Anatomy and Physiology of the Immune System

Question 1

Leukocytes

Answer 1

nucleated cells of the blood, white blood cells, when you centrifuge anticoagulated blood, they sediment on top of the packed red cells forming buffy coat.

Question 2

Mononuclear cells

Answer 2

leukocytes whose nucleus has a smooth outline, monocytes (immaturemacrophages in tissue) and lymphocytes. Can be hard to distinguish macophages and lymphocytes

Question 3

Polymorphonuclear cells

Answer 3

cells whose nucleus is lobulated, also called granulocytes because they usually have prominent cytoplasmic granules. They are eosinophils, basophils and neutrophils

Question 4

Granulocytes

Answer 4

white blood cells that have cytoplasmic granules, also known as polymorphonuclear cells, they are eosinophils, basophils and neutrophils

Question 5

Dendritic cells

Answer 5

cells that connect the innate immune response and adaptive immune response, act as antigen presenting cells to other cells in the immune system

Question 6

Mast cells

Answer 6

granules full of histamine, role in allergy and anaphylaxis. Very similar to basophil granulocytes

Question 7

Plasma

Answer 7

yellow fluid portion of blood in which the particulate components (blood cells) are suspended. 55% of blood volume

Question 8

Serum

Answer 8

the clear liquid that does not contain blood cells nor clotting factor, it is the blood plasma with fibrinogens removes, includes all proteins not used in blood clotting and electrolytes, antibodies, hormones, etc

Question 9

Sketch schematically a neutrophil; eosinophil; basophil; small lymphocyte; lymphoblast; plasma cell; monocyte. Include the characteristic features which are used to distinguish each cell type

Answer 9

Do this and check your answer

Question 10

List the normal adult white cell count and differential percentages. From these, calculate absolute counts for the different cell types (as cells of that type/uL)

Question 11

Name the major central and peripheral lymphoid organs.

Answer 11

• Central organs: ones in which lymphocytes deveolp, the bone marrow and the thymus
• Peripheral organs: mature cells are organized to trap and respond to foreign invaders, includes lymph nodes, spleen, Peyer’s patch and mesenteric lymph nodes of gut, tonsils, adenoids

Question 12

Describe the recirculation of lymphocytes from blood to lymph and back; include in your discussion the specialized features of lymph node blood vessel endothelium that permit recirculation

Answer 12

Lymphocyte in the blood encounters the cells lining certain postcapillary venules in the peripheral lymphoid tissues (especially lymph nodes). These endothelial cells are unusual (not flat, but HIGH AND CUBODIAL). Recirculating lymphocytes may bind to and pass between the endothelial cells into the lymph node, where they may stay, or pass into the lymph which drains from that lymph node to the next node in the chain. Lymph goes to large lymph channels (thoracic duct, near heart) –> venous blood –> circulatory loop starts over again. Thus, there are 2 circulation: blood and lymphatic, in which lymphocytes cross from blood to lymph at nodes and from lymph back to blood at heart.

Question 13

Antigen:

Answer 13

substance that can be recognized by the immune system

Question 14

Immunogen:

Answer 14

an antigen in a form that can give rise to an immune response, that is, which can immunize

Question 15

Antigenic determinant and epitome:

Answer 15

small part of a large antigenic molecule, fits (lock and key) into lymphocytes receptor and activates lymphocyte, an isolated antigenic determinant is not usually an immunogen; it can be recognized by antibody, but is too small to trigger an immune response

Question 16

tolerogen:

Answer 16

antigen delivered in a form, or by a route, which does not give rise to an immune response, and which furthermore prevents an immune response to subsequently administered immunogen which has the same epitopes

Question 17

Discuss lymphocyte activation by antigen with respect to: role of dendritic cells, receptor binding, proliferation, differentiation

Answer 17

a. Each lymphocyte has receptors, there are many copies on each cell, but all are identical (ie: each cell has single specificity). T cell receptors are alpha and beta chains. B cell receptors are samples of the antibodies that the cell will eventually secrete. The antigenic determinant (presented by the dendritic cell) fits into the lymphocyte receptor. To activate T or B cell: 1. The fit between receptor and antigen must be good enough, 2. Several nearby receptors must be simultaneously bound by antigen, 3. For T-cells only, other cell surface molecules must be involved too. Activated cell proliferates and differentiates

Question 18

Humoral immunity: (types of lymphocytes involved, the nature of the molecules they release when activated, the types of inflammatory cells they preferentially involved, if they can be transferred by serum)

Answer 18

this is the antibody mediated response, and this occurs extra-cellularly where all the bacteria etc. live. B lymphocytes are the main cells involved. B cells transform into plasma cells which secrete antibodies. Cytokines are also released. Can be transferred by serum

Question 19

cell mediated immunity: (types of lymphocytes involved, the nature of the molecules they release when activated, the types of inflammatory cells they preferentially involved, if they can be transferred by serum)

Answer 19

T lymphocytes become activated. These in turn activate macrophages, NK cells, and cytotoxic T lymphocytes. Cytokines are released when the T cells become activated. Not transferred by serum.