Health and Disease

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Health and Disease
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What your syllabus says

• Prescribed Focus Areas
• 5.1explains how social factors influence the
  development and acceptance of scientific ideas
• 5.3evaluates the impact of applications of
  science on society and the environment
• 5.5analyses how current research might affect
  peoples lives

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• Knowledge
  
  
• 5.12technology
• b) Discuss the benefits and problems associated
  with medical and industrial uses of nuclear
  energy describe some medical applications of
  electromagnetic radiation
• 5.85.8.4 relates the structure and function of
  living things to models, theories and laws
• Humans
• a) Describe the role of, and interaction between,
  coordination systems in maintaining humans as
  functioning organisms
• b) Describe some responses of body systems to
  infectious and non-infectious diseases

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Skills

• 5.13.3 Choosing equipment or resources
• Describe ways to reduce the risk to themselves
  and others when working in the laboratory or
  field.
• 5.14 Performing first-hand investigations
• follow the planned procedure when performing an
  investigationsafely and efficiently construct,
  assemble and manipulate identified equipment
  
• g) record data using the appropriate units
• 5.16accesses information from a wide variety of
  secondary sources
• 5.17explains trends, patterns and relationships
  in data and/or information from a variety of
  sources
• 5.18selects and uses appropriate forms of
  communication to present information to an
  audience
• 5.19uses critical thinking skills in evaluating
  information and drawing conclusions

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Focus Verbs

• Identify
• Describe
• Explain
• Discuss
• outline

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Spelling

• Vaccine
• Infectious
• Health
• Antibody
• Disease
• Virus
• Traditional
• Immune
• Pathogen
• Bacteria
• Medicine
• System

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Lets Make a Glossary

• Construct a table that will show the terms and
  their meanings used in the spelling list. You
  will add to this glossary throughout the topic.
• Glossaries are a very useful tool for studying
  for exams because they let you define terms in
  your own words clearly in questions and know what
  key words you can use instead of being
  conversational in your answers. This will help
  you to get better marks in your School
  Certificate.

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Disease

• The study of disease is called pathology and
  people working in this field are called
  pathologists.
• A disease is defined in biology as anything that
  stops the body functioning properly. This does
  not only include the flu, but also other
  conditions such as colour blindness.
• NOW add these to your glossary

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• Other definitions you will need to remember are
  
• An organism is any living thing.
• A micro-organism (often called a microbe) is a
  very small organism that cannot be seen with the
  naked eye but can be seen using a microscope.
  Some micro-organisms consist of only one cell.

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• An pathogen is an organism that causes disease.
• A host is the organism being affected by the
  pathogen.

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• A parasite is a pathogen that uses the host for
  food and/or shelter and has a negative effect on
  the host.
• An infection is where a pathogen enters the
  body and is able to cause disease. The pathogen
  will multiply and have numbers that are so large
  that symptoms will show.

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• SYMPTOMS are the physical effects on the body by
  a disease. These can include fever, increased
  sweating, a rash, coughing etc.
• INCUBATION PERIOD is the time between entry of
  the pathogen and the development of symptoms.
  Some diseases have short times, such as influenza
  and ebola. Others have longer times, such as up
  to 3 weeks with Chickenpox. This can be a problem
  because the hosts can be spreading the disease
  before they know they have it.
• TRANSMISSION is the passing of disease from one
  person to another.

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• Virulence is a measure of how much damage a
  disease does to the host. Highly virulent
  diseases cause very serious symptoms, perhaps
  death.
• Can you think of some examples?

Endemic means that a disease regularly affects a
small number of people in the population. What
examples do you know of ?
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• An epidemic is when there are higher than
  normal numbers of people being affected by a
  particular disease in a certain place.

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• A pandemic is when an epidemic spreads across
  countries. This was recently an issue with the
  SWINE FLU, and then the Avian Influenza (Bird
  Flu) before that.

