L.2: lymphatic system

Question 1

What is the lymphatic system & what are its 3 main functions?

Answer 1

• it is an independent group of vessels that:

a) collect & return interstitial fluid to the blood vascular system

b) protect from disease

c) absorb lipids from the gastrointestinal tract (GIT)

Question 2

What is oedema?

Answer 2

• oedema is the swelling of tissues when there is an excess of interstitial fluid in the tissues.

Question 3

Oedema is caused by an excess of interstitial fluid in the tissues. What causes the excess of interstitial fluid in the first place?

Answer 3

• the excess of I.F is due to an increase in I.F pressure from its negative value (-6.3 mmHg) to a positive value b/c of the following disease conditions:

1- increased capillary pressure
2- decreases plasma proteins
3- lymphatic obstruction
4- increased capillary permeability

Question 4

What causes increased capillary pressure?

Answer 4

• local venous obstruction by blood clots, frequent right cardiac failure, or increase in venous pressure

Question 5

What causes a decrease in plasma proteins?

Answer 5

• nephritis (kidney become inflamed and have problems filtering waste from the blood)
• or severe burns can lead to loss of albumin
• decrease in PCOP

Question 6

What causes lymphatic obstruction?

Answer 6

• protein accumulation in interstitial fluid
• increase IFCOP due to filariasis

Question 7

What causes an increase in capillary permeability?

Answer 7

• burns or allergic rxns cause loss of fluid & protein into the interstitial spaces.

Question 8

Define & describe the structure of lymphatic vessels.

Answer 8

• they end blindly in terminal lymphatic capillaries instead of connecting two areas (like the blood capillaries does w/ arteries and veins)
• it has thin and m permeable endothelium w/ loose overlapping cells in hat flap inward forming small non-return valves
• interstitial fluid, protein, bacteria, particles, hormones enter but can’t leave

Question 9

How to the larger lymphatic vessels w/ non-return valves function?

Answer 9

• it functions as a lymphatic pump helped by the contraction of the body muscles.

Question 10

What is the speed of lymph flow during exercise and during rest?

Answer 10

• during exercise: increased 5-15 times
• during rest: sluggish - approx. 120 ml/hr

Question 11

How do the terminal lymphatic capillaries help the blood capillary beds?

Answer 11

• it drains the excess interstitial fluid from the capillary beds.
• as fluid of out the capillary bed, fluid from the tissue will be forced into the terminal lymphatic vessel

Question 12

Is lymphatic fluid similar to interstitial fluid? What does lymphatic fluid contain?

Answer 12

• yes!
• and it contains proteins (2g/100 ml), fat droplets, and lymphocytes

Question 13

What are lymph nodes & where are they found?

Answer 13

• they are masses of 2 types of white blood cells:
  • lymphocytes
  • macrophages
• located at the junctions of lymph vessels

Question 14

What is the function of lymph nodes?

Answer 14

• act as filters of the system by stopping bacteria & foreign particles

Question 15

What is a lymph node from the gut called?

Answer 15

• a ‘peter’s patch’

Question 16

What are most of the dark tissue composed of?

Answer 16

• lymphocytes (a type of WBC)

Question 17

State the steps of the Lymphatic system flow in the lower and left upper body.

(Hint: 6)

Answer 17

1. Terminal lymphatic capillaries (lacteals)
2. Lymphatics (lymph nodes)
3. Cisterna chyli (large sac that lies on the posterior abdominal wall below the liver)
4. Thoracic duct (drains all of left side of body including everything below our body on both sides of body)
5. Then enters venous system at the junction of the left subclavain & left jugular veins

Question 18

State the lymphatic system flow steps of the upper right body.

Answer 18

• same steps as left & lower flow but instead of draining into the thoracic duct, it drains through the right lymphatic duct and enters the genius system at the junction of the RIGHT subclavian and RIGHT jugular veins

Question 19

Is the lymphatic system equal on both sides? Why?

Answer 19

• NO!
• b/c left upper side (including left head & arm) and lower part of body drain through thoracic duct while the upper right side drains through right lymphatic duct

Question 20

What are sentinel lymph nodes?

Answer 20

• 1st nodes to which cancer cells may spread from a tumour.

Question 21

In breast cancer, where are the sentinel lymph nodes located?

Answer 21

• in the armpit (axilla)

Question 22

What is & explain sentinel lymph node biopsy.

Answer 22

• procedure that examines the senital lymph nodes that contains cancer cells in the breast.
• steps of this procedure

1) coloured due or radioactive tracer is injected into breast tissue surrounding tumour

2) the injected substances drains into the sentinel lymph nodes & identifies them for surgical removal

3) sentinel lymph nodes are surgically removed and examined for cancer cells