Lecture #1 Flashcards
The Pulmonary Circuit has _____ pressure and _____ resistance. The Systemic Circuit has ______ pressure and _____ resistance.
Low, Low
High, High
Role of cardiovascular system? (7)
Gaseous Exchange Waste Removal Delivery of Nutrients Delivery of Hormones Defense Thermal Exchange Tissue Hydration
What is cardiac output? Three variables it depends on?
Volume of Blood Pumped Per Minute
HR, Force of Contraction, and SV
What does non-sucking pump mean
Outflow is intermittent and inflow is continuous
Systemic Vascular Resistance =
Total Peripheral Resistance
Four important variables in CV function?? Part of CV that controls them?
Heart/CO
Arterioles/Resistance
Veins, Venules/Capacity
Veins, Venules/Blood Volume
BV layers from outside to inside.
Adventitia (Connective Tissue)
Media (Smooth Muscle)
Intima (Vascular Endothelium)
Which BV layers are absent in capillaries?
Caps lack media and adventitia.
Three things synthesized by Intima?
Prostacyclin – Vasodilator, inhibitor of platelet aggregation
NO – same + inhibits leukocyte adhesion
Endothelin – Vasoconstrictor
Cells the usually surround capillaries?
Pericytes
What do pericytes do anyway?
Regulate tight and adherens junctions
Regulate vascular stability and angio
Contractile
Phagocytic
Two vessel types that lack media.
Capillaries
Non-muscular Venules
What could cause media contraction?
Sympathetic stim of alpha 1 adrenergic
Vasoconstrictors (VP, ATII, Endothelin, adrenaline)
Loss of vessel tone will cause what changes to capacitance and resistance?
Vasodilation
More Capacitance
Lower Systemic Resistance
Main controllers of vasodilation?
Metabolically generated substances (H+, CO2, Adenosine)
Vasodilators (Prostacyclin, NO)
Who hangs out in the adventitia?
Fibroblasts
Immune Cells
Stem Cells
Adrenergic Nerve Endings
What are vasa vasorum?
Small BV for big BV (like aorta)
Three major by-passes of the fetal circulation.
Ductus Venosus
Foramen Ovale
Ductus Arteriosis
How is fetal liver blood flow controlled?
Fetal ductus venosus contraction
Describe the route of blood through a fetus
Placenta, Ductus Venosus, Inf. VC, RA, Foramen Ovale, LA, LV, Aorta, Umbilical arteries to placenta for oxygenation, or lower half of body
What happens to blood that doesn’t make it through foramen Ovale?
Mixes with SVC blood, into RV, Pulmonary Trunk, Ductus Arteriosis, Aorta
Relationship of Pressure, Flow, and Resistance
Pressure Change = Flow X Resistance
Most important variable in resistance?
radius of the tube
What does the fourth power law establish?
Resistance is proportional to 1/r^4
At birth, resistance of the ______ circuit increases and resistance of the _______ circuit decreases.
Increase in Systemic
Reduction in Pulmonary
What causes rise in systemic resistance?
Loss of Placenta
How does the increase in systemic resistance cause changes in blood flow?
Increased systemic pressure increases LA pressure
Pressure Increase Closes Foramen Ovale
What two factors cause the pulmonary resistance to fall?
Relieved Hypoxic Pulmonary Vasoconstriction
Mechanical Factors
Name the four structural changes that occur at or after birth.
Closure of ductus venosus
Closure of foramen ovale
closure of ductus Arteriosus
Increase in LV Mass, Decrease in RV
What is a relic of the ductus venosus?
Ligamentum Venosum
Describe ductus venosus closure.
Within a few hours of loss of umbilical blood flow, the muscular wall of ductus will contract, closing the lumen
How does the foramen ovale close?
Higher RA pressure pushes the valve against the septum secundum. It eventually adheres.
What is the relic of foramen ovale?
Fossa Ovalis
If fusion if the foramen ovale doesn’t entirely happen - is this a problem?
Probably not – pressure will likely hold it closed anyway.
How does ductus arteriosus close?
Pressure changes reverse blood flow in the duct. Exposure to oxygen causes the media to constrict, eventually closing and filling with fibrous tissue.
Also…bradykinin helps with vasoconstriction.
Relic of the ductus arteriosus?
Ligamentum Arteriosum.
Three common types of congenital heart defects…
Stenosis
L –> R Shunts
R –> L Shunts
Difference between post-ductal and pre-ductal coarction of aorta.
Post ductal – Common – Ductus closes, patients survive normally, but rarely live past 40
Pre ductal – No ductal flow reversal at birth, fetal blood flow pattern persists.
Three causes of L –> R Shunts
Patent Ductus Arteriosus
Ventricular Septal Defects
Atrial Septal Defects
Patent ductus arteriosus associated with…
Maternal Rubella
Premature Birth
Most common atrial septal defect?
Patent Foramen Ovale
Two sources/signs of R–>L Shunt
Preductal Coarctation of the aorta (patent ductus)
Tetralogy of Fallot
Four Defects associated with Tetralogy of Fallot
Dextroposed Aorta (can override septum)
Pulmonary Valve/Trunk Stenosis
Ventricular Septal Defect
Right Ventricular Hypertrophy
So…explain why exactly Tetrology of Fallot leads to blue babies.
In this condition, the blood is being pushed through the defect between the ventricles, allowing almost all of the blood that enters the heart to leave without being oxygenated.
Treatment for Fallot?
Widen the pulmonary Stenosis
Close the Septal Defect
Reconstruct the Flow pathway
