Lecture 2 - Lymphatics Flashcards
What are the 4 parts of the lymphatic system?
- Fluid (lymph)
- Vessels (lymphatics)
- Structures and organs that contain lymphatic tissue (nodes)
- Red bone marrow (site of lymphocyte production)
Where is lymph fluid found?
Almost every tissue in the body
Describe the lymphatic system.
Immune system combined with cardiovascular system
What are the 3 main functions of lymphatic tissue?
- Drain interstitial fluid
- Transport dietary lipids (triglycerides)
- Protect against invasion
Which lymphatic tissue function does gross anatomy focus on? What is the purpose of this function?
- Drain interstitial fluid
Because 10% of plasma fluid does not return into circulation via normal venous return after being distributed to the tissues
Describe a lymphatic capillary. How does it work?
Blind-ended capillaries wrapped around cardiovascular capillaries with openings/flaps open in one direction (so fluid cannot flow back) when the interstitial fluid pressure on the outside is larger than it is on the inside of the capillary
What lymph capillary structure allows it to embed itself in most tissues?
Anchoring filaments
What are the specialized lymph capillaries of the gut called? Where are they found?
Lacteals
Mostly in microvilli of small intestine and a little in large intestine
What does each intestinal microvilli contain?
A vascular capillary and a lacteal
What do the GI lymphatics bypass in the first go around of fat absorption? Where do they bring the lipids instead?
Liver is bypassed and fats are brought directly to the heart
What does the vascular capillaries of the GIT absorb? Where do they bring these first? How?
Water soluble nutrients
Liver via portal circulation and the hepatic portal vein connecting the 2 capillary beds
What are the 2 circuits of the heart? What does each end with?
- Systemic
- Pulmonary
Each ends with capillaries
What is the pathway of interstitial fluid through the lymphatic system?
Fluid stuck in tissues => blind end of lymphatic capillaries => lymph nodes => lymphatic vessels with valves => cardiovascular venous circulation => heart right atrium
What is the function of the lymphatic vessel valves?
They can only move the lymph in one direction
What are lymph nodes?
Dilated portions along lymphatic vessels where the immune system interacts with the lymph
Are lymph nodes evenly distributed throughout the body?
NOPE
What are the 4 body parts where lymph is not found?
- Avascular tissues
- CNS
- Portion of spleen
- Red bone marrow
What are 3 examples of avascular tissues?
- Cartilage
- Epidermis
- Cornea of eye
How many lymph nodes in our body?
~500
In what color is lymph depicted in in graphics?
Green
Where are lymph nodes usually not found?
Legs, forearms to hands
Are lymph nodes symmetrically distributed throughout the body?
NOPE
What plays the role of the lymphatics in the CNS?
Cerebrospinal fluid
Why are lymphatics hard to find in a body?
Because they are very small and look just like connective tissue and are within it
Where are most lymph nodes found?
The trunk
How do we categorize lymph nodes? Describe the first kind.
- Superficial: can be palpated
2. Deep
What are the 3 superficial lymph nodes?
- Cervical nodes
- Axillary nodes
- Inguinal nodes
When do axillary nodes become enlarged?
- Pulmonary infection
2. Breast cancer
What is the major site of breast cancer metastasis?
Axillary lymph nodes
When do inguinal nodes become enlarged?
Superficial infection below the belly button
When do cervical nodes become enlarged?
Throat infection
What nodes are enlarged in the bubonic plague?
Inguinal nodes
What are the 3 major deep lymph nodes?
- Tracheo-bronchial nodes
- Aortic nodes
- Iliac nodes
Where are the tracheo-bronchial nodes found?
Trachea and bronchioles
Where are the aortic nodes found?
Abdominal aorta
Where are the iliac nodes found?
Iliac vessels
When do tracheo-bronchial nodes become enlarged?
Lung cancer
When do aortic nodes become enlarged?
- GIT cancers
2. Testicular cancer
When do iliac nodes become enlarged?
