The Lymphatic System

Question 1

What are the functions of the Lymphatic System?

Answer 1

1- The return of interstitial fluid and proteins from the peripheral tissues to the blood: to help maintain fluid balance

2- Absorption and return of fats from small intestine to the general circulation. Lacteals absorb digested fats from the intestine and transport them to the blood.

3- The production, maintenance and distribution of lymphocytes, that protect the body against foreign antigens (viruses, bacteria…)

Question 2

How is fluid build up outside the vessels prevented?

Answer 2

The plasma that leaves the blood capillaries and doesn’t return becomes part of the interstitial fluid which then drains into lymphatic vessels and become lymph to be returned to circulation.

Question 3

What happens to proteins that leave blood vessels? Why don’t they return to the vessel?

Answer 3

The leaking plasma proteins which are small in size (the large ones can’t leave the vessel) will become part of the interstitial fluid. They can’t get back into the blood capillary because of the concentration gradient but can move through the more permeable lymphatic vessels.

Question 4

Pathway of lipids through lacteals

Answer 4

Lacteals –> lymph vessels –> cisterna chyli –> Thoracic duct –>Venous system

Question 5

Lymph within lacteals is known as — and has a —- appearance.

Answer 5

Chyle, milky

Question 6

What other than lipids do lacteals carry?

Answer 6

Lipid-soluble vitamins

Question 7

Lymphatic tissues that filter body fluids are? What do they filter?

Answer 7

The spleen, lymph nodes, and tonsils.

• Lymph nodes filter lymph
• Spleen filters blood
• Tonsils filter swallowed and inhaled materials

Question 8

What are the 4 components of the lymphatic system?

Answer 8

1. Fluid:
   Called Lymph (clear and watery), flows through the lymphatic vessels. Fluid from the intestines (chyle) contains fats.
2. Vessels:
   A network of lymphatic vessels that begins in the peripheral tissues and connects to the venous system.
3. Lymphatic organs and tissues:
   Found throughout the body and contain large numbers of lymphocytes (Ex. Lymph nodes, spleen and thymus).
4. Lymphocytes and other immune system cells

Question 9

Which has a higher protein content plasma or lymph?

Answer 9

Lymph

Question 10

Lymph pathway

Answer 10

Lymphatic capillaries, afferent lymphatic vessels with valves, lymph node, efferent lymphatic vessels which merge into lymphatic trunks, collecting ducts, and venous blood (internal jugular and subclavian veins).

Question 11

Difference between lymphatic system and cardiovascular system?

Answer 11

Lymphatic system is a one-way system going from tissues towards the heart without a pump. Cardiovascular system is a circuit carrying blood from and to the heart.

Question 12

How does the lymphatic system make up for the lack of pump?

Answer 12

1- Contraction of skeletal muscles against lymphatic vessels during movement
2- Respiratory pump: Breathing that leads to changes in pressure within the abdominal and thoracic cavities
3- Contraction of smooth muscles in larger vessels
4- Valves in lymphatic vessels that prevent lymph backflow

Question 13

What is fluid accumulation in the tissues called? Why does it occur?

Answer 13

Edema, it occurs due to lymphatic vessel obstruction

Question 14

Lymphatic capillaries arise —- in tissues. What does this mean?

Answer 14

blindly, not from larger vessels like blood capillaries

Question 15

Properties of lymphatic capillaries

Answer 15

1- Closed at one end 
2- Run parallel to blood capillaries
3- One layer of endothelial cells 
4- Lacteals are a special form 
5- More permeable than blood capillaries 
6- Not found in cartilage and epidermis

Question 16

What region was thought to have no lymphatic capillaries and recently been proved otherwise?

Answer 16

CNS

Question 17

What are minivalves? When do they open and close?

Answer 17

Lymphatic capillaries: made of adjacent endothelial cells, loosely bound together with overlap, forming minivalves.
IF pressure > open: Fluid and proteins can enter the capillary
Lymphatic pressure > close: lymph cannot escape back into IF.

Question 18

What prevents the lymphatic capillary from collapsing when IF accumulates? How ?

Answer 18

Collagen filaments that anchor the endothelial cells to the connective tissue.
When IF accumulates, swelling will pull the anchoring filaments making spaces between the cells to prevent collapse.

Question 19

Lymphatic vessels have —- and are similar to —- but with —

Answer 19

semilunar valves, veins, thinner walls

Question 20

State the lymphatic trunks

Answer 20

Lumbar, intestinal, bronchomediastinal, subclavian, and jugular.

Question 21

State the 2 lymphatic ducts? Which one is the main? From where do they collect lymph?

Answer 21

1- Main one: thoracic duct or the left lymphatic duct
begins as a dilation that is called cisterna chyli that receives lymph from right and left lumbar trunk as well as from intestinal trunk, left jugular, left subclavian and left bronchomediastinal trunks.
2- Right lymphatic duct: receives lymph from the right jugular, right subclavian, and right bronchomediastinal trunks.