Biology 1201A Lecture Notes - Lecture 30: Myocyte, Eosinophil, Ureter
2 Oct 2016
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Ways it can go wrong:
•What if bacteria got into the bone marrow? The B-cell will bind to it and be killed as if it
responded to self — thus it wont’ get out into the lymph system to trigger immune response to
that bacteria.
•Not too much of an issue, because even if you have bacterium in the bone marrow for a
couple weeks or a month, it will eventually go away and your bone marrow can make those
specific antibodied B-cells again. (and hopefully you already had some B-cells for that
pathogen in your lymph nodes).
•When the process goes wrong, you get an autoimmune disease, where the body attacks itself.
•Ex: Myasthenia Gravis:
•Muscle fibers have receptors on them that receive neural stimulation to activate/contract the
fiber.
•In myasthenia gravis, you develop antibodies against that muscle receptor. When those
antibodies bind, it either stops the muscle fiber from functioning or destroys the receptor.
So it’s harder for muscles to contract and be stimulated. You slowly become paralyzed.
HOW WHITE BLOOD CELLS MOVE AROUND:
•Neutrophils circulate in the blood, but only do their work in the tissues at the site of an
infection.
•How do they know where to squeeze out of the blood vessels into tissues?
•Macrophages at the site of infection will gobble up bacteria and release chemical signals
that tell endothelial cells of a nearby blood vessel that there’s an infection there.
•As a result, the endothelial cells express proteins that stick to the neutrophils. And then,
because they’re stuck, the neutrophils squeeze through endothelial cells in an active process.
In the tissue, they phagocytose the bacteria and then die. (When they die neutrophils
become pus.)
•Immune cells only ever cross from the blood into the tissue; it’s impossible for them to go the
other way. To enter circulation (such as for macrophages to present antigens to T and B cells),
they must enter the lymphatic vessel and go to the lymph nodes. In the lymph node is antigen
presentation, which causes B and T cells to activate and go to the side of the infection. How do
they get there?
•The activated T cells enter the thoracic duct (final, fat lymphatic vessel) and eventually drain
back into the blood. Once in circulation, those cells act similarly to neutrophils; they can see
from endothelial proteins where the infection is, and then squeeze out between cells to fight
bacteria in the tissue.
•B cells don’t really need to be in the tissue, though, so they mostly hang out in the lymph nodes.
Their job is to release antibodies that can float around the body themselves and go to the
infection site on their own.
BLOOD CELLS LINEAGES
•In the blood vessels, you have about 10 different kinds of blood cells, from RBCs to T-cels, to
B-cells, to platelets, and more… where do they all come from? Bone marrow! Specifically
from the heads of long bones and from different flat bones (like the sternum) throughout the
body.
•All blood cells have a single precursor: a pluripotent hematopoietic stem cell
•This pluripotent cell gives rise to two different lineages: myeloid and lymphoid
find more resources at oneclass.com
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Document Summary
When those antibodies bind, it either stops the muscle fiber from functioning or destroys the receptor. So it"s harder for muscles to contract and be stimulated. And then, because they"re stuck, the neutrophils squeeze through endothelial cells in an active process. In the tissue, they phagocytose the bacteria and then die. (when they die neutrophils become pus. : immune cells only ever cross from the blood into the tissue; it"s impossible for them to go the other way. To enter circulation (such as for macrophages to present antigens to t and b cells), they must enter the lymphatic vessel and go to the lymph nodes. In the lymph node is antigen presentation, which causes b and t cells to activate and go to the side of the infection. How do they get there: the activated t cells enter the thoracic duct (final, fat lymphatic vessel) and eventually drain back into the blood.
