Lymphatic system Flashcards
What four things does the lymphatic system consist of?
-Lymph
-Lymphatic vessels
-Lymphatic tissue
-red bone marrow
What are the functions of the lymphatic system?
-drainage of interstitial fluid
-transporting dietary lipids and lipid soluble vitamins (A,D,E,K)
-facilitation of the immune response
How does lymph form?
structural relationship between cappilary bed of the blood vascular system and lymphatic cappilaries.
Describe hydrostatic pressure
the pushing force exerted by a fluid
~30-10 mmHg between arterial and venous end
Describe interstital fluid pressure
slightly negative -3mmHg which contributes to the outward pull of fluid from the cappilaries
Describe collodial osmotic pressure
the pulling force created by blood proteins that are too large to pass through the pores of the membrane
~28mmHg in the cappilaries
Describe interstital osmotic pressure
is ~8mmHg
-created by a small number of plasma proteins that have leaked into the extracellular tissue space
How is blood plasma converted into interstital fluid?
blood hydrostatic pressure pushes blood plasma out of the blood cappilaries to bathe surrrounding tissue.
Decribe the role of the protein albumin in the formation of lymph
-albumin is too large to leave the cappilaries and creates an osmotic pressure inside the cappilaries
-the blood osmotic pressure pulls interstital fluid back into blood cappillaries
How does drainage of unreturned interstital fluid occur?
-lymphatic cappilaries and lymph vessels
how does fluid enter the lymph cappilary?
-one way minivalves
-once inside it is known as lymph
Dsecribe the process involved in the drainage of lymph
-lymph cappilaries join to form lymph vessels
-lymph vessels are similar to veins-they have certain internal structures to ensure lymph flows one way
-lymph vessels drain into one of two ducts which return lymph to blood
name the two lymph ducts
-right lymphatic duct
-left thoracic duct
Describe the fuction of the right lymphatic duct
-drains upper right side of the body and right arm
-returns lymph to the right subclavian vein
Describe the function of the left thoracic duct
-drains the rest of the body
-the left thoracic duct begins with the cisterna chyli amd returns lymph to the left subclavian vein
describe how lymph drains into the cisterna chyli
-lymph cappilaries in small intestine-lacteals
-lacteals carry fat laden lymph-chyle
-lacteals join together to form vessels
-vessels containing fat laden lymph drain into cisterna chyli
Describe the links between the CV and lymphatic system
-plasma forms interstital fluid
-interstital fluid returned to the plasma
-fluid that is not returned to the plasma enters the lymph cappilaries to form lymph
-lymph is returned to the CV
What is oedema?
palpable swelling produced by an increase in interstital fluid volume
What factors influence oedema?
-increased cappilary filtration pressure
-decreased cappilary colloidal osmotic pressure
-increased cappilary permeability
-obstruction to lymph flow-lympoedema
Where can you find lymph nodes?
-pharyngeal region/tonsils
-thymus
-spleen
-Peyers patch in intestine
-appendix
What pathway is lymph recieved?
afferent (going towards vessels)
What pathway is lymph drained?
efferent (going away from vessels)
Describe the structure of lymph nodes
-surrounded by connective tissue capsules
-trabeculae project inwards from capsules forming compartments
-each compartment is made up of reticular cells
between recticular cells are lymphocytes
What is the function of recticular cells?
phagocytise unwanted substances
What do lymphocytes produce?
antibodies
Name some structures in the recticular cells of lobule
-macrophage
-reticular cells on reticular fibres
-lymphocytes
-medullary sinus
-reticular fibers
Describe the peyer’s patches
-direction of absorption and possible entry of microorganisms
-nodules also found in mucosa of other tubular structures in respiratory, urinary and reproductive systems
What does MALT stand for?
Mucosa
Associated
Lymphoid
Tissue
Name the five types of tonsils
2x palatine (either side of the oral cavity)
2x lingual (at the base of the tongue
1x Pharyngeal or adenoid
(on the posterior wall of the nasopharynx)
What is the structure if the thymus gland?
-found in the mediastinum above the heart
-surrounded by a connective tissue capsule with inward projecting trabeculae
What is the function of the thymus gland?
-produce thymic factor
-thymic factor is important in setting up the immune system and the formation of T lymphocytes
Describe age involution of the thymus gland
thymus is largest in childhood
-after childhood the thymus decreases in size
where is the spleen located?
left side of abdominal cavity below the diaphragm
What is the spleen comprised of?
recticular cells-lymphatic tissue
red pulp
white pulp
What is the function of red pulp?
removes worn out platelets and RBCs, stores platelets and produces RBCs in the foetus
What is the function of white pulp?
Carries immune funtion and removes blood borne pathogens
State and describe One (1) other
mechanism that works in combination with valves to aid in the movement of lymph
from the periphery of the body back to the heart
Mechanism: Skeletal muscle pump (1 mark).
Description: The action of skeletal muscles contracting during movement.
squeezes the lymph fluid back towards the heart (1 mark).
Mechanism: Respiratory pump (1 mark).
Description: During inhalation, thoracic volume increases while thoracic.
pressure decreases. The thoracic pressure is lower than the abdominal pressure.
so, lymph flows towards the thorax/heart (1 mark).
