Lymphatic system Flashcards
What are the contents of the lymphatic system?
- Lymph
- Lymphatic vessels
- Lymphatic tissue
- Red bone marrow
What are the functions of the lymphatic system?
- Drainage of interstitial fluid (from high hydrostatic pressure in capillaries forcing out blood which needs to be collected)
- Transporting dietary lipids and lipid soluble vitamins (A,D,E,K)
- Facilitation of the immune response
Whats the process of the formation of lymph?
Structural relationship between capillary bed of blood vascular system and lymphatic capillaries (blood plasma that’s been pushed out)
1. Blood hydrostatic pressure pushes blood plasma out of the blood capillaries to bathe surrounding tissues
2. This blood plasma is now known as interstitial fluid
3. Blood protein Albumin too large to leave capillaries and creates osmotic pressure inside capillary
4. Blood osmotic pressure pulls interstitial fluid back into the blood capillaries
5. Not all interstitial fluid returns – it needs to be drained otherwise swelling occurs
6. Drainage occurs via lymphatic capillaries and lymph vessels
7. Lymphatic capillaries are blind ended – dead ends for one way movement
8. With lower pressure than interstitial fluid
9. Fluid enters lymph capillary via one way minivalves (stopping backflow back into blood vessels) once inside – this is known as lymph
Whats hydrostatic pressure?
Pushing force exerted by a fluid (30-10mmHg between arterial end and venous end)- from inside to outside the blood vessels
Whats interstitial fluid pressure?
Negative -3 mmHg contributing to outward pull of fluid from capillaries
Whats colloidal osmotic pressure?
Pulling force created by blood proteins that are too large to pass through the pores of the membrane (28 mmHg in capillaries) (the difference in protein concentration on inside and outside of blood vessels)
Whats interstitial osmotic pressure?
8 mmHg created by small number of plasma proteins that have leaked into extracellular tissue space
How is lymph drained?
- Lymph capillaries join together forming lymph vessels (eventually join back into blood vessels as drains into blood stream to maintain blood pressure)
- These are similar to veins and have valves
- Drain into two ducts in cardiovascular system
- right lymphatic duct
- left thoracic duct
What are the two ducts of the lymphatic system?
right lymphatic duct
left thoracic duct
Whats the right lymphatic duct?
- Drains upper right side of body and right arm
- Returns lymphatic duct returns lymph to right subclavian vein
Whats the left thoracic duct?
- Drains rest of body
- Begins with cisterna chyli and returns lymph to left subclavian vein
What are lacteals?
- In small intestines lymph capillaries are known as lacteals
- Lacteals carry fat laden lymph known as chyle
- Lacteals join together to form vessels
- These vessels containing fat laden lymph drain into cisterna chyli
Describe the relationship between cardiovascular and lymphatic system?
- Plasma form interstitial fluid
- This is returned to plasma
- Fluid not fully returned enters lymph capillary to form lymph
- This lymph is returned to cardiovascular system
Whats oedema?
- Palpable swelling produced by increased interstitial fluid volume
- Evident when interstitial fluid increases to 2.5 – 3L
What factors influence oedema?
- Increased capillary filtration pressure
- Decreased capillary colloidal osmotic pressure
- Increased capillary permeability
- Obstruction to lymph flow
Whats lymphoedema?
obstruction to lymph flow
What are lymph nodes?
- Filter lymph (an immune response looking for pathogens)
- Found along lymph vessels
- They are in capsules
- Bean shaped structures that receive lymph from afferent vessels (going towards) - entering
- Lymph is drained by efferent vessels (going away from) – exit
Describe the structure of lymph nodes
- Connective tissue Capsules
- More afferent vessels in and less efferent vessels in order to slow the process to allow immune cells to search
- Trabeculae (project inwards to capsule to form compartments made of framework of reticular cells where phagocytosis occurs) for immune cells to sit – B and T cells stay here – cortex (inside) and medulla (outside)
- Between reticular cells are lymphocytes which produce antibodies
What are lymph nodules?
- Not contained within capsule
- Found in areas of body that are exposed to outside world – to stop bacteria and pathogens getting into body
- Eg. Peyer’s patches in intestines found in mucosa of tubular structures
- Normally mucus lined – Mucosa associated lymphoid tissue
What are peyers patches?
- In intestines
- Example of lymph nodule
- Found in mucosa of tubular structures
How do tonsils effect the lymphatic system?
- Filter air
- Surround opening in respiratory and digestive tracts
- 5 tonsils 2x palatine (oral cavity), 2x lingual (base of tongue) and 1x pharyngeal or adenoid (nasopharynx posterior)
How does the thymus gland effect the lymphatic system?
- Found in mediastinum above heard
- Surrounded by connective tissue capsule with inwards projecting trabecular
- Produce thymic factor
- Most active in childhood as physically larger then gets smaller – age involution
How do thymic factor effect the lymphatic system?
- Important in setting up immune system and formation of T lymphocytes (T cells)
How does the spleen effect the lymphatic system?
- Filters blood
- Left side of abdominal cavity below the diaphragm
1. Reticular cells – lymphatic tissue
2. Red pulp – removes worn out platelets and RBC storing and producing then in a foetus
3. White pulp – carries out immune function removing blood borne pathogens
What do reticular cells do in the spleen?
cells dound in lympathic tissue removing red and white pulp in blood filtration
What does the filtration of blood seperate blood into using reticular cells?
- Red pulp – removes worn out platelets and RBC storing and producing then in a foetus
- White pulp – carries out immune function removing blood borne pathogens
