Lecture 22 - Lymphatic System

Question 1

What are the functions of the lymphatic system? (4)

Answer 1

• Return of lost substances
• Maintenance of blood volume
• Fluid balance
• Carries out immune response

Question 2

What are the structural components of the lymphatic system? (4)

Answer 2

• Lymph plasma
• Lymphatic vessels
• Lymphoid organs
• Lymphatic tissue

Question 3

Describe the function of lymphatic capillaries/vessels and how they carry it out

Answer 3

• Lost plasma components in interstitial fluid enter lymphatic capillaries (made of endothelial cells) because of the pressure gradient and its high permeability - fluid now is called lymph
• Lymph travels through lymphatic vessels being pushed by muscle contraction (body movement), vessels contain a lot of valves to prevent backflow

Question 4

What are the primary lymphoid organs?

Answer 4

The thymus and bone marrow

Question 5

What are the secondary lymphoid organs?

Answer 5

The spleen and the lymph nodes

Question 6

Explain the pathway of lymph (6 components)

Answer 6

Lymphatic Capillaries
I
Afferent lymphatic vessels
I
Lymph node
I
Efferent lymphatic vessels
I
Lymphatic trunks
I
Lymphatic ducts
I
Heart

Question 7

What are the two major lymphatic ducts and where are they located

Answer 7

• Right Lymphatic Duct
  
  • Drains into the right subclavian
    vein
• Thoracic Duct
  
  • Drains into the left subclavian
    vein

Question 8

Explain what sections of the body are drained by which lymphatic duct

Answer 8

• Upper Right Quadrant: Right lymphatic duct (drains into right subclavian vein)
• Upper left quadrant and both lower quadrants: Thoracic duct (drains into left subclavian vein)

Question 9

What makes red bone marrow a lymphoid organ

Answer 9

• Contain stem cells that:
  
  • Turn into RBC
  • Turn into WBC (T/B Cells)
  • Platelets

Question 10

What section of the bone is red bone marrow found in?

Answer 10

Found in the epiphyses of long bones (ends)

Question 11

Where is the thymus located?

Answer 11

Posterior to the sternum anterior to the great vessels

Question 12

Main function of the thymus?

Answer 12

Matures and proliferates T cells

Question 13

Describe features of thymus histology (5)

Answer 13

• Covered by capsule layer
• Organized into thymic lobules, divided by trabeculae (extensions of the capsule)
  
  • Each has a cortex (dark staining) and medulla (light staining)

Question 14

List the 4 categories of lymph nodes

Answer 14

• Cervical
• Inguinal
• Axillary
• Intestinal

Question 15

What is the function of the lymph nodes? (2)

Answer 15

• Filters incoming lymph before it are brought back into circulation
• Role in immune function

Question 16

What are the trabeculae in lymph nodes?

Answer 16

Provide a space for blood vessels to enter the nodes

Question 17

Describe the general pathway of lymph through a lymph node

Answer 17

• Enters through the afferent lymphatic vessels
• Travels through the subcapsular sinuses and trabecular sinuses
• Filtered by immune cells in the cortexes and medulla
• Exits through the hilum and into the efferent lymphatic vessels

Question 18

Explain the difference in function between white pulp and red pulp in spleen histology

Answer 18

• White Pulp: Aggregations of B and T cells - develop around arteries supplying spleen
• Red Pulp: Splenic cords - contains immune cells, filter our old RBC, clean blood the blood /

Question 19

Where are Peyer’s Patches found? What is their function?

Answer 19

The ileum of the small intestine
- Responsible for regulating and fighting off gut bacteria

Question 20

Where is the appendix found and what is it’s main function?

Answer 20

Connected to the cecum of the large intestine
- Contain lymphatic nodules that fight off gut bacteria

Question 21

List the three main types of tonsils?

Answer 21

• Pharyngeal
  
  • Top of nasopharynx
• Palatine
  
  • Oropharynx
• Lingual