Lymphatic system Flashcards
Why is the lymphatic system important?
Critical for maintaining constant blood volume
What two pressure forces act on capillaries that causes them to lose fluid?
Hydrostatic pressure and colloid osmotic pressure
What is hydrostatic pressure?
The force of a fluid pressing on the walls of the blood vessel
What are the 2 fluids in and surrounding capillaries that exert hydrostatic pressure?
Blood plasma on the inside and the extracellular fluid on the outside
What is the colloid osmotic pressure?
Fluids will flow from an area with high protein concentration to an area with low protein concentration
Why is there a net fluid loss from capillaries?
There is a lower protein concentration in the extracellular fluid than in the blood plasma
What does the Starling-Landis hypothesis describe?
Pressure differences along the capillary to model fluid exchange across capillary walls
What happens to the capillary osmotic pressure through the vessel?
Stays constant. The losses and gains of fluids aren’t enough to change the osmotic pressure
What happens to the hydrostatic pressure through the vessel?
Declines
When does net filtration from the capillaries occur?
Right at the ends of the arteries to about the centre
When does net reabsorption from the capillaries occur?
From the centre of the capillaries until the venules
Why does net filtration and net reabsorption from capillaries occur?
Pressure differences between the osmotic pressure and the hydrostatic pressure
What is the pressure difference between the osmotic and hydrostatic pressures in the capillary when net filtration is occurring?
Hydrostatic pressure is greater than the osmotic pressure
What is the pressure difference between the osmotic and hydrostatic pressures in the capillary when net reabsorption is occurring?
Hydrostatic pressure is less than the osmotic pressure
What is the problem with a closed circulatory system in the sense of maintaining blood volume?
The hydrostatic pressure gradient will always drive fluid out of the blood vessels and decrease the blood volume
How does having a lymphatic system get around the fluid loss problem with a closed circulatory system?
System collects the fluid drawn out of the capillaries and sends it back to the heart
Where does the lymphatic system drain into?
Into the inferior vena cava, which then empties into the right atrium
What is the fluid that enters the lymphatic system called?
Lymph
How does the lymphatic system maintain unidirectional flow?
Valves
How can mast cells mess with the lymphatic system?
They release histamine in response to injury, which causes vasodilation and more fluid loss due to increased hydrostatic pressure. Causes swelling, blisters, inflammation
What is elephantiasis?
Condition caused by parasitic filarial worms. Blocks the lymph nodes and causes a huge amount of swellling
What is a pulmonary edema?
Fluid build-up in alveoli
What causes a pulmonary edema?
Heart attack, congestive heart failure, trauma to lung, inhalation of noxious gases. Causes the left side of the heart to pump less than the right side
What happens during a pulmonary edema?
Because the left heart isn’t pumping as much, blood gets backed up to the lungs, which increases the hydrostatic pressure and net filtration in the pulmonary capillaries. The increased pressure causes the fluid to go into the alveoli, which decreases gas exchange
What are the symptoms of a pulmonary edema?
Difficulty breathing, coughing blood, pale skin
Where are mechanoreceptors found in the heart? What do they monitor?
Atrial walls: monitor filling and contraction
Ventricular walls: monitor stretching in response to the diastolic blood volume
Where are chemoreceptors found? What do they monitor?
Found in arteries and respond to changes in blood CO2 or H+ concentrations
