Transcript Sex and Behaviour * Immune Response to Parasites

If you have done Higher Human Biology this is just
revision!!! Use the key areas to create revision notes!
HOMEWORK: ACTIVITY G – Self Study Task – Immune response to parasites
READING:
http://jbiol.com/content/8/7/62
Sex and behaviour:
Immune response to parasites
CfE Advanced Higher Biology
Unit 2: Organisms and Evolution
SQA mandatory key area
• Non-specific defenses in mammals: physical barriers,
chemical secretions, inflammatory response,
phagocytes, natural killer cells destroying abnormal
cells.
• Mechanism of specific cellular defenses in mammals:
apoptosis, phagocytosis, T lymphocytes, B
lymphocytes and immunological memory cells.
• Epidemiology and herd immunity. The herd immunity
threshold is the density of resistant hosts in the
population required to prevent an epidemic.
• Endoparasites and antigenic variation.
Key concepts 1
• Specific cellular defence in mammals involves
immune surveillance by white blood cells, clonal
selection of T lymphocytes, T lymphocytes targeting
immune response and destroying infected cells by
inducing apoptosis, phagocytes presenting antigens
to B lymphocytes, the clonal selection of B
lymphocytes, production of specific antibody by B
lymphocyte clones, long term survival of some
members of T and B lymphocyte clones to act as
immunological memory cells.
Use the videos from
https://www.khanacademy.org/scie
nce/biology/humanbiology/immunology to help you
study the following and answer the
self-study task questions (you will
receive a paper copy and we will go
over the answers in class)
Key concepts 2
• Epidemiology is the study of the outbreak and
spread of infectious disease.
• Endoparasites mimic host antigens to evade
detection by the immune system, and modify hostimmune response to reduce their chances of
destruction.
• Antigenic variation in some parasites allows them to
evolve fast enough for them to be one step ahead of
host immune cell clonal selection.
Classification of microbes
Giardia
Algae
Fungi
TrichophytonATHLETES FOOT
Bacteria
E.coli
Protozoa
Viruses
Cold /flu
Endoparasites
• Those that live inside the host are
called endoparasites (including all parasitic worms).
Endoparasites can exist in one of two forms:
intercellular parasites (inhabiting spaces in the
host’s body) or intracellular parasites (inhabiting
cells in the host’s body).
• Intercellular parasite – Legionella (Legionnaires
disease)
• Intracellular parasites - Plasmodium (Malaria)
Pathogens and disease
An infectious disease is a disease
resulting from infection of a host
organism by a pathogen, a diseasecausing organism.
There are several different types of
pathogen including bacteria, fungi,
viruses and parasites.
Infectious disease is a major cause
of death worldwide.
It is estimated that 14.7 million
people died in 2002 due to
infectious diseases.
Transmission – short task
Select one of the following
diseases to study:
• Athletes foot
• Cholera
• Gastroenteritis (caused
by Campylobacter or
Salmonella)
• HIV
• Tuberculosis
• Malaria
Find out the following:
1. Transmission method
2. Type of microorganism
3. Symptoms
4. Prevention/treatment
Present your findings to
the class
Control of disease
• Quarantine
• Antisepsis (prevent disease infection through inhibition or
arresting the areas of growth of the infection).
• Individual responsibility (good hygiene, care in sexual health
and appropriate storage/handling of food),
• Community responsibility (quality water supply, safe food
webs and appropriate waste disposal systems)
• Control of vectors
Epidemiology – important revision from here!
• Is the study of the outbreak and pattern of infectious
diseases to determine the factors which affect their
spread.
ACTIVITY G:
Non-specific and specific
defences
Outbreaks of disease can occur on different levels:
• sporadic – (occasional occurrence) the disease occurring
occasionally, singly or in scattered instances.
• endemic – (regular cases occurring in an area) it is continually
present in a population but at a low level (for example the
common cold).
