Secondary Lymphoid Tissue

Question 1

Where are secondary lymphoid tissues found?

Answer 1

They are found in sites where mature lymphocytes are exposed to and stimulated by antigen

Question 2

What are secondary lymphoid tissues also known as?

Answer 2

They are known as peripheral lymphoid organs

Question 3

What are tissues involved in the secondary lymphoid tissues?

Answer 3

Lymph vessels, lymph nodes, spleen and mucosa associated lymphoid tissue (MALT)

Question 4

What is the lymphoid migration like to the secondary lymphoid tissues?

Answer 4

It is highly specific

Question 5

What do the lymphoids enter?

Answer 5

They enter via high endothelial venues which express specific adhesion molecules on their endothelium to which lymphocytes bind

Question 6

What does adhesion lead to?

Answer 6

Adhesion leads to the lymphocyte sweeping through the endothelium into the node

Question 7

What do lymph vessels do?

Answer 7

They drain tissue fluid from the connective tissue

Question 8

Where do the lymph vessels empty?

Answer 8

They empty primarily via the thoracic duct to the left venous angle between the interior jugular vein and subclavian vein

Question 9

Describe the thoracic duct

Answer 9

It is 45cm long, it has several branches and drains all lymph in the left head/neck and left thorax

Question 10

Where does the thoracic duct start?

Answer 10

At T12 and ascends behind the right crus to right of the aorta and oesophagus, then crosses the midline of T5

Question 11

Where does the thoracic duct lie?

Answer 11

Lies superficial to posterior intercostal arteries, crosses the azygos systems, to the left vertebral and left subclavian arteries

Question 12

What is the flow like in valves?

Answer 12

Unidirectional

Question 13

What is carried to lymph nodes?

Answer 13

Antigen from pathogens and other foreign materials is drained from the site of infection and then carried to the lymph nodes

Question 14

Describe lymph nodes

Answer 14

They are highly organised, bean shaped structures at junctions between lymph vessels

Question 15

What are the lymph nodes aggregated (together)?

Answer 15

Neck and groins

Question 16

What is the function of the lymph nodes?

Answer 16

To filter lymph from tissues

Question 17

What is trapped in the lymph nodes?

Answer 17

Antigens and then they are taken up by antigen presenting cells which is then presented to lymphocytes passing through the node

Question 18

What do Afferent lymphatics do?

Answer 18

They enter the node in the cortex and then pass through the parachuted and exit via the efferent lymphatics in the medulla

Question 19

Where do high endothelial venues enter in the lymph node?

Answer 19

In the paracortex

Question 20

Where are B cells and T cells located in the cortex?

Answer 20

They are located in the primary and secondary follicles in the Cortex

Question 21

What are primary follicles?they contain B cells and are the site at which germinal centres form which then form secondary follicles

Question 22

Where do lymphocytes enter the node?

Answer 22

They enter the High endothelial venues at which point they are then exposed to antigens

Question 23

What happens if the B cell when entering the HEVs do not detect an antigen?

Answer 23

Then it leaves via the efferent lymph node and later returns to the blood via the thoracic duct

Question 24

Describe the spleen

Answer 24

It is a fist-sized organ, associated posteriorly with the left ribs 9 and 11, though separated from them by the diaphragm superiorly

Question 25

Where does the spleen rest?

Answer 25

On the left colic flexure of the large intestine. The tail of the pancreas points towards the spleen. It sits on the left side of the abdomen within the hypochondrium region

Question 26

What does the spleen collect?

Answer 26

It collects antigens from the blood, presenting it to lymphocytes

Question 27

What is the function of the spleen?

Answer 27

It serves to filter the blood, removing and disposing of ageing red blood cells and immune complexes

Question 28

What are the two distinct components of the spleen?

Answer 28

Red pulp and white pulp

Question 29

What is red pulp?

Answer 29

Is a well perfused-tissue responsive for the filtration role of spleen, removing ageing and damaged red blood cells from circulation

Question 30

What does white pulp do?

Answer 30

Has many similarities to a lymph node. It is packed with T cells, B cells and dendritic cells and sifts antigens from the blood instead of the lymph

Question 31

Where are T cells located in the spleen?

Answer 31

In the periarteriolar lymphoid sheath (PALS)

Question 32

Where are B cells located in the spleen?

Answer 32

Beyond the sheath in a corona around a germinal centre