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• PFA5.1 The history of science
• Describe historical cases where developments in
  science have led to the development of new
  technologies

Universal Flu Vaccine digital article including
videoclip. http//www.abc.net.au/catalyst/stories/
2613604.htm
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Causes of Disease
Disease can be caused by many factors, some
infectious, some avoidable and others you are
born with The body could be invaded by
micro-organisms such
as bacteria, viruses, protozoa and fungi. These
diseases are usually infectious.
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• Parasites such as worms could be caught from
  other infected people. These would then invade
  the body.

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• Some part of the body could malfunction due to
  some imperfection or fault. For example, diabetes
  can develop if the pancreas isnt working
  properly.

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• Environmental factors might cause your body not
  to

function properly (e.g. air and water pollution,
normal but still damaging exposure to UV
radiation).
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• Lifestyle factors can also cause disease. These
  factors

are self-inflicted and include drug abuse,
overuse of alcohol, smoking, sunbaking and
high-fat, high-sugar diets.
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• Genetic disorders or diseases that your parents
  either had or carried. You do not catch these
  diseases, but are born with them.

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Infectious Disease

• There are many ways that pathogens can be shared.
  An infectious communicable disease is a disease

• that is transmitted easily from person to person.
  The disease is said to be endemic if small
  numbers of cases are present in the population
  and an epidemic if large numbers of people are
  affected. An outbreak happens when the disease is
  suddenly out of control.

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Diseases Caused by Micro-Organisms
Not all micro-organisms are harmful to humans. In
fact, some are very helpful. Some micro-organisms
serve as food sources, others help decompose
wastes, some help protect us from disease and
others aid digestion. Only a few micro-organisms
cause disease. The micro- organisms that cause
disease are known as pathogens and include
varieties of bacteria, viruses, protozoa and
fungi.
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Bacteria

• One characteristic that is used to identify
  bacteria is their shape. They may be rod-shaped
  (bacilli), spiral (spirilla) or spherical
  (cocci). All bacteria consist of only one cell,
  but they can join together in pairs, chains or
  clusters. Bacteria can multiply very quickly
  under the right conditions. If conditions are not
  favourable for growth, some types of bacteria can
  form thick-walled spores that allow them to
  withstand cold, heat and prolonged drying. They
  can remain inactive for days or even years.
  Antibiotics can kill many types of bacteria.

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Common Bacteria Shapes
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Viruses

• Viruses are so small that they can be seen only
  with an electron microscope. Viruses are not
  considered to be living things because they do
  not self-reproduce, feed, grow, produce waste or
  move. They do move from place to place, but only
  if they hitch a ride on something else, like
  other organisms, wind or water. Viruses are
  parasitic invaders made of DNA (or a similar
  material called RNA) in a protein coat. If
  viruses come into contact with a suitable cell
  (called a host cell) they can attach to the cell
  and enter it. They hijack the cell and force it
  to make more virus particles. The cells make so
  many virus particles that they burst open,
  releasing the virus particles, which then invade
  other cells.

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• Some viruses invade cells and remain dormant or
  inactive for long periods of time. An example is
  the herpes simplex virus, which is responsible
  for cold sores. Cold sores come and go, but the
  virus is always there, awaiting the right
  conditions for rapid reproduction and
  re-appearance. Others do not kill the cell they
  infect, but re-program it in a way that

causes it to become cancerous. Viruses are hard
to treat as they are not stopped by antibiotics.
With most viral infections you have to wait until
your body itself stops the invading virus.
Foot and Mouth Virus
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The Problem with Viruses

• Because they are so small, viruses are difficult
  to isolate in the laboratory. They also multiply
  so rapidly that new strains are appearing all the
  time. As yet no chemicals can eradicate a viral
  infection.

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Protozoa

• Diseases caused by protozoa (sometimes called
  protists) are most often seen in tropical and
  subtropical areas. Like bacteria, protozoa are
  singlecelled. Most protozoa are harmless to
  humans, but some parasitic types can cause
  serious illness. Protozoa sometimes form
  protective cysts around themselves if conditions
  are unfavourable, allowing them to survive
  between outbreaks. Giardia and Cryptosporidium
  are both examples of protozoa that contaminate
  water supplies.

