Organisation Of Lymph

Question 1

What is the difference between the immune system and the lymphatic system?

Answer 1

Immune system is a network collective of cells, proteins, tissues and organs of the body working together to protect the body from infectious microorganisms.
Lymphatic system is the collection of secondary lymphoid organs, fluids and vessels of the immune system

Question 2

What is the difference between primary and secondary lymphoid organs?

Answer 2

Primary - they generate lymphocytes e.g., bone marrow and thymus
Secondary - do not generate lymphocytes, e,g., lymph nodes as a site of maturation of lymphocytes

Question 3

What does the lymphatic system do?

Answer 3

It drains tissue fluid from the extracellular compartment and processes tissue fluid through lymph nodes. It then returns tissue fluid back to the systemic circulation through venous channels.

Question 4

Where is the lymphatic system absent?

Answer 4

(Debatably the CNS), eyeball, inner ear, cartilage, bone and avascular planes

Question 5

How is lymph formed?

Answer 5

When hydrostatic pressure is greater than oncotic pressure, tissue fluid leaves the capillaries at the arterial end. 90% of it returns on the venous end, but 10% passes through the tissues into the lymphatic system.

Question 6

What is tissue fluid?

Answer 6

Interstitial fluid
Occupies the extracellular compartment of the body

Question 7

Composition of lymph

Answer 7

96% water, 4% solutes

Question 8

Rate of production and flow of lymph

Answer 8

Production at rest: 3-4 litres of lymph a day
Flow rate of 120ml/hour: 100ml through thoracic duct and 20ml through right lymphatic duct

Question 9

Importance of the lymphatic system

Answer 9

• Assists capillaries in the return of plasma fluid and proteins that leak into extracellular space back to circulatory system
• Absorbs and transports fats from digestive system
• Fluid balance of the body
• Cell volume regulation
• immunological functions of the body

Question 10

Clinical importance of the lymphatic system

Answer 10

• major constituent of immune system
• conduit for spread of infections, malignant diseases (secondary tumours) and a site for primary tumours
• blockage of lymph circulation leads to lymphoedema
• primary site for infections

Question 11

Structure of the lymph node

Answer 11

Kidney shaped, capsule cortex and medulla
Lymph enters though afferent channels, percolates through sinuses and leaves through efferent channels (which have valves)

Question 12

What are in lymph nodes?

Answer 12

Phagocytes and macrophages to clean up lymph

Question 13

General drainage of lymph

Answer 13

Lymphatic channels start as microscopic channels, gradually becoming vessels, which will drain into superficial then deep nodes, and collect to become trunks, and then either the right lymphatic duct or thoracic duct. Ducts drain into the venous system (by subclavian veins), returning it into the circulatory system, becoming a constituent of blood.

Question 14

What does the right lymphatic duct drain?

Answer 14

Drains lymph from upper right quadrant of the body - right side of head, neck, thorax and upper limb

Question 15

Where does the right lymphatic duct enter the venous system?

Answer 15

Enters the venous system at the right venous angle - point of union of the right subclavian vein and internal jugular vein

Question 16

What does the thoracic duct drain?

Answer 16

Drains lymph from the rest of the body - left side and bottom right.

Question 17

Where does the thoracic duct enter the venous system?

Answer 17

Enters venous system as the left venous angle - point of union of left subclavian vein and left internal jugular vein

Question 18

How are superficial and deep nodes separated?

Answer 18

Investing layer of fascia in the neck

Question 19

What are regional and terminal lymph nodes?

Answer 19

Regional drain specific anatomical regions of the body and can be superficial or deep. Terminal lymph nodes are the point of confluence of lymph drainage from many regional lymph nodes and are always deep. Lymph drains from regional nodes into terminal nodes (then trunks then ducts)

Question 20

How are superficial lymph nodes arranged?

Answer 20

An outer circle: forming a collar around the lower margins of the head from chin to occiput bilaterally
An inner circle: within the outer circle surrounding the upper airway passages and part of the tonsillar system of the head. For the Walder’s ring of lymphatic tissues.

Question 21

Where are deep lymph nodes found?

Answer 21

Within deep fascia, beneath SCM, found in carotid sheath
Surround IJV

Question 22

How does lymph drain into superficial nodes?

Answer 22

Power system with no energy (no pump). Superficial tissues into superficial nodes then deep nodes.

Question 23

How does lymph drain into deep nodes?

Answer 23

Deep tissues can drain lymph directly into terminal lymph nodes or into regional first then terminal nodes.

Question 24

What are deep nodes further divided into?

Answer 24

Superior deep lymph nodes and inferior deep lymph nodes
(Basically above or below SCM) omohyoid is the anatomical boundary.

Question 25

What is the waldeyer’s ring?

Answer 25

Nodes of lymphoid tissue assembled as a circle around the entrance of the mouth and nose into the pharynx. Consists of tonsils.

Question 26

What are the paired and unpaired nodes of the waldeyer ring?

Answer 26

Paired nodes: palatine tonsil, tubal tonsil
Unpaired nodes: pharyngeal tonsil, lingual tonsil

Question 27

Is the Waldeyers ring superficial or deep?

Answer 27

Superficial.

Question 28

What is retropharyngeal abscess?

Answer 28

Puss accumulates in the space between the prevertebral fascia and buccopharyngeal membrane. May lead to compression of the pharynx, thus dysphasia and dysarthria.

Question 29

Diseases of the lymphatic system

Answer 29

Lymphadenitis - infection of lymph nodes
Lymphangitis - inflammation of lymph nodes
Lymphoedema - chronic pooling of lymph in tissue
Lymphocytosis - high lymphocyte count from infection, autoimmune disorders etc
Cancers of lymph system (lymphoma), e.g., Hodgekins disease