Chapter 31

Question 1

Lymphatic system functions (3)

Answer 1

Maintain fluid balance in the body

Plays a role in immunity

Fat absorption and transport

Question 2

Structures of the lymphatic system

Answer 2

Lymph, lymphatic vessels, lymph nodes, thymus, tonsils, spleen

Question 3

Intersitial fluid (IF)

Answer 3

Plasma that has already filtereed out of the capillaries and is in tiny spaces between cells of tissue

Question 4

Lymph is

Answer 4

Excess Intersitial fluid that isnt absorbed by tissue cells or reabsorbed by the blood before it flows out of the tissue

Question 5

Lymphatic vessels

Answer 5

Permit one-way movement of lymph towards heart
Collect excess IF (as lymph) and returns it to the blood stream via veins
Two types:
Lymphatic capillaries
Lymphatic ducts

Question 6

Lymphatic capillaries

Answer 6

Microscopic, blind-ended (open at one end) tubes found in tissue spaces wherever blood capillaries are (except bone, teeth, bone marrow and CNS)
Walls are simple squamous epithelium and are very porous/permeable due to structure
Called ‘lacteals’ in the intestinal wall (Digestive System)

Lymphatic Capillaries
Similar to veins but have thinner walls, more valves, and contain lymph nodes
Edges of cells loosely overlap each other = one-way ‘swinging doors’ (e.g. valves)
Fluid pressure in interstitial fluid determines if fluid will move into our out of lymphatic capillaries:
When fluid pressure is greater in interstitial spaces than in lymphatic capillaries, ‘doors’ are pushed open & fluid moves in
When fluid pressure is greater inside the lymphatic capillary than in interstitial spaces, doors are pushed shut, preventing lymph from leaking backwards
1

Question 7

Right lymphatic ducts

Answer 7

Drains lymph from right upper extremity, right side of head, neck, and upper torso  right subclavian vein

Question 8

Thoracic duct

Answer 8

Thoracic Duct
Largest lymphatic vessel
Drains lymph from the rest of the body  left subclavian vein
A structure called cisterna chyli found along its course (storage area for lymph moving towards entering the venous system)

Question 9

Function of lymphatic vessels

Answer 9

Remove high–molecular-weight substances and even particulate matter from interstitial spaces
Lacteals absorb fats and other nutrients from the small intestine

Question 10

Circulation of lymph

Answer 10

No pump

Relies on breathing and skeletal muscle contractions

Question 11

Lymph nodes or glands

Answer 11

Filter lymph
Located in clusters along the pathway of lymphatic vessels where they converge to form larger trunks (see Figures in Textbook)
Functions include defense and WBC formation

Question 12

Structure of lymphatic nodes

Answer 12

Oval shaped
Fibrous capsule
Biological filters

Question 13

Flow of lymph

Answer 13

In to node via several afferent lymph vessels

Drained away from node by a one or more efferent lymph vessels

Question 14

2 functions of lymph nodes

Answer 14

Defense functions

Hematopoesisis

Question 15

Denfense function

Answer 15

Mechanical filtration (physcial trapping of particles) 
Biological filtration (cells destroy and remove particles)

Question 16

Hematopoeisis

Answer 16

Maturation of some lymphocytes and monocytes

Question 17

Closer look at defense functions

Answer 17

If any antigens/pathogens are detected in the lymph entering the lymph node, various WBCs in the lymph node will get to work to eliminate them (e.g. phagocytosis)
Other immune system cells are called into action and ‘sent’ to the lymph nodes. The increased numbers of immune system cells fighting the infection will make the node expand and become ‘swollen’

Question 18

Lymphatic drainage of the breast

Answer 18

Clinically important as cancer cell infections can spread along lymphatic pathways to lymph nodes and other organs in the body
Drained by 2 sets of lymphatic vessels
Drains skin over the breast (minus the skin of the areola and nipple)
Drains underlying substances of breast, plus the skin of the areola and nipple

Question 19

___% of lymph from the breast goes to the axillary lymph nodes

Answer 19

85%

Question 20

TONSILS COMPOSED OF WHAT 3 MASSES

Answer 20

Palatine tonsils (“the tonsils”) are the largest, and most often infected. On each side of throat
Pharyngeal tonsils (adenoids)
Lingual tonsils

Question 21

FUNCTION OF TONSILS

Answer 21

To gather and remove pathogens entering pharynx

Question 22

Thymus

Answer 22

Primary organ of lymphatic system
Vital role in immunity – its hormones (thymosin) enable lymphocytes  T cells
Lymphoid tissue organ located in mediastinum
Completes most of its work in childhood. In adults, lymphoid tissue is largely replaced by fat and connective tissue in a process called involution

Question 23

Spleen

Answer 23

Largest lymphoid organ in body; ovoid shape
Located in upper left quadrant of abdomen
Often injured by trauma to abdomen
Surgical removal called splenectomy

Question 24

Spleen function

Answer 24

Defense: filtration & phagocytosis of bacteria and other pathogens
Tissue repair: spleen has a reservoir of monocytes that can migrate to sites of injury to promote healing & repair
Hematopoiesis – monocytes & lymphocytes complete their development in the spleen
Destroys & Recycles: Destroys old RBCs & platelets; stores breakdown products of RBCs (e.g. iron & hemoglobin) which can be ‘reused’
Blood reservoir