Muscle Physics & Heart as Pump Flashcards
What is a rough average for stroke volume at rest?
70 ml/beat
Average cardiac output for people at rest is ______ and can go up to ______ during exercise.
5 L/min; 40 L/min
Inotropy is _________.
the strength of the contraction independent of the Frank-Starling law
As soon as the pressure is higher in the ventricles, the ________ close.
tricuspid and mitral valves
Frank-Starling curves show ___________.
the amount of pressure that the heart can produce from a given initial volume
The Frank-Starling law is __________.
independent of the autonomic nervous system
What are the three molecular bases of the Frank-Starling Law of the Heart?
(1) sarcomeres are more calcium-sensitive when stretched, for unknown reasons; (2) cardiac titin is stiff, and like a spring it creates more contractile force when stretched; and (3) stretched filaments create a better lattice arrangement for interaction
In terms of the PV loop, pre-load is __________.
the end-diastolic volume
In words (not equations), cardiac output is ____________.
the amount of blood pumped by the heart in one minute
What is the cardiac index?
It is a measure of cardiac output normalized to body size, given in units of L/min/m^2; the normal range is 2.5 - 5.0
Which can change to a larger percentage, heart rate or stroke volume?
Heart rate, so larger changes in cardiac output will have a greater change in heart rate than in stroke volume
What three things influence stroke volume?
Contractility and preload (which have a positive effect), and afterload (which has a negative effect)
The heart rate is set by the _______ and regulated by the _______ and ______.
sinoatrial node; autonomic nervous system; humoral effects
