Lymphatic system

Question 1

Ducts (Lymphatic)

Answer 1

Two ducts; Right lymphatic duct = minority of lymph drainage, Thoracic duct (left lymphatic duct) = majority of lymph drainage

Question 2

Haematopoiesis

Answer 2

Production of all blood cells

Question 3

Linear system

Answer 3

The lymphatic system is a linear system which moves fluid (cells, proteins, macromolecules) and transports it back to the vascular system
(as opposed to the cardiovascular system which is a circular & closed system).

Question 4

Lymph: content

Answer 4

A water fluid similar to blood plasma but with less plasma proteins. Contains: water, leukocytes, plasma proteins (seeped out of capillaries), fats absorbed from the small intestine, bacteria & cell debris from damaged tissue

Question 5

Lymphadenopathy

Answer 5

Swelling of the lymph nodes caused by incomplete phagocytosis of microbes in the early stages of infection

Question 6

Lymphatic system

Answer 6

A network of tissues, vessels and organs that work together to move ‘lymph’ back into the circulatory system. Consists of thin walled vessels that transport fluid throughout the body and drain into the ducts
Functions:
1) Returns proteins, lipids and water from the interstitial fluid to the blood
2) Immunity against harmful organisms

Question 7

Lymphatic system: parts

Answer 7

Consists of:
Lymph fluid (lymph), Lymph vessels, Lymph nodes, Lymph organs (spleen, thymus, tonsils / adenoids), bone marrow, Peter’s patches, appendix), Lymphoid tissue, Bone marrow

Question 8

Metastasis

Answer 8

Metastasis of malignant tumour can occur via lymphatic vessels & establish secondary cancers

Question 9

Mucosa Associated Lymphoid Tissue (MALT)

Answer 9

Small aggregations of lymphoid tissue found in areas of the body exposed to the external environment – ‘first line of immune defence’. Can be found in adenoids, tonsils, small & large intestine. MALT in the GIT is called GALT.

Question 10

Node (Lymphatic) locations

Answer 10

Cervical (neck), axillary, inguinal (groin), vertebral column (side spine), mesenteric (intestinal)

Question 11

Nodes (Lymphatic)

Answer 11

Lymph nodes are filled with immune cells and filter lymph and remove foreign matter such as microbes, cell debris & tumour cells. Lymph enters nodes via afferent vessels (many), where they are trapped & destroyed and filtered lymph leaves via efferent vessels (few – to slow down flow)

Question 12

Spleen

Answer 12

The largest lymph organ. Contains white pulp and red pulp.
White pulp contains lymphocytes & macrophages
Red pulp contains all the components of circulating blood
Functions; Haematopoiesis in foetus, Blood reservoir, Phagocytosis of worn-out defective erythrocytes (graveyard for RBC), Immunity – T& B-Lymphocytes

Question 13

System functions; absorption

Answer 13

Lacteals absorb fat-soluble substances / nutrients from the small intestines into the body: dietary fats, fat soluble vitamins (ADEK & K)

Question 14

System functions; immunity

Answer 14

Lymph organs are concerned with the production & maturation of lymphocytes; lymph nodes, spleen, thymus & bone marrow

Question 15

System functions; tissue drainage

Answer 15

Blood arrives at tissue (high pressure) = some of the fluid / nutrients forced out of capillaries into interstitial fluid. (Remaining cells / plasma proteins in blood create osmotic pressure which maintains blood volume – tissue fluid is at lower pressure). Lymphatic system drains / recirculates the fluid & returns it to the blood.

Question 16

System functions; tissue drainage mechanics - lymphatic pumps

Answer 16

Lymphatic fluid is drained with assistance of the following;
* Mild, rhythmical contractions of lymphatic vessels (lymphatic pump)
* Skeletal muscle pump; movement/exercise drains fluid. Esp.calfmuscles
* Respiratory pump; during inhalation air pressure drops in the thoracic region. Lymph moves from high to low pressure

Question 17

Thymus

Answer 17

A bi-lobed organ that plays important role in immune development & antibody production in early life (atrophy begins in puberty), declining throughout life - tissue is replaced by fat).
Contains epithelial cells, T-lymphocytes & macrophages. Epithelial cells produce ‘thymosin’ – promotes the maturation of T-lymphocytes (learn difference between self / non self - 1.5 % pass the test, those that don’t pass the test are sent to apoptosis). T-cells that leave the thymus migrate to lymph nodes / tissue where the colonise.

Question 18

Vessels (Lymphatic)

Answer 18

Resemble veins but have thinner walls & more valves, and follow same route as veins. Two types:
Capillaries; located in spaces between cells, blind-end tubes – one-way structure, recall – lacteal is a blind-ended lymph vessel in the small intestine
Larger lymph vessels; have three layers of tissue like veins, numerous cup-shaped valves (one-way direction), vessels unite to form lymph trunks

Question 19

Lymphatic pumps;

Answer 19

Lymphatic pump - contractions of the lymphatic vessels
Skeletal muscle pump - movement / exercise drains fluid
Respiratory pump - breathing helps move lymph

Question 20

Lymph organs

Answer 20

Spleen, thymus, tonsils / adenoids, bone marrow, Peter’s patches, appendix

Question 21

Peter’s patches

Answer 21

Small masses of lymphatic tissue in the small intestine that contain lymphoid cells that monitor and destroy bacteria.