Immune System Notes

Pathogen

any disease-causing organism or agent

• foreign infections/microbes that cause sickness and disease

Antigen

a foreign substance that causes an immune response

What are some examples of antigens?

toxins or chemicals from bacteria, viruses, or other substances outside the body like Covid protein spikes

What is one example of an exception of an antigen (non-foreign antigen)?

Proteins on surface of RBC that gives you blood types

Acellular

not made of cells

What are some examples of acellular pathogens?

viruses and prions

Prions (give an example)

improperly folded proteins ex: Mad Cow Disease

What are some examples of cellular pathogens?

bacteria, fungi, protoctista, worms (flatworms, roundworms)

What are six ways you can get infected with pathogens?

• air (droplets)

• water

• direct contact (touch, wounds, etc.)

• insects

• food

• sexually transmitted

What is always the first line of defense to prevent infection?

Physical barriers

• intact skin

• mucus membranes

Mucus membranes

trap infection in places like lungs and nasal passages

What is the second line of defense to prevent infection?

Chemical barriers (antimicrobial substances)

What are some examples of chemical barriers?

acidic conditions, enzymes, lysosomes, microbiological environment

What is an example of an acidic condition?

Condition In the stomach

Where can enzymes be located?

saliva and the gut

Where can lysozymes be located?

sweat and tears

What is an example of a microbiological environment?

gut flora

Gut flora

cover the surface of the gut and prevent infection from getting in

What are some examples of immune cells (lymphocytes)

Macrophages, Helper T cells, Cytotoxic T cells, and B cells

How do macrophages move to get to sites of infection?

They use amoeboid movement

What do macrophages do?

recognizes pathogens and engulfs them

How do macrophages engulf pathogens?

By endocytosis

How do macrophages digest the pathogens?

Digest using enzymes from lysosomes

What can macrophages turn into?

Can become into antigen presenting cells

What do antigen presenting cells display?

Displays pieces of pathogen protein on cell surface

What do macrophages look for?

Look for helper T, B cells that “fit” antigen

How are Helper T cells activated?

activated by specific antigens

What is the main function of Helper T cells?

Carry pieces of antigens until the correct B cell is located

Do helper T cells kill the pathogen themselves?

No

What is the main function of Cytotoxic T cells?

directly kill pathogens like viruses and cancer cells

How are B cells activated?

When either a phagocyte or T cell present an antigen

What occurs after a B cell is activated?

It undergoes repeated mitosis and gets cloned many times

What two types of cells that B cells can turn into?

Plasma and memory cells

Plasma cells

produce and secrete large concentrations of specific antibodies into the blood

Memory cells

stay in the blood and cause a faster immune response the next time that antigen is encountered

Why is there a faster immune response with memory cells?

Antibody production is faster with the second exposure to the same pathogen (why we get vaccinated)

Antibody

Y shaped molecules made of 4 polypeptide chains that are joined together by disulphide bonds; made by plasma B cells

What is the purpose of cloning B and helper T cells?

allows rapid generation of specific immune cells to fight infection

Which type of B lymphocyte produces antibodies?

Plasma B cells

What is the shape of an antibody?

Y shaped

Which type of B lymphocyte protects you against getting reinfected by the same pathogen?

memory cells

Vaccine/vaccination

a small amount of antigens or genetic material is injected and triggers antibody production

What are some examples of antigens/genetic material in vaccines?

Heat killed particles of a pathogen, RNA, etc.

Does a vaccine trigger the disease to occur?

Triggers immunity without causing the disease

How does the immune system react to a vaccine?

Reacts as though you have been infected and makes B cells, antibodies, memory cells, etc.

Why is the second immune response always faster?

Because memory cells exist

What occurs if a virus mutates quickly?

Viruses like the common cold, flu can mutate which then causes memory cells to fail to recognize the new antigen, making you sick

Why is the first immune response always slower?

since B cells must be located before antibodies can be made

Which two cells locate B cells?

Macrophages and helper T cells

Zoonosis

process of a non-human disease spreading to humans ( or any disease from one to another species); usually more dangerous to the species it spreads to

What are some examples of pathogens that transferred to humans by zoonosis?

HIV, bird flu, swine flu, COVID, tuberculosis (from cows), and rabies (many animals)

Herd immunity

transmission of pathogens is slowed if a sufficient percentage of a population is immune to a disease

How does herd immunity form?

By getting sick or vaccination

What is the effect of a population for herd immunity?

members of a population are interdependent in building herd immunity

What happens when there is less people in the “herd’ for herd immunity?

The preventable disease will spread

Label A in terms of a antibody production and response graph

time

Label B in terms of a antibody production and response graph

antibody concentration

Label C in terms of a antibody production and response graph

Primary immune response (low affinity) antibodies

Label D in terms of a antibody production and response graph

Secondary exposure

Label E in terms of a antibody production and response graph

Secondary immune response (high affinity) antibodies

Innate (non-specific) immunity

phagocytes ingest or attack anything foreign

Adaptive (specific) immunity

(I.e. B cell, helper T)

• immunity against a specific antigen/pathogen

• antibodies and memory cells made

• improves efficiency of immune system

What are the two chemical equations for blood clotting?

Clotting factors (catalyst)

Prothrombin (inactive) → Thrombin (enzyme and active)

Thrombin (catalyst)

Fibrinogen (inactive) → Fibrin (insoluble protein fibers and active)

Fibrin (what is its main function?)

forms a mesh over the wound that traps platelets and blood cells to form a scab