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Discuss what is meant by the terms
health and disease
HEALTH
• A state of physcial, mental and social well being
• Not just the absence of disease
DISEASE
• A condition that impairs the normal function of the body and/or mind
• Resulting in bad health
• Can be caused by:
–
–
–
–
–
–
Deficiency – caused by poor diet
Inherited – caused by genetic faults from parents
Degenerative – gradual decline of body tissue or function
Infectious – transmitted by a pathogenic organism
Mental – caused by changes to the mind
Physical – permanent or temporary damage to part of the body
Discuss what is meant by the terms
health and disease
Good Health Factors
• Free from disease
• Able to perform normal
physical and mental tasks
• Well fed with a balanced
diet
• Usually happy with a
positive outlook
• Suitable housed with proper
sanitation
• Well integrated into society
Bad Health Factors
• Poverty and lack of shelter
• Lack of clean water and
sanitation
• Poor nutrition and hygiene
• Poor or inadequate health
services and education
• Lack of financial resources
for health car
Questions
• Health can be defined as a state of complete ....................................., mental and
social well-being. It is not merely the absence of infirmity or .....................................
Many people may consider themselves healthy, even though they do not fully
match the above criteria. [2 marks]
•
•
•
•
State one example of a disease that fits into each category.
mental disease ...............................................................................................
self-inflicted disease .......................................................................................
inherited disease ............................................................................................ [3
marks]
Define and discuss the meanings of
the terms parasite and pathogen
PARASITE
Define
• An organism that lives on or in another leaving thing
• That causes harm to the host
Discuss
• How – harms by taking nutrition from the host
• What – causes damage by allowing secondary infection
• Where – can be external (on their host e.g. head louse)
can be internal (in their host e.g. tapeworm)
Define and discuss the meanings of
the terms parasite and pathogen
PATHOGEN
Define
• An organism that causes disease
• By taking nutrition from the host
Discuss
• Bacteria
– What: Prokaryotes that reproduce rapidly
– How: release waste products toxic to humans or damage cells
• Fungi
– What: sends out a reproductive hyphae which grows on the surface of the skin to
release spores
– How: causes redness and irritation
• Virus
– How: invades cells and takes over genetic materials and other organelles
– The cell makes more copies of the virus
– The host cell bursts to release new viruses
• Protoctist
– How: enters the hosts cells and feeds on the contents
Question [5 marks]
Describe the causes and means of transmission of
malaria, AIDS/HIV and TB + Discuss the Global
impact of malaria, AIDS/HIV and TB - MALARIA
Transmission
1.
2.
3.
4.
5.
6.
7.
Female anopheles mosquito bites
infected individual and consumes
parasite gametes
Gametes fuse and zygotes develop in
mosquito’s stomach
Plasmodium develops and migrates to
the mosquito’s salivary glands where
they become infective
Uninfected individual is bitten and
saliva is injected so parasites enter the
bloodstream
Plasmodium migrates to the liver and
reproduce
Infective stages enter the bloodstream
Parasites invade red blood cells where
they multiple and rupture the cell
Global Impact
Risk Factor
•
•
•
•
•
Incidence – no.
of new cases
Children and pregnant women
Poverty
Lack of shelter and protection
from mosquitos
Lack of affordable medication
or vaccination
Tropical or hot climates
219 million
Prevalence- no. 300 million
with disease at a
time
Mortality – no.
of people who
die per uear
3 million
Morbidity –
propotion of
population
3%
Question [8 marks]
99. Use your knowledge and the information shown in the diagram above to complete
the passage below.
Malaria is caused by a single-celled organism called .................................. . The
organism is transmitted from one person to another by female .............................
mosquitoes. A mosquito takes up the gametes of the malarial parasite when it
feeds on the blood of an ................................... person. Fertilisation occurs in the
mosquito’s stomach and the immature parasites reproduce. Infective stages of
the parasite migrate to the mosquito’s salivary glands. A new person becomes
infected when the mosquito takes another meal of ................................ . The
parasites enter the liver of the new victim where further reproduction takes place
before migrating to the red blood cells. When an organism, such as the mosquito,
is involved in transmission it is called a ............................. . The malarial parasite
can also be transmitted by .......................... ............................. .[6]
(b) Describe two ways in which the transmission cycle of malaria can be disrupted. [2]
Describe the causes and means of transmission of
malaria, AIDS/HIV and TB + Discuss the Global
impact of malaria, AIDS/HIV and TB – HIV/AIDS
1.
2.
3.
4.
