The lymphatics Flashcards
What is the lymphatic system?
Drainage system: Returns extracellular fluid to bloodstream
What are some extracellular fluid that is returned to the blood stream in the lymphatic system? 3
- Plasma
- Interstitial fluid
- Lymph
Where does plasma seep?
Through the capillary walls
Where does the interstitial fluid seep?
Plasma seeps through the capillary walls and circulates among the body tissue
Where does the lymph drains out of?
Interstitial fluid that drains out of the tissue and enters the lymphatic ducts
What is the lymphatic system similar to?
Circulatory system
What are some differences between the circulatory and lymphatic system? 3
- no pump
- One direction
- Lymph nodes
What does the lymphatic system consist of? 4
- Capillaries
- Vessels
- Ducts
- Nodes
Where is the lymphatic system located?
Throughout the body
Where does the lymphatic system course?
Along the circulatory system
The capillaries are what kind of structures?
Blind-ended structures in the interstitial spaces
What does the capillaries wall consist of?
A single endothelial layers
What does the capillaries join and do?
They join to form larger vessels (valves control direction of flow)
What is the direction of the capillaries? (what is the pathway)
Superficial > deep> Nodes > towards chest > Bloodstream
What are important components of the RE system? And how are they distributed?
Nodes, which are distributed throughout the body
What is the shape of the nodes?
Beam shaped (ovoid) accumulations of lymph tissues, flusters along lymph vessels
What is the measure of the lymph nodes?
From 1mm to 1-2 cm
What is the nodes surrounded by?
Connective tissue capsule
What does afferent vessels drain into?
Nodes
What does afferent vessels carry?
Lymph through sinuses
What does the afferent vessels filter?
Filter out/ destroy bacteria and malignant cells
What do the germinal centers of the afferent vessels do? 2
- Produce lymphocytes
- Empty into the lymph prior to leaving the node
Where doe the efferent vessels leave?
Only at the hilum
Are the lymph nodes a site of disease?
Rarely site of primary disease, usually secondary
Where is the major node bearing areas? 2
Retroperitoneum at the
1. Iliac/ hypogastric
2. Aorta/IVC (360 degrees)
What are other lymphatic tissues we need to know? 3
- Tonsils
- Thymus
- Spleen
What kind of channels is the lymphatic circulation?
Deep and superficial channels
Nodes are clustered at what key locations? 4
- Axillary nodes (upper limbs)
- Cervical nodes (Neck)
- Inguinal nodes (lower limbs)
- Intestinal nodes (peyers patch)
The lymphatic circulation drain into how many vessels and what are they?
Two vessels
1. RT lymphatic duct: drains RUQ
2. Thoracic duct (LT): Remaining 3/4 of body
What is the physiology of lymph? What is it similar to? What kind of enzymes are they? What’s the albumin mix?
- Extracellular fluid formation
- Similar to plasma
- Higher albumin with a small # of leukocytes/ no erythrocytes
- Digestive enzymes
What is lymph flow like? 2
- Slow under resting conditions
- Flow depends kneading action of muscles and valves
What is the function of the lymphatic system? 4
- Phagocytosis
- Immunity
- Drainage
- Excretion
What is the excretion function of the lymphatic system?
Absorption and circulation of end products of fat digestion
What is the patient scanning position of the lymphatic system?
Midline, in supine or decubitus
What planes do we scan the lymphatic system in?
2 planes
1. Sag
2. Trans
What are common sites for lymph nodes? 5 (in the abdomen)
- para-aortic, para caval
- Mesenteric and celiac axis
- Around the pancreas
- Renal splenic hilum, porta hepatis
- Along iliac vessels
What kind of pressure do we use to scan and why?
Gentle pressure to displace bowel
What should a sonographer see? 3 (in terms of a lymph node)
- Not typically visualized in the abdomen
- Homogenous
- Low level echoes
What is the AP measure of the lymphatic system in AP?
<1CM
What are some pitfalls of scanning the lymphatic system? 4
- Enlarged para-aortic nodes may mimic aneurysm
- Bowel gas may obscure our visualization of lymph nodes
- Enlarged lymph nodes surrounding vessels may make evaluation of these vessels and their bifurcations difficult
- Fluid filled areas (such as hydronephrosis) may obscure enlarged nodes
