Y.7 Invading The Body Flashcards
How pathogens Exeter the body?
1) cuts in skin
2) through the digestive system via contaminated food or drinks
3) through the respiratory system or by inhaling
4) through the mucosal surface eg inside the nose , mouth and genitals
How does stomach acid help with barrier
Provide acidic environment and that is unfavourable to many pathogens to survive
*however some may survive and travel to intestine where they infect the gut wall cells and cause disease
How does the gut and skin flora help with barrier
The intestine and skin is covered in harmless microorganisms (flora)
They compete with pathogens for nutrients and Space this limits the number of pathogens living in the gut and on the skin and makes it harder for them to infect
How does the skin prevent infection
Skin acts as a physical barrier
—> if damage pathogens can enter to the bloodstream
The blood clots the Area of damage to prevent pathogens from entering but may get in before the clot
How does lysozyme help with
Musocsal surfaces (eyes,mouth and nose) produce secretion (tears, saliva and mucus) these secretion all contain enzyme called lysozyme . Lysozyme kill bacteria by damaging their cell wall makes the bacteria burst open (lyse)
How does vector works
Living organism carry the pathogens and transmit them between hosts
—> insects such as flies and mosquitoes are common vector for disease
How does inhalation work in invading the body
Droplets from respiratory tract will suspended in the air when an infected person coughs, sneezes or talks
These droplets contain pathogens that can be inhaled by healthy people
The airway provide an entry point into the respiratory system of a new host and another infection occurs
How does ingestion invade the body
Pathogen can enter through the digestive system when we ingest contaminated food or drink
If food is undercooked as heat destroyed most of the pathogens
These pathogens can make their way through the lining of the gut and cause disease
How does indirect contact can invade the body
Inanimate objects can contain large number of pathogens that may be transferred between host
An infect individual may touch or cough on an object which is later touched by a healthy individual who transfer the pathogens to their mouth or node by touching their face
How does inoculation invade the body
Pathogens enter through broken skin providing it with a direct route into the blood stream
Transmission could be through sexual contact sharing a needle during drug use or bites or scratches from infected animal
How does direct contact invade the body
Pathogens that spread this way will require some part of the host to come into direct contact with a healthy individual
Pathogen that spread by this route can then pass through the mucous membrane and enter the blood stream
How does sebum help
Oily substance which contain chemical substance that inhibit growth of infectious microorganisms
What are endotoxins
Lipopolysaccharides that are integral part of the outer layer of the cell wall of the gram negative bacteria
Act as a toxin to other cells
How to endotoxins work
The lipopolysaccharides that are an integral part of the outer cell wall of the gram negative bacteria
The polysaccharide stimulate the immune response. The effects happens mainly around the bacteria itself and not directly fatal
What are exotoxins
Soluble proteins produced and released into the body by the bacteria as they metabolise and reproduce in then cells of their host : these proteins act as toxins in different ways
Directly fatal
What are host tissue invasion
The bacteria directly attacks the tissue and cells of the host and is linked to the production of endotoxins and exotoxins
What is tuberculosis
Communicable disease
Affects and destroy the lungs and it’s tissue and supremes the immune system making it less able to fight against the disease
Spread in form of droplets
Primary infection
Bacteria is inhaled into the lungs and slowly multiply causing no symptoms
If the immune system is fully active it will cause the localised inflammatory response engulfing the bacteria and farming a mass of tissue called TUBERCULE
After a while the inflammation would fully disappear and lungs heal
Active stage
Some bacteria are able to survive past the primary infection stage as they have adapt which allows them to do so
Allowing them to remain dormant and reproduce until the immune system weakens
They will then cause active tuberculosis
The most effective bacteria are selected to pass their DNA reproducing very quickly
Causing serious damage
Continued active stage
Active TB is usually the result of the deactivation of old or controlled infectious rather than the new one
Bacteria reproduce rapidly causing rather noticeable symptoms such as
Night sweat
Loss of appetite
Weight loss
The patient will start coughing out liquid produced in the lungs called septum
If the infectious become serious the lungs is heavily damaged the patient will start coughing blood.
Alveoli start to breakdown and produce large inefficient air sacs
—> bacteria also attacks T cells to stop production of antibodies and although the body raise its temperature to kill the bacteria the bacteria can survive up until 42c
Metabolic enzyme start to denature at 40c eventually the patient dies due to organ failure no respiration or due to invasion by opportunistic disease
Treatment and control of antibiotics
These antibiotics kill rapidly reproducing bacteria as well as hidden bacteria in the tissue
Improving living standards
People living in crowded areas as well as malnourished or unhealthy immune system are most vulnerable to TB preventing these conditions can prevent disease
Immunisation
How does deterioration social condition increase TB
Increasing migration of refugees and foreign travel as well as increasing drug use is all increasing the cases of TB
How is HIV transmission
1) exchange of fluids
2) inoculation through blood
3: mother to fetus
HIV life cycle step 1 BINDING
On the surface of a T cell HIV binds to a CD4 receptor
HIV life cycle step 2 FUSION
The virus fuse with the host cell membrane and release genetic material (RNA) into the cell
HIV life cycle step 3 REVERSE TRANSCRIPTION
The single stranded HIV RNA is converted into double stranded HIV DNA by reverse transcriptase enzyme
HIV life cycle step 4 intergation
After the HIV DNA enter the cells nucleus, the enzyme integrase cuts the cell DNA and insert cells DNA into it
HIV life cycle step 5 TRANSCRIPTION AND TRANSLATION
The enzyme RNA polymerase makes RNA copies of DNA. HIV RNA is either inserted into new virus particles or processed and translated into HIV protein
HIV life cycle step 6 ASSEMBLY
The long protein chain cuts into the individual protein by the enzyme HIV protease a new virus is assembled with these protein and HIV RNA
HIV life cycle step 7 RELEASE
The new virus particles is released from the host cell, taking with it part of the cell membrane and capable of infecting other cell
STAGE 1 ACUTE HIV syndrome
May not experience any symptoms at first.
Afterwards May feel unwell
- fever
-tiredness
-swollen glands
Stage 2 CHRONIC STAGE
after infection symptoms may disappear
Often this period the person may not show symptoms for years due to
- well-nourished
- anti- retrovirus drug
Stage 3 SYMPTAMATIC DISEASE
Gradually the virus reduces the number of helper T cells
-B cells no longer activated
-no antibodies are produced
Patient suffers
-weight loss
Fatigue
Diarrhea
Night sweat
Stage 4 advanced AIDS
Lack of T helper cells decreases the body ability to fight off infection
Leading to AIDS
Symptoms
-dementia
Factor affecting how quickly HIV progress to AIDS
The number of existing infection
The strain of HIV the person is infected with
Their age
Access to healthcare
Ways to prevent HIV
1) celibacy and having one sexual partner
2) using condoms during sexual activity to prevent virus transfer
3)using clean needles if injecting drugs
Vaccines preventing HIV
HIV is able to mutate quickly so by the time the vaccine goes through the virus would’ve adapted against
Natural selection favours mutated viruses
Drug therapy HIV
Helped pro long life expectancy as they are anti-retrovirus will help keep the immune system strong to fight off the AIDS
