*Health and disease (Ch22, 23) Flashcards
Definition of health
- A state of physical, mental and social well-being
Healthy lifestyle
- Balanced diet
- Regular exercises
- Sufficient rest
- Good personal hygiene
- Avoidance of smoking
- Avoidance of alcohol
- Avoidance of drug abuse
Advantages of doing regular exercise
- Improve the functioning of the lungs and heart
- Help reduce body weight
- Improve strength of muscles
- Improve flexibility of joints
- Reduce stress
Infectious disease
- Caused by pathogenic microorganisms
- pathogen, host, environment
Virus (organism / non-organism)
Organism
- Can reproduce in a cell
- Have genetic materials of controlling life processes
Not organism
- Non-cellular organisms (no cytoplasm, cell membrane, organelles)
- Cannot replicate by themselves
- No metabolism outside the host cells
Structure of virus / Mode of reproduction of virus
- A protein coat enclosing nucleic acid
- Have head and tail
- Cannot reproduce by themselves
- Reproduce within host cell
- Virus is host specific
Infectious disease caused by virus
- Influenza
- Hepatitus B
- Dengue fever
- Japanese encephalitis
- Common cold
- Measles
- Smallpox
- SARS
- AIDS
- COVID-19
Bacteria
- Unicellular, prokaryotic
Structure
- Cell wall
- Cell membrane
- Cytoplasm
- Plasmid
- Ribosome
- Flagellum
Reproduction
- By asexual reproduction
Infectious diseases caused by bacteria
- Cholera (dehydration)
- Tuberculosis
Transmission by droplets
- Droplets from the respiratory tracts -> eyes
- Common cold
- Influenza
- COVID-19
- Cover the mouth during coughing or sneezing
- Wear a surgical mask
- Avoid going to crowded places
Transmission by air
- Pathogens attach on dust particles
- Cover the mouth during coughing or sneezing
- Wear a surgical mask
- Avoid going to crowded places
- Keep good ventilation
Transmission by contaminated food or water
- Cholera (by water / food)
- Tuberculosis (by food)
- Wash hands before taking meals / preparing food
- Cook food thoroughly
Transmission by body fluids
By blood
- Hepatitis B
- AIDS
- Do not share razors, toothbrush or needles
- Screen blood before transfusion
By semen and vaginal fluid
- AIDS
- Syphilis
- Use condoms during sexual intercourse
- Have only one sexual partner
Why antibiotics are not effective in treating viral infections?
- Virus does not contain cell wall / cell membrane
- Virus does not carry out protein synthesis / DNA synthesis on their own
- Antibiotics cannot act against virus
Transmission by vectors
Flies / Cockroaches:
- Cholera
Mosquitoes
- Malaria
- Dengue fever
- Japanese encephalitis
- Destroy the breeding places of mosquitoes by clearance of accumulated water (impossible to clear all stagnant water)
- Directly kill mosquitoes by spraying pesticides / larvicidal oil (contaminate the environment, kill pollinating agents (bees), evolution of resistant strain)
- Prevent mosquitoes from biting by wearing long-sleeved clothing and applying mosquito repellents
Transmission by direct contact
- Athlete’s foot
- Hand-foot-mouth disease
- Avoid physical contact with infected people
- Wash hands frequently
Why children are more vulnerable to hand-foot-mouth disease?
- Weak immune system
- Poor personal hygiene
Notes P.9
Antibiotics
- Chemical produced by bacteria and fungi to kill / inhibit growth of other organisms
- Enables the to win the competition for resources to support their life
Discovery and development of antibiotics
Hypothesis
- Mould produce substances to kill bacteria
- Mould kill bacteria
NOS
- Scientists are both collaborative and competitive in nature
Action of antibiotics
Killing bacteria
- Inhibit cell wall synthesis (bacteria burst when they absorb excess water by osmosis)
- Break down cell membrane of bacteria (cell contents leak out, the cell dies)
Inhibiting growth of bacteria
- Interfere with protein synthesis (bacteria cannot function and grow)
- Interfere with DNA synthesis (cannot carry out cell division, cannot multiply)
Broad-spectrum antibiotics
- Can act against different bacteria efficiently
Group of individuals highly recommended to receive vaccination
- Elderly: weak immune system
- Doctor / Nurse: frequently contact with patients, high risk of being carrier of pathogens
Indiscriminative use of antibiotics
- Use antibiotics to treat viral disease
- Patients stop taking antibiotics when they feel better
- Add antibiotics to animal feeds
Consequences of indiscriminative use of antibiotics
- Infectious bacteria become resistant to antibiotics
Natural selection:
- Genetic variation exist among bacteria in their resistance against antibiotic
- Increase in amount of antibiotic kills non-resistant form, resistant form has higher chance to survive
- Resistant form has higher chance to reproduce
- Proportion of resistant form increases - Kill beneficial mutualistic bacteria
- Allergy
- No effective drug to tackle infectious disease
- Productivity of disease-stricken people will reduce without effective treatment
- Development of new antibiotics have to keep pace with mutation for resistance, demanding more resources from society
Solutions to alleviate the consequence of indiscriminative use of antibiotics
- Proper use of antibiotics
- Prescribe only when necessary
- Take complete prescription (ensure all bacteria killed)
- Use narrow-spectrum antibiotic - Development of new drugs based on different mechanism in killing infectious bacteria
- Short term: implement effective measures to control spread of infectious bacteria an to eliminate the sources of contamination
Antibiotics vs vaccination
Antibiotics
- Curative measure
- Kill pathogens
- Only for bacterial disease
Vaccination
- Preventive measure
- Stimulate development of memory cells
