Physiology Term 1 Final Midterm (December 7) Flashcards
Define humoral immunity.
Immunity conferred by antibodies present in the blood plasma and other bodily fluids.
What do antibodies do?
Though they are produced by lymphocytes, antibodies circulate freely in the blood and lymph, where they bind primarily to extracellular targets—bacteria, bacterial toxins, and free viruses— inactivating them temporarily and marking them for destruction by phagocytes or complement.
Define cellular immunity.
Immunity conferred by activated T cells, which directly kill infected or cancerous body cells or cells of foreign grafts and release chemicals that regulate the immune response. Also called cell-mediated immunity.
What four key characteristics sets the adaptive immune system apart from the innate immune system?
- The adaptive immune system involves lymphoyctes called the T and B lymphocytes.
- It is specific
- It is systemic
- It has memory.
Define antigen.
Large organic molecules, usually a protein, stuck in a cell membrane which could be self or foreign.
Define MHC proteins.
Major histocompatibility complex. Molecules on the outer surface of the plasma membrane of all cells; help the immune system distinguish self from nonself. T cells recognize antigens only when combined with these proteins.
What marks a cell as “self” instead of non-self?
Self-antigens, particularly MHC proteins, mark a cell as self.
Which cells oversee humoral immunity?
B cells
Define T cells.
Non-antibody producing lymphocytes that constitute the cellular arm of adaptive immunity.
Define immunocompetence.
The ability of the body’s immune system to recognize (by binding) specific antigens; reflects the presence of plasma membrane-bound receptor.
Define self-tolerance.
Each lymphocyte must be relatively unresponsive to self-antigens so that it does not attack the body’s own cell.
Define antigen-presenting cell (APC)
A specialized cell (dendritic cell, macrophage, or B cell) that captures, processes, and presents antigens on its surface to T lymphocytes.
What two types of cells are involved in adaptive immunity?
T lymphocytes and B lymphocytes
Where are both T cells and B cells produced?
Bone marrow
Where do T cells mature?
thymus
Where do B cells mature?
Bone marrow. Then they go to the blood and lymph nodes.
What is the name of one of the important self-antigens contained on the cells?
MHC glycoprotein (major histocompatibility complex); also known as human leukocyte antigens - HLAs
What is the role of the MHC protein?
To present fragments of either your own proteins or foreign antigens.
What are the two main classes of glycoproteins?
Class 1 and Class 2.
Where are Class 1 found?
They are found on just about all cells in the body. (any cell with a nucleus)
Where are Class 2 found?
They are found on B cells, dendritic cells and macrophages.
How are B cells activated?
By an antibody challenge that usually happens in the spleen or the lymph node.
Describe what happens when a B cell comes into contact with an antigen.
Once it is bound onto the antigen, it is stimulated to start dividing. The cells it produces are known as clones. Keeps dividing and dividing and creating cells that identical to the parent cells.. After a while these clone cells start to differentiate and start to form plasma cells and occasionally a memory B cell.
Structurally, what do antibodies consist of?
Four looping polypeptide chains linked together by disulfide bonds.