BIOL 3320 Exam 3 Lymphatic System

How much water enters the lymphatic system?

15% (2-4 L/day)

How much of the plasma proteins enter the Lymphatic System?

About half

What are the main functions of the lymphatic system?

• Maintain fluid balance

• Protect body from infection and disease

How much flood do the capillaries reabsorb?

85%

What is immunity?

It is when excess filtered fluid picks up foreign cells from the tissue. It then passes through the lymph nodes where immune cells keep the foreign matter from moving further. This activates a protective immune response.

What is Lymph?

• The recovered fluid

• Clear, colorless - similar to plasma but less protein

• Starts as extracellular fluid - then picked up by capillaries

What do lymphatic vessels do?

transport the lymph

What are some key components of lymphatic tissues?

Made up of pieces of lymphocytes and macrophages that are in many organs of the body.

• they can change shape because they do NOT have a fibrous membrane

What are some key components of lymphatic organs?

• Defense cells are prominent here

• Separated from surrounding organs by connective tissue

• has fibrous membrane surrounding it.

What is the flow of lymph?

1. leaves circulatory system at the capillaries as interstitial fluid

2. picked up by lymphatic capillaries - then becomes lymph

3. travels to lymphatic vessels/ collecting vessels

4. Passes through lymph nodes

5. travels to lymphatic trunks

6. then one of two collecting ducts

   1. Right lymphatic duct (smaller)

   2. Thoracic duct (larger and longer)

7. travels to subclavian veins

   1. Right lymphatic duct (right subclavian)

   2. Thoracic duct (left subclavian)

What is in the tunica interna of the lymphatic vessels?

endothelium and valves

What is in the tunica media of lymphatic vessels?

elastic fibers and smooth muscle

What is the tunica externa of lymphatic vessels?

a thin outer layer

What are the mechanisms that help lymph flow?

• Forces similar to venous return but no pump (heart)

• flows at low pressure and slower speed than venous blood

• Moved by rhythmic contractions of lymphatic vessels

  • arterial pulsation rhythmically squeezes lymphatic vessels

• aided by skeletal muscle pump

• flow from abdomen to thoracic cavity aided by thoracic pump

• valves prevent back flow

• rapid blood flow in subclavian veins draws lymph in

• exercise increases lymphatic return

What is lymphatic tissue?

pieces of lymphocytes in the connective tissue of mucous membranes and various organs

What is diffuse lymphatic tissue?

• the simplest form of lymphatic tissue

• Present in body passages open to the exterior

• Mucosa-Associated Lymphoid Tissue (MALT)

  • lymphatic tissue found in mucous membranes

What are lymphatic nodules?

Dense masses of lymphocytes and macrophages that congregate in response to pathogens

• commonly found in lymph nodes, tonsils, and appendix

What is the difference between Lymphatic tissue and Lymphatic nodules?

Lymphatic tissue is the general reticular connective tissue containing lymphocytes and other immune cells, while lymphatic nodules are localized, dense aggregations of lymphatic tissue that form small immune surveillance sites, often in mucosal membranes and lymph node cortex.

What are Peyer patches?

Dense clusters of lymphatic nodules in the ileum (the distal portion of the small intestine)