Cardiovascular Effects of the Sympathetic Division

Running for our lives, focused on an escape route, our bodies kick into high gear in search of safety. The nervous system, wired long ago, gives us the strength to engage our muscles in dangerous situations, or affords us the energy to flee to safety. This sympathetic response powers our heart rate, oxygenates the lungs and muscles and boosts the metabolism so that we may flee danger with focused passion.

Sympathetic Nervous System

• Cardiac output is a reaction to innervation of the bundle of His and Perkinje fibers in the heart.

  Sending and receiving electrochemical impulses from the brain, the sympathetic nervous system extends from the brain stem to the coccyx. Attaching above and below each vertebra, spinal nerves transmit impulses to all areas of the body. Neural connections up and down the spine stimulate the organs, muscles and tissues of the body. These Impulses turn on receptors in the organs and tissues that increase pressure in the blood vessels, enhance cardiac output and send powerful energy to the heart. By reducing the blood flow to the skin and flooding the skeletal muscles with additional energy, the body is now ready to respond to danger. Our pupils dilate, oxygen floods the bloodstream, energy surges from fat and glycogen stores; the body is prepared to respond to danger.

Cardiovascular System

• The cardiovascular system pumps blood that is rich in oxygen through the heart, muscles and blood vessels. The pulmonary arteries deliver oxygen and remove carbon dioxide from the lungs. At the same time, systemic circulation transports nutrition and energy to our muscles, organs and tissues. This massive network of arteries, veins and lymph nodes fight bacterial invasions and flood the body with oxygen. Releasing chemical and electrical messages that maintain all the systems of the body, the parasympathetic nervous system maintains our day-to-day functions. Under stress, however, the sympathetic nervous system dumps hormones and electrical impulses into the bloodstream that circulates throughout the body. Once this system shuts down unnecessary functions of digestion and elimination, it shoots oxygen through the bloodstream and glucose to the muscles preparing us to protect ourselves from a dangerous situation.

Nerve & Heart Connection

• Anger is an electrochemical reaction resulting from oxygen and chemical hormones flooding the bloodstream.

  Surfacing in the middle of the back or the thoracic area, spinal nerves innervate or control the heart muscles. Sensory and motor nerves also known as afferent and efferent nerves maintain constant communication with the brain and the rest of the body. Baroreceptors in the heart send information through these sensory nerves to the brain and sends motor impulses back to the heart. These impulses allow the body to respond to increased activity, fear responses and strenuous movement. Increasing pressure on blood vessels enhances the pumping action of the heart. The energy that powers the hear muscles comes from the electrical stimulation of nerve tissue in the bundle of His and Purkinje fibers.

Considerations

• Receiving impulses from deep within layers of the brain stem, the autonomic or "automatic" nervous system controls our heartbeat, internal temperature, thirst, hunger and our response to stress. Humans do not control these automatic functions of the body required for survival. These functions are managed by a piloting system that allows humans to focus on endeavors within our control. Chemical changes in the brain produce ancient evolutionary reactions to stress.