Download 31.1 Pathogens and Human Illness

13.1 Ecologists Study Relationships
KEY CONCEPT
Germs cause many diseases in humans.
The first lines of defense against invading pathogens
are the body’s nonspecific defenses (it doesn’t matter
what is invading the body, the body will attack it)
31.1 Pathogens and Human Illness
Viruses, bacteria, viroids, and prions can all cause
infection.
1 nanometer (nm) = one
billionth of a meter
100 nm
eukaryotics cells
10,000-100,000 nm
viruses
50-200 nm
prokaryotics cells
200-10,000 nm
viroids
5-150 nm
prion
2-10 nm
13.1 Ecologists Study Relationships
• Fungi, protists, invertebrates also cause
infection
31.1 Pathogens and Human Illness
• Different pathogens cause common infectious diseases.
31.1 Pathogens and Human Illness
Pathogens can enter the body in different ways.
– person-to person
contact
– breathing in infected
air
– animal bite
– contaminated water
– contaminated food
31.1 Pathogens and Human Illness
Many body systems protect you from pathogens.
• Many other tissues and systems help the immune
system.
– Skin is a physical barrier to infection. It releases
sweat, oils, and waxes.
– Mucous membranes trap pathogens entering
the body. Secretes mucus (sticky fluid that traps
pathogens)
31.1 Pathogens and Human Illness
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 move
extracellular
capillary wall
toward infection and
space
damaged tissue
– characterized by
swelling, redness, and
white blood cell
pain
- includes chemical
messengers such as
histamines (increase
blood flow to area)
31.1 Pathogens and Human Illness
The Inflammatory Response occurs
• If blood vessels are damaged – platelets & proteins clot
the blood
• Chemicals releases, attract white blood cells to engulf
pathogens
platelets
blood vessel
fibrin
clot
white blood cell
red blood cell
31.1 Pathogens and Human Illness
• Fever – sign that the body is fighting an infection.
• In fever, body temperature increases.
– Low fevers stimulate white blood cells to mature.
– High fevers can cause seizure, brain damage, and even
death.
31.1 Pathogens and Human Illness
Organs of the immune system
• Bone marrow – soft material found inside long bones
– Makes red & white blood cells & platelets
• Thymus – behind heart
- WBC’s mature here; develop ability
to recognize specific pathogens
• Lymph Nodes – found in neck, arm pit, groin
(“swollen glands”)
- Filter pathogens from lymph (extracellular fluid), contain WBC’s
• Spleen – behind stomach
- Filter & clean lymph of cell
fragments and abnormal tissue,
contain WBC’s
31.1 Pathogens and Human Illness
Cells and proteins fight the body’s infections.
• White blood cells attack infections inside the body.
– Phagocytes engulf and destroy pathogens.
– T cells destroy infected cells.
– B cells produce antibodies.
31.1 Pathogens and Human Illness
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.
antigens
virus
31.1 Pathogens and Human Illness
Immunity
• Being resistant to a specific pathogen
Active immunity:
1. Being infected and survive
2. vaccination
Passive immunity occurs without
an immune response:
1. mother’s milk
2. Genetics
3. Blood transfusion
31.1 Pathogens and Human Illness
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. (allergy
symptoms)
31.1 Pathogens and Human Illness
• 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.
31.1 Pathogens and Human Illness
• 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.
31.1 Pathogens and Human Illness
In autoimmune diseases, white blood cells attack the
body’s 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.
31.1 Pathogens and Human Illness
• There are over 60 autoimmune diseases.