Chapter 20 Lymphatic Study Guide

Which mechanisms provide lymph transport?

- "milking action" from skeletal muscles - pressure changes in thorax from breathing - valves to prevent back flow

Are lymph vessels high or low pressure conduits? Describe the mechanisms by which lymph fluid is moved through the lymphatic vessels.

- Lymph vessels are low pressure conduits; close at one end causing only a one way path for lymph to flow.

Lymph nodes

- filters debris from lymph (phagocytes) - immune system activation (lymphocytes)

What are the main functions of the lymphatic system?

- return fluid to the bloodstream - provide structure for immune system - transport fatty acids from intestines to the blood stream

Lymphatic capillaries function

- weave between blood capillaries and tissues - overlapping epithelial cells operate as one way mini-valves - high permeability, allowing bacteria, cancer cells, etc to enter lymphatic system

How do the lymphatic capillaries differ from blood capillaries structurally and functionally?

Blood capillaries form veins and lymphatic capillaries unite to form larger lymphatic vessels; thinner walls and more valves.

In which direction does lymph flow?

It flows in a one-way system which is towards the heart

Identify the secondary lymph organs.

Lymph nodes Tonsils Spleen Peyer's Patches & Appendix

How does the lymphatic system both help and hinder the spread of cancer through the body?

Lymph nodes help rid the body of cancer cells by immune mechanisms. Lymph vessels may also be used to spread cancer cells throughout the body if immunity is not effective against the cancer cells.

What are the main structures of the lymphatic system?

Lymphatic vessels Lymph Lymph organs

Lymph organs

Primary (where lymphocytes mature) Secondary (lymphocytes encounter antigens)

Lymphatic vessels

capillaries --> vessels --> trunks --> ducts

phagocytes

cell which engulf, digest, destroy pathogens

Lymphatic capillaries structure

endothelial cells lack tight junctions

Tonsils

expose lymphocytes to bacteria and pathogens

Peyers patches & Appendix

expose t-lymphocytes to bacteria and pathogens from digestive tract

macrophages

from monocytes, "live another day" (keeps fragment and waves flag to other pathogens the rest has been destroyed)

Where does it come from?

interstitial fluid that enters the lymphatic vessels

What are the consequences of obstruction of the lymph flow?

lymphedema not curable, must focus on improving lymph flow

neutrophils

most common WBC, "suicide mission" (dies after threat is destroyed)

Lymph

plasma --> interstitial fluid --> lymph

T-lymphocytes

recognize infected cells and attack them activates B cells

B-Lymphocytes

recognizes foreign pathogens and produce plasma cells

Where are these structures located and what do they do?

red bone marrow and thymus gland T cells mature in Thymus gland B cells mature in red bone marrow

plasma cells

release antibodies to tag pathogens for destruction by phagocytes

Spleen

site for lymphocyte storage and activation; filters blood of old RBC's

Why are they defined as primary?

t cells and b cells are born and mature in these organs

What types of immune cells are located in the lymphatic system?

t-lymphocytes b-lymphocytes plasma cells phagocytes macrophages neutrophils

What is lymph?

the fluid contained in lymphatic vessels

Describe the transport of lymph from beginning to end.

through the body in its own vessels making a one-way journey from the interstitial spaces to the subclavian veins at the base of the neck. Since the lymphatic system does not have a heart to pump it, its upward movement depends on the motions of the muscle and joint pumps. As it moves upward toward the neck the lymph passes through lymph nodes which filter it to remove debris and pathogens. The cleansed lymph continues to travel in only one direction, which is upward toward the neck. At the base of the neck, the cleansed lymph flows into the subclavian veins on either side of the neck.

Identify the primary lymph organs.

thymus red bone marrow

Why are they defined as secondary?

where mature cells encounter their antigens and are activated