1. Chap 19 – Lymphatic System
Homework: Read Chap 19. Review anatomical structures & physiology (per diagrams).
Learning Objectives:
1.List the functions of the lymphatic system.
2. Describe the source of lymph & its transport.
4. Describe lymph tissue.
5. Describe lymph nodes (locations structure and distribution of the lymph vessels.
3. Explain the, histology, function, etc.)
6. Name and describe other lymphoid organs of the body.

2. What’s the Problem?
These patients have an imbalance called ___________.

3. Opening Discussion
What does the lymphatic system do? How does it tie-in to what we have been studying?

4. Circulatory Dilemma
Problem: Capillaries are known to be ‘leaky’ vessels. They leak about 3L of interstitial fluid into tissue spaces daily.
All this fluid must be returned to the cardiovascular system to ensure sufficient blood volume
How does it get returned?

5. Lymphatic System To The Rescue!
The lymphatic system - an elaborate system of drainage vessels that collect excess interstitial fluid and return it to the bloodstream

6. How Does It Work? Instructions: 1. Take time to reflect.
2. Review Figure 19.1 (page 680) and the associated text, “Distribution and Structure of Lymphatic Vessels”.
3. Write a 1-3 sentence summary in your own words of how it basically works. Place the summary in your notes next to this slide.
4. Be prepared to share with class.
Estimated Time: 3-5 minutes

7. Lymph Vessels
A __________ system in which lymph flows toward the heart
Lymph vessels include:
Microscopic, permeable, blind-ended capillaries
Lymphatic collecting vessels
Trunks and ducts

8. Lymph Collecting Vessels
Have the same three ______ as veins
Have _______ walls, with more internal valves
Collecting vessels in the skin travel with superficial veins
Deep vessels travel with arteries

9. Lymph Capillaries Similar to blood _________, with modifications
Remarkably ___________
Loosely joined endothelial minivalves (withstand interstitial pressure and remain open). Also, function as one-way gates that:
a) Allow interstitial fluid to enter lymph capillaries
b) Do not allow lymph to escape from the capillaries

10. Lymph Capillaries continued
During inflammation, lymph capillaries can absorb:
_____ debris
__________
______ cells
Cells in the lymph nodes:
Cleanse and __________ this debris
Lacteals – specialized lymph capillaries present in intestinal mucosa
Absorb digested fat and deliver chyle (fatty lymph) to the blood

11. Lymph Transport
The lymphatic system _______ an organ that acts as a pump
Vessels are ____-pressure conduits
Uses the same methods as _____ to propel lymph
Pulsations of nearby arteries
Contractions of smooth muscle in the walls of the lymphatics

12. General Distribution of Vessels and Regional Lymph Nodes
Label your practice diagram.
Page 682

13. Lymphatic Trunks
Lymphatic trunks are formed by the union of the largest collecting ___________
Major trunks include:
Paired ________, bronchomediastinal, subclavian, and ________ trunks
A single intestinal trunk
Lymph is delivered into one of two large ______
_____ lymphatic duct – drains the right upper arm and the right side of the head and thorax
_______ duct – arises from the cisterna chyli and drains the rest of the body

14. Lymphatic Trunks
Label your practice diagram
Page 682

15. Lymphoid Cells
____________ are the main cells involved in the immune response . The two main varieties are _ cells and _ cells (protect the body against foreign antigens such as bacteria, viruses, & cancer)
__________ – phagocytize foreign substances and help activate T cells
________ cells – spiny-looking cells with functions similar to macrophages
________ cells – fibroblastlike cells that produce a stroma, or network, that supports other cell types in lymphoid organs

16. Lymph Nodes
Lymph nodes are the principal lymphoid ________ of the body
Nodes are imbedded in _______ tissue and clustered along lymphatic vessels
Aggregations of these nodes occur near the body surface in inguinal, _______, and cervical regions of the body

17. Functions of Lymph Nodes
Their two basic functions are:
____________ – macrophages destroy microorganisms and debris
________ ______ __________ – monitor for antigens and mount an attack against them

18. Lymph Node Structure
________ are bean shaped and surrounded by a fibrous capsule
Nodes are ______________ (trabeculae extend inward)
Nodes have two histologically distinct regions: a _______ and a _______

19. Lymph Node Structure continued
Label your practice diagram.

20. Lymph Node Structure continued
The cortex contains _________ with germinal centers, heavy with dividing B cells
__ _______ circulate continuously among the blood, lymph nodes, and lymphatic stream
_________ cords extend from the cortex and contain B cells, T cells, and plasma cells
Throughout the node are lymph _______ crisscrossed by reticular fibers. Macrophages reside on these fibers and phagocytize ______ matter

21. Other Lymphoid Organs The ____, ______ gland, and _______
_________ patches and bits of lymphatic tissue scattered in connective tissue
All are composed of reticular connective tissue and all help protect the body
Only lymph nodes filter lymph

22. Spleen
_________ lymphoid organ, located on the left side of the abdominal cavity beneath the diaphragm
Functions
Site of lymphocyte proliferation
Immune surveillance and response
Cleanses the ______
Stores blood ________

23. Spleen Structure, page 686 Two distinct areas of the spleen are:
_____ pulp – area containing mostly lymphocytes suspended on reticular fibers and involved in immune functions
_____ pulp – remaining splenic tissue concerned with disposing of worn-out RBCs and bloodborne pathogens

24. Thymus
A bi-lobed organ that secrets hormones (thymosin and thymopoietin) that cause T lymphocytes to become immunocompetent
The size of the thymus varies with age
It increases in size and is most active during ________
It stops growing during adolescence and then gradually _________

25. Thymus continued
The thymus _______ from other lymphoid organs in important ways
It functions strictly in T lymphocyte ________
It does not directly fight _______
The thymus consists of star-shaped epithelial cells (not reticular fibers)

26. Tonsils
Simplest lymphoid organs; form a ring of lymphatic tissue around the _______
Like little crypts - ____ and ______ bacteria and particulate matter

27. Other continued
Peyer’s patches – isolated clusters of lymphoid tissue, similar to tonsils
Found in the wall of the distal portion of the _____ _________
Similar structures are found in the appendix
_____ – mucosa-associated lymphatic tissue (protects the digestive and respiratory systems from foreign matter)