Transmission
Caused by human
immunodeficiency virus
Virus enters the body and
remains inactive
Once the virus becomes active,
it destroys T helper cells in the
immune system
Person is unable to defend
against pathogens and
therefore infections
Global Impact
Risk Factor
•
•
•
•
•
•
•
Exchange of biology fluid
Unprotected sex
Unscreened blood transfusions
Use of unsterilised surgical
equipment
Sharing hypodermic needle
Across the placenta during
childbirth
breastfeeding
Incidence – no. of
new cases
5 million
Prevalence- no.
with disease at a
time
45 million
Mortality – no. of 30 million
people who die per
uear
Morbidity –
propotion of
population
0.64%
[7 marks]
15. The Human Immunodeficiency Virus (HIV) is
spread by exchange of body fluids between
an infected person and an uninfected person.
This often occurs as a result of unprotected
sexual intercourse.
The diagram below shows the percentage of
people infected with HIV in different parts of
the world at the end of 2002.
(i) The percentage of people infected with HIV is
much higher in Sub-Saharan Africa than in
much of Europe.
Suggest three reasons why the percentages
are so much higher in Sub-Saharan Africa. [3]
(ii) Explain why it is useful to collect information,
such as that shown in the figure above. [4]
[8 marks]
48. Why it is
difficult to
prevent the
spread of
HIV/AIDS and
explain why the
increase in the
number of
cases is so
much higher in
some parts of
the world than
in others. [7+1]
Describe the causes and means of transmission of
malaria, AIDS/HIV and TB + Discuss the Global
impact of malaria, AIDS/HIV and TB – TB
1.
2.
3.
4.
Transmission
Caused by mycobacterium
tuberculosis and
mycobacterium bovis
Transmitted by droplet
infection
When people with active TB
cough, sneeze, speak or spit
they expel release the bacteria
through droplets
It can be inactive or controlled
in the immune system
Global Impact
Risk Factor
•
•
•
•
•
•
Incidence – no.
of new cases
8.8 million
Overcrowding
Poor ventilation
Poor health
Poor diet
Homelessness
Living or working with those
who have TB
Prevalence- no. 14 million
with disease at a
time
Mortality – no.
of people who
die per uear
1.6 million
Morbidity –
propotion of
population
30% of worlds population but can
be inactive
Question [8 marks]
64. Both Fig. 1 and Fig. 2 are photographs of lung tissue taken through
a light microscope at the same magnification.
Fig. 1 shows healthy lung tissue.
Fig. 2 shows lung tissue damaged by tuberculosis.
(a) Name the organism that causes tuberculosis. [1]
(b)Suggest how damage to lung tissue in tuberculosis, as seen in Fig. 2,
is likely to affect a person with this disease. [2]
(c) Outline the reasons why tuberculosis has not been eradicated. [5]
Define the terms immune response,
antigen and antibody
IMMUNE RESPONSE
• The response to a pathogen
• Involving the action of lymphocytes and the production of
antibodies
ANTIGEN
• Molecules that stimulate an immune response
• Recognised as foreign by the immune system
ANTIBODY
• Molecules secreted by the lymphocytes in the immune system
• In response to an antigen
• Can identify and neutralise antigens
Describe the primary defences against pathogens and parasites
including skin and mucus membrane and outline their importance
SKIN
•
Main primary defence as body is covered by skin
•
Has an outerlayer called an epidermis which consists of a layer of cells
•
Produced by mitosis at the base of the epidermis
•
Migrate to the surface of the skin
•
As they migrate they dry out and the cytoplasm is replaced by keratin
•
This is called keratinisation
•
The cells are dead when they reach the surface
•
Dead cells are discarded
•
Keratinised layer of dead cells acts as a barrier to pathogens
MUCOUS MEMBRANE
•
Epithelial layers contain mucus secreting cells called goblet cells
•
Mucus in the airways lines the passages and traps any pathogens in the air
•
Epithelial layer also has ciliated cells which are hair like organelles that can move
•
When they move, they waft the layer of mucus to the top of the trachea
•
It enters the oesophagus
•
It is swallowed and passes down the digestive system
•
Pathogens in the digestive system are killed by the acidity of the stomach
•
This denatures the pathogen’s enzymes
OTHER DEFENES
•
Eyes are protected by antibodies in tear fluid
•
The ear canal is lined by wax which traps pathogens
•
The vagina is protected by maintaining relative acidic conditions
Questions
26. (a) Name the type of cell that produces
antibodies.
49. (b) Name the molecules, released by plasma cells,
that attack the parasite when it enters the body.
