogens
What are phagocytes?
White blood cells that engulf and absorb wasteful or harmful material?
How do phagocytes function?
They use their large-lobed nucleus to stretch around bacteria, engulf it and digest it using enzymes
What is an antibody?
Protein produced by immune system that attacks antigens
What is an antigen?
Protein on pathogen’s surface that triggers an immune response
What are lymphocytes?
White blood cells that produce antibodies
How to antibodies help destroy pathogen?
By binding/attaching to pathogen
What do some lymphocytes become?
Memory cells, that produce antibodies again quickly if same pathogen enters body again
What is an antitoxin?
Substance produced by white blood cells that can neutralise toxins?
How to antitoxins neutralise toxins?
Binding to toxins
What is vaccination?
Process of injecting small quantities of dead or inactive pathogens to stimulate white blood cells to produce antibodies
What does vaccinating a large part of the population do?
Reduce spread of pathogen
What should specific bacteria be treated with?
Specific antibiotics
Can antibiotics kill viral pathogens?
No
What is a painkiller?
Medicine that treats disease’s symptoms but doesn’t kill the pathogen
Why is it difficult to develop virus-killing drugs?
Because it difficult to do this without damaging body’s tissues
