1. Fiona Corkhill, Livy Masuret, Corson Ellis, and Eleanor Medley
The Immune System
Fiona Corkhill, Livy Masuret, Corson Ellis, and Eleanor Medley

2. Background The body’s defense mechanism.
made up of organs and cells that protect the body against foreign invaders such as bacteria and viruses.
Relies on the body’s ability to differentiate between self and non-self.
Livy

3. 3 Lines of Defense
Livy

4. The First Line of Defense
Non Specific Barriers (cannot distinguish between microorganisms) (1).
the skin.
mucous membranes.
hairs and cilia.
tears, sweat and saliva: contain enzymes that can break down bacteria.
Livy

5. Leukocytes generic term
WBC’s: lymphocytes, monocytes, neutrophils, macrophages, eosinophils, basophils
Produced and stored in many locations that are called lymphoid organs such as the thymus, spleen, and bone marrow (6).
Lymph nodes throughout the body also house leukocytes (6).
They circulate through lymphatic and blood vessels.
The 2 types of leukocytes are phagocytes and lymphocytes (7).
fionaswAg

6. Phagocytes White blood cells
White blood cell chasing a bacteria and eventually engulfing it
White blood cells
Rush to the site of infections and engulf and destroy the invading bacteria: uses phagocytosis (type of endocytosis where the cell eats)
Distinguishes self and not-self via marker proteins in the cell membrane.
Digest other cells, microorganisms, and other foreign bodies (via phagocytosis) (1).
Also eat dead or diseased cells (5).
3 types: granulocytes, macrophages, dendritic cells(6).
Corson Ellis

7. Second Line of Defense Blood System
produces white blood cells in bone marrow and transports them to the site of the infection
distributes cells through arteries, capillaries, and veins
Lymphatic System
protects and maintains the internal fluid environment
filters lymph which contains white blood cells at the lymph nodes, where the pathogens are removed and antigens are presented to T cells (6).
fionaswag

8. The Second Line of Defense (continued)
Still Non-Specific
Complement System/Inflammation
Releases proteins that causes an inflammatory response
histamine helps to fight the invader by widening blood vessels and increasing capillary permeability (10).
chemotactic factors bring phagocytes to the site of the infection
causes local swelling
Cells
Phagocytes
Phagocytes engulfs and destroys pathogens (5).
Macrophages, larger cells, can phagocytize larger substances, and large numbers of dead cells.
TLR signaling
Macrophages, B cells, dendritic cells have TLR proteins that recognize foreign molecules
Family of proteins that react to all pathogens
Corson Ellis

9. T cells T lymphocytes are also known as T cells
Immature T cells are located in the Thymus gland (neck), also produced in bone marrow
Structure:
T Cells are types of white blood cells (2).
surface contains thousands of T cell receptors.
Function:
Search for and destroy foreign invader substances (antigens) (1).
There are multiple types of T cells.
Helper T Cells: Stimulates the activation of B cells by releasing cytokine
Killer T Cells: When in contact with virus or tumor cells, they release chemicals which destroy the damaged cell (cytokine)
Livy

10. B Cells Origin: Produced in the bone marrow, like T cells (3).
Structure:
Immunoglobulins held on the surface of the cell (9).
Function:
Are stimulated by antigen, or a foreign substance in the body.
Split and create plasma cells (long-lived b cell that secretes large amounts of antibodies).
All plasma cells “remember” what substance stimulated them (3).
Produces antibodies, proteins structured to bind and neutralize antigens.
Corson Ellis

11. Antibodies Structure: Two binding sites, Y shaped (9).
Can be water soluble, to protect areas without the presence of a B cell.
Function:
Specific to particular antigen (similar to enzyme-substrate specificity)
Y shape allows for the formation of a lattice to facilitate breakdown by phagocytes and macrophages (1).
fiona swag

12. The Third Line of Defense
Used when non-specific methods are not effective enough and the infection becomes too widespread.
Specific: meaning that it can distinguish between microorganisms and respond accordingly (11).
Adaptive: meaning it creates an immunological memory after an initial response to a pathogen, allowing it to have a heightened/enhanced response if exposed to the same pathogen again (3,11).
Antigens on the pathogen identify the intruder, stimulating this response (4). EM

13. Third Line of Defense (continued)
Both APCs (dendritic cells) and B cells detect pathogens and present to T cells. The dendritic cell tells the T cell what to do, and the T cell tells the B cell by releasing cytokine to influence its response (10).
T cells trigger antibody production by B cells (11).
Cytotoxic T cells and phagocytes destroy infected cells
B cells divide and differentiate into plasma cells to produce antibodies, small amount of clones become memory cells that remain in the body for years (11).
If a second infection with the same antigen occurs, the body has a quicker and more efficient response: the person does not present symptoms, is “immune” EM

15. Works Cited
"Immune System." KidsHealth. Ed. Yamini Durani. The Nemours Foundation, 01 Oct Web. 13 Nov <
MedicineNet. "T Cell." MedicineNet. MedicineNet, 28 Aug Web. 16 Nov <
MedicineNet. "B Cell." MedicineNet. MedicineNet, 28 Aug Web. 16 Nov <
Muller, Michael. "The Immune System." BIOS 100. University of Illinois at Chicago, Aug Web. 16 Nov <
"Phagocyte." UXL Science. U*X*L, Science in Context. Web. 13 Nov Document URL
Science Learning. "The Body's Second Line of Defence." Science Learning Hub RSS. University of Waikato, 8 Nov Web. 16 Nov <

16. Works Cited (continued)
WestOne Sevices. "Our Internal Defences." Second Line of Defence – Leucocytes (white Blood Cells). WestOne Services, Web. 16 Nov <
Wilson, John H., and Tim Hunt. Molecular Biology of the Cell, 4th Edition: A Problems Approach. New York: Garland Science, Print.
Wilson, John H., and Tim Hunt. Molecular Biology of the Cell, 4th Edition: A Problems Approach. New York: Garland Science, Print.
Sompayrac, Lauren. How the Immune System Works. Malden, MA: Blackwell Pub., Print.
"Brent Cornell." Third Line of Defence. N.p., n.d. Web. 17 Nov < disease/third-line-of-defence.html>.
"Brent Cornell." Second Line of Defence. N.p., n.d. Web. 17 Nov < disease/second-line-of-defence.html>.