Expert: Florence M Rollwagen - 3/22/2009

Question
QUESTION: Question
Steroid and non-steroid hormones differ in how they affect target cells. How do they differ? How is it that a common second messenger like cAMP can have different effects depending on the cell involved? How is it that hormones affect some cells and not others?

ANSWER: Hi Jerry:  Although I think this is a homework question, I'll direct you to a website that you can use:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellSignaling.html#Seco


Hope this helps.

If this is not a homework problem, write back and we'll discuss it.

FM Rollwagen, PhD

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QUESTION: FM
could you tell me the interactions and origins of the different types of T cells and B cells and the role of "recognition." Describe the interplay of these cells in a specific immune response.?
JM Yes It's homework

ANSWER: Hi Jerry:  Thanks for your question (and honesty).  Trust me on this, there are entire courses on just that subject.  Scientists spend 40 years studying it, so there's no way I can summarize it in such a small space.

I sent you a link, did you look at it?

Here's another link:
http://www.biology.arizona.edu/immunology/immunology.html

If this is homework, the answers should be in your textbook.  Did you look there?  Or are you looking for the easy way out?  

I can just get you started:

T and B cells are blood cells, so they originate in the bone marrow.  T cells are called that because they mature through the thymus (T is the first letter of thymus - immunologists are not very original!).  The thymus is an organ in the chest, right above the heart.  It is large in children, but disappears at puberty.  Its role is to "teach" the T-cells what "self" looks like.  That is, how to recognize our own body, so it can attack "non-self".

B-cells also mature, but we don't know exactly where or how.  They do undergo genetic recombination to account for the variety of antibodies that they secrete.

T cells, B cells and macrophages are part of the "adaptive" immune response, the one that learns what an antigen is and how to get rid of it.  T and B cells talk to each other via cytokines (soluble mediators) as well as specific cell surface receptors (CD28 and B7) and/or CD4 MHCII.  There is also an innate immune response that doesn't have to learn anything.  It just exists in almost all vertebrates.

This should get you started.  Check out the links I gave you and see if they make sense now.

FM Rollwagen, PhD

---------- FOLLOW-UP ----------

QUESTION: Well yes honesty is key and this is a course elective where i just need to get started a lot of the time and since we are encourged to do so....
I will get started on that but in the meantime (Human Service Major..so)
Explain the importance of immunological memory cells as you would to a friend with no science background. Describe in detail how and when memory cells arise and explain how they form the basis for effective immunizations. Be sure to include a narrative description of the numeric information in Fig 10.15 in the text (page 188). Elaborate and be specific in your answer.
No good deed goes un-noticed ..so they say
lol jerry  " Can you take me higher?"

Answer
OK, I'll get you started.  But you really need to use the information in your textbook (helpfully noted as page 188).

Memory cells are generated at the same time as the primary immune response (you should know these terms).  They can lay dormant for a long time (years) and become activated by being exposed to the same or closely related organism (or antigen).  This is the way vaccines work.  They stimulate the primary response, then when someone is infected, they go into action giving a potent and quick immune response that clears the infection.

You'll have to add to this from the information in Fig 10.15.

Don't send me any more homework problems, the purpose of education is to teach you to figure out these things for yourself.

FM Rollwagen, PhD