1. title
Body defence

2. 19.2 Non-specific defence methods 19.3 Specific defence methods
content
Body defence
19.1 What is body defence?
19.2 Non-specific defence methods
19.3 Specific defence methods
19.4 Vaccination

3. 19.1 What is body defence? a function of the mammalian body which
protects it from diseases caused by pathogens
2 types of defences
prevent pathogens from entering the body
fight against pathogens which have already entered the body

4. defence methods that prevent all types of pathogens

5. NON-SPECIFIC defence methods
defence methods that prevent all types of pathogens
pathogens

6. defence methods more powerful !
SPECIFIC
defence methods more powerful !
defence methods that defend against certain type(s) of pathogens
pathogens

7. 19.2 Non-specific defence methods
digestive system
all have non-specific protective methods to prevent or reduce the entry of pathogens
enter our body through
respiratory system
pathogens
first line of defence
reproductive system
skin

8. Physical barriers Skin epidermis stops entry of pathogens
sebum & sweat
contain antiseptics
sebum

9. Physical barriers Ciliated epithelium of the respiratory tract
pathogens trapped by mucus and cilia
cilia beat to move the trapped pathogens upwards to be swallowed

10. Chemical barriers Gastric juice secreted by gastric glands
with hydrochloric acid that can kill pathogens
gastric gland

11. Chemical barriers Other secretions
kill or stop the growth of pathogens
examples
sweat and oils
saliva
tears
mucus

12. AFTER 1 DAY Blood clotting
prevents the entry of pathogens through wounds
fibres hold the edge of a wound together
epidermal cells
red blood cell caught in fibres to form a clot
AFTER 1 DAY
connective tissue
tiny platelets help in making fibres from some blood proteins
damaged blood vessel

13. AFTER 2 DAYS Blood clotting
edges of the epidermis start to grow together
white blood cell leaves blood vessel and moves towards the wound
AFTER 2 DAYS
white blood cells start to engulf bacteria and debris

14. AFTER A WEEK Blood clotting scab thin layer of epidermis
white blood cells still in action, then gradually return to blood vessels

15. Blood clotting scab falls off intact epidermis repaired blood vessel
new connective tissue

16. Phagocytosis the engulfing and digesting process
of pathogens by phagocytes
a kind of white blood cells
during which the pathogens are killed and digested by enzymes
Phagocytosis

17. The inflammatory response
pathogens
phagocytes in tissue engulf and digest pathogens
skin
more phagocytes come out of the blood vessel
blood vessel dilates
phagocyte in blood

18. Inflammatory response
The inflammatory response
Inflammation
because of the dilation of blood vessels and extra tissue fluid,
the infected area becomes red, swollen and painful
Pus
a whitish liquid from the wound
contains dead white blood cells
Phagocytosis
Second line of defence
Inflammatory response

19. 19.3 Specific defence methods
pathogens not killed by phagocytes
get into blood
immune response triggered
specific and more powerful
but takes time to begin
disease may have serious effects before initiation of immune response

20. Antibody production antibodies are produced by lymphocytes lymphocytes
a kind of white blood cells
antigens
lymphocytes
detected by
produce
proteins on the surfaces of pathogens
Y- shaped proteins
antibodies

21. do not kill pathogens directly
Antibodies
do not kill pathogens directly
act against pathogens in a number of ways:
Lysis
hole
antibodies attached make holes in the cell walls/protein coats
pathogen lysed and killed
antibodies
pathogen

22. do not kill pathogens directly
Antibodies
do not kill pathogens directly
act against pathogens in a number of ways:
Help in phagocytosis
antibodies attached to bacteria and make it easier for phagocytes to engulf them
a phagocyte engulfing a bacterium
the bacterium is engulfed and killed by the phagocyte

23. do not kill pathogens directly
Antibodies
do not kill pathogens directly
act against pathogens in a number of ways:
Sticking pathogens together
pathogens stuck together by antibodies and cannot reproduce or enter cells due to the large size
antibodies
pathogens

24. the breaking-down process of dead pathogens in the liver
Detoxification
the breaking-down process of dead pathogens in the liver
Not all pathogens lead to the formation of antibodies
Some pathogens lead to other kinds of immune responses

25. days after first infection
Primary and secondary immune responses
concentration of antibodies in blood
days after first infection 7 14 21 28 35
When a type of pathogen enters the body for the first time,
it stimulates the production of antibodies.
latent period
first infection
Primary response

26. days after first infection
Primary and secondary immune responses
concentration of antibodies in blood
days after first infection 7 14 21 28 35
After this first response, ‘memory cells’ will ‘memorize’ the pathogen.
certain kinds of white blood cells
latent period
first infection
Primary response
Recovery

27. days after first infection
Primary and secondary immune responses
concentration of antibodies in blood
days after first infection 7 14 21 28 35
Next time when the same pathogen enters,
many more antibodies will be produced
in a much shorter time.
latent period
shorter latent period
first infection
re-infection
Primary response
Recovery
Secondary response

28. 19.4 Vaccination Natural immunity Artificial immunity
Inborn body defence
Vaccination

29. antigens memorized by the lymphocytes
19.4 Vaccination
Injection of
controlled
amounts of
Primary response
a pathogen
antigens memorized by the lymphocytes
an altered form of a pathogen which have been made harmless

30. more lymphocytes and specific antibodies produced in a shorter time
19.4 Vaccination
Enhanced
resistance
to injected
diseases
if infected again
Secondary response
more lymphocytes and specific antibodies produced in a shorter time

31. Concept diagram Body defence diseases pathogens
is the protection of the body from
consists of
diseases
caused by
pathogens
non-specific defence methods
specific defence methods
have
consist of
include

32. Concept diagram non-specific defence methods physical barriers
consist of
physical barriers
chemical barriers
blood clotting
phagocytosis by phagocytes
include
include
often associated with an
skin
ciliated epithelium (of the respiratory tract)
gastric juice
other secretions e.g. tears
inflammatory response
the second line of defence ( kills pathogens or makes them harmless)
the first line of defence (prevents entry of pathogens)
natural immunity

33. specific defence methods
Concept diagram
specific defence methods
have
include
antibody production
(by lymphocytes)
other methods
immune response
natural immunity

34. Concept diagram specific defence methods primary response
have
primary response
secondary response
on future re-exposure to same antigens leads to
has is
memory
a more powerful and faster response
due to production of
memory cells
basis of artificial immunity by vaccination