5- Lymphatics I Flashcards
How are lymphatic vessels similar to blood vessels?
Both blood vessels and lymphatic vessels come from a COMMON embryiologic origin that separates during development, which allows for common, yet distinct pathways.
How do Lymphatic vessels differ from blood vessels?
- Completely different vascular network
- Collects extravasated fluid from tissues (whereas blood vessels deliver fluid)
- Filter lymph
- Return lymph to circulation
What are the two main functions of the lymphatic system? What are two specifics for each function?
- Maintain homeostasis
- Cardiovascular assistance with fluid management
- Transportation of fats from small intestine to veins
- Immunologic role
- Filter particulate matter
- Develop and deliver antibodies
How does homeostasis impact fluid management?
It is the pathway for fluid return from the interstital tissues back to the vascular system
How much fluid per day is returned back to the vascular system via the lymphatic system?
2 liters/day
What are lacteals?
Lymphatic vessels found in the intestines that are responsible for the transport of lipids into lymph fluid (aka. chyle)
Where do the lymphatic vessels transport fat to?
To the blood via the thoracic duct and sent to the liver for processing
What are primary lymph organs?
Red bone marrow
Thymus
What are secondary lymph organs?
- Lymph nodes
- Spleen
- Lymphatic Nodules (Pharygeal Tonsils)
How are primary valves different than secondary valves?
Primary valves are :
- Are on smaller vessels
- Have only ONE valve (secondary have two to prevent retrograde)
- Have only endothelial cells (secondary have smooth muscle and endothelial cells)
Describe the basic outline of the Lymph System
- Thin walled channels of endothelial cells
- Join together to form larger vessels
- Primary lymph valves have ONE-WAY microvalves
- Large vessels collect lymphatics (have endothelium and smooth muscles w/ secondary valves that restrict retrograde)
- Nodes - located along the path of the collecting lymphatics
- Large lymphatic vessels ultimately drain into left and right subclavian veins
What is a lymphagion?
Pre-nodal or “afferent” collecting vessels
Where do trunks return the lymph to? via?
Venous system via lymphatic ducts.
Describe the superficial Lymph System
Drains the skin (not epidermis), musculoskeletal structures, located in groups near veins and travel through the fascia to the deep system
Describe the movement of the lymph flow.
Movement goes from peripheral tissues toward the midline of the body then toward cervicothoracic junction.
Describe the Deep Lymph System
Drains the thorax, abdomen, pelvis and perinerium
How does interstitial fluid get into the lymph capillary?
Hydrostatic Gradients
Oncotic gradients (dependent on proteins inside and outside the vessels)
Mechanical forces (local arterial pulsations and vasomotion, local alveolar expansions, local musculoskeletal compressions upon lymph vessels, passive motion of extremities)
Describe the piston activity of the respiratory diaphragm
Inhalation = Diaphragm descends –> increases pressure in intra-abdominal space causing fluid to flow into the terminal vessel
Because aveolar sacs are expanded, there is external mechanical pressure on surrounding pleural lymph nodes.
How much of lymph fluid is derived from abdominopelvic fluids?
50%
True or False: Respiratory function holds little or no effect on the efficiency of the lymphatic system
False. Proper respiratory function improves the efficiency of the lymphatic system.
What is in Lymph Fluid?
Fatty Acids
Fat
Chyle
Immune Cells (WBC, lymphocytes in post-nodal duct, antigen-presenting cells, dendtric cells)
What are key properties of Lymph capillaries (terminal lymphatics)?
- Larger than blood capillary
- One way permeability (fluid only goes in)
- Single layer of non-fenestrated endothelial cells that overlap
- Incomplete Basement Membrane
- No tight junctions : therefore permeable to large particles and proteins
- Lack smooth muscle
Describe a Lymphangion.
- Begins at the first bicuspid valve, which marks the beginning of the lymphangion or pre-nodal collecting vessel
- Drain superficial capillary network
- Transport lymph to regional nodes (via affarent vessels)
- Possess smooth muscle layer for intrinsic contractile properties and coordinated flow
- Pump like arteries: has a filling phase (7 seconds); contraction phase (1 second) and refractory period (1 second).
- 130-150 microns in diameter
Does lymphatic fluid enter or exit the lymph capillaries during the expansion phase of the capillaries?
Enter! (Influx)
