The lymphatic and immune system

Question 1

What is the lymphatic system?

Answer 1

A network of tubes that drain fluid (lymph) that has leaked from the blood vessels into the tissue.

[the lymph is then emptied back into the bloodstream via lymph nodes]

Question 2

The lymphatic system contributes to homeostasis by performing three key functions.

Answer 2

1. drains excess interstitial fluid
2. transports dietary lipids
3. carries out immune responses

Question 3

What are the 4 main components of the lymphatic system?

Answer 3

1. Lymph - the fluid (note: the major difference between lymph and interstitial fluid is location)
2. Lymphatic vessels
3. Lymphatic organs and tissues
4. Red bone marrow (the site of lymphocyte production)

Question 4

What are the 4 lymphatic vessels?

Answer 4

1. Lymphatic capillaries - located in the space between cells, closed at one end, greater permeability than blood capillaries
2. Lymphatic vessels - capillaries merge to form vessels which move lymph in and out of lymph nodes
3. Lymphatic trunks - vessels exit nodes in particular regions of the body where they unite to form trunks (i.e. merging point)
4. Lymphatic ducts - lymph passes from trunks into two main channels: the thoracic duct and right lymphatic duct before being drained into venous blood

Question 5

Lymphatic capillaries are tiny thin-walled vessels that collect lymph fluid from the tissues. This allows them to regulate what?

Answer 5

Pressure of the interstitial fluid

Question 6

What are lacteals?

Answer 6

Specialised lymphatic capillaries in the small intestine that absorb and transport digested fats from the small intestine into the blood

Question 7

What helps fluid to enter lymphatic capillaries when tissue pressure is high, working as one-way valves? (what type of cell)

Answer 7

Overlapping endothelial cells

Question 8

A number of lymph trunks drain lymph into different areas of the body. Name the areas that the following trunks drain into…

1) Lumbar trunk
2) Intestinal trunk
3) Broncho mediastinal trunk
4) Subclavian trunk
5) Jugular trunk

Answer 8

1) from the lower limbs, pelvis, kidneys, adrenal glands, abdominal wall

2) stomach, intestines, pancreas, spleen, part of the liver

3) thoracic wall, lung, heart

4) upper limbs

5) head and neck

Question 9

A key function of lymphatic vessels is to return WHAT to the bloodstream?

Answer 9

Lost plasma proteins and plasma

Question 10

What is the main collecting duct in the lymphatic system?

Answer 10

The thoracic duct

Question 11

What are the main two functions of the thoracic duct?

Answer 11

1) receives lymph from the left side of the head, neck and chest, left upper extremity, and the entire body below the ribs

2) drains lymph into venous blood via the left subclavian vein

Question 12

What are the main two functions of the right lymphatic duct?

Answer 12

1) receives lymph from the upper right side of the body

2) drains lymph into venous blood via the right subclavian vein

Question 13

Put the following steps into the right order of flow

> lymphatic ducts
lymph capillaries
interstitial fluid
junction of the internal jugular and subclavian veins
lymphatic vessels

Answer 13

1) interstitial fluid

2) lymph capillaries

3) lymphatic vessels

4) lymphatic ducts

5) junction of the internal jugular and subclavian veins

Question 14

What are the main classifications of lymphatic organs and tissues?

Answer 14

Primary and secondary

Question 15

Primary lymphatic organs provide an environment for stem cells to divide and mature into B and T lymphocytes.

Name the primary lymphatic organs.

Answer 15

Red bone marrow - B cells continue to mature here

Thymus - Pre-T cells migrate from red bone marrow and mature in the thymus

Question 16

Secondary lymphatic organs and tissues provide a site for most immune responses to occur.

Name the secondary lymphatic organs.

Answer 16

Lymph nodes

Spleen

Lymphatic nodules (follicles)

Question 17

Which primary lymphatic organ gives rise to pre-T cells and mature, immunocompetent B cells?

Answer 17

Red bone marrow

Question 18

The thymus is structured into a cortex and medulla. The cortex is responsible for the proliferation and maturation of immature T cells (pre-T cells) which have migrated from the red bone marrow. What is the medulla responsible for?

Answer 18

Release of mature and immunocompetent T cells into the blood to migrate to lymph organs

Question 19

The spleen works as part of the lymphatic system to filter blood. There is red and white pulp.

Red pulp consists of venous sinuses filled with blood and splenic tissue and is responsible for the removal of ruptured/worn-out red blood cells, and the storage of platelets.

What is the function of the white pulp?

Answer 19

Lymphatic tissue responsible for the performance of B cells, T cells and macrophages which are involved in immune functions.

Question 20

Lymphatic nodules are egg-shaped masses of lymphatic tissue that are NOT surrounded by a capsule. Large aggregations in specific parts of lymph nodes include…

Answer 20

1) Peyer’s patch (small intestines)

2) Tonsils

3) Adenoids

4) Palatine tonsils

5) Lingual tonsil (base of tongue)

6) Appendix

Question 21

Lymph nodes are bean-shaped and often occur in groups, scattered throughout the body. They slow the flow of lymph and function as a type of filter, trapping foreign substances. Lymph flows only in one direction within a node entering through a WHAT lymphatic vessel?

Answer 21

Afferent lymphatic vessel

(contains valves)

Question 22

What is the route of lymph through a node? (5 steps)

Answer 22

1) Afferent lymphatic vessels

2) Subcapsular sinus

3) Trabecular sinus

4) Medullary sinus

5) Efferent lymphatic

Question 23

Name the cells of the medulla of a lymph node

Answer 23

B cells
Plasma cells
Macrophages

Question 24

Name the cells of the inner cortex of a lymph node

Answer 24

T cells
Dendritic cells

Question 25

Name the cells AROUND the germinal centre of the outer cortex of a lymph node

Answer 25

B cells

Question 26

Name the cells IN a germinal centre of the outer cortex of a lymph node

Answer 26

B cells
Follicular dendritic cells
Macrophages

Question 27

Where do B cells mature?

Answer 27

Red bone marrow

Question 28

Where do T cells mature?

Answer 28

Thymus

Question 29

T cells kill by…?

Answer 29

Lysis

Question 30

Antigen presenting cells in lymph nodes include…?

Answer 30

Dendritic cells and follicular cells

Question 31

B cells give rise to what?

Answer 31

Plasma cells

Question 32

Plasma cells make what?

Answer 32

Antibodies

Question 33

What are the two types of immunity?

Answer 33

Innate (non-specific) and adaptive (specific)

Question 34

Innate immunity acts as the first line of defence by supporting external physical and chemical barriers. Give some examples of physical and chemical factors.

Answer 34

PHYSICAL
- epidermis of skin
- mucous
- hairs
- saliva
- vomiting
- lacrimal apparatus
- defecation

CHEMICAL
- sebum
- gastric juices
- vaginal secretions

Question 35

The return of lymph is maintained by two pumps…

Answer 35

Skeletal muscle and respiratory pumps

Question 36

The main duct for the return of lymph to the blood is the…?

Answer 36

Thoracic duct

Question 37

Which organ removes worn-out red blood cells?

Answer 37

Spleen

Question 38

Tears contain an enzyme that break down certain bacteria called…?

Answer 38

Lysozymes