Pelvic cancers
What are the 2 main drainage ducts to the lymph tissue? % of fluid drainage through each? Describe what each drains.
- Thoracic duct: 75% => all the rest
2. Right lymphatic duct: 25% => Right part of thorax, neck, head, and right upper limb
How does lymph node draining from cancer differ from that from an infection?
Drainage of cancer metastasis is different from drainage of an infection in
that the lymph node will be harder and less tender to the touch
What is the largest/most dilated lymph vessel of the body?
Thoracic duct
Where does the thoracic duct meet the cardiovascular circulation?
Where the left internal jugular and the left subclavian vein come together
Where does the right lymphatic duct meet the cardiovascular circulation?
Where the right internal jugular and the right subclavian vein come together
What kind of veins are the right/left internal jugular and subclavian veins? Where do they drain into?
Brachiocephalic veins
They both drain in the superior vena cava
What is the size of the thoracic duct comparable to?
A nerve!
What are 4 factors that cause the movement of the lymph fluid?
- Contraction of skeletal muscles
- Breathing movements
- Smooth muscle cells surrounding lymphatic vessels
- Gravity
What kind of breathing movements will help move lymph fluid?
Negative pressure breathing
What 6 factors would increase edema in peripheral tissues? Which 3 are changes to our Starling forces?
- *Increased capillary hydrostatic pressure
- *Reduced capillary oncotic pressure
- *Increased tissue oncotic pressure
- Increased blood vessel wall permeability
- Obstruction of fluid clearance
- Changes in water retaining properties of the tissue (aka hormone levels)
What happens when lymph fluid flow stops?
Edema
What is an edema?
Lymph fluid accumulation in a tissue
When does increased blood vessel wall permeability happen? Why?
When you have an immune reaction, the capillary walls become leaky to allow more fluid, white blood cells, etc. to reach the site of infection
When does obstruction of lymph fluid clearance happen commonly?
Pregnancy when pregnant women sleep on their back, they often wake up with painful, swollen legs because the weight of the fetus obstructs the iliac lymph flow out of their legs
What are ascites?
Abnormal accumulation of abdominal fluids due to an edema specific to the portal system
What are the 3 gross anatomy principles of lymph?
- Know to which lymph node a particular lesion (infection/cancer) will drain to
- Know what body regions are drained by an enlarged lymph node
- When multiple lymphatic regions are involved, consider systemic disease
Why do testicles drain to the aortic nodes? What is this a problem for?
Because of their original position in the abdomen
Makes it hard to detect testicular cancer because these nodes are deep
What is lymphedema? What is it due to?
Condition of localized protein-rich fluid retention in the interstitium and painful tissue swelling caused by a compromised lymphatic system
What is lymphedema a common side effect of? Why?
Cancer surgeries because often, lymph nodes need to be removed because of metastasis
What is a lymphadenopathy?
Any disease of the lymph node
What is a lymphoma?
Any neoplasm (tumor) of the lymphoid tissue, whether benign or malignant
What is lymphangitis? What most commonly causes this?
Inflammation of lymph vessels or nodes
Strep infection
What is elephantiasis? What is it caused by?
Massive swelling caused by a parasitic worm living in lymph vessels and blocking lymph drainage
What is pitting edema?
Observable swelling of body tissues due to fluid accumulation that may be demonstrated by applying pressure to the swollen area
What do lymphatics return to the cardiovascular system?
Proteins, lipids and water
What % of serum proteins are returned to cardiovascular system via lymphatics?
40-50%
What are the 9 steps of lymphedema?
- Obstruction of lymphatics
- Protein build up in tissue
3a. Increased tissue oncotic pressure
4a. Increased fluid in tissue
5a. Tissue swelling
3b. Fibroblasts proliferation stimulation
4b. Fibroblasts obstruct the lymph channels
5b. Increase protein in tissue
What is cellulitis?
Bacterial skin infection with undefined borders
Why does lymphedema often lead to cellulitis?
