1. By Jinsu ChangBy Jinsu Chang

3. 6.3.1 define pathogen6.3.1 define pathogen
 Pathogen is "any living
organism or virus that is
capable of causing a
disease"

4. BacteriaBacteria

5. ProtozoaProtozoa

6. VirusVirus

7. FungiFungi

8. 6.3.2 Explain why antibiotics are effective6.3.2 Explain why antibiotics are effective
against bacteria but not against pathogensagainst bacteria but not against pathogens
• Bacteria are Prokaryotic cells
• Somatic cells (body cells) are Eukaryotic cells
• Prokaryotic cells and eukaryotic cells have different biochemical reactions and
pathways
• They both have a different structure (Prokaryotes have a cell wall made of
Peptidoglycan body cells don’t)
• Antibiotics are chemicals that take advantage of the difference between the
two!!!!
• *No effect on Virus!

9. THERE ARE MANY WAYSTHERE ARE MANY WAYS
ANTIBIOTICS TAKE ADVANTAGE OFANTIBIOTICS TAKE ADVANTAGE OF
THE DIFFERENCE BETWEEN EUKTHE DIFFERENCE BETWEEN EUK
AND PROKAND PROK

10. Selectively block protein synthesis inSelectively block protein synthesis in
bacteria, but no effect on body cellsbacteria, but no effect on body cells

11. Inhibit the production of new cell wall byInhibit the production of new cell wall by
bacteria, which block ability to grow andbacteria, which block ability to grow and
divide through binary fissiondivide through binary fission

12. Preventing the entrance ofPreventing the entrance of
pathogens to our bodypathogens to our body
 “It is best to prevent than to cure”
 There are many ways to prevent entrance of pathogens:
 1) Stay away from sources of infection
 2) Human body is designed to protect us from
pathogens because it is obviously impossible to stay
away from all pathogens

14. SkinSkin
Skin is a barrier to
infection

15. DermisDermis
The underneath layer of the skin is very
much alive. It contains sweat glands,
capillaries, sensory receptors and dermal
cells that give structure and strength to
the skin.

16. EpidermisEpidermis
The layer on top of the dermis.
Epidermal layer is constantly replaced as
underlying dermal cells die and are
moved upwards.

17. Stomach AcidStomach Acid
The layer on top of the dermis.
Epidermal layer is constantly replaced as
underlying dermal cells die and are
moved upwards.

18. Scab FormationScab Formation
Blood Clotting and scab formation stops
pathogens from getting in.

19. TearsTears
Tears are antiseptic and kill microbes
(pathogens)

20. MucusMucus
 Mucus can trap incoming pathogens and so prevent
from reaching cells they could infect.
 Some Mucus membrane are lined with cilia, which are
hair-like extensions capable of a wave-like movement.
This movement moves trapped pathogens up and out
of mucous-lined tissues.

21. Area with mucous membrane What it is and does
Trachea Tube which carries air to and from the
lungs
Nasal Passages Tubes which allow air to enter the
nose and then the trachea
Urethra Tube which carries urine from bladder
to the outside
Vagina Reproductive tract leading from
uterus to the outside

22. TracheaTrachea

23. Nasal PassagesNasal Passages

25. Role of phagocyticRole of phagocytic
LeucocytesLeucocytes
 Leucocytes are the cells in our bloodstream that help
us fight off pathogens that enter our bodies and also
provide us with an immunity for many pathogens we
encounter a second time.

26. MacrophageMacrophage
 Macrophages are large
white blood cells that are
able to change their
cellular shape to
surround an invader and
take it in through
phagocytosis.
 *Macrophages can easily
change their shape. Thus
they are able to squeeze
their way in and out of
capillaries.

27. MacrophageMacrophage
 Recognizes whether the cell is a natural part of the
body and therefore ‘self’ or not part of the body and
therefore ‘not-self.’
 Recognition is based on protein molecules that make
up part of the surface of all cells and viruses (antigens).
 *Doesn’t recognize which pathogen it is, just determine
is ‘self’ or ‘not self’

28. Macrophages in ActionMacrophages in Action

29. Macrophage in ActionMacrophage in Action

30. Antibodies are produced inAntibodies are produced in
response to a specific pathogenresponse to a specific pathogen
 Leucocytes that produce antibodies are called B
lymphocytes.
 There are many types of B lymphocytes and each B
lymphocyte can produce only one type of antibodies.

31. Antibodies vs AntigenAntibodies vs Antigen

32. Steps of a typical ImmuneSteps of a typical Immune
responseresponse
1. A specific antigen type is identified
2. A specific B lymphocyte is identified that can produce an
antibody which will bind to the antigen
3. The B lymphocyte and several identical B lymp. Clone
themselves to increase the number of the same type of B lymp.
4. The newly formed ‘army’ begins antibody production
5. Newly released antibodies circulate in the bloodstream and
eventually find their antigen match
6. Using various mechanisms, the antibodies help eliminate the
pathogen
7. Some of the cloned B lym. remain and give immunity from a
second infection by the same pathogen.

33. HIV invades Helper T-cellsHIV invades Helper T-cells

34. Risk Factors in HIVRisk Factors in HIV
transmissiontransmission
• No risk:
– Skin Contact
– Toilet Seats
– Mosquitoes
• Low Risk:
– Saliva/kissing
– Ingestion
– Childbirth
• High Risk:
– Breast feeding
– -Sexual Intercourse
– -Blood-Blood contact

35. Social Implications ofSocial Implications of
AIDSAIDS
 Social Impacts:
 Discrimination and stigma from those around
 Abuse and harrassment
 May not be able to find work
 May not be healthy enough to work
 Expense of medications bankrupts families
 Risk of spreading in a family or community
 Burden of care for the sick