MODULE SUPPLEMENT: CARDIOVASCULAR SYSTEM
Additional Functional Changes

Additional functional changes are outlined in the table below.

Earlier we discussed the idea that myocardial cells handle calcium differently which can slow relaxation. This, plus increased stiffness of the myocardium, causes blood to flow more slowly into the ventricles during early diastole, a time when blood normally flows passively down its concentration gradient from the atria to the almost empty ventricles. Estimates are that the early diastolic filling rate decreases about 50% between 20-80 years of age (Lakatta & Sollatt, 2002).

At rest, this slowed early diastolic filling is not of functional significance because the ultimate end-diastolic volume is not reduced. However, the reason that end-diastolic volume is not reduced is because of an increase in late diastolic filling, which occurs as a result of the atrial "kick" or atrial contraction. This means older persons require a more forceful atrial 'kick' to top off ventricular filling, which is necessary for an adequate contraction.

Why is this clinically significant? Write down two clinical events that might compromise this adaptive strategy.

When you have finished answering this question, continue with the course content.