Lymphatic System

Question 1

What does the lymphatic system consist of?

Answer 1

Cells, tissues and organs and is distributed throughout the body

Question 2

Lymphatic system functions to…

Answer 2

1. provide a defense mechanism
2. return extracellular fluid to circulatory system
3. Transport nutrients, waste and hormones into circulatory system

Question 3

lacteals

Answer 3

lipids absorbed in the small intestine by these specialized lymph vessels

Question 4

lymphoid cells

Answer 4

B and T-lymphocytes and monocytes (macrophages)

Question 5

recirculation of lymphocytes

Answer 5

critical for immune protections, i.e. the site of detection is usually not he site of infection

Question 6

B-lymphocytes

Answer 6

humoral mediated

Question 7

T-lymphocytes

Answer 7

cell mediated

Question 8

Lymphoid tissues

Answer 8

B-cells forming nodules. reticular fiber network, located in a mucosa of digestive, urinary, respiratory, and reproductive tracts

Question 9

Types of Lymphoid tissues (NOT GLANDS, NOT ORGANS)

Answer 9

MALT (either mucosa, gut or bronchiole), tonsils, peyer’s patches (aggregated lympoid nodules)

Question 10

Lymphoid organs

Answer 10

must be surrounded by a capsule to be an organ. tonsils are not organs.
Characterized by dense connective tissue capsule, cortical trabeculae divide organ into compartments. Divided into Primary or Secondary organs

Question 11

Primary/Central lymphoid organs

Answer 11

Bone marrow and thymus. Do not fight infection. Lymphocytes arise and are educated here

Question 12

Secondary/Peripheral lymphoid organs

Answer 12

sites where lymphocytes respond. Spleen and lymph nodes

Question 13

Spleen

Answer 13

removes antigens in blood, defective blood cells, stores iron removed from destroyed RBCs. supplied by splenic artery, drained by splenic vein. Red and “white” pulp

Question 14

Lymph nodes

Answer 14

many, small, filter lymph

Question 15

Thymus

Answer 15

2 lobed organ. Degenerates as we age. Found behind manubrium in adult, looks like fat. maturation of T-lymphocytes. Has cortex and medulla. Does not destroy antigens!

Question 16

Cortex of thymus

Answer 16

densely packed dividing T-cells achieving immunocompetence. maturing T-cells that recognize “self” antigens are destroyed. surviving T-cells enter medulla

Question 17

Medulla of thymus

Answer 17

lightly packed T-cells, light staining. Thymic (Hassall’s) corpuscles-collections of degenerating epithelial reticular cells.

Question 18

epithelial reticular cells in thymus

Answer 18

1. produces thymic hormones
2. stimulates maturation of T-cells
3. isolates thymocytes from antigens
4. destroys T-cells that recognize self

Question 19

White pulp of spleen

Answer 19

Lymphoid nodules. central arteries enter into the white pulp through the lymphoid nodules. (splenic artery-trabecular artery-central artery-capillaries)
Central arteries surrounded by lymphoid tissue. Called PALS. nodules called PWP. white pulp=PALS + nodule

Question 20

PALS of spleen

Answer 20

Periarterial lymphocytes sheath. dense area of T-lymphocytes

Question 21

PWP

Answer 21

peripheral white pulp. area of B-lymphocytes

Question 22

Marginal zone of spleen white pulp

Answer 22

capillaries drain into area surrounding sheaths. site of activation and destruction. site of T and B-lymphocytes and macrophages. antigens from the blood enter lymph tisse, activate the immune response, and are destroyed. T-lymphocytes and antibodies flow into sinusoids then into circulation

Question 23

Red pulp of spleen

Answer 23

large quantities of RBCs. venous sinuses-blood flows from marginal zone and forms sinusoids. Splenic cords-fibrous reticular connective tissue and macrophages, surround the venous sinuses, phagocytose and destroy defective RBCs

Question 24

Lymph nodes

Answer 24

not glands, but ORGANS. they have a capsule. filters lymph along the network of lymph vessels. intersects with immune system.Antigens not only destroyed, but activate T and B-lymphocytes

Question 25

Afferent lymph vessels

Answer 25

carry lymph into lymph nodes. efferent vessels carry filtered lymph out (e for exit)

Question 26

Within the lymph node, lymph fluid…

Answer 26

percolates through sinuses composed fo reticular fiber networks and macrophages

Question 27

Lymph node comparments

Answer 27

separated by trabeculae. each has a cortex and medulla.

Question 28

Lymph flow

Answer 28

Subcapsular sinus, superficial (outer) cortex, deep cortex (paracortex) medullary cords, hilum

Question 29

Valves in lymph vessel

Answer 29

necessary because there is no pump like in circulatory system. flow of lymph is slow

Question 30

lymph trunks

Answer 30

lymphatic collecting vessels converge to form trunks. 5 major ones: lumbar, intestinal, bronchomediastinal, subclavian, jugular.

Question 31

lymph ducts

Answer 31

trunks drain into lymph ducts (the largest lymph vessels)

Thoracic Duct and Right Lymphatic Duct

Question 32

antigen

Answer 32

foreign molecule

Question 33

Cell-mediated immune response

Answer 33

antigen presenting cell (APC) phagocytoses an organism/cell.
APC present an antigen from the organism/cell to T-helper cell
T-helper re-presents the antigen AND a cofactor to T-cytotoxic cells
T-cytotoxics damage cell membrane of any cell with the specific antigen
T-memory cells are also produced
T-suppressor cells inhibit T-cytotoxic cells when episode is over

Question 34

Humoral mediated immune response

Answer 34

B-cells recognize an antigen and become activated by T-helper cells.
Transform into plasma cells.
B-memory cells also produced
Produce antibody that binds to the antigen (called opsonization/marking)
Macrophages phagocytose and digest the opsonized cell

Question 35

Primary versus secondary response

Answer 35

the immune response is mediated by both T cells and B cells, activation is slow. In the secondary one, the memory cells make the response quicker and stronger