Explain Sympathetic - Nerves System
Sympathetic, as the word suggests, means to sympathize. The body sympathizes during fight, flight and fright reaction. For example, have you ever felt your heart beat faster when in the dark or when frightened? This increase in the heart rate is termed as 'positive chronotropic effect '(Chrono: from chronological meaning related to time or rate). The heart also beats with an increased force as you may have experienced your heart pouncing against a heaving chest after a sprint. This is called as positive inotropic effect, as the increase in force is brought about by the changes in ion concentration across the cell membrane. Calcium within the cell makes the heart beat stronger. (To remember, milk gives strength and milk has calcium). Have you ever wondered about the mechanism that makes the beat faster? Nature has designed a beautiful mechanism which symbioses the electrical impulse and the solid heart. A flame is ignited in the heart, which then travels to the cardiac muscle, imparting it energy to contract. The rate of transmission of this flame or electrical impulse increases during sympathetic situations and is termed as positive dromotropic. An increase in the excitability of the cardiac tissue is termed as positive bathmotropic.