These questions are to help you quiz yourself. To see my answers, select the area underneath the question using your mouse. (click and drag)  Don't print this out, or the answers will be visible as well!enated blood from the placenta. It is also high in nutrients, and low in wastes.

Chapter 16:
Describe the structure of a lymphatic capillary. It begins as a closed ended capillary. The cells overlap one another, and act as valves to allow tissue fluid to enter, but not leave, the lymphatic capillary. The cells are also anchored to tissue cells, so that when the tissue swells due to edema, the valves open to let the fluid in.
Is lymph a circulating fluid? No, it drains from the tissues back into the circulatory system.
The tissue fluid of the right leg drains into which of the two lymphatic ducts? The thoracic duct
The tissue fluid of the right arm? The right lymphatic duct.
What happens when the flow of lymph is blocked? The tissue fluid and leaked proteins are not returned to the circulatory system. The accumulation of blood proteins, such as albumin, draws more fluid into the tissue, and we see edema.
What are lacteals and what do they do? Lacteals are the lymphatic vessels found in the vili of the small intestines. They pick up absorbed lipids from the digestive tract. The high fat content of the lymph gives it a "milky" appearance and that's why they are called lacteals.
Where is your thymus?  It is found in the mediastinum, above the heart (but below the thyroid gland).
Is it bigger or smaller than it was 10 years ago? Smaller; it begins to atrophy or shrink after puberty.
If you were born without a thymus, what part of your immune system would be affected? Because the thymus is the site of the differentiation of T cells, you would not have any cell-mediated immunity.
If you can feel your spleen, it is considered to be pathologic. Where would you look for your spleen? In the left upper quadrant of your abdomen, partially protected by the lower ribs.
If you are immune to a disease, you are said to have resistance to that disease. If you could still catch it, we say that you are susceptible to the disease.
I said in class that you are never really alone. What did I mean, and why is it a good thing? You have a lot of bacteria that live on your skin, in your mouth and in your intestines. These bacteria are territorial, and can produce antibiotics and have other means of ensuring that harmful bacteria (to us) do not invade their territory.
How do transferrins prevent the growth of microbes? These are transfer proteins that bind up the free iron in our blood and tissues. Bacteria also require iron to grow. If they can't get any, they  can't reproduce and make us sicker.
Why is interferon a "Paul Revere" chemical? It is made by a virus infected cell. This chemical does not protect the cell that made it, but instead alerts surrounding cells that a virus is present, and gives them time to make their own antiviral proteins.
What is complement, and in what three ways does it act? Complement is not one, but between 10 and 20 inactive proteins normally found in blood. They can enhance inflammation, they act in opsonization (aid phagocytosis), and can destroy invading cells by punching holes in their cell membranes with membrane attack complexes.
What are the four cardinal signs of inflammation? Calor, tumor, rubor and dolor. In English: heat, swelling, redness and pain  ( and sometimes loss of function.)
Which stage of inflammation accounts for most of the signs of inflammation? Vasodilation and increased vessel permeability. The vessels increase in diameter, allowing more red, warm blood into the area, and the vessels become leaky, allowing fluid into the tissues which accounts for swelling (and possibly pain).
 What are the body's two major types of phagocytes? Neutrophils - these are the first phagocytes on the scene of an infection - and macrophages - who were mild-mannered monocytes in the blood stream, and then transformed into macrophages in the tissues.
What is chemotaxis?  Chemo =  chemical    taxis = movement. (think taking a taxi) Complement, damaged tissue and even some microbes, give off chemicals that attract neutrophils and macrophages and cause them to move to the site of tissue damage or infection.
Why is adherence of the phagocyte to a bacterium sometimes difficult? What makes it easier?  Some bacteria try to hide from our immune system by covering themselves with a slimy capsule. This makes it difficult for the phagocytes to hold onto them, like trying to catch a greased pig. Complement and antibodies can bind to these bacteria, and help the phagocytes to hold on to and consume them. (opsonization)
What are natural killer cells?  These  are a type of lymphocyte that can kill cells directly, rather like Tc cells, but without the specificity. They can attack a wide range of cells, including developing tumor cells.
What is the "magic word" when talking about immunity?  Specific
What is the "magic number"? Two. Each step in immunity needs two signals before it will progress to the next step.
What is an antigen? What characteristics make for a good antigen? An antigen is any substance that stimulates and immune response. Good antigens are large, recognized as foreign and complex.
Would polyethylene be a good antigen? Lipids ? Why or why not?  Both of these can be large and foreign, but tend to be too simple and regular to stimulate the immune system.
Would penicillin be a good antigen?  By itself, no. It is foreign and complex, but too small to be recognized by the immune system. It is what we call a hapten. If it climbs aboard a larger molecule, like blood albumin, then the immune system can "see" it, and will respond to it (as many of you well know).
What is an Antigen Presenting cell, and what does it do? What type of cell does it activate? An antigen presenting cell is a macrophage, that in the process of doing its job, has picked up a foreign antigen, and placed it in a special molecule, called the MHC II complex on its membrane. Now that antigen is someplace that the cell can carry it around and "show" or present it to other cells, which can then interact with it. The macrophage is "looking" for a helper T cell that has a receptor on its surface that matches the antigen-MHC II complex. When it finds one (and the body may only start out with a very few cells that match this particular antigen, so it may take some time) they bind together around the antigen and  "get all excited." The macrophage or antigen presenting cell makes interleukin-1, which stimulates the helper T cell to make interleukin-2. The interleukin - 2 will affect other cells, but also stimulates the helper T cell to reproduce itself, so that we now have many helper T cells that respond to this specific antigen. This will be helpful next time we come in contact with this particular antigen.
A Tc cell comes in contact with an antigen, and interleukin-2 is present. How will it react to the antigen?
First, it will clone itself and produce activated Tc Cells and memory cells. The Tc cells will then search out more cells that have the antigen on their surface, and then they will bind to the antigen. Then, they will either release perforins that will punch holes in the membrane of that cell, or they will activate the infected cell's own self-destruct mechanism.
Activated B cells become what and produce what? They become plasma cells and produce antibodies.
Why is the secondary immune response so much faster than the primary immune response?
The first time we "see" an antigen, we may have only a handful of cells that match that antigen. It takes a while for them to reproduce to the point where they can overcome the infection. The second time we encounter the antigen we have numerous memory cells lying in wait. They respond so fast that we never get sick.
You are allergic to poison ivy. What type of response is this? What cell is involved? What causes the problem?
This reaction is a delay-ed type hypersensitivity reaction, that is mediated by a T cell called a Td cell. The main problem is tissue damage and inflammation.
You are allergic to bee-stings. Within minutes, you have difficulty breathing. What is happening? This is an immediate type hypersensitivity reaction.  You have IgE antibodies bound to your mast cells. When antigen binds to the antibody, it causes the mast cell to release histamine. This causes your larynx to swell and your bronchioles to constrict. It also can cause widespread vasodilation, which lowers blood pressure until you go into anaphylactic shock.
I give you immunity by sticking you with a needle. Is this natural or artificial immunity ? Artificial
You make antibodies yourself. Is this active or passive immunity? Active
Which lasts longer, active immunity or passive immunity? Why? Active immunity. When the antibodies are all used up, you can make more. If you got them from someone else (passive immunity), you have to get more from someone else; you can't make your own. When the antibodies are gone, they're gone!