(Lecture 13, Chapter 15) Lymphatics Flashcards
How does the body respond to damage to its tissues and/or cells?
Inflammation, swelling due to accumulation of ECF
ECF = _____ + ________ ____
plasma + interstitial fluid
What is lymph/lymph fluid?
- Plasma and water move into surrounding interstitial fluid from blood in the capillaries
- IF is collected into lymphatic vessels, and then known as lymph
Where is lymph collected and released?
- Collected at peripheral tissues
- Empties into the venous system
Is the lymphatic system an open or closed system?
Open; lymphatic vessels aren’t directly connected to capillaries
Fluid is collected, filtered in ____ ___, and returned to the blood
lymph nodes
What are the responsibilities of cells, tissues, and organs in the lymphatic system? (2)
- Drainage (returning IF to the bloodstream)
- Immunity (enhancing the body’s ability to defend against infection, illness, and disease)
T/F: Lymph doesn’t have to be replenished/regenerated
False
Lymphatic Vessels
Carry lymph and lymphocytes from peripheral tissues to the veins
Lymph Nodes
- Monitor the composition of lymph
- engulf pathogens
- stimulate immune response
Spleen
- Monitors circulating blood
- Engulfs pathogens
- Recycles RBCs
- Stimulates immune response
Thymus
Controls development/maintenance of T cells
Lymphocytes
- Main cell type in lymphatic system
- Surrounded by lymph
- Respond to invading pathogens, abnormal body cells, foreign proteins
Lymph Capillaries
- Open-ended
- Surround blood capillaries
- Embedded in capillary bed
Structure of lymphatics
- Lymphatics have valves that form from overlapping epithelial cells, creating bulges
- Valves ensure that flow of lymph is unidirectional
- No tight junctions or basement membranes; they would prevent the flow of lymph
Lymph flow
- Aided by slow/sporadic contraction of skeletal muscle
- Movement is independent of a pump (unlike the cardiovascular system)
- Valves open when the pressure of IF in interstitial space exceed that in lymphatic capillaries
T/F: Proteins can enter both lymphatic and blood capillaries
False, they can only enter lymphatic capillaries
Substances that can easily enter/exit lymphatic capillaries (3):
- Larger particles
- Cell debris
- Pathogens
Thoracic Duct
Collects lymph from below and above/to the left of the diaphragm
Right Lymphatic Duct
Collects lymph from above/to the right of the diaphragm
What blood vessels do the thoracic duct and right lymphatic duct drain into?
Thoracic Duct: left subclavian vein
Right Lymphatic Duct: right subclavian vein
Functions of lymph nodes
- Macrophages in lymph nodes remove/destroy microorganisms and debris
- Lymph nodes filter macrophages and debris, preventing them from going to other body parts
- Activate immune mechanisms; nodes are located where lymphocytes often encounter antigens and foreign particles
How does bottleneck flow occur in lymph nodes? Why is it beneficial?
- There are many afferent lymphatic vessels and only one efferent lymphatic vessel per lymph node
- Increased residence time = more time for immune function to work
List of lymphoid organs (5)
- Spleen
- Thymus
- Tonsils
- Peyer’s patches
- Appendix
Where are Peyer’s patches located? What is significant about this?
- Located in the small intestine
- Lots of absorption occurs in the small intestine, so there are more opportunities for pathogens (and other stuff that has to be filtered out) to be absorbed
Edema
Lymphatics fail to collect and drain fluid, causing it to accumulate
- causes pressure/pain, can be severe if it occurs around the heart or nerves
- Drained with a needle
- e.g. hyperthyroidism/goiters
