Histology II: lymph organs

Question 1

name 5 lymphoid systems (/organs)

Answer 1

bone marrow
thymus
lymph nodes
MALT system
spleen

Question 2

what is the MALT system?

Answer 2

“mucosa associated diffuse lymphoid tissue” -system initiates immune responses to specific antigens encountered along all mucosal surfaces.

Question 3

What is the chief cellular constituent of lymphatic tissue?

Answer 3

Circulating lymphocytes

Question 4

Where are T lymphocytes produced?

Answer 4

in the thymus (in young individuals as the thymus shrinks away with age)

(they account for the majority of circulating lymphocytes)

Question 5

T lymphocyte function?

Answer 5

involved in cell-mediated immunity

roles include:
killing infected host cells, 
activating other immune cells, 
producing cytokines and 
regulating the immune response.

Question 6

What does it mean to be cell-mediated?

Answer 6

the immune response that does not involve antibodies but rather incorporates the activation of macrophages and various lymphocytes

Question 7

B lymphocyte function?

Answer 7

They are involved in the production and secretion of various circulating antibodies, also called immunoglobulins (IgG), the immune proteins associated humoral immunity.

Question 8

What does humoral immunity refer to?

Answer 8

Humoral immunity is the process of adaptive immunity manifested by the production of antibodies by B lymphocytes.

Question 9

What is the major difference between humoral and cell-mediated immunity?

Answer 9

humoral immunity produces antigen-specific antibodies, whereas cell-mediated immunity uses macrophages and cellular apoptosis.

Question 10

Name 5 cells of the immune system.

Answer 10

T lymphocytes
helper T lymphocytes 
B lymphocytes (plasma cells and memory b's)
NK cells (natural killer lymphocytes)
APC cells (antigen-presenting cells)

Question 11

difference between T lymphocytes and helper T lymphocytes?

Answer 11

cytotoxic T cells destroy virus-infected cells and tumor cells

whereas

the helper T cells secrete cytokines to activate or regulate other cells in the immune system

Question 12

Activated B lymphocytes differentiate into?

Answer 12

Plasma cells and

Memory B cells

Question 13

Plasma cell function?

Answer 13

synthesize and secrete specific antibodies

Question 14

Memory B cell function?

Answer 14

memorizes the characteristics of the antigen that activated their parent B cell

so if they later encounter the same antigen, it triggers an accelerated and robust secondary immune response.

Question 15

APC cell function?

Answer 15

antigen-presenting cells

boost immune responses by showing antigens on its surface to other cells of the immune system.

detects, phagocytizes, and informs the adaptive immune response about an infection

Question 16

APC cells include what all cells?

Answer 16

macrophages,
Kupffer cells in the liver,
Langerhans´ cells in the epidermis,
dendritic cells of spleen and lymph nodes.

Question 17

describe the thymus structure

Answer 17

lobules surrounded and connected by connective tissue,
outer cortex,
central medulla,
Hassal’s corpuscles found in medulla

Question 18

thymal lobules made up of what cells?

Answer 18

Most cells in the lobules are thymolymphocytes (T cells),
markedly more in the cortex than in the medulla.

Epithelioreticular cells form the extensive meshwork of the thymus.

Question 19

Where are Hassall’s corpuscles found?

Answer 19

In the thymic medulla

Question 20

What does APC cell refer to?

Answer 20

antigen-presenting cells

Question 21

Hassall’s corpuscles’ function?

Answer 21

are a potent source of the cytokines that instruct dendritic cells in the thymus to induce development of regulatory T cells

Question 22

hassall’s corpuscles made of what

Answer 22

derived from epithelioreticular cells

Question 23

Outer layer of spleen?

Answer 23

fibrous capsule

Question 24

What are splenic trabeculae?

Answer 24

Fibrous connective tissue that branches into the spleen, connected to the capsule

Question 25

What is found between splenic trabeculae?

Answer 25

the splenic pulp that contains darker white pulp which is surrounded by lighter red pulp.

Question 26

White splenic pulp consists of?

Answer 26

a thick accumulation of lymphocytes (surrounding a central artery)

Question 27

Within the white splenic pulp the branch of the trabecular artery is called?

Answer 27

the central artery

Question 28

What are the structures consisting of lymphocytes that aggregate around the central splenic arteries called?

Answer 28

lymphatic nodules and lymphatic sheaths.

Question 29

What do the lymphatic nodules that surround the splenic arteries consist of?

Answer 29

B lymphocytes

Question 30

What do the lymphatic sheaths that surround the splenic arteries consist of?

Answer 30

chiefly T-lymphocytes

Question 31

Splenic red pulp consists of?

Answer 31

splenic sinuses and splenic cords.

Question 32

What are the splenic sinuses lined by?

Answer 32

endothelial cells

Question 33

What do the splenic cords consist of?

Answer 33

a loose meshwork of reticular cells and reticular fibres that contain large numbers of erythrocytes, macrophages, lymphocytes, plasma cells and granulocytes.

Question 34

What is the role of the red splenic pulp?

Answer 34

blood filtration removal of particulate material, macromolecular antigens, and aged, abnormal, or damaged blood cells from circulating blood.

Question 35

What is the role of the white splenic pulp?

Answer 35

activation and proliferation of T-lymphocytes differentiation of B lymphocytes and plasma cells secretion of antibodies

Question 36

What are the two types of lymphatic vessels?

Answer 36

Afferent lymph vessels | Efferent lymph vessels

Question 37

Describe afferent lymph vessels.

Answer 37

convey lymph towards the node and enter it at several points on the convex surface

Question 38

Describe efferent lymph vessels.

Answer 38

convey lymph away from the node at the hilum, a depression on the concave surface of the node.

Question 39

What are the supporting elements of the lymph node?

Answer 39

Capsule Trabeculae Reticular tissue

Question 40

What is the capsule of a lymph node made up of?

Answer 40

dense connective tissue

Question 41

What are lymphatic trabeculae?

Answer 41

extend from the capsule into the substance of the node, forming a gross framework

Question 42

What is the purpose of the reticular lymph tissue?

Answer 42

reticular cells and reticular fibres form a fine supporting network

Question 43

A lymph node is divided into what main parts?

Answer 43

darker-stained cortex and lighter-stained central medulla.

Question 44

The lymphatic cortex is formed by?

Answer 44

lymphatic nodules or lymphatic follicles with the germinal centre in the middle.

Question 45

The lymphatic medulla consists of?

Answer 45

the medullary cords and medullary sinuses

Question 46

What do the lymphatic medullary cords contain?

Answer 46

``` dendritic cells lymphocytes macrophages plasma cells reticular cells ```

Question 47

Where does the filtration of lymph occur more specifically?

Answer 47

within a network of interconnected lymphatic channels called sinuses.

Question 48

Name the 3 types of lymphatic sinuses.

Answer 48

Subcapsular sinuses Trabecular sinuses Medullary sinuses

Question 49

Where are subcapsular sinuses found?

Answer 49

between capsule and lymphatic follicles. Afferent lymphatic vessels drain lymph into these sinuses.

Question 50

Where are trabecular sinuses found within lymphnodes?

Answer 50

they pass inwards along the sides of the connective tissue trabeculae and drain into medullary sinuses.

Question 51

Where are medullary sinuses found?

Answer 51

are spaces that separate the medullary cords, they converge near the lymphatic hilum, where they drain into the efferent lymphatic vessel.