SB5: Health, Disease And The Development Of Medicines Flashcards
Define health
Health is the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity
What is a disease?
A condition where part of an organism doesn’t work properly
What are communicable diseases usually caused by?
Bacteria, viruses, fungi and parasites
What are two types of causes of non-communicable diseases?
Genetics and lifestyle factors
If a person has AIDS, why do they have an increased chance of suffering from diseases like flu?
A person with AIDS is less able to fight off the pathogen that causes flu because their immune system is weakened by the HIV virus
Explain why bacteria such as Salmonella make you feel ill
They produce toxins (poisons) inside the body that damage cells and tissues
What communicable disease is caused by Helicobacter pylori bacteria?
Stomach ulcers
How do viruses replicate?
They live inside body cells and replicate using the cell’s machinery to produce many copies of themselves
How do viruses spread within the body?
Infected cells eventually burst and release the new viruses into the tissue and/or blood
What makes you feel ill when you have a viral infection?
The cell damage caused by infected cells bursting
What are protists?
Eukaryotic organisms that are usually unicellular
What are parasites?
Organisms that live on or inside other organisms and can cause them damage
How do fungi, made up of hyphae (thread-like structures), cause disease in animals and plants?
The hyphae grow and penetrate the skin or surface of plants causing disease. The hyphae can produce spores which can be transferred to other plants and animals
Give an example of a plant disease caused by fungi
Chalara Ash die-back disease
Give examples of human diseases caused by fungi
- Athlete’s foot
- thrush
- ringworm
State five methods that pathogens are spread
- Drinking or bathing in dirty water
- Airborne (carried in air)
- Swallowing contaminated water or food
- Bodily fluids e.g blood, vomit, saliva
- Animal vectors transmit pathogens
What could infected individuals do to reduce the spread of a pathogenic bacteria?
- Isolate themselves
- Avoid crowded public spaces
- Sleep alone
- Practise good hygiene - cover mouth and nose with tissue when coughing and sneezing, disposing of tissues in a bin
- Good ventilation can reduce likelihood of transmission
What are the main symptoms of an infection caused by Vibrio cholerae?
Diarrhoea that lasts for a few days leading to severe dehydration and ultimately, if untreated, death
How is the pathogen Vibrio cholerae spread?
Through contaminated water sources
Explain why most cases of cholera occur in developing countries
Clean water is not widely available
How can the spread of cholera be reduced?
By making sure that everyone has access to clean water supplies
How does the Heliobacter pylori bacteria cause stomach ulcers?
It inflames the stomach lining which can lead to the lining becoming damaged. The damage allows stomach acid to penetrate the stomach lining, creating a hole (the ulcer) that exposes the tissue underneath
What are the symptoms of stomach ulcers?
Stomach pains, nausea and vomiting
How can the transmission of Helicobacter pylori be reduced?
- clean water supplies
- hygienic living conditions: disinfecting food preparation areas, washing hands before eating or handling food, keep toothbrushes separately
- infected people should not prepare or serve food
- thorough cleaning of utensils
What is Ebola and what does it cause?
A virus that causes haemorrhagic fever
Describe the symptoms caused by Ebola
Fever that causes internal bleeding and bleeding from eyes, nose or mouth, often leading to death
How is Ebola spread?
Through contact with bodily fluids of an infected individual
How was the spread of West African Ebola reduced during the 2013-2016 epidemic? (6 marks)
- infected individuals were isolated from others
- bodies were left untouched until they could be collected by officials wearing protective clothing covering the whole body
- medical staff wore protective clothing coving the whole body
- sterilising areas where the virus may be present
- treatment centres were set up where infected individuals were isolated
- bodies buried in mass graves by people wearing full body protective clothing
- community awareness campaigns about the protective factors individuals could take, eg avoiding contact with infected people and hand washing using soap and water
Describe the symptoms of Chalara ash dieback
Loss of leaves and bark lesions (wounds) leading ultimately to death of tree - directly or because the tree is weakened so much that it cannot defend itself from other pathogens
How is the fungus that causes Chalara ash dieback transmitted?
- through the air by wind - spores
- by the movement of infected ash trees from one area to another
How can the spread of Chalara ash dieback be slowed down?
- removing young infected ash trees and replanting with another species of tree
- putting restrictions on the import and movement of ash trees
How do the vectors become infected?
