principles of lymphatic system

Question 1

What is the lymphatic system?

Answer 1

part of circulatory system (sometimes said to be part of immune system too)

Question 2

What is the lymphatic system comprised of?

Answer 2

• lymph
• lymphatic vessels
• immune cells
• lymphoid organs

Question 3

What does the lymphatic system do?

Answer 3

• fluid balance (returns interstitial fluid back to circulation)
• protection (scanning/processing of pathogens)
• fat absorption from GI tract

Question 4

What is lymph?

Answer 4

fluid similar to plasma but containing substances too large to pass through blood capillary walls

Question 5

How is lymph formed?

Answer 5

fluid gets pushed out of capillaries by high arterial (hydrostatic) pressure

Question 6

Where does lymph go?

Answer 6

it is brought back into venous circulation via a network of lymphatic vessels

Question 7

Where do networks of lymphatic vessels start?

Answer 7

blind-ended capillaries found in intercellular spaces

Question 8

What is a key feature of lymphatic capillary lumen?

Answer 8

they are bigger than blood capillaries

Question 9

What are the key features of lymphatic capillary walls?

Answer 9

• one layer of endothelial cells
• lack tight junctions
• discontinuous basal lamina
• anchoring filaments made of collagen

Question 10

What are key features of lymphatic vessel walls?

Answer 10

• increasing amounts of smooth muscle and connective tissue
• still relatively thin
• valves are present (beaded appearance)

Question 11

What is an afferent lymphatic vessel?

Answer 11

takes lymph into lymph node

Question 12

What is an efferent lymphatic vessel?

Answer 12

takes lymph away from lymph node

Question 13

Describe superficial lymphatic vessels

Answer 13

• subcutaneous layer of skin (follow veinous drainage)
• drain superficial structures
• drain into deep lymphatic vessels

Question 14

Describe deep lymphatic vessels

Answer 14

• accompany arteries
• drain viscera (internal organs)
• larger and drain into lymphatic trunks

Question 15

What are the key features of lymphatic trunks?

Answer 15

• receive lymph from lymph vessels
• unite to form lymphatic ducts

Question 16

How are lymphatic trunks named?

Answer 16

they are named according to the region of the body they drain

Question 17

What are the 4 pairs of lymphatic trunks?

Answer 17

• lumbar (abdomen)
• bronchomediastinal (thorax)
• subclavian (around clavicles)
• jugular (neck)

Question 18

What are the key features of lymphatic ducts?

Answer 18

• similar to small veins
• underdeveloped tunica adventitia
• vasa vasorum

Question 19

What are the two main lymphatic ducts?

Answer 19

• right lymphatic duct
• thoracic duct

Question 20

What does the right lymphatic duct drain and into what?

Answer 20

drains the right upper quadrant of the body into the right venous angle

Question 21

What does the thoracic duct drain and into what?

Answer 21

drains remainder of body into left subclavian vein

Question 22

What is the cisterna chyli?

Answer 22

dilated collecting sac formed by merging of lymphatic trunks draining the lower half of the body

Question 23

Where does the thoracic duct originate from?

Answer 23

cisterna chyli

Question 24

Which lymphatic duct is the largest in the body?

Answer 24

thoracic duct

Question 25

What does the thoracic duct ascend through?

Answer 25

aortic hiatus in diaphragm (hole in diaphragm for passage of aorta)

Question 26

What do the primary lymphoid organs do?

Answer 26

production and maturation of lymphocytes

Question 27

What are the primary lymphoid organs?

Answer 27

- bone marrow - thymus

Question 28

What happens in the bone marrow (in terms of immunity)?

Answer 28

- T cell and B cell differentiation - B cell maturation

Question 29

What happens in the thymus (in terms of immunity)?

Answer 29

T cell maturation

Question 30

What are secondary lymphoid organs for?

Answer 30

activation of lymphocytes and immune response initiation

Question 31

What are some examples of secondary lymphoid organs?

Answer 31

- lymph nodes - aggregations of lymphatic tissues in mucosal tissues - spleen

Question 32

What are the functions of the spleen?

Answer 32

- filters blood - immunity to blood borne pathogens - removes senescent and defective erythrocytes (RBCs) - recycles iron from degraded haemoglobin

Question 33

What is the largest lymphatic organ and where is it located?

Answer 33

- spleen - abdominal cavity

Question 34

What are the two main regions of the spleen?

Answer 34

- white pulp - red pulp

Question 35

Describe the white pulp region of the spleen

Answer 35

consists of lymphatic tissue

Question 36

Describe the red pulp region of the spleen

Answer 36

large numbers of erythrocytes, macrophages, other immune cells

Question 37

Describe the structure of lymph nodes?

Answer 37

- oval - slight depression on side called hilum - fibrous capsule and gland substance - below capsule is sub capsular substance

Question 38

What is the gland substance divided into?

Answer 38

- cortex: outer portion - medulla: inner portion

Question 39

What are the functions of lymph nodes?

Answer 39

- filtration of lymph - immunity (plasma cells here produce antibodies) - produce lymphocytes (in germinal centre of lymphatic nodules) - provide portal of entry to lymphocytes into lymphatic vessels

Question 40

What are primary nodes?

Answer 40

the first node/group within a chain

Question 41

What are terminal nodes?

Answer 41

last node/group within a chain

Question 42

How is lymph drainage of the breast distributed?

Answer 42

- 75% axillary - 25% parasternal nodes

Question 43

What are the 3 important mucosa associated lymphoid tissues?

Answer 43

- GI tract (GALT) - respiratory system (BALT) - genitourinary tract (MALT)