Session 4 - Lymphatic System

Question 1

What is the Lymphatic system made up of?

Answer 1

Fluid (Lymph), vessels (Lymphatics), cells (lymphocytes, dendritic cells and macrophages), tissues and organs

Question 2

How is the lymph in the lymphatics forced back up the body?

Answer 2

Skeletal muscles contract putting pressure on the vessels, forcing the fluid back up. Larger Lymphatics also have smooth muscle in their walls which can contract. Value ensure flor of the lymph in one direction only. Also pressure changes in the Thorax.

Question 3

Where does the Lymph fluid pass back into the blood?

Answer 3

At the Jugular and subclavian veins.

Question 4

What is the lymph fluid made up of? (4)

Answer 4

Proteins, excess interstitial fluid, lymphocytes and fats which have been absorbed in the villi of the small intestine

Question 5

What are the organs involved in the Lymphatic system? (3)

Answer 5

Lymph nodes, thymus and the spleen

Question 6

What is Mucosal Associated Lymphatic Tissue? (MALT)

Answer 6

MALT are bundles of Lymphatic cells called Lymphatic nodules located within the mucous membranes lining the gastrointestinal, respiratory, reproductive and urinary tracts. They contain lymphocytes and macrophages. It a a diffuse system.

Question 7

What are the sub divisions of MALT? (2)

Answer 7

GALT (gut associated lymphoid tissue) which lines the small intestines. BALT (bronchus associated lymphoid tissue).

Question 8

Give 3 examples of Lymphatic nodules

Answer 8

Tonsils, Peyer’s Patches and vermiform Appendix.

Question 9

Where are follicular dendritic cells located?

Answer 9

In the germinal centres of the lymph nodes

Question 10

What are the functions of the Lymph nodes?

Answer 10

They filter the lymph fluid and remove pathogens and abnormalities.

Question 11

Why is the lymph fluid returned to the blood system via veins?

Answer 11

As the veins have a lower pressure so minimises the impact of the blood pressure.

Question 12

What are the 3 main roles of the Lymphatic system?

Answer 12

Forms part of the immune system, absorbs fats from the digestive system and absorbs excess interstitial fluid (3 litres a day).

Question 13

Why are there Peyer’s patches located in the ileum of the small intestine?

Answer 13

In case the valve between the colon and the ileum stops working as the colon is full of bacteria which could then enter the ileum.

Question 14

What are lymphatic nodules?

Answer 14

Oval shaped concentrations of Lymphatic tissue. Large aggregations of these nodules are found in the appendix and make up the tonsils and Peyer’s Patches.

Question 15

What is a Lymphatic organ?

Answer 15

Lymphatic tissue enclosed by a connective tissue capsule.

Question 16

Why is the Lymph fluid protein rich?

Answer 16

Because proteins cannot be directly reabsorbed by blood vessels.

Question 17

What type of cells form the lymph capillaries?

Answer 17

Endothelial cells

Question 18

Where on a lymph node is the draining vein, feeding artery and efferent Lymphatic vessel located?

Answer 18

Hilum

Question 19

What do the outer cortex of lymph nodes contain?

Answer 19

Densely packed lymphocytes arranged in masses called Lymphatic nodules. The nodules contain germinal centres, where the lymphocytes are produced.

Question 20

Through what vessels does the lymph fluid enter the lymph nodes?

Answer 20

Afferent Lymphatic vessels

Question 21

What are the 3 types of tonsils?

Answer 21

Palatine, Lingual and Pharyngeal (Adenoid)

Question 22

What is the function of the tonsils?

Answer 22

The tonsils are aggregations of Lymphatic nodules embedded in a mucous membrane which produce antibodies and lymphocytes.

Question 23

What are the functions of the spleen?

Answer 23

Haemopoietic functions: Filters the blood, removes old red blood cells by phagocytosis, retrieves iron from haemoglobin,
Immune function: produces B cells which develop into plasma cells. Contains professional antigen presenting cells.

Question 24

Where is the thymus located?

Answer 24

In the super mediastrium (above the heart)

Question 25

What is the role of the thymus?

Answer 25

Where the bone marrow derived stem cells mature in T lymphocytes (thymol cell education).

Question 26

What is the cause of enlarged lymph nodes and what is this called?

Answer 26

Lymphadenopathy is caused when the germinal centres fill with lymphocytes during an infection which causes the swelling.

Question 27

What causes Lymph Oedema?

Answer 27

If your Lymphatics aren't working properly or if your born without them.

Question 28

What is cellulitis?

Answer 28

An infection beneath the skin caused by static fluid

Question 29

What are professional antigen presenting cells and where are they found?

Answer 29

They are found in lymph nodes. They present antigens in their cell surface membrane to activate T lymphocytes. Examples include B cells and macrophages.

Question 30

What type of responses can B and T cells produce?

Answer 30

An inflammatory response, which is mediated by neutrophils and macrophages. A specific immune response (via the humoral and cell mediated responses ).

Question 31

How do lymphocytes enter and leave a Lymph node

Answer 31

They enter via the feeding artery and leave via the efferent Lymphatic vessel

Question 32

What organs take over the functions of a spleen following a splenectomy?

Answer 32

The liver and bone marrow

Question 33

What is the role of follicular dendritic cells?

Answer 33

Cause a rapid increase in the number of B cells (particularly B memory cells). Trap and present antigens opsonised by complement or antibodies, which the B cells must bind to, to become memory cells otherwise they go through apoptosis.