Because fibroblasts open channels in the integument that allow bacteria to enter the subcuticular space
What is the integument?
Skin
What are the 2 types of causes of lymphedema? Describe each.
- Primary: failure is caused by congenital hypoplasia or aplasia of the peripheral lymphatics or by valvular incompetence
- Secondary: lymphatic drainage is altered by an acquired blockage of the lymph nodes or by disruption of the local lymphatic channels
What are 3 primary causes of lymphedema?
- Congenital lymphedema = Milroy disease
- Lymphedema Praecox = Meige disease
- Lymphedema tarda (incompetent valves)
What are 5 secondary causes of lymphedema?
- Filariasis
- Podoconiosis
- Malignancy and cancer treatment
- Postsurgical mechanism (e.g. masectomy)
- Massive obesity
Can lymphatics regenerate?
NOPE
What is the most common cause of lymphedema in the world?
Filariasis
What is the common difference between the cause of an edema and the cause of a lymphedema?
Cause of edemas is usually systemic and cause of lymphedema isn’t
What is filariasis?
Parasitic disease caused by an infection with roundworms of the Filarioidea type spread by blood-feeding black flies and mosquitoes
What is erysipelas?
Bacterial skin infection with defined borders
What is podoconiosis?
Disease of the lymph vessels of the lower extremities that is caused by chronic exposure to irritant soils
Why does massive obesity cause lymphedema?
- Because excess fat puts pressure on lymphatic system, which will run a lot slower
- Low muscle tone and more sedentary so less skeletal muscle contraction
What are fibroblasts?
Cells that lays down fibrous tissue and secrete the extracellular matrix
What is the difference between Milroy and Meige disease?
Age of onset
What are the 9 signs and symptoms of lymphedema?
- Chronic swelling
- Primarily lower extremity involvement
- Fevers, chills, and generalized weakness
- Fatigue related to the size and weight of the extremity
- Severe impairment of daily activities
- Embarrassment in public
- Recurrent bacterial or fugal infections
- Recurrent episodes of cellulitis, lymphangitis, fissuring, and/or ulceration
- Erythema and thickening of the skin
What % of lymphedema cases involve the extremities?
80%
What is erythema?
Superficial reddening of the skin, usually in patches, as a result of injury or irritation causing dilatation of the blood capillaries
Is a lymphedema usually pitting at first?
Yes - usually starts as pitting and develops into non-pitting with radial enlargement
What is elaphantiasis nostra verrucosa?
Long-term consequence of lymphedema: area of cobble-stoned, hyperkeratotic papillomatous plaques; the plaques can be covered with a crust, can be weepy or oozing a clear or yellow fluid, and/or can have a foul-smelling odor
Are sample analyses usually necessary to diagnose lymphedema?
NOPE, but can help to define underlying causes
What imaging studies can be done when a person is being seen for a lymphedema? What is the purpose of each?
- Plain radiographs to exclude abnormalities of the bone
- CT when malignancy is suspected or to show causes of obstructions
- Ultrasounds to evaluate the lymphatic and venous systems
What are the 3 main goals of the treatment/management of lymphedema?
- Restore function
- Reduce physical and psychological suffering
- Prevent infection
Note: if secondary, the underlying etiology should be treated
What are the 6 nonpharmacological treatment of lymphedema?
- Maintenance of appropriate hygiene and skin care
- Physical therapy and compression stockings
- Weight loss
- Avoiding constrictive clothing
- Elevating affected limb
- Surgery
What are the 3 pharmacological treatments of lymphedema?
- Topical or systemic antifungal or antimicrobial therapy to prevent sepsis (short term and long term)
- Diethylcarbamazine for filariasis treatment
- Benzopyrones to decrease excess edematous fluid, decrease skin temperature, and reduce infections
What is osteomyelitis?
Bone infection
Potential other 7 causes of lymphedema?
- Trauma
- Varicose vein surgery
- Congestive heart failure
- Peripheral vascular surgery
- Burns
- Insect bites
- Extrinsic pressure
