Chapter 31 Flashcards
What are the functions of the lymphatic system?
- to maintain fluid balance
- immunity
- absorption of fats from small intestine and transport to large systemic veins
Why is the lymphatic system considered part of the circulatory system?
- consists of a moving fluid derived from blood/tissue fluid
- consists of vessels that return the lymph to the blood
- the vessels parallel venous return
What is the difference between hydrostatic pressure and osmotic pressure?
What does this have to do with in the interstitial spaces and lymphatic system?
- hydrostatic = fluid pushing out
- osmotic = fluid wanting in
- plasma is drained into interstitial spaces so it wants to leave there via lymphatic vessels
What structures are included in the lymphatic system?
- lymph
- lymphatic vessels
- lymphoid tissue (reticular tissue, contains lymphocytes, located along vessels
What is lymph?
-clear, watery-appearing fluid in lymphatic vessels
What is interstitial fluid?
-fluid that fills the spaces between the cells
What is unique about lymphatic vessels? How do they begin?
- do not form a closed circuit
- begin blindly in the intercellular spaces of soft tissues in the body
What are the blind-ending vessels in the small intestines called?
- lymphatic capillaries
- the openings in the small intestines are called lacteals
What is the structure of the lymphatic system?
-single layer of flattened endothelial cells
Where are lymphatic vessels found?
- next to blood capillary networks
- interstitial spaces
What is the structure of the lymphatic vessel network?
-they branch and anastomose extensively
What is the right lymphatic duct? What regions of the body does it drain?
- one of two beginning branches before they branch off like trees
- drains right arm, right side of head, and right thoracic cavity (right upper quadrant)
What is the thoracic duct? What regions of the body does it drain? Where does it empty into?
- one of two beginning branches before they branch off like trees
- drains the lower extremities, left arm, left thoracic cavity, abdominal cavity, and left side of head (everything except right upper quadrant
- empties into the left subclavian
What is the cisterna chyli? Location? Function?
- dilated sac at the lower end of the thoracic duct
- at L2
- where fatty lymph (chyle) collects from the intestines
What is different between lymphatic vessels and veins?
- thinner walls
- more valves
- located at certain intervals
- very permeable
What is the importance of their permeability?
-allows very large molecules and proteins to be removed from the interstitial spaces
What is the circulation of lymph?
-lymph capillaries -> lymph vessels -> lymph nodes -> lymph trunks -> lymph ducts
How is lymph circulation kept?
- pressure
- respirations and skeletal muscle contractions
What is the flow of lymph called?
-lymphokinesis
What are the primary lymphatic organ? Function?
- red bone marrow
- thymus
- stem cell division and immunocompetence
What are the secondary lymphatic organs? Function?
- lymph nodes
- spleen
- lymphatic nodules
- site of most immune responses
Where is the thymus located?
- in the mediastinum
- in the lower neck
What is the structure of the thymus? Function?
- two pyramidal lobes divided into lobules by connective tissue septa
- covered by a fibrous capsule
- final site of lymphocyte development
- secretes thymosin which allows maturation of T cells
What is the thymic cortex? Location?
- where immature t cells migrate to mature (from red bone marrow)
- outside portion
