Download Study Guide Answer Key Animations: This page has multiple

Study Guide Answer Key
Animations:
This page has multiple animations; you may find the T-cell animations and the ones for HIV infections
particularly useful!
http://highered.mheducation.com/sites/0072507470/student_view0/chapter22/animation__cytotoxic_tcell_activity_against_target_cells__quiz_1_.html
An overview of the lymphatic system
http://www.as.wvu.edu/~sraylman/physiology/human_lymphatic.swf
1. What is lymph?
excess tissue fluid carried by lymphatic vessels
2. Where does it come from (production)?
Lymph is a clear fluid found in between cells. It carries immune cells, some proteins and other nutrients to
the tissues.
3. Compare the transport of lymph through the body with the circulation of blood. (How is it propelled?
What direction is it moving in?)
Blood is circulated throughout the body by the heart. Lymph does not have a pump; it moves through the
body by a “milking” motion as the skeletal muscles squeeze the lymph vessels. Lymph only moves in one
direction: toward the heart.
4. Describe the structure of lymph capillaries.
The walls overlap, forming flap-like mini-valves
Higher pressure inside keeps the valves closed
The capillaries are anchored in place by filaments.
5. How does lymph move through the collecting vessels? Include a detailed description of the internal
structure of the vessels.
Fluid is pushed through as muscles squeeze the vessels. The flaps inside close behind the fluid (similar to
the way the semi-lunar valves in the blood vessels work). This keeps the fluid from flowing back down the
vessels.
6. What types of materials does lymph fluid return to the bloodstream? Where are they returned to the
bloodstream?
Materials returned to the blood include: water, blood cells and proteins. These are returned to the blood
in the veins near the heart (the right lymphatic duct and the thoracic duct).
7. What types of harmful materials may end up in the bloodstream?
Bacteria, viruses, cancer cells, cell debris
8. Describe the function of the lymph nodes. What specialized cells may be found in the lymph nodes, and
what are their roles?
Filter lymph fluid before it is returned to the blood.
Specialized defense cells in the lymph nodes:
Macrophages – engulf and destroy foreign substances
Lymphocytes – provide immune response to antigens
9. What are the other organs (there are 4) associated with the lymphatic system? Where is each one
located?
a. Spleen – left side of the abdomen, lateral to the stomach
b. Thymus – superior to the heart, below the sternum
c. Tonsils – around the openings of the pharynx
d. Peyer’s patches - found in the wall of the small intestine
10. Describe the specific roles of each of the organs listed above in immune response.
a. Spleen – filters blood, destroys worn out blood cells, forms blood cells in the fetus, acts as a blood
reservoir
b. Thymus – Functions at peak levels only during childhood. Produces hormones (like thymosin) to
program lymphocytes (it is responsible for the education/maturation of T cells).
c. Tonsils – Trap and remove bacteria and other foreign materials in the lymph fluid
d. Peyer’s patches - found in the wall of the small intestine
11. What does MALT stand for? What tissues are included in this category?
Mucosa-Associated Lymphatic Tissue. These tissues include Peyer’s patches, tonsils and other small
accumulations of lymphoid tissue. Sentinels of the respiratory and digestive tracts.
12. Differentiate between nonspecific & specific immune defenses.
a. Nonspecific defense system: protects against a variety of invaders. This system responds
immediately to protect body from foreign materials;
b. Specific defense system: the response is specific to a certain pathogen. This is what we know as
the immune system
13. Give 3 examples of barriers that make up the First Line of Defense. Describe how each one functions to
protect the body.
a. The skin – a physical barrier to foreign materials. Skin pH is acidic to inhibit bacterial growth.
Sebum is toxic to bacteria.
b. Stomach mucosa: secretes hydrochloric acid. It also has protein-digesting enzymes.
c. Body Openings/Secretions: Saliva and lacrimal fluid (tears) contain lysozyme. Vaginal secretions
are very acidic. Mucus traps microorganisms.
14. Describe the cells that make up the Second Line of Defense.
Phagocytes (neutrophils & macrophages): engulfs foreign material into a vacuole. They secrete enzymes from
lysosomes to digest the material.
Natural killer cells can lyse and kill cancer cells. Can destroy virus- infected cells.
15. Describe the inflammatory response.
This response is triggered when body tissues are injured
Produces four cardinal signs: redness, heat, swelling, pain
16. What are the functions of the inflammatory response?
Results in a chain of events leading to protection and healing.
Attracts white blood cells to the site of injury to destroy pathogens and clean up debris.
Releases chemicals to make blood capillaries “leak” fluid into the area, which causes swelling and redness.
The swelling helps isolate the foreign substance from further contact with body tissues.
Sets the stage for tissue repair.
17. Distinguish between a bacteria and a virus.
A bacteria is a prokaryotic organism that can reproduce on its own. Bacteria are considered “alive” – they
can reproduce without another organism and they can maintain their own homeostasis.
A basic virus has two parts: 1) the DNA or RNA that carries its genetic information, and 2) an outer protein
shell that protects the genetic information. It is not alive: it can’t reproduce by itself and it doesn’t
metabolize.
18. How does a virus infect an organism? Describe the steps from the virus entering the body until it is
replicating (for example, how does it get inside of the cell?). How does this process differ from an
infection by a bacteria?
First the virus needs to get inside a cell. A virus uses camouflage to trick the cell into thinking the virus is
not a threat.
Next, the virus incorporates its DNA or RNA information in the cell’s DNA. The cell is tricked into making
new viruses.
19. Describe the role of complement proteins in your immune system.
Complement proteins consist of a group of at least 20 plasma proteins. They are activated when they
encounter and attach to cells (a process called complement fixation).
Complement proteins can damage foreign cell surfaces. Their tools include vasodilators, chemotaxis,
and opsonization.
20. What is interferon? Which cells produce it and why?
Interferon consists of secreted proteins produced by virus-infected cells.
These proteins bind to healthy cell surfaces to inhibit viruses binding (helps protect other cells from
becoming infected).
21. What is a fever, and why is it an important part of immune response?
A fever is an abnormally high body temperature. Hypothalmus heat regulation can be reset by pyrogens
(secreted by white blood cells). High temperatures inhibit the release of iron and zinc from liver and spleen
needed by bacteria. Fever also increases the speed of tissue repair
22. What is a macrophage?
An immune cell responsible for consuming foreign particles and infectious pathogens. It also has an
important role as an antigen presenting cell during immune response.
23. What is a lymphocyte? What cells fall into this category?
Cells that originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes,
spleen, and thymus. Two main types of lymphatic cells, T cells and B cells.