deck_16394788 Flashcards
What are the 3 major functions of the lymphatic system
Functions of lymphatic system
- Draining excess IF
- Carry out immune responses
- Transporting dietary lipids absorbed by GI tract to blood
What are the 4 components of Lymphatic system
Components of Lymphatic system
Lymph
Lymphatic vessels
Lymphatic tissues
Lymphocytes
How is lymph different from IF?
Lymphatic Fluid
Contains immune cells
Why does lymph have a “milky” appearance?
Lymphatic Fluid
Absorbed dietary lipids
Lymphatic vessels are often called what?
Lymphatic vessels
Lymphatics
Where does the lymphatic network begin?
Lymphatic Vessels
Lymphatic capillaries
In what ways are Lymph capillaries different from blood capillaries?
Lymphatic Vessels: Capillaries
Closed @ one end
Larger diameter
Thinner walls
What is the purpose of overlapping endothelial cells in lymph capillaries?
Lymphatic Vessels: Capillaries
One-way valve permitting entry
Due to pressure changes
What are lacteals?
Lymphatic Vessels: Capillaries
capillaries located in small intestine
Carry dietary lipids
What is Chyle
Lymphatic Vessels: Capillaries
Creamy white lymph in lacteals
Lymphatic vessels are similar to veins in what way?
Lymphatic Vessels
Contain valves to prevent backflow
Vessel bulges at each valve
Superficial lymphatics are located where?
Lymphatic Vessels
Subcutaneous layer of skin
Mucous membranes
Serous membranes
Deep lymphatics are located where?
Lymphatic Vessels
skeletal muscles, organs of neck, limbs, trunk
6 steps of lympatic flow
From periphery to central vasculature
Lymphatic Flow
- Begins as IF
- Enter lymphatic capillaries
- Travel to regional lymph nodes
- Enter lymphatic trunks
- Drain into R or L lymphatic duct
- Return lymph to blood at subclavian veins
What are the 5 principle lymphatic trunks
Lymphatic flow: Lymphatic Trunks
Lumbar
Intestinal
Bronchomediastinal
subclavian
jugular
Which two ducts do Lymphatic trunks drain into?
Lymphatic Flow: Lymphatic ducts
Thoracic duct
Right lymphatic duct
Thoracic duct collects lymph from?
Lymphatic Flow: Lymphatic Ducts
Entire body inferior to diaphragm
Left side superior to diaphragm
Right lymphatic duct collects lymph from?
Lymphatic Flow: Lymphatic Ducts
Right side superior to diaphragm
Where does the Thoracic duct begin?
Lymphatic Flow: Lymphatic ducts
Cisterna chyli (anterior to L2)
How does lymph move
Lymph movement
- Pressure in interstitial space
- Skeletal muscle contractions
- Pressure during breathing
What is lymphedema?
Lymphadema
Blocked lymphatic drainage
most often in limbs
Lymphoid tissues may be either?
Lymphoid tissues
Lymphoid nodules
lymphoid organs
What are lymphoid nodules
Lymphiod tissues
densely packed lymphocytes in area of areolar tissue
no capsules
What are lymphoid organs?
Lymphoid tissues
Separated from surrouding tissues w/ capsule
What are two groups of Lymphoid tissues?
Lymphoid tissues
Primary lymphatic tissues
Secondary lymphatic tissues
What composes secondary lymphatic tissues
lymph nodes, spleen, lymphatic nodules
Where lymphocytes activated/cloned
What composes Primary lymphatic tissues
Red bone marrow
thymus
Where lymphocytes are made/matured
What occurs in RED BONE MARROW
Give rise to immunocompetant B cells
Pre-T cells (migrate to thymus)
What occurs in thymus?
produces hormones (thymosins) for T-cell development
Where is the thymus located?
- Mediastinum (posterior to sternum)
Covered in capsule dividing into R and L lobes
What does each thymus lobule consist of?
Dark outer cortex
Lighter cental medulla
What does the cortex of the thymus do?
Regulates T cell development within epithelial reticular cells
What happens at the outer cortex of the thymus
Detritic cells: t-cell maturation
Epithelial cells: educate T-cells
Macrophages: clear out cells
surviving T-cells enter inner medulla
After 3 weeks T cells enter medulla? How many survive?
2% survive and enter medulla. Rest apoptosis death
What are lymph nodes?
small lymphoid organs surrounded by firbous connective capsule
Where are large lymph glands located?
Neck, groin, axillae
What is the function of lymph nodes?
Remove 99% of pathogens before returning to bloodstream
Where are important lymph nodes located
Head and neck
Arms
Legs
What are lymph nodes covered by?
Dense CT
What do trabeculae do in lymph nodes?
Divide into compartments
support
route for blood vessels
What is a lymph node stroma?
composed of capsule, trabeculae, reticular fibres, fibroblasts
How does the lymph node function
Foreign substances trapped in reticular fibres in sinuses
Macrophages destory
Lymphocytes create immune response
What is a hilum in the lymph node?
indentation where vessels enter node
What is the spleen composed of?
Largest mass of lymphoid tissue in the body
What are the functions of spleen?
- remove abnormal RBC
- Store iron from RBC
- Initaite immune response
Describe the diaphragmatic surface of the spleen
smooth and convex
conforms to shape of diaphragm and body wall
What are the two indentations on the visceral surface of the spleen
Gastric area (stomach)
Renal area (kidney)
What is the internal anatomy of the spleen?
Outer capsule of collagen/elastic fibres
Trabeculae
Parenchyma
What is parenchyma made of? How many types are there?
Made of pulp
Red pulp
White pulp
What is white pulp in parenchyma
spleen
lymphatic tissue arranged around central arteries
What is red pulp in parenchyma?
spleen
blood filled venous sinus called splenic Billroths cords
What is the function of white pulp
spleen
carry blood to central arteries of white pulp
acts as immune filter
What are the functions of red pulp?
Spleen
removal of RBC and platelets
Storage of platelets
Production of blood cells during fetal life
What is treatment of removing spleen called?
Splenectomy
What are lymphoid nodules?
masses of lymphatic tissue with no capsule
Where are lymphoid nodules located?
mucous membranes
GI, urinary/reprod. tract/respiratory airways
What is MALT? what does it do?
- Mucosa associated lymphoid tissue
Protect epithelia from pathogens and toxins
What are tonsils? Where are they located?
- Large lymphoid nodules on wall of pharynx
location: pharyngeal, palatine, lingual
- Large lymphoid nodules on wall of pharynx
What are two examples of MALT disorders?
Tonsillitis
Appendicitis
