Unit 5: Protection and Control

The Three Lines of Defense

•What is the immune system?

•What are our bodies protecting us against?

What is the Immune System?

• Helps protect our bodies against foreign invaders called pathogens

Pathogens

• Anything trying to cause disease, such as:• Viruses

• Bacteria

• Fungus

• Parasites

• These can be found anywhere so our bodies must have major defenses to protect us.

How Do Pathogens Make us Sick?

• Some pathogens, like bacteria, may release toxins that destroy healthy cells.

• Other pathogens, like viruses, enter the body cells and use the cell's machinery to replicate itself.

• Sometimes, damaged or dead body cells can become harmful to the other cells.

How can pathogens spread?

Contaminated water and food

• Coughing• Sneezing

• Needles• Bodily fluids• Bites/stings

• Human to humancontact

• Human to animalcontact

Types of Defences

• Non-Specific Defences (AKA Innate immunity) • Respond to many pathogens

• Specific Defences (AKA Adaptive immunity) • Target specific pathogens

First-Line (non-specific) Defences

• First-Line Defenses = physical and chemical barriers• Skin ̶ barrier to infection

• Sweat- flushes out bad bacteria

• Tears Contain chemicals

• Saliva that kill pathogens

• Mucus ̶ traps pathogens

First-Line (non-specific) Defences

• Cilia- fine hairs lining the windpipe that move the mucus and trapped particles away from the lungs

• Stomach acids ̶ destroy pathogens present in food

• Urine- flushes out pathogens from the bladder

• “Friendly” (beneficial) bacteria- stop other harmful bacteria from taking over

Second-Line (non-specific) Defences

• First line of defences is broken

• Inflammatory response (5 sequence)• redness, swelling, warmth, pain, and loss

of function in the area of infection

• Damaged cells release chemicals • influx of blood to the area carrying

macrophages – giant white blood cells that ingest large numbers of bacteria (phagocytosis).

Second-Line (non-specific) Defences• A mixture of phagocytes, dead cells, bacteria, and body fluids collects in the

wound producing pus.

• Pus drains or is absorbed by the body, pathogens are destroyed, the inflammation goes away, and the wound heals.

Third-Line (specific) Defences

• The immune response – when the inflammatory response is insufficient the pathogen is specifically targetedfor destruction.• recognizes, attacks, destroys, and

remembers pathogens that enter the body.

• It does this by producing antibodies and specialized cells that bind to and inactivate pathogens.

Antibody vs Antigen

Antibody• Proteins in blood that bind to

antigens to destroy them

Antigen• Any foreign substance that can

cause an immune response (e.g. bacteria, viruses)

The Immune Response

• Immunity• The ability of the body to identify

and fight infections through the production of antibodies

Two Types of Immunity

• Active Immunity – the body produces its own antibodies and killer cells.

• Passive Immunity – a person is given the antibodies or antibiotics to fight the disease in the form of medicine (ex: penicillin).

Recap

• https://www.youtube.com/watch?v=PSRJfaAYkW4

Unit 5: Protection and Control

The Immune Response

What is the immune system?

• All the parts of the body that are involved in the recognition and destruction of foreign materials.

• Immune system is made up of:• Bone marrow

• White blood cells (phagocytes and lymphocytes)

• Various tissues of the lymphatic system (lymph nodes, tonsils, thymus and spleen)

Immune System

• The immune system provides immunity, the ability for the body to fight off infection through the production of antibodies or cells that inactivate foreign substances or cells.

• The basis of the immune system lies in the body’s ability to distinguish between its own substances or “itself”, and foreign substances “non self”.

What do we do?

• Your body recognizes antigens as foreign substances such as germs or pathogens which act like threats that may disrupt the normal functioning of your body.

• In order to stop this disruption, your body produces antibodies to protect itself and destroy the antigens and the antigen-producing pathogens

Antigens

• Any substance that can cause an immune response

• Viruses and microorganisms have substances on their outer surfaces that are antigens.

• Antigens are threats!

