The Lymphatic System

Question 1

What is the role of the lymphatic system?

Answer 1

The lymphatic system acts as a counter-current system, draining all waste materials, recycling surplus fluids, salts, proteins, fats and immune cells back to the body

Question 2

What is Chronic Oedema?

Answer 2

Lymphatic failure caused by

• insufficient fluid drainage
• lymph load exceeding lymph drainage capacity

Question 3

What are the 2 basic functions of lymph nodes?

Answer 3

1. Clean up lymph before re entry into blood stream
   
   • sieve out, trap and destroy (inorganic) foreign
     materials
2. Monitor lymph for signs of (organic) predators
   
   • vital in immune system response

Question 4

How is chronic Oedema / lymphoedema managed?

Answer 4

Physically based - stimulate lymph drainage and reduce blood vascular filtration
- no known drug can help

Question 5

Describe the structure of the dermal lymphatic vascular network

Answer 5

Lymphatic capillaries are slightly larger than the vascular capillaries
They are also known as initial lymphatics
- blind ended
- have no smooth muscle
- have an incontinuous basement membrane

Question 6

What is secondary lymphoedema?

Answer 6

Damage caused to the lymph drainage system

Question 7

What are lymph nodes?

Answer 7

Lymph nodes/glands are filter stations positioned at intervals along the lymph drainage route

Question 8

What are lymphatic collecting vessels?

Answer 8

Thinner vessels with valves to ensure lymph flow

Question 9

What are the mechanisms for chronic oedema to occur?

Answer 9

Relative lymphatic failure
=> lymphatic failure with increased capillary filtration

Absolute lymphatic failure (Lymphoedema)
=> lymphatic failure with no increased capillary function

Lymphodemia
=> sustained increased capillary filtration exhausting lymph drainage

Question 10

What is lymph?

Answer 10

Lymph is interstitial (tissue fluid) containing salts, proteins, and cells originally formed from a plasma ultrafiltrate

Question 11

What is the effect of lymphatc dysfunction to the rest of the body?

Answer 11

Can cause respiratory diseases, CVS, Infections, GI Crohn’s Disease, cancer metastasis and obesity

Question 12

What is primary lymphoedema?

Answer 12

Intirnsic lymphatic failure caused by developmental abnormality of the lymph system
- phenotypes vary in age of onset, site, inheritance
patterns, associated features and genetic causes

Question 13

What is the role of the lymph system in fat homeostasis?

Answer 13

The lymphatic system is responsible for gut fat absorption and peripheral fat re-absorption
The intestinal lymphatic system is responsible for dietary fat absorption
Disturbance in lacteal function leads to malabsorption

Question 14

Describe the structural features of lymphatic collecting vessels

Answer 14

Covered in smooth muscle
Have luminal valves
Basement membrane present

Question 15

What is the role of the lymphatic system in homeostasis?

Answer 15

The lymphatic system’s priority is to maintain fluid balance, achieved by:

• Up to 8 litres a day of plasma filtered into tissues and
  reabsorbed almost entirely by lymph drainage
• Steady state: vascular filtrate fluid drains with periods of
  transient absorption

Question 16

What is the role of lymph nodes?

Answer 16

Lymph is transported to larger vessel leading to lymph nodes
- Nodes filter lymph where there’s no interaction with the
immune system
- After passing through series of lymph nodes, large
lymphatic vessels eventually discharge lymph into neck
veins

Question 17

How is chronic venous disease and Oedema caused?

Answer 17

Occurs when a higher volume of fluid is leaving the blood vessels and entering the feet, ankles and leg tissues
This lymph load requires draining by lymph system from tissues
However if lymph drainage is overwhelmed it causes Oedema

Question 18

What is the significance of cellulitis?

Answer 18

Dermal lymphatics are vital immunologically in any tissue

Recurrent cellulitis is caused by a lymph drainage problem

Question 19

Outline the flow of lymph through the network of lymph vessels

Answer 19

1. Lymph in small blind ending tubes
2. Drains into small streams, and into bigger channels
3. Drained into lymph glands
4. Eventually drains back into blood circulation in neck
   veins

Question 20

How does lymph drainage failure effect tissue immunity?

Answer 20

A common complication of impaired lymph drainage is disturbed immune cell trafficking and increased infections

Question 21

What is the consequence of fluid build up?

Answer 21

Build up of fluid in tissues for any length of time is a failure of the lymph system e.g. Oedema

Question 22

What is the role of initial lymphatics?

Answer 22

Absorb fluid, salts, proteins and cells from tissues to form lymph

Question 23

In the lymph drainage system, which part of the process is the rate limiting step?

Answer 23

Lymph drainage is the rate limiting step

If lymph drainage goes robust, oedema doesn’t occur despite increased fluid volumes

Question 24

Describe what tissue immunity is in the lymph system

Answer 24

The spleen contains WBCs that respond to antigens collected from the

blood. There are also tissue lymphoid clumps around the body which trap antigens and present them to lymphocytes
- > triggering immune response

Question 25

What are the effects of lymphoedema on the body?

Answer 25

Results in swelling 
Fluid build up of cells and fats 
Predisposition to infections 
Elephantiasis 
Podoconiosis

Question 26

What is the lymphatic system?

Answer 26

Network of drainage tubes connected to lymph glands which acts as drainage channels for the body’s tissues

Question 27

What other health condition can cause lymphoedema?

Answer 27

Lymphoedema can occur after treated heart failure due to a high sustained
lymph load = equivalent to hypertensive heart failure

Question 28

How is lymph drainage initiated?

Answer 28

Lymph drainage begins with fluid absorption from tissues

Question 29

Describe the features of lymphoedema

Answer 29

• Most common lymphatic disease
• Chronic swelling due to lymph drainage failure
  => results in Venous disease
• if oedema persists after vein treatment, lymph drainage
  is permanently damaged - in permanent state of
  lymphoedema

Question 30

What is the role of lymph collecting vessels?

Answer 30

Contract to pump lymph along
Valves ensure lymph flows in one direction
-> downstream to lymph glands