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• Another example is the common tropical disease,
  malaria. Malaria is caused by Plasmodium, which
  live in the red blood cells and cells of the
  liver. Falciparum malaria, the most dangerous
  type, is fatal in about 20 of untreated cases.

• Initial infection occurs through a female
  Anopheles mosquito bite.

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Fungi

• Very few fungi cause disease in humans and those
  that do commonly invade the hair, skin and nails.
• Fungi are opportunistic pathogens. They are not
  usually associated with infection, but they can
  cause infection if the conditions are ideal or if
  the persons immune system is not working
  properly.

• People can have lowered immunity due to a number
  of causes and all are more susceptible to these
  fungal infections. Tinea (athletes foot),
  ringworm and thrush are all opportunistic fungal
  infections.

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Diseases Caused by Macroscopic Parasites

• Parasites that can be seen without a microscope
  are called macroscopic parasites.

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Flukes

• The most common type of disease-causing
  macroscopic parasite is the flatworm. Parasitic
  flukes are flatworms, best

known for causing disease in many animals,
including humans. Intestinal flukes, blood
flukes, lung flukes and liver flukes all affect
humans, causing damage to the organs they
inhabit, resulting in serious illness for the
host. For example, blood flukes can damage blood
vessels near major organs like the bladder and
kidneys.
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Tapeworm

• Another type of flatworm is the tapeworm, which
  can sometimes live in human intestines. One type
  of tapeworm causes hydatid disease. If the
  tapeworms eggs are swallowed by humans, the tiny
  embryos will hatch

hatch from the eggs and move from the intestines
into the bloodstream. Cysts develop wherever the
embryos end up, most often in the liver. Here
they are capable of killing the host human.
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Life Cycle of a Blood Fluke
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Bird Flu

• Bird flu, or more correctly avian influenza A
  virus, usually only infects birds. But sometimes
  these flu strains mutate into more dangerous
  forms. This happened in Hong Kong in 1997 when
  avian influenza (H5N1) infected both poultry and
  humans. This was the first time a bird flu had
  ever transmitted directly to

humans. During this outbreak, 18 people were
hospitalised and six of them died. To control the
outbreak, authorities killed about 1.5 million
chickens to remove the source of the disease.
Further outbreaks occurred in 2003 and 2004.
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• Pathologists are concerned about the possibility
  that genes might swap between bird flu and human
  flu. This could happen if a person got infected
  with both diseases at the same time. The new bug
  would then have the potential to be as deadly as
  bird flu, and as easy to catch as human flu. It
  could then bring us the next pandemic.

• Similar pandemics have occurred in the past
• 195758, Asian flu caused about 70 000 deaths.
• 196869, Hong Kong flu caused approximately 34
  000 deaths. This virus still circulates today.

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Transmission and Control of Infectious Diseases

• You can get infectious diseases by direct or
  indirect transmission.
• Direct transmission comes about by direct contact
  with the infected person or by contact with
  droplets of body fluid. Diseases transmitted by
  direct contact are called contagious diseases.

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• Indirect transmission occurs through an
  intermediary agent like an insect, air or
  contaminated water. Carriers of disease are
  called vectors. An example of a vector is the
  mosquito that carries malaria from person to
  person.

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Natural control

• The first line of defence
• The human body has several mechanisms for coping
  with disease. The first defence is the outer
  layer of the skin, consisting of dead cells.
  Harmful pathogens

on the skin can be shed with the dead cells.
There are also a lot of good bacteria on your
skin, which help fight the invaders.
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• The second line of defence

• The second line of defence is in your blood, as
  white blood cells or leucocytes. They travel in
  the blood to the site of infection, converge on
  the pathogens, digest them and engulf their
  remains. Dead micro-organisms and dead white
  cells are left behind and form the discharge call
  pus.

