Lymphatic System Flashcards
Function
Immune defense/response, cardiovascular homeostasis (maintain blood volume, edema prevention), and fat reabsorption from the gut
Function: immune defense
produces immune system response, returns lymphocytes from lymphatic organs to the blood, and filters and purifies fluid before returning to the venous system
Function: edema prevention
reabsorb fluid, water and substances from the interstitial tissue spaces (water, cellular debris, waste products, protein molecules, immune system cells) that cannot be reabsorbed by venous capillaries
Function: maintain blood volume
transport lymph fluid to venous system at the junction of the jugular vein and subclavian vein (venous angle)
Function: digestion
responsible for transporting lipids from food (chlyomicrons) that are absorbed by the bowel. If there is a problem in this process, fluid can build up and lead to edema.
Lymphatic vessels
form one way system, lymph travels via a network of vessels of varying diameter (smallest to largest) and passes thru a series of lymph nodes until it is returned to the vascular system at the venous angle
larger diameter, less vessels
Venous system vs. lymphatic system
venous system: blood flows superficial to deep
lymphatic system: can divert fluid from deep into peripheral and then into the superficial system (creating pressure change to impact the way that the fluid flows.
Both venous and lymphatic system have:
smooth muscles to move fluid through, and arterial and perforating vessels.
Lymphatic vessel system: superficial
Embedding in subcutaneous fatty
tissue, just under dermis, located above the fascia, drains the skin & subcutaneous tissues
Lymphatic vessel system: deep
Below the fascia, runs parallel with arteries/veins, drains muscle, joints, tendon sheaths, nerves
Organs have an organ specific vessel
draining system
Special thing about lymph vessels:
meet at perforating vessels that transverse the fascia, and if the superficial system can be drained, it can pull up fluid from the deep system and drain that too
Anatomy of lymph vessels
Lymphatic capillaries, Lymph node clusters
(initial lymphatics), Pre-collectors, Collecting vessels (lymph angions), Trunks, Ducts, Watersheds
Lymph capillaries
Located between tissue cells (interstitial spaces) and blood capillaries in loose connective tissues of the body, occur wherever blood capillaries are located, composed of a single layer of endothelial cell, contain filaments that are anchored to connective tissue
Function: Reabsorption
Process
- Fluid pressure in the interstitial spaces increases, causing the flaps/valves of the initial lymphatic vessel to open (anchoring filaments tension is increased)
- Protein molecules, water etc enters the initial lymphatic vessel and is now called lymph fluid.
- Pressure in initial lymph capillary is lower than in interstitial spaces
Precollectors
vessel that connects the initial lymph capillaries to the lymph collectors of the superficial lymphatic system, and also connect superficial lymph capillaries to deep lymph collectors = perforating precollectors
• Underdeveloped valves and smooth muscles
• Perforate fascia, located in the parasternal, paravertebral & intercostals areas
Collecting vessels
Progressively larger diameter vessels, used for transport, have well developed valves & smooth muscle, promote directional flow, prevent reflux, and have characteristics similar to veins
Lymph angion
area in between valves in collecting vessels where fluid moves, have smooth muscle walls innervated by the sympathetic nervous system
Similarities between collecting vessels and veins:
Three layers
More valves
Thinner walls
Lymph trunks:
Union of the larger collecting vessels, lymph moves into the deep system into larger
collecting vessels via lymph trunks
Ducts
R lymphatic duct drains R upper quadrant
Thoracic duct drains the L upper quadrant, B lower quadrant, B LE, pelvis, and abdomen
All lymph fluid ends up in:
R lymphatic duct or thoracic duct
Only direct connection with venous system is:
junction of ducts and jugular/subclavian veins
lymph nodes
biological filter, mainly located in the respiratory and intestinal region, bean-shaped and run along vessels in chains, and are afferent and efferent vessels
Why bottleneck in lymph nodes?
more afferent vessels coming in than efferent vessels coming out, allows phagocytosis to occur, and fluid to be reabsorbed, and thus there is less going out. Time slows in the lymph region to allow more to absorb, and water also comes in.
Why so many lymph nodes at respiratory and intestinal region?
These are areas of our body where we ingest a lot of crap: from breathing and swallowing in, and also from eating, so this helps to protect us especially in those places.
Regions of many lymph nodes
head and neck (cervical regions), supraclavicular, axillary region, mamillary area, down the thoracic trunk, inguinal, (any major artery = lymph node region)
Lymph flow
from left and right lumbar trunk and intestinal trunk, into cisterna chyli, and then up the trunk into the thoracic duct
Watersheds
Boundary you cannot cross, divide the body into parts. Tells you which lymph nodes fluid will drain at different body regions. In the superficial network (not the deep), they can cross the watershed in times of fluid overload (they can send some fluid across to other nodes). Area where there are not a lot of lymph nodes, so we’ll need to find the alternative drainage routes in times of fluid overload.
3 watersheds
sagittal, clavicular, and transverse, coronal, spine/scapula, chaps
Manual drainage
drain trunk/UE to axillary region, elbows or neck
drain LE to groin or popliteal
In lymphatic system, function is always a result of:
anatomy
Overall pathway
capillary bed, lymphatic capillaries, precollectors, collecting vessels, nodes, trunks, venous angle
