Stroke volume increase as more blood needs to be pumped around the body, so the size and force of the contraction increase to get sufficient volume of blood to the needed parts of the body in one beat. Heart rate increases due to the fact that the muscles need that oxygen quickly, so to do this effectively the heart rate is increase so that this supply is sufficient. And due to the fact that cardiac output is equal to heart rate time stroke volume, the cardiac output will also increase. As shown in figure one and in figure two you can see that the heart rate before exercise is at resting heart rate of 60, this stays like this until Just before the activity starts. This rise is called the anticipatory rise due to the fact that the participants are anticipating the activity and may cause their heart rate to rise.
This rise is cause by the adrenal glands secreting adrenaline which is transported around the body in the firing lightly before the activity has even began. This whole process is usually described as the anticipatory rise. When the activity takes place a rapid increase in the heart rate increase, this is due to the body needing to get enough oxygen to the active muscles. So this demand of oxygen will be noticed by the body and makes the AS node to start firing more violently to get that demand of oxygen met. As you can see in figure one the heart rate doesn’t reach a state of steady state as it is still in constant demand of oxygen, whereas in figure two it reaches steady state as it is sufficient with the oxygen supplied. But we will talk more about steady state in the ext assignment.
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And it is a massive difference from resting, so the heart needs to pump more powerfully to supply that blood to the parts of the body that need it. The heart rate is increase by different factors, like neural, intrinsic and hormonal factors, but in order for the heart to know when to change the rate and volume of the beat, other things come into play. The graphs would show the same trend when stroke volume come into play. We did a test to show the trend of the heart rate values. This was the Chester step test. Be monitored our blood pressure and our heart rates. We also did a test to show the trend of heart rate with maximal exercise, this was a 2/3 minute sprint. Both tests showed a significant similarity to the graphs above.
Booth of them showed an anticipatory rise due to the adrenalin being released, and then a rapid increase in heart rate due to the oxygen demand being higher. Control of Heart Rate (321) There are three different ways in which the body can control heart rate. One of them is neural. There are three main receptors used to control heart rate; Preceptors, Preprocessors and Competitors. Preceptors are stretch receptors in the loud vessels; they monitor change in blood pressure within these vessels. Preprocessors are located in the tendons, Joints and muscles. They monitor movement. Competitors monitor the chemical changes within the body, mainly in the blood. They monitor co levels, pH. Levels etc.
Exercise will each cause a change in the body, which is picked up by these receptors. The receptors then send impulses to the Cardiac control centre (ICC) located in the medulla obbligato. When it’s seen that exercise or activity is taking place, the ICC will send impulses down the sympathetic river called the accelerator. This nerve then feeds down to the AS node and starts causing it to fire rapidly. This in turn increases heart rate and stroke volume to cope with the exercise. When recovering from exercise the receptors will pick it up and send impulses back up the ICC, then impulses are sent down the parasympathetic nerve, called the vague nerve. This also feeds to the AS node and tells the node to stop firing.
This will then reduce heart rate and stroke volume, to allow body to recover from exercise. The second factor that helps control heart rate is called intrinsic factors. This is based on the Starlings Law of the Heart; Starling suggests that if you have a more successful venous return, the return of the flow of blood back into the heart through the even java. If this is more successful, and more blood is heart to stretch. This then causes the AS to contract with more force and power, which provides a higher stroke volume. So when venous return increases due to exercise Starlings law comes into effect. Starlings law is based on if there is a larger venous return that in turn means that the stroke volume will increase.
The final factor is Hormonal. Hormonal factors are a main reason for anticipatory rise before and activity. The hormone being secreted from the adrenal glands is adrenaline. This adrenaline then causes the AS to fire faster, which increase the heart rate and stroke volume. An example for all of these factors would be our Chester step test, before you start the race; the adrenal glands would adrenalin and would cause an anticipatory rise in heart rate due to the adrenalin, also due to the fact that people were watching us carry out this test so that would make our heart rate faster due to nerves. This would increase the firing speed of the AS node.
And as you start the test, the chemotherapy’s would notice the change of concentration of oxygen and carbon dioxide in the blood so, that would force an impulse up to the ICC and cause an impulse from the accelerator nerve and cause the AS to start firing faster. Also preceptors and preprocessors would notice the change in blood pressure and the movement in the Joints that is occurring. Blood Pressure Changes to Exercise Blood pressure is the pressure that the blood causes against the walls of the vessels. There are two forces that create this pressure, one of them being the heart. If the earth pumps faster and stronger then it will cause the blood to be forced out of the aorta and pulmonary artery faster, this will cause more pressure.
And the other factor is the resistance of the blood vessels, like the length and radius. There are two measurements f blood pressure. They are systolic and diastolic. Systolic is the pressure exerted on the arteries when the heart contracts and diastolic is the pressure exerted on the arteries when the heart relaxes and fills with blood. Blood pressure is measure in meg. Normal resting values of blood pressure would be McHugh for Systolic and might for diastolic. Blood pressure can vary with age, race, gender and physical activity. For my sub-maximal exercise of the Chester step test, my highest blood pressure reading came in at 1 50 systolic and 90 diastolic, with my resting values at 110 systolic and 60 diastolic.
This shows that blood pressure increases during exercise due to heart pumping blood faster and harder through the arteries, which cause force to be exerted on the artery walls. This increase in blood pressure would also be the same for the majority of sports. Much like heart rate, blood pressure can show an anticipatory rise, due to adrenalin which increases heart ate. This would then consequently increase the blood pressure. If you have Systolic pressure from 120-139 meg and Diastolic of 70-might this is considered to be called pre hypertension and anything over McHugh systolic and 80+ meg diastolic is called hypertension. Hypertension increases the risk of cardiovascular disease or kidney failure.