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• The third line of defence
• When invaded by a pathogen your body responds by
  making antibodies. These antibodies are produced
  in a process called acquired immunity.
• The antibodies float around in the blood and
  attach to a specific part of the pathogen, which
  is called an antigen. The antibody disables the
  pathogen, which is then easily consumed by white
  blood cells, thus destroying the threat. A
  particular antibody will act against the antigens
  on only one type of pathogen. The body can
  continue to produce antibodies long after the
  pathogen has been destroyed. The body will be
  immune to that particular pathogen as long as the
  antibodies are present.

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The process of acquired immunity
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Vaccinations

• The threat of many of the killer diseases of the
  past has been greatly reduced, and sometimes
  eliminated, by the development of vaccines. A
  person can be immunised against a certain disease
  by being injected (inoculated or vaccinated) with
  a vaccine. Most children in Australia are
  routinely vaccinated against diseases like polio,
  tetanus and measles, chicken pox and tuberculosis
  
• Two types of immunity can be produced
• by vaccines

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• Active immunity the body is stimulated to make
  its own antibodies. This usually involves
  injecting a live but disabled version of the
  virus or bacteria. An example is the Sabin polio
  vaccine, which uses a live but non-contagious
  strain of the disease.

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• Passive immunity the body is injected with
  antibodies previously produced by another
  organism. This is good in emergency situations,
  where immunity is needed quickly. Unfortunately
  it does not last as long as active immunity.
  active immunity does not last forever. Production
  of antibodies can reduce with time and a booster
  shot (re-injection with the vaccine) may be
  needed.

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Antibiotics

• Antibiotics are drugs that are able to
  selectively kill off certain pathogens while
  leaving the patients own body cells intact.
  Although antibiotics can fight many bacterial
  infections, they are ineffective against viruses.
  Overuse and misuse of antibiotics have led to the
  development of antibiotic-resistant strains of
  bacteria. The more

antibiotics are used, the more quickly resistant
strains emerge. It takes up to 20 years to
develop new drugs and soon doctors might be left
without any drugs to fight the new strains.
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Non Infectious Diseases

• Genetic disorders are caused by abnormalities in
  one or more genesthis means that the code
  contained on the chromosomes for building new
  cells is faulty. These genetic abnormalities may
  be caused by mutations mutagens such as
  radiation, drugs, chemicals and some viruses may
  be responsible. Once a new gene mutation has
  happened, the disorder it causes will be passed
  on to future generations. Eg Downs syndrome,
  Haemophilia

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Diseases Caused by Diet

• Malnutrition
• People in developing countries generally do not
  have the quantity or range of foods that you
  have, making them susceptible to malnutrition.
  Vitamin and mineral deficiencies can easily cause
  death.

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• Eating disorders Anorexia nervosa results in
  severe weight loss, often enough to cause massive
  organ failure and death. Bulimia nervosa is a
  related disorder characterised by a bingeing and
  purging cycle. The imbalance of electrolytes
  (mineral salts) that results from this cycle may
  cause heart failure.

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• Diabetes Diabetes mellitus is a disorder in which
  glucose, the energy source for your bodies, is
  not used correctly due to lack of a substance
  called insulin. Diabetes seems to have some sort
  of genetic component but there is no defined
  pattern of inheritance. There are two types of
  diabetes juvenile onset (Type I) mature
  onset (Type II).

• Being overweight is a common factor in Type II
  cases. If the insulin deficiency is serious,
  regular monitoring and injections are needed
  throughout the patients life.

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Diseases of the Circulatory System

• In Australia, heart disease is the leading cause
  of death in males over 35 and females over 60.
  Many of these diseases are caused by poor diet,
  smoking and a lack of regular exercise.

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Thrombosis and Embolism

• Thrombosis is a disease that causes a large,
  solid mass (a thrombus) to form on the inside
  wall of a blood vessel. Sometimes these large
  masses can detach and end up blocking major
  arteries, causing death. The blockage of a blood
  vessel is called an embolism. The embolism can
  result from a thrombus, gas, fat, tumour cells or
  some type of foreign body.

