28 Questions
Which vessel is more compliant according to the text?
Veins
What happens to blood volume in the venous circulation if compliance increases?
Increases
What is the relationship between resistance and flow according to the text?
Inversely proportional
How does viscosity affect resistance according to Poiseuille’s law?
Increasing viscosity increases resistance
What factor can help increase stroke volume by increasing preload on the heart?
Skeletal muscle movement and venous valves
What happens to stroke volume, cardiac output, and blood to the brain when there is no venous return from the legs?
They all decrease
What is the primary determinant of afterload?
Resistance of the arterial system
What factor can increase cardiac workload without increasing cardiac output?
Increased afterload
What primarily determines heart rate?
Balance between SNS and PNS
Which factor can increase vascular tension and subsequently increase blood pressure?
Increased activity in vasomotor center
What do baroreceptors do when stretched due to high pressure?
Inhibit the cardiovascular control center in the medulla
What is the effect of baroreceptor stimulation?
Lowers blood pressure
What is the effect of chronic hypertension on baroreceptors?
They can adapt and be reset to a higher level
What is the primary factor in the regulation of blood pressure?
Sympathetic nervous system
What does the SNS primarily release at the smooth muscle of most arteries?
Norepinephrine
What is the effect of increased afterload on stroke volume?
Decreases stroke volume
What is the primary determinant of flow per minute (Q) in the given equation Q=P1-P2 R?
Resistance (R)
How does doubling the radius of a vessel affect resistance?
Resistance decreases 16 times
Which part of the vascular system primarily alters blood flow through vasodilation and vasoconstriction?
Arterioles
What is the primary determinant of stroke volume (SV)?
Preload
How is mean arterial pressure (MAP) calculated?
[systolic BP + (2 x Diastolic BP)] / 3
What is the relationship between blood velocity and the cross-sectional area of vessels?
Blood velocity is inversely proportional to the cross-sectional area
What determines the force generated by muscle fibers in the heart?
Initial sarcomere length and stretch on the individual fibers
Which factor influences blood pressure by determining cardiac output (CO)?
Heart rate
What can overstretching the heart lead to?
Limitation of effective contractions
What type of flow in vessels moves smoothly in the center and can cause thrombus formation at vessel walls?
Laminar flow
Which vessels are the primary sites of regulation of vascular flow?
Arterioles
What is the primary determinant of blood pressure and blood flow regulation?
Vascular resistance
Study Notes
Cardiac Output, Blood Pressure, and Blood Flow Regulation
- Resistance (r4) is the primary determinant of Q=P1-P2 R, where Q is flow per min, P is pressure, and R is resistance
- Resistance is inversely proportional to radius4; doubling the radius decreases resistance 16 times, increasing blood flow
- Vascular system primarily uses resistance to alter blood flow, through vasodilation and vasoconstriction of arterioles
- Arterioles are the primary sites of regulation of vascular flow, and drugs affecting arterioles have direct effects on BP and blood flow
- Blood velocity is inversely proportional to the cross-sectional area of vessels
- Laminar flow in the center of vessels moves smoothly, while turbulent flow at vessel walls can cause thrombus formation
- Arterial pressure pulses include systolic BP, diastolic BP, pulse pressure (PP), and mean arterial pressure (MAP)
- MAP is calculated as [systolic BP + (2 x Diastolic BP)] / 3, an estimation of average blood pressure throughout the cardiac cycle
- Blood pressure is influenced by cardiac output (CO) and vascular resistance, determined by heart rate, stroke volume, and resistance to ejection of blood from the ventricles
- Stroke volume (SV) is determined by preload, which is proportional to venous return, and the Frank-Starling law
- The force generated by muscle fibers is proportional to the initial sarcomere length and the stretch on the individual fibers, allowing the heart to adjust its SV based on venous return
- Overstretching the heart can limit its effective contractions, but this is rare and occurs only in chronic disease
Test your knowledge of cardiac output, blood pressure, and blood flow regulation with this quiz. Explore concepts such as resistance, arteriole regulation, blood velocity, arterial pressure pulses, and the factors influencing stroke volume and blood pressure.
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