Week 4 - Lymphatic System

Question 1

What is the Lymphatic System?

Answer 1

The organ system includes:

• Lymphatic vessels
• Lymph Nodes
• The Thymus
• The Spleen
• Lymph
• It plays a role in the body’s defense against infection.
• Acts as a secondary circulatory system

Question 2

What are the functions of the Lymphatic System?

Answer 2

• Picks up excess interstitial (tissue) fluid and returns it to the blood. This provides a 2nd system for circulation.
• Defense and immunity
• Helps in fat absorption and delivery to the blood (lacteals)
• This function is accomplished by lacteals, lymphatic capillaries found in the small intestine.

Question 3

What are the Lymphatic capillaries?

Answer 3

microscopic, closed-ended tubes.
They extend into interstitial spaces, forming complex networks that parallel the networks of the blood capillaries.
The walls of the lymphatic capillaries are formed from a single layer of squamous epithelial cells.
These thin walls allow tissue fluid (interstitial fluid) to enter lymphatic capillaries. Once inside the lymphatic capillaries, this fluid is called lymph.
Location: Found all over the body, except the central nervous system

Question 4

What are Lymphatic vessels?

Answer 4

Have walls similar to those of veins, but thinner.
They have valves that prevent the backflow of lymph.
They collect and carry away excess tissue fluid from interstitial spaces, eventually returning it to the blood.
Larger lymphatic vessels pass through organs called lymph nodes, and then merge to form larger lymphatic trunks.

Question 5

What are lymph nodes?

Answer 5

Mass of lymphoid tissue located along the course of a lymphatic vessel.
Contain LYMPHOCYTES which help defend the body against disease.

Question 6

What are lymphatic trunks?

Answer 6

• They drain lymph from the lymphatic vessels
• They join one of two collecting ducts
• the thoracic duct or the right lymphatic duct

Question 7

Which lymphatic duct drains lymph from the right lower limb?

Answer 7

the thoracic duct

Question 8

What are Lymphatic Pathways?

Answer 8

Start as Lymphatic capillaries that merge to form larger vessels
Then Lymphatic trunks, that empty into the veins in the thoracic cavity.

Question 9

Where can you NOT find lymphatic capillaries?

Answer 9

The Central Nervous System

Question 10

What are collecting ducts?

Answer 10

The lymphatic trunks empty into 1 or 2 collecting ducts; thoracic or right lymphatic duct
Right Lymphatic Duct: Drains the right side of the head and neck, right arm, right thorax, and empties into the right subclavian vein.
Thoracic Duct: Larger collecting duct, drains rest (majority) of the body, and empties into left subclavian vein.

Question 11

What does the Thoracic Duct do?

Answer 11

• It is the largest collecting duct
• Drains the majority of the body
• Empties lymph into the left SUBCLAVIAN vein.

Question 12

What does the Right Lymphatic Duct Do?

Answer 12

• Drains the right side of the head and neck
• the right arm
• right thorax
• and empties into the SUBCLAVIAN vein.

Question 13

What are the steps of the Lymphatic Pathway?

Answer 13

1. Lymphatic Capillaries
2. Afferent lymphatic vessel
3. Lymph Node
4. Efferent Lymphatic Vessel
5. Lymphatic Trunk
6. Collecting Duct
7. Subclavian Vein

Question 14

What is tissue fluid?

Answer 14

• Made up of water and dissolved substances that leave blood capillaries by filtration and diffusion
• Almost the same as blood plasma, except it does not contain large plasma proteins, which are too large to pass through capillary walls
• Plasma proteins create plasma colloid osmotic pressure, that draws most of the fluid back into the capillaries
• Fluid that does not return to the capillaries, is known as tissue fluid.

