The Cardiovascular System. Unit 3 (Ch.15). Structure of the Heart. About as big as your fist. Located within your thoracic cavity. In the mediastinum Sits on the diaphragm 14 cm long by 9 cm wide. Coverings of the Heart. Pericardium encloses the heart Layers: 1.fibrous 2.visceral
Unit 3 (Ch.15)
*Physical exercise, body temperature, and concentration of various ions affect heartbeat.