Science (Semester 2) Flashcards
What’s the difference between infectious and non-infectious diseases?
Infectious diseases: diseases that can be spread between individuals
Non-infectious diseases: diseases that cannot be spread between individuals
Name at least three examples of pathogens and the diseases caused by each.
- Macroparasite
A multicellular organism (etc. a tick) that is usually parasitic. Absorbs nutrients across the cell membrane.
Example disease: Cysticerosis - infection from eating undercooked contaminated meat, caused by tapeworm - Fungus
A unicellular or multicellular organism that feeds on organic matter.
Example disease: Tinea - fungal infection that occurs (often) between the toes - Bacterium
A unicellular organism with a cell wall but no nucleus or organelles
Example disease: Chlamydia - sexually transmitted infection
Explain at least one example of how science is currently helping society respond to outbreaks of disease
- Devil facial tumour disease
- Occurs in Tasmanian devils: symptoms include lesions and swelling on the face
- Caused by contagious cancer, spread by biting
- Caused Tasmanian devil to be protected and endangered
- Science research focused on monitoring spread of disease, learning more about the disease and managing it to avoid extinction of the Tasmanian devils.
- Discovery made: Tasmanian devils lacked genetic diversity related to fighting infection
- Avian influenza
- Has occured in many adaptations
- 2009: Swine flu pandemic (H1N1 strain) occurred
- Concern: virus will remain in bird populations and change into form that transmits directly form human to human, like Spanish flu.
- CSIRO researched gene silencing, which prevents mechanisms that viruses use to take over their host’s cells
- …in addition to early detection of the flu and vaccines
Outline the first line of defence against disease entering our bodies.
- Consists of physical and chemical barriers
- Stops pathogens from getting inside the body
What are the physical components of the first line of defence?
Skin
- thick layer of dead cells provides physical barrier
- natural flora colonise linings (skin, digestive system, lining of nose), reducing surface areas for pathogens to colonise.
- Breaks or damages to skin allow pathogens to enter.
Mucous membranes
- Lines entrances to body (etc. nose, ears)
- Produces mucus that traps foreign particles and directs them out of the body
Hairs and cilia
- Hairs within nose trap dust, dirt, microbes and pollutants
Urine, defecation and vomiting
- flushes out pathogens from the bladder area and digestive system
What are natural flora?
a community of microbes
What are the chemical components of the first line of defence?
Enzymes in tears, sweat and saliva
- Breaks down the cell wall of bacteria
Stomach acid
- Hydrochloric acid kills bacteria and parasites that have been swallowed
Outline the second line of defence against disease entering our bodies.
Seeks and destroys pathogens
Consists of general / non-specific immune responses
What are the non-specific immune responses in the second line of defence?
Blood clotting - stops additional infection through skin damage
Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
Outline the third line of defence against disease entering our bodies.
Targets remaining pathogens.
Consists of specific immune responses that create antibodies.
What are antibodies?
immune proteins produced in response to and counteracting a specific antigen
What is natural active immunity?
Natural active immunity occurs when antibodies remain in the blood after an infection is fought, and will react to the same pathogen again.
Outline the components of the immune systems and our body’s response to infection.
- First line of defence
- Physical and chemical barriers
- Stops pathogens from getting inside body
- Second line of defence
- Seeks and destroys pathogens
- Consists of non-specific immune responses such as:
- Blood clotting - to stop additional infection through skin damage
- Inflammation - to increase the amount of blood (carrying white blood cells) reaching an infected area
- Fever - to heat up the body and destroy pathogens that cannot survive in extreme heat
- Phagocytosis - Large white blood cells that envelope pathogens and destroy them via enzymes
- Third line of defence
- Targets remaining pathogens
- Consists of specific immune responses that create antibodies
- Antibodies are protein molecules that bind to target pathogens.
- They remain in the blood after an infection is fought, and will react to the same pathogen again.
- This is called natural active immunity.
Give an example of a common medicine and its use.
Aspirin: used to reduce the symptoms of illness.
How are medicines used?
Medicines are used to:
- Change how cells work - Replace substances missing from your body - Destroy micro organisms and abnormal cells - Reduce the symptoms of illness
Recall the types of immunities.
- Natural active immunity
- Acquired active immunity
- Natural passive immunity
How does natural active immunity operate?
when a person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.
How does acquired active immunity operate?
a short-term immunisation by the injection of antibodies that are not produced by the recipient’s cells
How does natural passive immunity operate?
occurs during pregnancy, when antibodies are transferred from one person to another through natural means
How are non-infectious diseases acquired?
Diet and lifestyle choices
- poor supply of the proper nutrients to your body can affect the function of your cells
- EXAMPLE: Lack of Vitamin C = Scurvy
Genetic disorders
- Result of mutation in DNA or chromosomes at some stage
- EXAMPLE: Fragile X syndrome
Environmental factors
- Exposure to toxins, carcinogens and radiation
- etc. nuclear reactions that release a toxic amount of radiation
Outline the causes of some non-infectious diseases
Scurvy: diet and lifestyle choices, due to a lack of Vitamin C
Fragile X syndrome: inherited genetic disorder, caused by variation in the FMR-1 gene on the X chromosome
Skin cancer: environmental factors, overexposure to UV radiation
What causes congenital analgesia?
Inherited mutation/disorder in the SCN9A gene
- ability to transfer signal to dorsal root neurons blocked, so no pain propagation
What are the symptoms of congenital analgesia?
- Frequent physical injuries
- Absent or reduced sense of smell
- Lack of pain sensation
- Inability to feel foreign objects in eye
- Common mouth injuries
What does blood clotting do?
Stops additional infection through skin damage