KEY CONCEPT Germs cause many diseases in humans. - PowerPoint PPT Presentation

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KEY CONCEPT Germs cause many diseases in humans.

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Title: PowerPoint Presentation Author: McDougal Littell Last modified by: Stephanie Resillez Created Date: 9/14/2006 4:17:10 PM Document presentation format – PowerPoint PPT presentation

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Title: KEY CONCEPT Germs cause many diseases in humans.


1
KEY CONCEPTGerms cause many diseases in humans.
2
Germ theory states that microscopic particles
cause certain diseases.
  • Germ theory proposes that microorganisms cause
    diseases.
  • proposed by Louis Pasteur
  • led to rapid advances in understanding disease

3
  • Kochs postulates support the theory.
  • Disease-causing agents are called pathogens.

4
There are different types of pathogens.
  • Bacteria are single-celled organisms.
  • cause illness by destroying cells
  • release toxic chemicals

5
  • Viruses are genetic material surrounded by a
    protein coat.
  • force host cells to make more viruses
  • very small

6
  • Fungi can be multicellular or single-celled.
  • take nutrients from host cells
  • occur in warm and damp places

7
  • Protozoa are single-celled organisms.
  • use host cells to complete their life cycles
  • take nutrients from host cell

8
  • Parasites are multicellular organisms.
  • grow and feed on a host
  • possibly kill the host

9
  • Different pathogen cause common infectious
    diseases.

10
Pathogens can enter the body in different ways.
  • Pathogens can be transferred by direct or
    indirect contact.
  • Indirect contact does not require touching an
    infected individual.
  • touching an infected surface
  • breathing in infected air

11
  • Vectors carry a pathogen and transmit it into
    healthy cells.
  • Direct contact requires touching an infected
    individual. Includes
  • kissing
  • sexual intercourse
  • hand shaking

tick
12
KEY CONCEPT 31.2The immune systems consists of
organs, cells, and molecules that fight
infections.
13
Many body systems protect you from pathogens.
  • The immune system is the body system that fights
    off infection and pathogens.
  • Many other tissues and systems help the immune
    system.
  • Skin is a physical barrier to infection.
  • Mucous membranes trap pathogens entering the
    body.
  • The circulatory system transports immune cells.

14
Cells and proteins fight the bodys infections.
  • White blood cells attack infections inside the
    body.
  • Phagocytes engulf and destroy pathogens.
  • T cells destroy infected cells.
  • B cells produce antibodies.

15
  • Three types of proteins fight off invading
    pathogens.
  • Complement proteins weaken pathogen membranes.
  • Antibodies make pathogens ineffective.
  • Interferons prevent viruses from infecting
    healthy cells.

16
Immunity prevents a person from getting sick from
a pathogen.
  • In all immunity, pathogens are destroyed before
    you get sick.
  • Passive immunity occurs withoutan immune
    response.
  • mothers milk
  • genetics
  • Active immunity occurs after aspecific immune
    response

17
KEY CONCEPT 31.3The immune system has many
responses to pathogens and foreign cells.
18
Many body systems work to produce nonspecific
responses.
  • Nonspecific responses are the same for every
    pathogen.
  • In inflammation, blood vessels become leaky.
  • white blood cells movetoward infection
    anddamaged tissue
  • characterized by swelling, redness, and pain

19
  • In fever, body temperature increases.
  • Low fevers stimulate white blood cells to mature.
  • High fevers can cause seizure, brain damage, and
    even death.

20
Cells of the immune system produce specific
responses.
  • Specific immune responses begin with the
    detection of antigens.
  • Antigens are surface proteins on pathogens.
  • Each pathogen has a different antigen.

21
  • There are two specific immune responses.
  • Cellular immunity uses T cells to destroy
    infected body cells.

22
  • There are two specific immune responses.
  • Humoral immunity uses B cells to produce
    antibodies.

23
  • Both responses produce memory cells.
  • specialized T and B cells
  • provide acquired (active) immunity

24
The immune system rejects foreign tissues.
  • Tissue rejection occurs in organ or tissue
    transplants.
  • Tissue rejection is the result of an immune
    response.
  • immune system detects protein markers on the
    donor tissue
  • makes antibodies against the donors tissue

25
KEY CONCEPT 31.4Living in a clean environment
and building immunity help keep a person healthy.
26
Many methods are used to control pathogens.
  • Antibiotics and antiseptics cause pathogens to
    burst.

27
  • Antiseptics kill pathogens outside of the body.
  • do not target specific pathogens
  • examples include vinegar and soap
  • Antibiotics kill pathogens inside the body.
  • target one specific bacterium or fungus
  • not effective against viruses

28
  • Antibiotic resistance can cause medicines to
    become ineffective.
  • Some bacteria in a population have genes that
    make them immune to antibiotics.
  • These bacteria spread the gene, making the
    antibiotics useless.

29
Vaccines artificially produce acquired immunity.
  • Vaccines also control pathogens and disease.
  • given to prevent illness
  • contain the antigen of a weakened pathogen

30
  • Vaccination provides immunity.
  • stimulates a specific immune response
  • causes memory cells to be produced
  • allows immune system to respond quickly to
    infection
  • has such a fast response, a person will not get
    sick

31
KEY CONCEPT 31.5An overactive immune system can
make the body very unhealthy.
32
Allergies occur when the immune system responds
to harmless antigens.
  • An allergy is an response to a harmless antigen.
  • Allergies are caused by allergens.
  • Allergens are antigens that cause an allergic
    reaction.
  • Allergens cause inflammation responses.

33
  • There are many different allergens.
  • food, e.g. peanuts, milk, wheat, etc.
  • airborne, e.g. pollen, dust mite feces, mold,
    etc.
  • chemical, e.g. nickel, medicine, bee stings, etc.

34
  • Allergens can cause anaphylaxis.
  • Anaphylaxis is an extreme inflammation response.
  • Blood vessels and airways become too porous.
  • If not treated immediately, anaphylaxis can cause
    death.

35
In autoimmune diseases, white blood cells attack
the bodys healthy cells.
  • Autoimmune diseases are failures of the immune
    system.
  • White blood cells cannot recognize healthy cells.
  • White blood cells attack healthy body cells.
  • Tissues fail because of attack.

36
  • There are over 60 autoimmune diseases.

37
KEY CONCEPT 31.6When the immune system is
weakened, the body cannot fight off disease.
38
Leukemia is characterized by abnormal white blood
cells.
  • Leukemia is cancer of the bone marrow.
  • characterized by immature white blood cells
  • causes weakened immune system

39
  • Leukemia leads to opportunistic infections.
  • occur because white blood cells cannot fight
    infections
  • if immune system were healthy, would fight these
    infections

40
HIV targets the immune system.
  • The human immunodeficiency virus (HIV) is a
    retrovirus.
  • attacks and weakens the immune system
  • is transmitted by mixing infected blood with a
    bodily fluid

41
  • HIV infection leads to AIDS.
  • HIV reproduces in and destroys T cells.
  • The body cannot replace T cells fast enough.
  • T cells cannot help in immune responses.

42
  • AIDS is acquired immune deficiency syndrome.
  • several opportunistic infections
  • very low amount of T cells
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