The mosquitos suck up the malarial protists when they feed on infected animals
How do the vectors infect other animals?
The malarial protist does not affect mosquitos. When mosquitos feed on an animal they introduce the protist into the animals blood stream
What are the symptoms of malaria?
- repeated episodes of fever
- hot and shivery
- lethargy
- sweating
- headaches
- vomiting
- diarrhoea
- muscle pains
- ultimately it can lead to death
What damage can the malaria protist do to the body?
- damage red blood cells
- damage to the liver
What preventative measures can be taken to protect people from mosquitos?
- removing sources of standing water where mosquitoes breed
- upturning containers that are used to collect rain water
- spraying insect repellent onto skin and clothes
- sleeping under a mosquito net
What are the symptoms of Chlamydia?
There are usually no symptoms caused by Chlamydia
What can be the result of an untreated case of Chlamydia?
Infertility in women and in men
How can the transmission of Chlamydia be reduced?
- by wearing a condom during sexual contact
- avoiding sexual contact if infected
- getting treatment - antibiotics
How can a person find out if they have been infected with Chlamydia?
Screening is available - medics can carry out a test for the presence of Chlamydia
How can HIV be controlled?
Treatment leads to a zero viral load which means individuals cannot pass on the virus
How is HIV spread?
Exchanging infected bodily fluids such as blood, semen and vaginal fluids. Exchange of bodily fluids usually occurs during sexual intercourse/ contact and by sharing needles when taking drugs
How can couples reduce the spread of HIV?
- wearing a condom
- getting themselves tested, and if positive, getting and maintaining treatment (medication) to ensure their viral load reaches and stays zero
Describe the structure of viruses
A protein coat around a strand of genetic material
Name the type of pathways that a virus can reproduce through
The lytic pathway and the lysogenic pathway
Which pathway is when the virus is incorporated into the genome (DNA) of the host cell?
Lysogenic pathway
Which pathway is when the viral genetic material gets replicated along with the host DNA every time the host cell divides?
Lysogenic pathway
Which pathway is when the virus uses protein and enzymes in the host cell to replicate its genetic material and create the components of new viruses?
Lytic pathway
Which pathway produces host cells that split open once full of new viruses?
Lytic pathway
Which pathway requires a trigger such as the presence of a specific chemical causes the genetic material to leave the genome and enter the other pathway?
Lysogenic pathway
Which pathway leads to the release of new viruses?
Lytic pathway
During which pathway are new viruses assembled?
Lytic pathway
During which pathway does the virus lay dormant?
Lysogenic pathway
Describe two examples of physical plant defences
- plant leaves and stems have waxy cuticles which are a barrier to prevent entry by pathogens or damage by pests
- waxy cuticles repel water reducing the risk of pathogens transmitted in water
- plant cell walls are made of cellulose which act a barrier to pathogens
- hairy plant leaves and stems prevent pests from reaching the leaf surface to eat them
Describe what chemical defences plants can employ
- produce antiseptics which kill bacteria and fungi
- produce poisons which deter pests
How would a plant pathologist determine if a symptom of disease is due to a nutrient deficiency?
Observe the leaves and determine which nutrient the plant may be deficient in. Add that nutrient to the soil and observe any changes in plant symptoms
How would a plant pathologist determine if a symptom of disease is due to a pathogen?
Analyse the distribution of diseased plants. Use monoclonal antibodies to detect antigens unique to a specific pathogen. Take a tissue sample, then analyse the DNA to detect any pathogen DNA
Give two examples of the body’s physical barriers against pathogens
- skin - barrier which can create a scab to seal any cuts to keep pathogens out
- hair and mucus in nose - physically trap particles
- trachea and bronchi cells - secrete mucus to trap pathogens
- ciliated cells in trachea and bronchi - waft the mucus and any trapped particles and pathogens up to the throat to be swallowed
Give two examples of the body’s chemical barriers against pathogens
- stomach produces hydrochloric acid that kills pathogens
- produce enzymes called lysozymes which kill bacteria - found in tears and mucus
What is phagocytosis?
When a white blood cell engulfs foreign cells and digests them - consuming pathogens
What happens when a B-lymphocyte finds an antigen on a pathogen?
They start to produce antibodies specific to that pathogen
How are antibodies involved in an immune response?
The antibodies bind to the pathogen so
other white blood cells can detect them
and destroy the pathogens