Lymphatics

Question 1

What are the roles of the lymphatic system?

Answer 1

• removal of excess water from the ISF
• removal of infectious agents and dead cells
• antigen presentation
• movement of lymphatic cells
• transport of dietary lipids from the gut

Question 2

Lymph will contain a lot of lipids from the gut in what form?

Answer 2

Chylomicrons

Question 3

Why do chylomicrons enter the lymph system and where do they enter the lymphatic system?

Answer 3

They are too large to enter blood capillaries.

They enter lymphatic vessels within the small intestinal villi – lacteals

Question 4

All lymph passes through at least one lymph node, what occurs at these nodes?

Answer 4

Foreign material is exposed to and removed by phagocytes, and fresh lymphocytes are recruited from the cortex

Question 5

What is a group of lymph nodes referred to as?

Answer 5

A lymphocentre

Question 6

Which ducts receive drainage from the head, neck and proximal forlimbs?

Answer 6

Tracheal ducts

Question 7

What is chyle?

Answer 7

The fluid in the thoracic duct where the majority of fluid ends up before draining back into the CV system

Question 8

What are the initial 6 embryological lymph sacs?

Answer 8

• paired jugular sacs
• cisterna chyli sac
• retroperitoneal sac
• paired iliac sacs

Question 9

Where do the B and T lymphocytes come from to supply the lymph sacs?

Answer 9

B lymphocytes - bone marrow

T lymphocytes - thymus

Question 10

What is the importance of removing extra water from circulation into the ISF?

Answer 10

Prevents oedema

Question 11

Movement of lymph within lymphatic vessels, like blood, is due to … ?

Answer 11

Hydrostatic pressure differences – bulk flow

Question 12

What other factors does the lymphatic system rely on to move lymph?

Answer 12

1. External pressure from skeletal muscle propels lymph along the vessels
2. Lymphatic vessels contain valves, preventing backflow of lymph

Question 13

Which 3 circumstances can cause oedema and effusions due to failure of lymphatic drainage?

Answer 13

1. Disease of the lymphatic system
2. Capacity is overwhelmed (e.g. congestive heart failure (CHF) leads to excessive ISF volume)
3. Derangement of hydrostatic pressure gradient preventing drainage (e.g. a tight bandage)

Question 14

How is the main structure of lymphatic vessels similar to blood vessels?

Answer 14

They possess a tunica intima, media and adventitia