Question 15

Discuss Lymph Formation and Function…

Answer 15

1. Filtration from the plasma usually occurs to a greater extent than reabsorption; this leads to tissue fluid formation
2. Rising osmotic pressure in the tissues interferes with the return of fluids to the bloodstream
3. Increasing tissue fluid hydrostatic pressure forces some fluid into lymphatic capillaries, where it is now called lymph.
4. Most substances, including small proteins, are returned to the blood via the lymph.

Question 16

What is the function of Lymph?

Answer 16

Transports foreign particles, including bacteria and viruses, to the lymph nodes for recognition and destruction.

Question 17

What factors help in the movement of Lymph?

Answer 17

Hydrostatic pressure of tissue fluid
Skeletal muscle contraction
Breathing movements
Contraction of smooth muscle in the walls of the vessels
Valves that prevent backflow

Question 18

What is Edema?

Answer 18

Accumulation of lymph in the interstitial spaces, due to interference with the flow in lymph.
Swelling from an injury or inflammation.
excess fluid trapped in body tissues.

Question 19

What do Lymphatic tissues contain?

Answer 19

Lymphocytes

Macrophages and other cells

Question 20

What is the name given to unencapsulated lymphatic tissue that is associated with the digestive, respiratory, urinary, and reproductive systems?

Answer 20

Mucosa associated lymphoid tissue (MALT)

Question 21

what structures of the body contain lymphatic nodules?

Answer 21

Tonsils
Appendix
Peyer’s Patches

Question 22

What are encapsulated lymphatic organs?

Answer 22

Lymph Nodes
Thymus
Spleen

Question 23

What are Lymph Nodes?

Answer 23

Bean-shaped
Blood vessels, nerves, and efferent lymphatic vessels enter or exit at the indented HILUM of the lymph node
Afferent lymphatic vessels enter on the convex surface of the lymph node

Lymph Nodes are are covered with a connective tissue capsule, that extends inside the node and divides it into lymphatic nodules and spaces called SINUSES.

Question 24

What is the function of lymph nodes?

Answer 24

1. Filter lymph and remove bacteria and cellular debris before lymph is returned to to the blood.
2. Immune serveillance: Monitor body fluids; performed by lymphocytes and macrophages
3. Centers of lymphocyte production

Question 25

Where are lymph nodes located?

Answer 25

Found in chains along the parts of the larger lymphatic vessels.

Question 26

Where are large areas of concentrations of lymph nodes found?

Answer 26

Cervical, thoracic, axillary, supratrochlear, abdominal, pelvic and inguinal regions.

Question 27

Where does filtered lymph exit the lymph nodes from?

Answer 27

Filtered lymph leaves the lymph node through efferent lymphatic vessels.

Question 28

What is the function of lymphocytes?

Answer 28

Attack viruses, bacteria, and parasitic cells that enter a lymph node (white blood cell).

Question 29

What is the function of macrophages?

Answer 29

Engulf and destroy foreign particles, debris, and damaged cells.

Question 30

What is the thymus?

Answer 30

A soft, bi-lobed organ located on the sternum, anterior to the aorta.
Surrounded by connective tissue capsule that extends inwards and divides into lobules.

Question 31

What do the lobules in the thymus contain?

Answer 31

Lymphocytes, some of which mature into T cells or T Lymphocytes, that leave the thymus to provide immunity.

Question 32

what is the function of the thymus?

Answer 32

Secretes hormones called thymosins, which influence maturation of T Lymphocytes.

Question 33

What happens to the thymus during our lives?

Answer 33

Children: Large in size
Adults: Small in size
Elderly: Replaced by adipose and connective tissue.

Question 34

Where is the spleen?

Answer 34

Lies in the upper left abdominal cavity

Question 35

What is the structure of the spleen?

Answer 35

• Largest lymphatic organ in the body
• Contains blood instead of lymph
• Composed of white pulp, which contains many lymphocytes and red pulp, which contains red blood cells, macrophages and lymphocytes

Question 36

what is the function of the spleen?

Answer 36

Filters the blood and removes damaged blood cells and bacteria.