Lymphatics Quiz Flashcards
What is capillary filtration?
The sum of the hydrostatic and osmotic forces favors the net movement of water from the capillary to the interstitial space
Movement of fluid out of the capillary
What is capillary reabsorption?
The sum of the hydrostatic and osmotic forces favors the net movement of water from the interstitial space to the capillary
Movement of fluid back into the capillary
What are the Starling Forces with regards to capillary filtration/reabsorption?
Capillary Pressure, Interstitial Fluid Pressure, Plasma Colloid Osmotic Pressure, Interstitial Fluid Colloid Osmotic Pressure
What is osmosis?
Water moves from a region of high concentration to one that has a lower concentration of water
If Net Driving Forces are positive, does it favor capillary filtration or reabsorption?
Filtration NDF>0 filtration
NDF<0 Reabsorption
Are hydrostatic pressures within the capillary equal at the arteriolar end and the venous end?
No, equal at venous end
Under normal circumstances, what Net Driving Force favors fluid movement INTO the capillary?
Reabsorption
plasma oncotic pressure
What would the Net Driving Forces be in a patient with congestive heart failure? Would they favor filtration or reabsorption?
Increased Capillary Hydrostatic Pressure
Filtration
What is the function of the lymphatic system?
The lymphatic system helps to maintain fluid balance, defend the body against disease, and absorb liquids from the intestine and transport them to the blood.
The lymphatic System collects and returns fluid that leaks from blood vessels. It absorbs fats and vitamins. Lastly, it defends against invading microorganisms and disease
How is plasma filtrate returned to the circulation by the lymphatic system?
Tissue pressure
Intermittent skeletal muscle activity
Lymphatic vessel contraction
System of one-way valves
What is the thoracic duct? Where is it found and what does it connect to?
the largest lymphatic vessel in the body
Left SC Vein
What things may cause edema?
Lymphatic obstruction
Change in capillary permeability
Reduction in plasma protein
Increased capillary hydrostatic pressure
Name 3 endogenously found vaso-constricting substances.
Catecholamines -Epinephrine -Norepinephrine -Dopamine Endothelin Serotonin Angiotensin II Vasopressin
Name 3 endogenously found vaso-dilating substances.
Histamine Adenosine Nitric Oxide (NO) Carbon Dioxide Potassium Hydrogen Ion Prostaglandins Acetylcholine Bradykinin
What is the Metabolic Mechanism? What substance is responsible for this mechanism?
Any intervention that results in an inadequate oxygen (nutrient) supply for the metabolic requirements of the tissues results in the formation of vasodilator substances which increase blood flow to the tissues
One of the most fundamental principles of circulatory function is the ability of each tissue to control its own local blood flow in proportion to its metabolic needs
What is the Myogenic Mechanism?
When the lumen of a blood vessel is suddenly expanded, the smooth muscle responds by contracting in order to restore the vessel diameter and resistance, The converse is also true.
What is Reactive Hyperemia? Give a common clinical example of Reactive Hyperemia.
the transient increase in organ blood flow that occurs following a brief period of ischaemia. Following ischaemia there will be a shortage of oxygen and a build-up of metabolic waste.
Example: Tourniquet, Raynauds
What is Autoregulation? What mechanism of blood flow regulation is thought to be involved?
Intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure
Possible explanations for Autoregulation:
Myogenic Mechanism
Name 3 endothelial factors that help regulate blood flow?
Vasoactive substances released from endothelium: Nitric Oxide (NO) Endothelium-derived relaxing factor Prostacyclin Endothelin Endothelial-derived hyperpolarizing factor (EDHF)
What is nitric oxide? How might it be helpful during one-lung ventilation?
It is a powerful vasodilator with a short half-life of a few seconds in the blood
used in critical care to promote capillary and pulmonary dilation to treat primary pulmonary hypertension
improves V/Q mismatch
Is Endothelin a vaso-dilator or -constrictor?
Potent vasoconstrictor
Why are blood vessels prone to vaso-constriction, vaso-spasm and thrombosis when the endothelium is damaged?
Decreased nitric oxide and prostacyclin production
Increased endothelin production
