Concerning the load experienced by ventricular muscle before and during a contraction: a. preload is the force per unit cross-sectional area of muscle during diastole. b. preload is increased by a rise in end-diastolic pressure. c. afterload is the ventricular wall stress after the aortic valve closes. d. afterload is influenced by the arterial blood pressure. e. preload and afterload are reduced by an increase in chamber radius 2. The Frank–Starling mechanism a. is an increase in cardiac contractility brought about by an increase in heart rate. b. is mediated by the autonomic nerve fibres innervating the heart. c. is triggered by stretch receptors in the aorta wall and carotid sinus. d. causes stroke volume to increase when the heart is distended. e. accounts for a reduction in arterial blood pressure following a haemorrhage.