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High Blood Pressure

• Hypertension is the name given to persistent high
  blood pressure. It can cause arteriosclerosis, or
  hardening of the arteries, and coronary heart
  disease. The worst type of arteriosclerosis is
  called atherosclerosis. It is characterised by
  fatty deposits within arteries. These deposits
  can eventually cause arteries to become blocked.
  Atherosclerosis can occur in any part of the
  body, not just the heart. It can be inherited,
  but is also strongly linked to environmental
  factors like smoking and diet.

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• In WA, a four year study of 50 children aged from
  10 to 16 and found that all the children had
  early signs of arteriosclerosis.

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Varicose Veins

• Irregularities in vein walls and weaknesses in
  the valves can stop blood flowing back to the
  heart normally. Varicose veins are the result and
  are usually seen in the legs, where blood must
  fight gravity to get back to the heart.
  Unsightly, bulging veins develop wherever blood
  is trapped.

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Heart Disease

• Coronary heart disease refers to anything that
  reduces blood flow to the heart and is usually
  caused by arteriosclerosis. It can cause milder
  attacks of chest pain, called angina, or a
  serious heart failure, called a heart attack.

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Cancer

• Cancer is one disease that is on the increase in
  Australia. Cancer occurs when the cell division
  that produces new cells occurs uncontrollably.
  Cell division is a carefully controlled process
  and even tiny changes within cells can be enough
  to disturb the process and produce cancer. A
  tumour is abnormal growth in the body.

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• There are two types
• A benign growth is one in which the cells are
  not rapidly dividing. A wart is an example of a
  benign tumour.
• A malignant growth is one in which
  uncontrollable growth is occurringthis is
  cancer.

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• A biopsy is carried out to determine whether a
  tumour is malignant or benign. A small sample of
  tissue is taken, and is then analysed under a
  microscope. Cancer can occur anywhere in the
  body. The most common sites for cancers are the
  skin and prostate in men, and the breasts in
  women

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• Factors that can lead to cancer are
• environmentalcigarette smoking (lung cancer),
  exposure to the sun (skin cancer), poor diet
  (bowel cancer), and exposure to certain
  chemicals, called carcinogens

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• genetic predispositiona family history of
  breast or prostate cancer suggests that you have
  a higher risk of developing those cancers. If a
  malignant growth is found, it needs to be treated
  before metastasis occurs. Metastasis is when
  cancerous cells find their way into the
  circulatory or lymph systems and travel to other
  parts of the body. The disease becomes very
  difficult to treat once secondary cancer sites
  (called metastases) develop.

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• Leukaemia is a type of cancer of the bone marrow
  and the tissues that produce blood cells. The
  first symptoms are usually fatigue, unexplained
  bruising and anaemia, caused by the lack of red
  blood cells. An abnormal number of white blood
  cells appear. Like most cancers, there is no
  known cure, but many treatment options are
  available. Common treatments for cancer are
  surgery, radiotherapy (using radiation to kill
  localised growths) and chemotherapy (using
  chemicals to poison cells). These treatments can
  have serious side effects.
• The best chance for surviving cancer is to detect
  it early while it is still small. Never ignore an
  unexplained lump anywhere on your body.

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Abuse of Psychoactive Drugs

• A drug is any substance that has the ability to
  alter a persons body chemistry. Psychoactive
  drugs are those that alter mood. Drug use is the
  controlled, beneficial use of a substance. Drug
  abuse is when a drug is used in a way that causes
  negative effects. People who use so-called
  recreational drugs like Ecstasy or marijuana are
  often unaware of the serious side effects that
  can occur. Often, users develop mental disorders
  that stay with them for life.

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Alcohol and Smoking

• Two of the most widely used and abused drugs in
  modern society are the legalised drugsalcohol
  and nicotine. Because they are legal, their use
  is much more widespread, open and accepted than
  illegal substances like heroin and amphetamines.

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Alcohol

• In Australia approximately 7 of all male deaths
  and 4 of all female deaths can be directly
  attributed to alcohol.
• Alcohol is technically a depressant drug.
  Although it doesnt necessarily make you
  depressed, it does depress your central nervous
  system, slowing down its responses.