• Our bodies will attempt to destroy antigens.

• Examples: • Viruses

• Microorganisms

• Tissues from other humans (transplants and blood donations)

Antibodies

• Type of protein in the blood produced by leukocytes

• Identifies and defends against antigens by binding to them, blocking their effect, and marking them for destruction by other white blood cells

• Each antibody is designed for a specific antigen

The Lymphatic System

• A series of vessels throughout the body that drains fluid (called lymph) from tissues and empties it back into the bloodstream.

• Main role= filter out foreign substances and cell waste from the body

• Produces a types of white blood cell called lymphocytes

Lymph Nodes

• Filter foreign matter from lymph

• Cells in the lymph nodes phagocytise, or eat:• Bacteria

• Old red blood cells

• Toxic waste

• Cell waste

• Valves to prevent backflow

• Moved along by squeezing action of smooth and skeletal muscle

• Clean lymph is returned to blood

Tissues of the Lymphatic System

• Spleen• Destroys old cells and other substances.• Makes lymphocytes.

• Thymus• Controls lymphocyte production and antibody

making.• Makes lymphocytes

• Bone marrow• Makes lymphocytes

• Tonsils and Adenoids• Make lymphocytes

Lymphocytes

• Lymphocytes are white blood cells that recognize specific antigens and either produces antibodies or kill foreign cells directly.

2 Types of Lymphocytes

• B lymphocytes (B Cells)

• T lymphocytes (T Cells)

• Both B and T cells are produced in the bone marrow.

• B cells remain in the marrow and mature there, while T cells mature in the thymus gland.

Primary Immune Response

• When an antigen enters your body for the first time, your immune system undergoes a primary immune response.

• During the first five days following exposure to an antigen, no measurable amounts of antibodies or specialized immune cells are present.

• Over the next 10-15 days there is gradual rise of these products.

Secondary Immune Response

• If the same antigen enters the body another time, a more rapid secondary immune response happens.

• Within 1-2 days after infection, high levels of antibodies or specialized immune cells are present in the blood.

Immune Responses 1 & 2

• Whether primary or secondary response- it will involve two categories of reactions.

• 1. involves specialized B cells that produce antibodies (antibody immunity)

• 2. involves specialized T cells that attack foreign cells directly. (cellular immunity)

B Cells and Antibodies (Antibody Immunity)• Macrophages eat antigens

and displays it on cell surface.

• B cells get stimulated by helper T cells that recognizes the antigen.

• B cells divide to make plasmacells and memory B cells.

• Plasma cells make antibodiesthat bind to antigens.

B Cells and Antibodies

• This attracts other phagocytes that eat and destroythe antigen-antibody complex.

• Suppressor T Cells release substances that slow down and stop plasma cells from making antibodies once infection has been stopped.

Memory B Cells

•Plasma cells live only a few days.

•Memory cells produced by B Cells can live for a lifetime.

•Produce secondary immune response when same antigen enters body again.

T Cells and Immunity (Cellular Immunity)

•When antigen is virus infected cell or cancer cell, a single T Cell recognizes antigen on the cell.

•Helper T Cell tells the T Cell to divide into Killer T Cells and Memory T Cells.

•Killer T Cell binds to antigens and makes it burst.

• Suppressor T Cells shut down Killer T Cells.

Types of Immunity

Active Immunity

• Body produces antibodies or killer T cells to attack antigens

Passive Immunity

• A person is given antibodies from another person or an animal.

• “Borrowed” Immunity

Active Immunity

•A result of having had a disease. (ex: Chicken Pox)

•Memory cells remain in body.

•Vaccination • Dead or weakened bacteria or virus given to patient.• Causes immune response, but too weak to cause disease.• Results in creation of Memory cells.

Passive Immunity

• Temporary (about a month)

•Body then destroys borrowed antibodies.

•Maternal immunity: • Antibodies from mother enter baby’s blood before birth.• Mother’s milk.

• Injection of certain antibodies when travelling.

