Lymphydema Flashcards
What are the causes of ACTIVE hyperemia
Anything that causes a greater demand for blood
Inflammation, infection, heat, friction, trauma, exercise
What are the causes of PASSIVE hyperemia
Anything that causes obstruction of the venous outflow
DVT, CHF, CVI (chronic venous insufficiency), Tumor
What is the mechanism for both passive and active hyperemia?
Vasodilation!
Name the major mechanism difference (and location of mechanism) between active and passive hyperemia
Active: due to increased blood flow on the pre-cap arterioles
Passive: due to obstruction on the venous side of the capillary bed
What is the result of both active and passive hyperemia?
Ultrafiltration: pressure in blood capillaries forces water to leave blood into the interstitium
What was starlings original equation?
Average BCP = COPp
In Starlings original equation (BCP =COPp) what did greater BCP cause?
Greater COPp cause?
BCP»_space;> COPp = ultrafiltration
COPp»_space;> BCP = reabsorption
What is the primary source of cellular nutrition?
Diffusion
How does diffusion proceed?
high to low concentration
How is diffusion measured?
L/min of flow
What is osmosis
Specialized diffusion through a semi-permeable membrane (capillaries)
Therefore generally water is moving from an area of low substrate concentration to an area of high to dilute it
Osmosis generally has a small contribution to normal nutrition of cells, diffusion mainly takes care of this. However, in what circumstances does osmosis become an important part of cell nutrition?
Disease states
How much flow volume is normal / day for osmosis?
2-4 L/day
Protein has a strong or high affinity for water
high
What is Albumin’s function
hold onto fluid volume in the blood
Its the primary protein in the blood
Why does COP develop?
Bc protein affinity to bind with water
What is the COP of plasma?
7g/% = 25 mmHg
What is ultrafiltration?
Hydraulic pressure of the blood capillaries forcing an additional amount of water to leave the blood and enter the interstitial space
When blood enters the capillary bed compare BCP to COPp and what this relationship creates.
BCP»_space; COPp
BCP wants to push water out and it wins out, therefore water moves into the interstitium
True or False: pre-capillary arterioles are passive structures?
False! they are highly muscularized and innervated by the ANS
Responsible for vasodilation and constriction which we know affects capillary pressure
What is the relationship between arterial BP and BCP
Decrease in arterial BP (due to vasodilation) = increase in BPC due to the greater influx of blood
What happens to central blood pressure when vasodilation occurs? BCP?
Central blood pressure: drops
BCP: increases
What is the result of both active and passive hyperemia
Ultrafiltration
Is BPC hydrostatic or osmotic?
Hydrostatic
What did Starling originally propose the extent of lymph function was?
What do we know now and what does that mean the role of the lymphatic system is?
takes 10% of the fluid not reabsorbed by the venous side of the capillary
We know now that there is almost no reabsorption of fluid in the capillary beds, therefore excess fluid is almost exclusively the responsibility of the lymphatic system.
How is the majority of capillary filtrate returned to blood circulation?
Thoracic duct
What is Glycocalyx?
What is it composed of?
What role does Glycocalyx play in reabsorption?
Carb rich layer coating the inner surface of the capillary vessel.
Composed of proteoglycans and glycoproteins therefore….
disrupts oncotic gradient (because its so high in proteins) AND prevents reabsorption of capillary beds due to creating a physical layer acting as a barrier
Compare and contrast the CV system and the lymphatic system
CV: closed, circular
Lymphatic: open, one way
This isn’t a question, just general things lymph system does specifically. She outlines four functions later that are less specific.
Recognizing, filtering and destroying bacteria, waste and other toxins
Launch immune system via T lymphocytes
Regulate lymph fluid volume
What are afferent lymph vessels?
bring unfiltered fluid to the lymph node for filtering
What are efferent lymph vessels?
Carry clean fluids away from the lymph nodes to the CV system to help form plasma in the blood
Is the lymphatic system a high or low pressure system?
low pressure
Where does lymphatic system pressure exceed CV system pressure?
What is the relevance of this?
The venous angle: therefore this is where the lymph gets dumped back into the CV system
Final common pathway of lymph
venous angle
At the level of the nodes what happens to excess water?
Excess water is given back to the venous side of the blood
3 major lymphatic functions
1) recycles proteins
2) immune surveillance: infection, cancer, removal of debris
3) Transportation of digested fat
Why is lymph responsible for filtering macromolecules?
They don’t fit through normally places, they generally require active transport, but not in lymph system
What is the significance of terminal ends to the lymphatic system?
Because they are tethered into the soft tissue, as tissue swells the anchoring opens and pores form allowing macromolecuels to fall i
Where do lymph capillaries sit?
just sub-epidermal;
Do lymph capillaries or lymph collectors have valves?
Lymph collectors
What part of the lymph system has anchoring filaments that create pores?
Lymph capillaries
Lymphangion is what
What is its pump?
“lymph heart”
No central pump! piggy backs on respiration, increased heart rate, MSK pump
Describe lymph collectors
Its a transport vessel: Valved
Highly muscular
Innervated by ANS
Resting rate of 6 beats/min
With ANS stimulation what happens to the rate of lymphangion?
increased rate
As more fluid is absorbed into the collector, the more the walls stretch and what is the result?
the more they end up contracted pulling more fluid towards CV system
What is the relevance of the lymphangion piggy backing on other systems
Exercising increases HR and MSK pump therefore increasing flow through the lymphatic system
Where are lymph collectors located?
superficial to fascial planes
What is in the lymph?
Protein, water, WBC, lymphocytes, CA cells, bacteria, viruses, fat, cellular debris, other debris (tattoo)
What two forces did Starling neglect?
COPi
Interstitial pressure
What do COPi and Pi do in terms of ultrafiltration
COPi: assists ultrafiltration
Pi: resists ultrafiltration
In a normal situation are COPi & Pi varrying much?
no