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells
Lymphocytes
Lymphocytes:
• A white blood cell that responds to a specific antigen in
the body
• There are two types
B Lymphocytes:
• A white blood cell that secretes antibodies to a specific
antigen
T Lymphocytes:
• A white blood cell that binds to a cell containing a
specific antigen
• Destroys the cell or stimulates other cells to destroy it
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – CELL SIGNALING
Cell Signaling
• The communication between cells that allows effective
coordination of a response
1. Communication happens through cell surface molecules
2. It uses the release of hormone-like chemicals called
cytokines
3. T+B Lymphocytes have antibodies in their cell surface
membranes that act as receptors
4. Receptors are complimentary to the shape of the foreign
antigen (can be in or on the host cell)
5. When the antigen is detected, the lymphocyte is activated
or stimulated
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – T LYMPHOCYTES
T Helper
T Killer
T Memory
• Release cytokines • Destroys the cells • Circulate in the
that stimulate B
to which they
blood long after
cells to develop
become bound
invading bacteria
• Usually by
have been
secreting
destroyed
chemicals
• Can respond very
quickly again if
the same type of
bacteria enters
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – B LYMPHOCYTES
Plasma Cells
• Syntehsise more molecules
of their particular antibody
• Released by exocytosis
B Memory Cells
• Circulate in the blood long
after invading bacteria have
been destroyed
• Can respond very quickly
again if the same type of
bacteria enters
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – CYTOKINES
• Hormone like proteins used for communication
between cells
Chemotaxis
• The movement of cells towards a particular chemical
Roles and examples:
• Macrophages release monokines to attract neutrophils
by chemotaxis
• Macrophages release monokines that can stimulate B
cells to differentiate and release antibodies
• T helper cells release interlukins to stimulate clonal
expansion and differentiation of B and T cells
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – SPECIFIC IMMUNE RESPONSE
1. Pathogen enters the body
2. Pathogens are engulfed and attacked by
macrogphages
3. Antigens on the pathogen are displayed on the surface
of cells that have been attacked or on macrogphages –
antigen-presenting cells
4. Many copies of the antigen are displayed so the T
Killer or T helper lymphocyte can detect it – clonal
selection
5. Reproduction of T helper or T Killer cells - clonal
expansion
Describe the structure ad mode of action of T lymphocytes and
B lymphocytes including the significance of cell signaling and
the role of memory cells – SPECIFIC IMMUNE RESPONSE
T Helper Cells
1. Release cytokines e.g.
interleukins
2. activate B cells
3. Reproduction of B cells –
clonal expansion
4. Differentiation of B cells to
plasma or memory cells
T Killer Cells
1. Search for infected cells
2. Attach to infected cells
3. Secrete toxic substances
into infected cells to kill the
cell and pathogens
Pathogen enters body
ANTIGEN PRESENTING CELL
Antigen on the pathogen are
displayed on the surface of cells
that have been attacked or on
macrophages
CLONAL SELECTION
Copies of the antigen are
displaced so B cells, T killer or T
helper cells can detect it
CLONAL EXPANSION
CLONAL EXPANSION
CLONAL EXPANSION
T killer cells divide by mitosis so
increase in numbers
T helper cells divide by mitosis
so increase in numbers
B cells divide by mitosis so
increase in numbers
Search for infected cells
Release cytokines INTERLEUKIN
Attach to infected cells
Secrete toxic substances into
infected cells to kill the cell and
pathogens
CLONAL EXPANSION
Activates B cells to reproduce
DIFFERENTIATION
Stimulates B cells to
differentiate to plasma or
memory cells
DIFFERENTIATION - PLASMA
DIFFERENTIATION – MEMORY
Sysntehsise more molecules of
their particular antibody
Circulate in the blood long aster
the invading bacteria have been
destroyed so they can respond
very quickly if the same type of
bacteria enters
QUESTION
1
bacteria engulfed by cells from the immune system
2
removal of antigens from bacteria
3
antigens presented on surface of
engulfing cells
4
correct T helper cells are selected
5
reproduction of T helper cells
6
release of cytokines
7
cytokines activate B cells
8
reproduction of B cells
9
10
some B cell clones
differentiate to make
plasma cells
plasma cells manufacture
antibodies
some B cell clones
differentiate to make
B memory cells
• Name the type of cell that
engulfs the bacteria in stage 1.
[1]
• Suggest how the antigens are
removed from the bacteria in
stage 2. [2]
• Explain how the correct T
helper cells are selected in
stage 4. [2]
• Name the type of cell division
used for reproduction of the T
helper cells in
stage 5. [1]
• Explain the importance of B
memory cells in immunity. [4]