Worksheet 14

1. Which of the following statements is incorrect? The lymphatic system, unlike the circulatory system is a one-way

system Eosinophils are phagocytic cells involved in the innate immune

response When infected with a pathogen, the innate immune response will

often work in coordination with the adaptive immune system T cells must identify self and non-self to bind None of the above

2. What is the correct sequence of the following events after a pathogen enters the body?

i. Fluid from the capillaries comes towards the pathogen and causes swelling and redness

ii. Chemical messengers are released by the mast cells in tissuesiii. Macrophages engulf bacteria and release chemical messengers iv. Influx of phagocytic cells destroys bacteria v. Pus is removed

I, II, III, IV, V II,III, I, V, IV III, II, I, IV, V II, III, I, IV, V IV, II, III, IV, V

1. II and III happen at the same time

3. Which of the following is incorrectly paired to its function? MHC II- allow communication between the cells involved in immunity B lymphocytes- find and release antibodies to destroy pathogens

floating freely in the fluids of the body Natural killer cells- to kill viruses in the body through phagocytosis Mast cells- to initiate an inflammatory response that draws the

immune system to the site of the pathogen Toll like receptors- to identify structural elements common to non-

self things and signal an inflammatory response as a result

4. Describe the function, structure, and locations of the lymphatic system. How is it different than the circulatory system?

• Series of vessels throughout body- one way system• Picks up excess water • Moves fats• Dumps it back into circulatory system through right thoracic duct-

subclavean vein• Doesn’t have arteries, does have veins and capillaries. • Capillaries are parallel to the capillaries in the circulatory system• Has valves and uses skeletal muscle• Fluid is called lymph• Along this system, there are lymph nodes- structures that traps nasty

things • If you cut one open its like a little mesh or trap with loads of

antibodies• Often times where cancer can be detected or found here• Other organs have lymphoid cells as well- defensive bodies• Tonsils are one of them- first line of defense after the mouth• Spleen, appendix, payer’s patches in the small intestine, and the

thymus are others with lymphoid system• 43.2

This chart should serve as a guide to this next bit of the material

5. What are some of the mechanisms in place in external innate immunity? How do each of these work?

Innate immunity is much less specific, happens in all animals from the moment they’re born, not dependent on identification of pathogen

Recognizes traits shared by many many pathogens Barrier defenses- skin is an example of that- there are many many

friendly bacteria who live on your skin who kill bacteria who try to compete for their resources

Secretions- our skin has oil and sweat glands that can trap or kill bacteria

Saliva has antimicrobial properties, HCl in your stomach Mucus membranes- sticky stuff that traps bacteria- doesn’t really kill

anything

6. Describe the process of phagocytosis.

A pathogen is surrounded by an outcropping of the plasma membrane

This plasma membrane is activated by receptors on the surface Eventually completely encircles the pathogen to form vacuole-like

phagosome Phagosome is then fused with a lysosome that contains some nasty

chemicals like hydrogen peroxide that destroy anything and everything inside

Resulting waste is eventually removed from the area as pus

7. What mechanisms are in place in the internal innate immune system? Discuss each.

Neutrophils are phagocytic cells that will do endocytosis to a pathogen

Brings it in through a vacuole, fuses lysosome with vacuole, kill pathogen

Monocytes are macrophages- live longer and are next line of defense Eosinophils- come in and get next to parasite and blast it with poisons There is a theory that we now don’t have as many parasites, and that

therefore the eosinophils attack allergens instead Dendritic cells- out in the tissues- help stimulate aquired immunity

There are many things that bacteria have that we don’t Toll like receptors find things in cells that aren’t like us- causes cells to

attack and kill Bacteria have polypeptoglycans- something no eukaryotes have Flagella made of flagellin rather than microtubules Double stranded RNA or RNA as genetic material- virus- attacks Can find these things both inside and outside cells

Natural killer cells don’t go after microorganism directly

Kill viral cells or cancerous cells by causing them to lyse- this kills whatever is infecting it as well

Viruses and cancer cause changes that can be detected by the body Antimicrobial proteins- 2 types Interferons- involved in viral infections- viral cell sends out

interferons- signals other cells to raise defenses and tells phagocytes to kill the cell

Complement system- more than 30 different proteins that are always out in body in zymogen form that get activated and poke holes in cells that are bad

Can be activated by anything in the non-specific innate immunity, but can also be activated in acquired immunity

But more than any one specific one of these defenses working by itself, it is the way they all work together that makes our immune system so effective. Think about how often you really get sick. And then think about how many bugs are all trying to take your resources at all times. The immune system is an incredibly efficient system when taken as a whole.

Bacteria and viruses cause you harm in 2 ways- kill cells directly though secreting toxins or by taking away resources

Pathogens enter the body Basophils come in and release histamine Mast cells in the tissue also release histamine Direct response of histamine is to cause vasodilation (larger vessels-

more blood) Indirect response of more blood flow- area gets red, gets hot,

capillaries get leaky – swelling Immune system uses a lot of chemical signaling- cytokines After histamine comes in, basophils and the rest of the white blood

cells come in to do macrophagy, lots of casualties on both sides causes pus, eventually gets cleaned up

The body also will induce fever to help fight infections There is a peptide called interleukin 1 that is released from

macrophages- goes up to the thalamus and raises the temperature of your body

Bacteria is very temperature sensitive- makes it tough for them to survive

High fever is dangerous because it denatures proteins, but a little fever is good because it helps fight against bacteria

Prostaglandins are helpful because they increase blood flow and temperature in body

Aspirin shuts down prostaglandins- reduces fever and inflammation

8. How do B and T cells come to be? 2 types Humeral response - B lymphocytes making antibodies This is activated by free floating pathogens in fluids of the body Other is cell mediated response- T cells Lymphocytes are main cell in this Come from bone marrow- lymphocyte stem cells are made, if it goes

to the thymus- it becomes a T cell, if it stays in Bone- B cell these cells are all specific to a single pathogen Mature B or T cells have antigen receptors These things recognize the foreign cells Antigen stands for antibody generator- anything that causes

antibodies to be made Can be a protein or part of protein or carbohydrate or any other

molecule- this molecule is called an antigen determinant or an epitope

9. Describe the MHC markers, why we have them, how they work, and how class I and II are different.

• T cells kill stuff that’s inside your cells • T cells must have BOTH self- and nonself- to be activated• Infected cells must take antigen from pathogen and attach it to MHC (major

histocompatibility complex) molecule on the outside of the cell• Self awareness of the embryo starts very very early• There are identifying markers present on every cell- there are 20 genes and

over 100 alleles• MHC’s are what you have to match when doing an organ transplant • There are 2 MHC classes- class 1 are found on every single cell in your body

except RBC- differentiate self from non-self• Class 2- found only on immune cells- critical in communication between

immune cells