BIOC34H3 Lecture : Lecture_6_Notes.rtf

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amethystsnake78

22 Feb 2012

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Lecture 6: stroke volume regulation (continued), afterload, and blood flow regulation: filling time, edv and sv. In the previous lecture we looked at factors affecting end diastolic volume (the amount of blood in the ventricles just before they contract) which is an important factor in determining stroke volume. We ended up looking at the effects of filling time on end diastolic volume; filling time is essentially the amount of time the heart spends in diastole. This limit on stroke volume can be countered by sympathetic stimulation. With sympathetic stimulation, the heart both beats faster, and relaxes faster. The increased rate is due to increased calcium mobilization (from the ecf and sr); the quicker relaxation time is due to the enhanced uptake of calcium by the sarcoplasmic reticulum. The heart therefore spends more time in diastole then in systole, giving extra time for it to fill with blood.

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Tips on solving this: Identify the factors that affect blood pressure; Describe the individual and collective effects of the Lasix, hot water and alcohol on blood pressure. Explain how each of the following factors affect blood pressure: peripheral resistance, heart rate, venous return, stroke volume, cardiac output, end systolic and diastolic volumes, and blood viscosity.

pinkhare248

9. In a physiology lab, the students designed an experiment toillustrate how the heart responds to changes in blood pressure.Everyone relaxed and then did a headstand. Which of the followingobservations are consistent with the change in the function oftheir hearts?

a. increased heart rate
b. decreased heart rate
c. increased stroke volume
d. decreased stroke volume
e. both decreased heart rate and increased stroke volume

indigocod65

Fill in the words or phrases that best complete each sentence. Be as specific as possible. thank you!

f. During embryonic development, ninety-nine percent of the cardiac fibers are specialized for the function called----------------- , whereas the remainder is specialized for----------------------- .

g. The action potential delay at the------------------------------- ensures that atrial excitation and contraction are complete before -------------------------- excitation and contraction commence.

h. The ------------------ is the volume of blood in the ventricle after ejection has been completed. An increase of this volume occurs when the stroke volume is------------------------ .

i. The three cations, K+, Ca2+, and Na+ have an important effect of heart function. Increased blood levels of Na+ blocks --------------------- inflow and results in a decrease in the force of contraction, while an excess of ----------------------- blocks the generation of action potentials.

j. An increase in parasympathetic activity has the following effect on stroke volume:-------------------- . An increase in parasympathetic activity ---------------------- atrial contractility.

lemonplatypus232

BIOC34H3 Lecture : Lecture_6_Notes.rtf

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