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• Alcohol has different effects depending on how
  much is consumed
• With a little more alcohol, muscle coordination
  becomes difficult and speech slurred. Reactions
  are slower and the senses become dulled. Alcohol
  is a cause of around one-third of all road
  deaths. Hence the legal blood alcohol limit in
  New South Wales for all learner and provisional
  licence holders was reduced to zero in May 2004.
• Alcohol initially gives a sense of warmth and
  wellbeing, and a loss of inhibitions.

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• If more alcohol is ingested, intoxication
  occurs. The person will be staggering, nauseated,
  possibly vomiting, and will have difficulty
  speaking. People are likely to fall into a coma
  if their blood alcohol content gets to 0.40.
  Death through heart and respiratory failure can
  occur at around 0.60. This rarely happens,
  however, since unconsciousness and vomiting have
  usually forced the person to stop drinking before
  then.

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• Alcohol also stimulates urine production,
  dehydrating body cells. Part of the liver is put
  out of action while it works on processing
  alcohol. A by-product of all this processing are

poisonous chemicals that are then released back
into the blood. It is a combination of
dehydration and these chemicals that give the
symptoms of a hangover. Binge-drinking is
particularly harmful since it gives no time for
the body to process the alcohol.
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Chronic Alcohol Abuse

• This causes many ill-effects including
• digestive problems alcohol destroys the lining
  of the stomach.
• malnutrition and vitamin deficienciesdiet is
  often neglected. Although alcohol is rich in
  kilojoules, it has no nutrients.
• destruction of the liveralcohol can cause
  cirrhosis, a disease where cells are replaced by
  fibrous tissue
• heart damagealcohol can harden artery walls
• destruction of brain cells
• slow deterioration of the central nervous
  system.

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• The abuse of alcohol can result in the disease
  called alcoholism, where drinking is compulsive
  and the person dependent on it. This dependence
  is most often psychological, but can develop into
  a physical dependence.

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Smoking

• More young women than men are currently smokers,
  one common reason being that it is an appetite
  suppressant. The nicotine in tobacco is addictive
  and once the habit is formed, it is not an easy
  one to give up. Withdrawal symptoms include
  intense craving, anxiety, sweating, depression,
  sleep problems and difficulty concentrating.

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• Smokers are likely to have
• more accidents than non-smokers, due to the
  slowing down of their reflex actions following a
  cigarette
• constriction of blood vessels, which means that
  smokers brains dont work as well as
  non-smokers brains

a middle-age death rate twice that of
non-smokers an increased risk of developing
many diseases, not just lung cancer an
increased risk of having low birth weight babies
with health problems and reduced intelligence if
the mother smokes during pregnancy bad breath
stained teeth and fingers.
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Environmental Hazards

• Exposure to radiation, heavy metals such as
  lead, and chemicals such as asbestos are all
  environmental hazards that can cause diseases.
  Although these hazards are usually avoidable,
  some people are exposed to them without warning.
  Many environmental diseases have only been
  diagnosed relatively recently, since many take a
  long time to develop. Asbestos was once

thought to be safe and many people innocently
exposed themselves to it in the past.
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Traditional Medicine

• Traditional Aboriginal medicine is a complex
  system linked to the belief and culture of the
  people, their knowledge of the land and of its
  flora and fauna.

Traditional medicine and health care are
holistic, taking a whole-being approach. It
recognises the social, physical and spiritual
dimensions of both health and life. Sorcery
remains a potent belief and the casting and
removing of spells is still practised.
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Good Nutrition

• To survive, organisms must take in nutrients. A
  nutrient is any substance that is used by an
  organism either as a source of energy or to build
  living tissue. Fats, proteins and carbohydrates
  can all be used by the human body to make

energy and so these are our main nutrients. A
balanced diet should consist of a variety of
foods including fresh fruit and vegetables,
breads and cereals, dairy products, fish, lean
meats and water.