Week 3: Lymphatics Flashcards
What are the main components of the lymphatic system?
Lymphatic fluid
Lymph vessels
Primary structures (bone marrow)
Secondary structures (lymph nodes)
What are the main functions of lymphatic tissue?
1) Drain interstitial fluid
2) Transport dietary lipids
3) Protecc against invasion
How does ISF move into the lymph vessels?
Small openings in the vessel endothelium allow lymph vessels to drain interstitial fluid. However, it can also be involved in the movement of cancer cells (metastasis)
What kind of lymphatics pass through the GI system and what is their main function?
The lacteal (lacteus = milky) lymphatics help transport triglycerides (fats) from the GI into the blood, and bypass the liver during the first go-around.
Why are fat-soluble toxins more dangerous relative to water-soluble toxins?
Lacteals can transport fats directly from the GI into the bloodstream, bypassing the detoxification step in the liver. As a result, fat-soluble toxins can be moved directly into the bloodstream instead of getting filtered out by the liver.
How does material move into lymph vessels?
1) Fluid and proteins exit capillaries and fill the interstitial space
2) Tissue pressure builds and opens blind-ended lymph vessels surrounding the capillaries
3) Fluid and proteins flow through the lymph circulation until they can drain back into the systemic system (thoracic duct into the subclavian vein)
Where would lymph NOT be found in the body?
1) Avascular tissues like cartilage, epidermis, cornea
2) Spleen
3) Red bone marrow
What are the main portions of a lymph node?
The sinus with germinal centers, trabeculae that act as canals through the node, the medulla with developing macrophages and T cells, and the hilum where material flows out of the node
What are the main superficial nodes of the lymphatic system?
“CIA”
Cervical (near face/neck)
Inguinal (pelvis)
Axillary (under armpit)
What are the deeper and/or less recognizeable lymph nodes?
“TIA”
Tracheo-bronchial
Iliac
Aortic
How does lymph drain starting in the pelvis?
It moves through the inguinal and iliac nodes
It continues upwards through the cisterna chyli
It moves superiorly through the thoracic duct
Finally, it deposits recycled lymph that is not degraded into the left subclavian vein
How does lymph fluid flow?
Contraction of skeletal muscles
Breathing movements
Smooth muscle cells surrounding lymphatic vessels
Gravity
What happens when lymph fluid stops flowing? As it relates to the pressure differentials in tissue, why does this arise?
Arrest in fluid flow causes edema
This is due to one or more of the following:
1) Increased hydrostatic pressure
2) Reduced capillary oncotic pressure
3) Increased ISF/tissue oncotic pressure
4) Increased blood vessel wall permeability
5) Obstruction of fluid clearance
6) Changes in water retentive properties of tissue
What can occur during liver failure, and why does it happen?
The decreased permeability of bloodflow through hepatic portal vessels (liver artery/veins) causes fluid buildup in the abdomen due to significantly increased hydrostatic pressure.
This causes ascites, significant swelling of the abdomen.
What are the three gross anatomical principles of lymph?
Principle 1: Know which lymph nodes drain a given area of the body where lesions might occur (infection/cancer)
Principle 2: Know what body regions are drained by an enlarged lymph node
Principle 3: When multiple lymphatic regions are involved, consider systemic disease
What is lymphedema? When is it especially prevalent?
Swelling due to accumulation of lymphatic fluid in loose connective tissue. This is common during cancer, but can be decreased if cancerous lymph nodes are removed.
