Transcript Your Immune System longx

Chapter 31. 1-3
You need to know
 Germ theory is the idea that certain microscopic
particles may cause diseases.
 Pathogen – disease causing agent
 There are different types of pathogens that cause many
different kinds of disease.
 Pathogens can enter the body in different ways.
5 Main Pathogens
 Bacteria – single-celled organisms. Release chemicals
that are toxic. Can destroy healthy body cells. (Food
Poisoning)
 Viruses – disease-causing strands of DNA and RNA
surrounded by protein coats. Take over healthy cell
and make more viruses.
 Fungi – multicellular or single. Piercing healthy cells
and take the cells nutrients. (Athlete’s foot)
Common Bacterial Pathogen – E. Coli
Food borne illness that can cause many
gastrointestinal issues. Reproduces very quickly, so not
much is needed to cause infection.
A Viral Pathogen – Zika Virus
A relatively ‘new’ and unknown
virus that is connected to the
increased incidences of
microcephaly of children
Common Fungal Pathogen –Cryptococcus
Found in soil in subtropical/tropical regions. Know
to cause infections to skin, soft tissue, lymph nodes,
and bone.
5 Main Pathogens
 Protozoa – single-celled organism that preys on other
cells. (Malaria)
 Parasites – organisms that grow and feed on a host.
Some kill the host and others just drain the body of
nutrients.
Common Parasitic Pathogen – Malaria
This is a small living organism that is causing issues
in other organisms by producing toxins or
chemicals that may be affecting the infecting tissue
Common Protazoan Pathogen – Giardia
muris
Intestinal parasite found in rodents,
birds and reptiles.
Entering the Body
 Pathogens can enter the body directly or indirectly.
 Some pathogens are spread by surviving on non-living
sources and then entering the body.
 Some spread through vectors, or, anything that carries
a pathogen and transmits it into healthy cells.
Our Protection
 The immune system is the body system that fights off
infection and pathogens.
 It includes different “layers” of protection.
 Your skin is the first line of defense. It’s a physical
barrier. It’s oily and sweaty so it can kill some
pathogens.
 Your eyes, nose, ears, mouth, excretory organs have a
mucus membrane and cilia to protect you as well.
White Blood Cells
 If pathogens get past your outer defenses, you use
specialized cells to attack those pathogens.
 White blood cells find and kill these pathogens.
 There are six specialized white blood cells, all have a
particular job.
 If a WBC eats another cell it’s called a phagocyte.
Lymphocytes
 After the phagocytes,
lymphocytes reach the
infection.
 Two kinds of lymphocytes
are T cells and B cells.
 T cells destroy infected
body cells
 B cells produce proteins
that inactivate pathogens
that have not yet infected a
cell.
3 Proteins of Immune System
 Complement proteins – weaken pathogen’s cell
membrane.
 Antibodies – destroy pathogens in a few ways:
 Bind to pathogen’s membrane proteins.
 Cause pathogens to clump together.
 Activate complement proteins.
 Interferons – prevent virus from entering healthy cells.
Immunity
 Passive Immunity – immunity that occurs without the
body’s reaction, you are just born with it.
 Active Immunity – immunity that your body produces
in response to a specific pathogen that is attacking
your body.
 Acquired immunity is when the body doesn’t get sick
from the same disease.
 This is considered a Specific immune response
Chapter 31.3-.5
How your body responds
 Some body systems respond non-specifically
 This means the body will respond the same way no
matter what kind of pathogen it is.
 The immune system produces specific responses
 This means you have special cells that are created to
fight off a particular pathogen.
Non-Specific
 Inflammation
 This where an affected area turns red, swells, itches,
becomes painful and increases temperature.
 This provides more space for white blood cells to work as
well as histamines opening up vessels.
 Fever
 This stimulates to production of interferons and helps to
stop viruses from spreading.
 Remember: Skin and Mucous membranes are non-
specific
Specific
 Specific immune defenses lead to acquired immunity
and they occur at a cellular level.
 Antigens – are markers on the surface of cells and
viruses that help the immune system identify them
 Memory cells – are specialized T and B cells that
remember an antigen that has already been in the
body.
Notice how unique shapes to
the antigens only fit to
particular antibodies. This
means your body needs to
make different ones for
different diseases.
Tissue Rejection
 You don’t always want foreign cells in your body, but
when you do, you want to make sure they don’t get
attacked by your body.
 This is called tissue rejection and is caused by the
protein markers on the new cells causing an immune
response.
Controlling Pathogens
 Keeping an area clean is the best protection
 Heat and chemicals (antiseptics) can kill pathogens
(soap, rubbing alcohol, vinegar)
 Antibiotics – medicines that target fungi or bacteria.
 Antibiotic resistance means there are newer strands of
bacteria/fungi that can survive attacks from
antibiotics.
Vaccines
 Vaccines work to prevent infection, not stop an
infection while it’s occurring.
 We insert the antigen of a pathogen into the body and
your immune system reacts and remember that
specific antigen.
 This makes your immune system capable of fighting
off that disease the next time it comes around.
Overreactions
 Allergy – Is an oversensitivity to a normally harmless
antigen.
 Allergens are what we call those antigens.
 When these allergens are recognized, histamines are
released (this causes inflammation).
 This inflammation isn’t just unnecessary, but
dangerous.
Allergens
 Food allergens – reactions to antigens found in specific
foods (affects 2/100 adults)
 Anaphylaxis – is when airways swell up and vessels to
become porous.
 Airborne allergens – allergens that are breathed in
(usually pollens). Sometimes pet dander and saliva can
cause this as well.
 Chemical allergens – metals (nickel) fairly common.
 These could be based on genetics or environmental
factors (like overexposure to something)
Autoimmune Diseases
 This is when the body’s immune system attacks its
healthy cells.
 More than 60 autoimmune diseases. (Some can be
acquired through pathogens, but many are linked to
genetics)
 Common ones include:
 Rheumatoid arthritis
 Type 1 Diabetes
 Lupus
 Multiple sclerosis (MS)