L4 - Lymphatic System

Question 1

give three functions of the lymphatics and immune system?

Answer 1

1. draining excess interstitial fluid
2. transporting dietary lipids
3. immune responses

Question 2

how does interstitial fluid re-enter circulation?

Answer 2

• capillaries at venous ends
• lymphatic capillaries

Question 3

what are lymph capillaries?

Answer 3

smallest lymph vessels, high permeability allows entrance of tissue fluid and bacteria, viruses and cancer cells

Question 4

what is the function of lymphatics?

Answer 4

collect lymph from lymph capillaries, accompany blood vessels

Question 5

give three features of lymphatics

Answer 5

• walls similar to blood vessels
• contain more valves than veins to ensure one way flow
• lymph nodes scattered along lymphatics

Question 6

which tissues do NOT have lymph capillaries?

Answer 6

CNS, bone marrow and avascular tissues e.g. cartridges, nails, cornea and hair

Question 7

what are lacteals?

Answer 7

• specialized lymphatic capillaries
• located in villi of small intestine
• receive digested fats
• fatty lymph (chyle)

Question 8

what surrounds lymph nodes?

Answer 8

fibrous capsule

Question 9

what type of lymph vessel enters the lymphnode?

Answer 9

afferent

Question 10

what type of lymph vessel leaves the lymphnode?

Answer 10

efferent

Question 11

give two functions of lymph nodes

Answer 11

• lymph percolates through
• antigens destroyed and activate B & T lymphocytes

Question 12

name the two lymph ducts

Answer 12

1. right lymphatic duct
2. thoracic duct

Question 13

where does the right lymphatic duct drain and where does it empty into?

Answer 13

drains the right side of the head, right upper limb and right thorax
empties into the right internal jugular vein and subclavian veins

Question 14

where does the thoracic duct drain and where does it empty into?

Answer 14

drains remainder of body
empties into venous circulation - left internal jugular vein and left subclavian veins
begins as cisterna chyli

Question 15

give three functions of the immune system

Answer 15

• recognize foreign molecules
• destroys pathogens
• main cells - lymphocytes - attack infectious organisms

Question 16

what are the primary lymphoid tissues?

Answer 16

immature lymphocytes acquire receptors to recognize antigens
- thymus - maturation of T lymphocytes
- bone marrow - maturation of B lymphocytes

Question 17

what are the secondary lymphoid tissues?

Answer 17

lymphocytes are activated in response to antigen
- lymph nodes
- spleen
- mucosal associated lymphoid tissue (tonsils, Peyer’s patches, mucosae of GIT, resp tracts)

Question 18

give 4 characteristics of the thymus

Answer 18

• immature lymphocyte develop into T lymphocytes
• functions strictly in lymphocyte maturation
• most active in childhood
• atrophies with age

Question 19

give 3 characteristics of the spleen

Answer 19

• largest lymphoid organ
• 2 blood-cleansing functions (removal of blood-borne antigens & removal and destruction of old blood cells)
• site of haematopoiesis in foetus

Question 20

describe the pulp in the spleen

Answer 20

white pulp: thick sleeves of lymphoid tissue
red pulp: surrounds white pulp, composed of venous sinuses and splenic cords

Question 21

give 3 facts about tonsils and name the three types

Answer 21

1. simplest lymphoid tissue
2. form a ring around border between oral cavity + pharynx
3. gather & remove pathogens
   palatine, pharyngeal, lingual

Question 22

where are Peyer’s Patches located?

Answer 22

in distal part of small intestine

Question 23

where is the appendix located?

Answer 23

tubular offshoot of caecum