Lymphatic Circulation

Question 1

What is the lymphatic circulation?

Answer 1

Consists of lymphatic capillaries in tissues and drains lymph through lymph nodes

Question 2

What is lymph

Answer 2

Is the interstitial fluid that enters then lymphatic system

Question 3

How much lymph is produced per day

Answer 3

Three liters per day

Question 4

Describe the composition of lymph

Answer 4

Lymph
Proteins (same amount as ISF but decreased compared to plasma)
All coagulation factors
Fibrinogen (decreases levels due to large MW and difficulty crossing membrane)
Fat
Lymphocytes

Question 5

Describe the structure of the lymph circulation

Answer 5

Present throughout body except CNS, bone marrow and cartilage

Consists of blind ending tubules with one way flap backed for unidirectional flow

Low pressure system (1mmHg) at rest

Question 6

What are the factors affecting lymph flow

Answer 6

Increased flow depends on
Intrinsic factors - smooth muscle cells in walls and valves

Extrinsic factors - muscle contraction, positive infra thoracic pressure, arterial pulsation, exercise, peristalsis

Question 7

Describe the flow of lymph

Answer 7

Capillaries 
Venues 
Lymph veins 
Lymph nodes 
Either left thoracic duct (80%) or eight lymphatic duct 
Subclavian veins

Question 8

What are the four main functions of lymph

Answer 8

1. Immune related - presents antigen presenting cells to lymph nodes, filtration and removal of bacteria - macrophages at lymph node phagocytosis bacteria in lymph

2 maintains low oncotic pressure of ISF - returns proteins back to circulation

3. Absorption and transport of fats - fats form chylomicron and transported into circulation via thoracic duct (bypasses portal system)
4. Formation of concentrated urine - removes protein rich ISF medulla and allows water to enter vasa recta and allows maintenance of osmotic gradient