• epidemic – (unusually high number of cases in an area )it has
suddenly increased above the normal endemic level and infects
many people.
• pandemic – (a global epidemic ) it is epidemic over a very wide
area (usually a continent or the world).
Depending on epidemiological studies,
measures are considered to control the spread
of diseases.
– preventing transmission
– drug therapy
– immunisation
Types of Immunity
Active immunity - antibodies made by individual in
two ways:
•Natural Acquired Active –Antibodies made by individual in response to
antigen
•Artificially Acquired -In response to vaccine.
Passive immunity - antibodies given to individual in
two ways
•Natural -Ingested with milk shortly after birth
•Acquired – injection of antibodies to combat a disease e.g. rabies
Active immunity
Antigens usually mixed with an adjuvant to form the
active vaccine and enhance the immune response.
Vaccines include:
– inactivated pathogen toxins
– dead pathogens
– parts of pathogens
– weakened pathogens.
Antibody responses
Memory cells – lymphocytes specific to antigen from first
exposure to it.
Edward Jenner & the Small Pox Vaccine
Use this website:
http://www.jenner.ac.uk/edwardjenner to find out
about how Edward Jenner developed the Small Pox
Vaccine.
Write a short note including:
– When he did this work
– How he linked cowpox and smallpox
– How he tested the vaccine
– When smallpox was eradicated.
The Independent - Thursday 22 May 2014
• The General Assembly of the WHO will take a vote on
Friday (23rd May) on whether to eradicate the variola
virus completely and forever by ordering the
incineration of stockpiles in Russia and the United
States, which are kept under an agreement signed in
1983 when Ronald Reagan was US President and the
Soviet Union was still a country.
• http://www.independent.co.uk/news/science/health-expertsto-vote-on-whether-to-destroy-the-last-few-samples-ofsmallpox-9412451.html
Any further news?
Search online for smallpox to find out!
Herd Immunity
The herd immunity
threshold depends on:
1. The disease
2. The efficacy
(effectiveness) of the
vaccine
3. The contact parameters
for the population.
Pros
Protects vulnerable and the
non-vaccinated
Reducing the spread of
diseases
Difficulties
The developing worldvaccination is not possible
due to malnutrition and
poverty
The developed worldvaccines are rejected by a
percentage of the
population.
The MMR controversy
In 1998, a scientific paper was published in the medical journal The
Lancet, speculating that the MMR vaccine could cause autism.
The authors thought that the MMR vaccine could damage the
bowel, allowing toxins that are normally destroyed in digestion to
move into the blood. If these toxins travelled to the brain they
might cause autism.
The authors did not prove that
this was the case but still
recommended that doctors
stop administering the MMR
vaccine until more research
was done.
The media’s role in the MMR controversy
Many studies have concluded that the MMR vaccine is safe and
only a few studies claim that it isn’t. However, this was not
reflected by the media coverage.
.The majority of coverage centred on the possibility of a link
between the MMR vaccine and autism, while the government
insisted that the vaccine was safe. This mixed message caused
confusion among the general public, leading to a drop in the
number of children being given the combined vaccine.
Should scientists be more careful about how they present their
research or should the media be responsible for how they
present controversial topics to society?
Antigenic variation
• Many pathogens like viruses, bacteria and protozoa can
evolve mechanisms that evade the specific immune system
of the human body and can affect vaccination strategies
globally.
• Antigenic variation is a process by which a pathogen is able to
change its surface proteins so that it can evade the host
immune responses.
• The antigenic profile will change as the pathogen passes
through the host population or in the original infected
host.
• Antigenic variation is particularly important for
pathogens as it allows them to:
- target hosts which are long-lived or susceptible to the
pathogen
- infect a single host on more than one occasion
- transmit the disease easily.
This drift results in small antigenic changes in the
pathogen population and will reduce the efficacy of B
and T cell memory during the host immune response.
Question
Use the information you have learned so far to explain why
people need to be immunised against Influenza annually.