- For both bacterial and viral diseases
Explanation for efficiency of antibiotics
- The antibiotic diffuse outward from the paper disc
- The farther away from the disc, the lower is the concentration of the antibiotics
- A larger clear zone indicates that antibiotic is effective in inhibiting bacterial growth even at a lower concentration
Sulpha drugs
- Competitive inhibitors
- Compete with metabolite essential in reproduction of bacteria for the active site of bacterial enzyme and stop bacteria from reproduction
Treatment for AIDS
- HIV attacks T-lymphocytes of immune system of the body
- AIDS is difficult to treat because mutation of viruses occur rapidly, and virus take over the enzyme machinery of human cells to reproduce
- Cocktail treatment reduces the chance for HIV to develop resistance to all the drugs at the same time
Non- infectious disease
- Caused by lifestyle, biological factors, genetic factors, environment
Coronary heart disease
- Consumption of high calorie food / fatty food / food rich in cholesterol
- Excess fat / cholesterol in diet diposits of inner wall of coronary arteries
- Increases the risk of plaque formation
- Leads to narrowing of the lumen of arteries, blockage in arteries, decrease blood flow to heart muscles
- Heart muscles do not have enough oxygen and nutrients supply and die
Stroke
- Artery supplying blood to the brain is blocked / A blood vessel inside the brain bursts under high blood pressure
- Supply of oxygen to the brain cells reduced
- Brain cells die due to insufficient oxygen supply
Treatments of cardiovascular disease
- Drugs
- Surgery (Balloon angioplasty, coronary bypass surgery)
Risk factors for coronary heart disease
- Unhealthy lifestyles
- Eating food rich in cholesterol / fat
- Smoking (Nicotine increases the chance of blocking blood vessel, causes vasoconstriction of blood vessels, carbon monoxide reduces oxygen-carrying capacity of blood)
- Lack of regular exercises - Biological factors
- Ageing (blood vessels become narrower and less elastic as people age)
- Gender (Male > Female)
- Family history
Diabetes mellitus
- High blood glucose concentration
- Presence of glucose in urine
Signs
- Excessive urine production (E1)
- High blood glucose level (Insufficient insulin to stimulate body cells / Body cells insensitive to insulin)
- Constant thirst
- Blurred vision
- Weight loss
Insulin-dependent diabetes (Type 1)
- Cause: little / no insulin (insulin-producing cells of pancreas destroyed by immune system)
- Risk factors: genetic factor / family history
- Occurrance: early life (5%)
- Control method: daily injection of insulin
Non insulin-dependent diabetes (Type 2)
- Cause: body cells insensitive to insulin
- Risk factors: obesity / lack of exercises / ageing / family history
- Occurrance: later in life (95%)
- Control method: small but frequent meals / reduce intake of food with high sugar content / eat complex carbohydrate / take regular exercise / frequent monitoring of blood glucose level / take appropriate medication of increase sensitivity of body cells to insulin
Mass production of insulin by recombinant DNA technology (Ch27)
- Eliminate chance of transmission of animal pathogens
- Eliminate possible allergens from animal insulin
- Eliminate possible immune response produced by patient against animal insulin
Formation of tumours
- When genetic control of cell division in a cell goes wrong, the uncontrolled cell division of body cells results in a mass of cells, forming a tumour
Benign tumour
- Remain within the tissue where they arise
- Grow slowly
- Cells surrounded by capsule
- Not life-threatening
Malignant tumour
- Spread to other regions (metastasis)
- Grow rapidly
- Cells not surrounded by capsule
- Life-threatening as tumour formed competes with normal tissues for nutrients and oxygen
Why genetic control goes wrong to form tumours?
- Gene mutation -> change in gene product -> production of unwanted protein -> leads to uncontrolled cell division
Treatment of cancers
- Surgery (remove localized tumour)
- Radiotherapy
- Chemotherapy (use anti-cancer drugs to kill cancer cells / inhibit their growth)
- Targeted therapy
Causes and prevention of cancers
- Exposure to radiation (ultraviolet light / high-energy radiation (X-ray) change structure of genes by mutation)
- Putting on sunscreen - Exposure to chemicals (asbestos)
- Exposure to pathogens
(hepatitus B virus -> liver cancer)
- Vaccination
(HPV -> cervical cancer)
- Avoid early sex, have only one sexual partner
- Cervical smear screening
- Immunization
Risk factors of cancer
Unhealthy lifestyles
1. Smoking
- Tar contains carcinogens
2. Alcohol abuse
3. Unhealthy diet (food may stimulate mutations)
- Red meat (eating too much red meat with little vegetables and fruits increases the chance of suffering from colorectum cancer: dietary fibre increases bulk of food to stimulate peristalsis of the gut, helps reduce time for carcinogens to stay inside the colon)
- Salted and smoked food
- Processed meat (contains carcinogenic substances)
- Deep-fried food (contains carcinogenic substances)
Why cancer remains one of the top killer diseases in HK
- Taking in more processed food that lacks dietary fibre
- More stressful lifestyle
- Lack physical exercise, higher chance of obesity
- Older age
- Excessive drinking
- Medical advancement -> death rate due to other diseases is lower
Prevention of diseases
- Breaking transmission link of pathogens (quarantine)
- Immunization programme (vaccinations induce the body to develop immunity against diseases, number of infected individuals is reduced)
- Screening programme
- Disease surveillance
- Health education
- Taking healthy lifestyles
Notes P.29
