Type: Response Essays
Sample donated: Renee Gutierrez
Last updated: May 26, 2019
During an exercisetest, the heart must compensate from rest to facilitate increased blood flow tothe body/muscles. In doing so, the hearttissue itself must be supplied with enough blood, oxygen, and nutrients to meetsuch heightened metabolic demands related to cardiac performance. The cardiovascular system is discussed withhaving an acute response to exercise,and how the body adapts. Withsignificant qualities the cardiac cycle contains is the blood flow, bloodpressure, heart rate, stroke volume, and cardiac output. Blood flow isprovided to the heart by two coronary arteries that raises from the left aorticsinus.
The left coronary artery, raisesfrom the left aortic sinus, has major branches and one that is known as theanterior interventricular artery, or the anterior descending artery, which supply blood within theinterventricular septum and anterior walls of both right and leftventricle. The right coronary arteryraises from the right aortic sinus, along with major branches to supply the heartwith blood, majority is the supplying to the atrioventricular node. Thearteries branch out into smaller arteries, then arterioles, that lie betweenthe myocardial muscle tissue supplying with blood.
The myocardiumneeds a constant supply of oxygen in order for the heart to continually pump. Myocardium capillaries are branches of cardiacveins which join to form the coronary sinus, an enlarged vein which emptiesinto the right atrium (Cardiovascular, n.d.). With the heart having three layers; theouter layer is called epicardium and it stops excess enlargement or movement ofthe heart, the middle layer is called the myocardium, and its job is tocontract and forcing the cardiac cycle. The endocardium, within the heart thatis a thin layer which lines and the inside chambers of the heart and the valves.The majority of the heart is myocardium, and is the thickest wall for cardiacfunction (Allen & Harper, 2014), more so in the left ventricle to giveenough pressure to pump blood into the aorta, and supply the systemic circuit.
Duringstrenuous exercise, the coronary blood flow increases up to 4-6times. The maximumincrease in coronary flow above resting levels is coronary flow reserve. Thebases of myocardial oxygen is the heart rate, myocardial tension, inotropicstate (contractility), and vascular resistance which is mainly modulated bymetabolic factors and neural stimuli, with circulating vasoactive substances (Movahed,et. al., 2009).The functioning descriptions described stated by Allen andHarper, of the Physiology response and cardiovascular changes during exerciseinclude the following: · Heart Rate increases · Increased sympathetic stimulation · Decreased parasympathetic stimulation · Cardio Output Increases · Stroke Volume increases · End Systolic Volume increases · Pulse Pressure increases · Mean Arterial Pressure increases · total peripheral resistance decreases · Oxygen extraction increases · Blood Flow to heart, muscle and skin increases · Blood Flow to brain increases (slightly) · Blood Flow to other Viscera decreases The force that theblood pushes against the internal walls of the heart and expanding the bloodvessels is known as the blood pressure. Arterial blood pressure increases anddecreases to accommodate the cardiac cycle. Systolic pressure is increasingduring the ventricular contraction to force the exertion of blood, anddiastolic pressure the ventricle relaxing having blood return to beoxygenated.
Due to the higher cardiooutput, and an increase in heart rate rises, the systolic pressure increasesand the diastolic pressure stays the same or is decreased during exercise byhaving the vasodilation of vessels. Withthe amount of exercise the person does over time, the heart begins toaccommodate to the pressure and therefore leads to reduced systolic anddiastolic pressures (Allen, Harper, 2014) In healthy humansduring maximum exercise heart rate can be increased up to 200bpm. The perception of the increase in heart rate is proficientlyaccompanied by the vagus nerve withdrawal and yet stimulated by the sympatheticsystem. The stroke volume also increasesat the onset of exercise due to the increased myocardial contraction anddepending on posture (upright vs. supine) how much blood is returned to thecentral circulation via the skeletal muscle pump which acts to empty the veinsin the lower extremities where blood pools due to gravity Equally, the strokevolume increases in respiration can also serve to improve blood return to theheart (Joyner & Casey, 2015).
Factors that affect the heart rate arethe autonomic nervous system, chemicals, temperature, emotions, gender, andage. Exercise isincreasingly used to decrease many illnesses and diseases. Throughout exercisetesting there are several changes that are encountered by functional aspects tothe heart. cardio output is increased due to a larger increase in the heartrate, and smaller increase of stroke volume. While the baseline of cardio output is 5 L/min, during exercise, cardiooutput may increase to a maximum value to 35 L/min. Most cardiac output goes to the exercisingmuscle, the heart, and also the skin to disperse heat. Due to the amount of blood flow to thesemajor organs vasodilation occurs, while the digestive system and kidneys havevasoconstriction is the reaction of the sympathetic system. The total peripheral resistance to blood flowis decreased due to the vasodilation of arterioles towards the muscles, heart,and skin of the body.
The counteraction isthat there is an increased blood flow return through the veins due to themuscular activity and so that will increase the cardiac output. The body itselfof cardiovascular to muscular changes in blood flow are inhibited by many otherfactors including, exercise centers in the brain, local chemical changes in themuscle, mechanoreceptors and chemoreceptors in muscle and arterialbaroreceptors (Movahed, et. al., 2009).In conclusion tothe acute response of the heart during an exercise, there are many factors thatgo along with the cardiovascular system. With guaranteed supply, having enough oxygen and nutrients for thedemands of the cardiac cycle to the heart achieve performance.
Taking the heartfrom being at rest to an exertion applied can be a lot to handle though theheart adapts and grows stronger.