Allergies

• High sensitivity reaction to normally harmless substances.

• Treats allergen like invader.

• Releases histamine: watery eyes, itching, sneezing, runny nose.

• Ex: pollen, molds, insect stings, dust, animal dander, foods, medications.

• Can be fatal

https://www.youtube.com/watch?v=sqrnShjM4II

Unit 5: Protection and ControlBacteria and Viruses

Similarities•Both are types of microbes (a microorganism)

•Both are spread by things such as:•Coughing/sneezing (influenza, tuberculosis, strep

throat)

Similarities

•Contact with infected people (syphilis, gonorrhea, chlamydia)

Similarities

•Contact with contaminated food and water(cholera, salmonella, E coli)

Similarities

•Contact with infected creatures (pets, livestock)(anthrax, swine flu)

Microbes can cause:

•Acute infections (short-lived).

•Chronic infections (can last a few weeks).

• Latent infections (may not experience any symptoms at first, but can reactivate over a period of months and years).

•Most importantly bacterial and viral infections can cause mild, moderate, and severe diseases.

The Difference Between Bacteria and Viruses

1. Bacteria:•Are complex, single-celled

creatures with a rigid wall and a thin, rubbery membrane surrounding its fluid filled inside.• They can reproduce on their

own.

https://www.youtube.com/watch?v=kxM_9DL2GYw

The Difference Between Bacteria and Viruses

•Most are harmless- we have good bacteria in our gut to help with digesting food, destroying disease-causing microbes, fighting cancel cells and providing us with nutrients.• Some are harmful- some bacteria invade the body,

use up its resources, destroy tissues, reproduce rapidly, release toxins

https://www.youtube.com/watch?v=kxM_9DL2GYw

The Difference Between Bacteria and Viruses

2. Viruses:•much smaller.• They have a protein coat and a core of genetic

material • (RNA or DNA)

https://www.youtube.com/watch?v=s-HThHRV4uo

https://www.youtube.com/watch?v=8FqlTslU22s

The Difference Between Bacteria and Viruses• They cannot survive without a host.

• They can only reproduce by attaching themselves to cells.

• They often take over their host cells- tricking them into making new viruses until the cells burst and die.

https://www.youtube.com/watch?v=s-HThHRV4uo

https://www.youtube.com/watch?v=8FqlTslU22s

How can they be treated?

•Often it is difficult to determine the origin of an infection because a lot of the same illnesses can be caused by either bacteria or viruses.• Examples: pneumonia, meningitis, pink eye

• All can be viral or bacterial

Antibiotics!

• Huge breakthrough in medical history• In 1928, Alexander Fleming

discovered penicillin, a mold that kills bacteria

Did you know…

•Antibiotics only treat *BACTERIAL INFECTIONS*.

•Unfortunately bacteria are very adaptable and the overuse of antibiotics has made them resistant to antibiotics.

•Antibiotics *ARE NOT*effective against viruses

What are vaccines?

• Complete the vaccines worksheet

What deadly disease has been globally eradicated?

HIV/AIDS

• HIV (human immunodeficiency virus)• Virus that attacks the body’s immune system, specifically helper T cells, which

help the immune system fight off infections.

• AIDS (acquired immune deficiency syndrome)• The most severe phase of HIV infection. People with AIDS have such badly

damaged immune systems that they get an increasing number of severe illnesses, called opportunistic infections.

https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/what-are-hiv-and-aids

How Do People Get HIV?

• HIV spreads when infected blood or body fluids (such as semen or vaginal fluids) enter the body.• during sex (especially anal sex and vaginal sex)

• through sharing needles for injecting drugs or tattooing

• by getting stuck with a needle with an infected person's blood on it

HIV is NOT spread through:

• pee, poop, spit, throw-up, or sweat (as long as no blood is present)

• coughing or sneezing

• holding hands

• sharing eating utensils or drinking glasses

https://kidshealth.org/en/teens/std-hiv.html

• https://www.youtube.com/watch?v=0TipTogQT3E