chapter 7 defense Flashcards
pathogen
disease causing organism.
Infectious disease
transmissible disease, spread from one person to another.
What are the most common pathogens?
bacteria and viruses
Other than bacteria and viruses, what other types of pathogens are there?
fungi and animal parasites
Prokaryote
Unicellular organism with simple internal structure i.e. no nucleus.
Where is DNA found in prokaryotes?
free in the cytoplasm or in PLASMIDS.
Do bacteria have a cell wall?
Do bacteria have a cell membrane?
Yes
Yes.
Flagella
thin, whip-like structure to help the cell move.
Why does the cytoplasm of a bacteria look granular?
Due to ribosomes.
Do bacteria have membranes around organelles like mitochondria or golgi apparatus?
no. They are prokaryotes.
Give two uses for bacteria
cheese making, yoghurt and sauerkraut.
Where are bacteria found on an average human body?
skin, alimentary canal, armpit,
Are all bacteria harmful?
No, many are useful i.e. aid digestion.
How are pathogens transmitted? (3)
- direct and indirect contact
- disease specific vectors
- contaminated food and water.
The body’s external defence mechanisms against pathogens include features of: (6)
- skin
- digestive tract
- urogenital tract
- respiratory system
- the ear
- the eye.
When pathogens enter the body, the non-specific immune responses are:
inflammation and fever.
What scale is used to measure the size of a bacteria?
microns, micrometres.
Ave diameter is 0.5 to 2 microns.
How can bacteria be studied?
on an agar plate.
Virus
An infectious agent (very small - nanometers) consisting of a protein sheath surrounding a core of nucleic acid.
They rely on living things for reproduction.
Name two scientists that discovered viruses.
Koch Pasteur
Can viruses be seen with a light microscope?
No - they are only measured in nanometres.
How are viruses studied?
With an electron microscope.
Name the two types of nucleic acids that a virus may contain.
Can they contain both?
DNA or RNA
NO.
DNA
deoxyribonucleic acid
RNA
ribonucleic acid
What chemical surrounds the nucleic acid in a virus?
A protein.
(some have a lipid /fat sheath.
Why are viruses not considered living things?
They cannot reproduce.
What happens when the newly made viruses leave the cell?
The host cell becomes damaged, changed or die.
Bacteriophages
Viruses that infect bacteria and kill them
Vector
intermediate hosts
e.g. flies or mosquitoes.
What vector was used in the bubonic plague?
fleas, rats.
What are the two types of transmission of contact?
direct - touch infected person
indirect- touch object previously touched by infected person
Give an example of an infection that is caused by ingestion of food/water.
dysentry
typhoid fever
salmonella
List some body fluids that may cause infection if exchanged
blood, saliva, semen, vaginal secretions
HIV
human immunodeficiency virus
List 3 diseases that are spread by bodily fluids
HIV Hepatitis B and C.
How are droplets spread? (4)
coughing, sneezing, talking, breathing
List 4 diseases that are spread by droplets
Ebola, mumps, covid, colds and influenza.
If a droplet dries out, are the viruses/bacteria killed?
Not always - many can stay VIABLE for a long time.
Chicken pox and measles are spread this way
Vectors (animals) can host a pathogen. Give an example of this.
mosquito - malaria, dengue fever
flies , ticks, mites.
rabies - bats, dogs
African sleeping sickness - tsetse fly.
Non specific defences
acts against all pathogens
specific defences
acts against a particular pathogen
List 7 external defences
skin mucous membranes hairs, cilia acid cerumen
What stops the skin from being a good barrier?
cuts and wounds
What openings need special/alternative methods of protection in the skin?
mouth, eyes, vagina, anus.
Why does the skin have its own bacteria?
Prevents pathogens from finding space to grow.
How does sebum help control pathogens?
It contains oils and fatty acids that kill pathogenic bacteria?
How does sweat help control pathogens?
It contains salts and fatty acids that prevent the growth of pathogens
Where do you find mucous membranes?
They line the body cavities that open to the exterior.
Mucous
A sticky fluid that traps pathogens and help stop them from entering the organism.
Where are mucous membranes found?
nasal cavities, digestive, urinary tract, reproductive system.
Where are hairs found that help tract pathogens
ears, nasal passages.
What percentage of pathogens are trapped by hair and mucous in the nose?
90%
Cilia
tiny, hair-like projections found on cells.
Found in nose and trachea.
May be coughed up.
Where are acids used for protection in the body?
stomach, vagina, urine, sweat.
