Download IMMUNE SYSTEM - Roslyn School

IMMUNE SYSTEM
What causes disease?
• Disease is:
a disruption in a human body system that
leads to corresponding disruption in
homeostasis
herpes
• Diseases fall into two categories
1. Noninfectious
2. Infectious
hemophilia
Noninfectious Diseases
• Diseases that cannot be transmitted from
one organism to another
• Examples
– Genetic disorders, heart diseases, most
cancers
Infectious Diseases
• Diseases that are contagious; can be
transmitted from one organism to another
• Examples
– Chicken pox, HIV, cold, strep throat
How are pathogens spread?
1. Air
2. Contaminated Objects/Infected
Organisms
3. Contaminated Food/Water
Salmonella enterica
Bacteria
diplo = double
staphylo = a bunch of grapes/clusters
strepto = are in chains
• Most are harmless
• Pathogenic bacteria cause disease
– Can reproduce in their host and release toxins
– Can produce enzymes that break down the
host’s tissues
Bacterial Diseases
• Bacterial meningitis
– Infection of the fluid surrounding the brain and
spinal cord
– Symptoms: high fever, headache, stiff neck
– May lead to brain damage and hearing loss
WHY?
Stomach Ulcer
• Sore/erosion of the lining of the stomach
• Many are caused by Helicobacter pylori
• Causes burning pain in the abdomen
Peptic ulcer seen under endoscopy
Helicobacter pylori seen
under an electronic microscope
Clostridium botulinum
• botulism
• when eaten - begins to reproduce and
release a toxin that destroys the tips of
nerve cells
• paralysis may result
Lyme Disease
• Spread through insects
• Caused by bacteria: Borrelia burgdorferi
• Attacks the nervous system
– Loss of memory
– Muscle weakness/paralysis
– Tingling/numbness in arms
– Headaches
Pathogen
• Any foreign matter that enters the body
that triggers and immune response
– Virus
– Bacteria
– Prion
Virus
• segments of nucleic acids
• smaller than bacteria
• replicate by infecting susceptible cells and
using them to reproduce more of the virus
• nonliving (do not grow, perform
homeostasis or metabolize)
• covered by a protein coat which may
contain RNA or DNA
– RNA viruses: HIV, influenza, rabies
– DNA viruses: warts, chickenpox,
mononucleosis
Replication of a virus
•
Lytic cycle: cycle of viral infection,
replication and cell destruction
• viral genes have entered a cell and use
host cell to replicate these genes and
make proteins
• proteins are assembled to make new
viruses
• host cell is broken open and newly made
viruses are released
• Lysogenic cycle: viral genome replicates
without destroying the host cell
• viral gene inserts itself into the host
chromosome (provirus)
• whenever the cell divides, the virus also
divides (resulting in two infected cells)
• in some lysogenic viruses, a change in the
environment can cause the provirus to
enter into the lytic cycle
•
•
• Viruses are often restricted to certain
types of cells
• flu attacks cells of the upper respiratory
tract
• HIV attacks white blood cells (body’s
immune system cells)
• Prions: infectious particles that are
composed of proteins but NO nucleic acid
(they cause infection by influencing how a
protein folds into shape)
• mad cow disease
First Line of Defense (nonspecific)
• Skin, sweat, & saliva
– Contain chemicals that kill or inhibit some
bacteria
• Mucus
– Covers internal membranes and traps
pathogens
• Stomach acid
– Destroys pathogens in food
Preventing Entry
• Throat, mouth, and nose has mucus
coatings
– Trap foreign material
– Skin protects our body a great amount
Non Specific Immune
Responses
• Occurs when the body has become
infected by a pathogen
– Fever
– Inflammation
– Activation of specific proteins to kill the
pathogen
Fever
• Normal temp 97.8-99 degrees farenheight
• 103 can kill the pathogens
• 105 can be fatal
– Why can a fever this high be fatal?
Inflammation
• During an infection cells and chemicals
that attack and destroy pathogens gather
around
• Histamines
– Chemical
– Blood vessels dialate- Increased blood flow
causes swelling and redness
Specific Immune Responses
• Most pathogens are destroyed by the
general immune responses
– White blood cells target a particular invader
• Macrophages
– White blood cell
– Destroys pathogens
– Engulfs the pathogens
Invader surface
• Contain antigens on the surface of the cell
– Composed of proteins
• Every antigen has a corresponding
antigen receptor on the surface of a white
blood cell
What else does this remind you of?
Activation of the Immune
System
• A specific immune response is triggered
by a helper t cell recognizing an invader
• Helper t cells coordinate two responses.
– Destroy infected cells
– Clean up pathogens
– Helper t cells have specific antigen receptors
– Releases chemicals with allow other white
blood cells to locate the pathogen
Long-Term Protection
• Preparation for future invasion my the
same pathogen
• Memory cells
– Carry antigen receptors to the target antigen
– Continues to circulate after the infection is
over
• Building an immunity
Vaccine
• Dead or weakened form of a virus
• Do not trigger a general immune response
• Causes the white blood cells to produce
specific antibodies to the pathogen and
causes memory cells to form
Acne
• Results when hair follicles become clogged with
oil, dead skin cells and bacteria
– whitehead: closed clogged up pore
– blackhead: open, clogged pore
– Pimples: small infection where bacteria entered
• Bacteria produce toxins that attract WBCs
• If a pimple bursts, there is an open wound
(where more bacteria can enter)
Viruses
• Cannot reproduce on their own
– Are they living?
• Use a living organism to reproduce
– Damages the host’s cells
http://www.youtube.com/watch?v=chtTYBCvHa8
http://video.nationalgeographic.com/video/swine-flu-
Bacteria
•
•
•
•
•
prokaryotes (lack nucleus)
single cell
circular DNA
reproduce by binary fission
flagella allows them to move (spins in a
circle)
• most have a cell wall
Bacteria cause disease
• Heterotrophic bacteria
– obtain nutrients by secreting enzymes that break
down complex organic structures and absorbing them
• Tuberculosis: mycobacterium tuberculosis
infects lung tissue and grows using the lungs
nutrients
– coughing up blood and sputum, chest pain, fever,
fatigue, weight loss, loss of appetite
• Bacteria can also secrete toxins (chemicals)
Antibiotics
• interfere with cellular process of bacteria
(since these processes do not occur in
viruses, they are ineffective against them)
Immune Disorders
• Allergy
– Overreaction to an antigen that is not normally
harmful
• Histamine is released by infected cells causing
inflammatory response
• Autoimmune Diseases
– Body fails to recognize some of it’s cells as
“self”
• Type I diabetes, multiple sclerosis, Graves disease
Organ Transplant
• Rejection
– The body does not recognize the new organ
as “self” and launches an attack against it
• People who receive transplants are given
immunosuppressants
– Body may be more
susceptible to infection
- Rejection can still occur
AIDS (Acquired Immune Deficiency
Syndrome)
• HIV (human immunodeficiency virus)
– Infects helper T cells
• Can remain dormant (not reproducing) for years
– Active stage
• Virus reproduces, spreads and destroys T cells
• Weakened immune system
• Symptoms of AIDS
– Swollen lymph glands, fever, weakness,
weight loss
lytic
cycle
Viruses enter host
1. Virus’s genetic material enters the host
cell
2. Virus uses host cell to reproduce its own
genetic material and make proteins
3. Proteins are assembled with viral DNA to
make new viruses
4. Host cell dies and breaks open, releasing
new viruses
Chicken Pox
• caused by Varicella zoster
• characterized by red, itchy spots
• spreads through air (droplets) or through
direct contact