SFP: hemodynamics Flashcards
For flow to happen there has to be…
A pressure gradient
What is cardiac output?
Sum of all tissue flow; determined by ventricles
What regulates blood flow to each organ?
Tissue demand; blood can be shunted away from tissues that don’t need it
If pressure falls acutely, which reflexes are activated?
Increased HR, contractility, venous return, and constriction of arterioles
What is the long term control of MAP?
The kidneys
How do lungs get more than 00% of CO?
They get 100% from the right side for pulmonary circulation, and 2% from bronchioles on the left side
Where is pressure lowest in the systemic circuit?
Right atrium
What is the windkessel effect?
Elastic arteries receive a bonus during ventricle ejection that slowly releases forward during ventricle diastole. This allows for continuous flow as opposed to pulsatility
How does having a stiff artery impact the windkessel effect?
The afterload to the ventricle increases, and the ability to stretch and receive the bolt for continuous flow is reduced. The risk for dissection is great.
Are veins or arteries more compliant?
Veins
Describe how a vessel can locally override a systemic sympathetic signal.
In a systemic sympathetic signal, areas of constricted blood flow can produce products like adenosine, lactate and protons, pCO2, and potassium. These can act as local vasodilators to dilate a specific vessel.
What is the biggest factor that controls resistance?
Radius
What are myogenic controls of flow?
Intrinsic property of vascular smooth muscle. They contort to oppose stretch and relax to oppose dilation. This allows them to keep the flow constant.
What are endothelial controls of flow?
Things like NO and endothelin
What are metabolic controls of flow?
Metabolic rates and products of local tissues can locally override a systemic signal and alter flow.
Vasopressin causes ___
Vasoconstriction
What is filtration?
Net fluid out of the capillary (positive)
What is reabsorption?
Net fluid movement into the capillary (negative)
What are the 4 starling forces?
Capillary hydrostatic pressure, interstitial fluid hydrostatic pressure, plasma colloid osmotic pressure, interstitial fluid colloid osmotic pressure
Which forces result in fluid leaving the capillary?
Hydrostatic pressure pushes fluid out and interstitial osmotic pressure pulls fluid out
Which forces result in fluid entering the capillary?
Plasma colloid osmotic pressure and interstitial fluid hydrostatic pressure
What is a main cause of edema in the cardiovascular system?
Increased venous pressure
What pathology is associated with expansion of a blood vessel?
Aneurysm
What pathology is associated with coarctation?
Stenosis
If vessel cross-sectional area increases what has to happen to velocity?
It decreases
What happens to potential energy when a vessel suddenly constricts?
Velocity increases, which increases kinetic energy and causes potential energy to lower. This forms a lower pressure inside the vessel that can cause collapse.
What does turbulent flow do to energy?
Causes energy loss and more pressure has to be generated
Describe how a dilated vessel can lead to aneurysm.
A dilated vessel can slightly lower kinetic energy, causing a small bump in potential energy. This causes an increase in pressure which combined with a thinning of the wall and increase in wall stress from dilation can cause aneurysm.
