Sport

Confine your report solely to the points specified below, paying close attention to the length limits. Marks are also given against each question (total marks 80). For some questions, you will need to consult textbooks or other reference sources. The report should be handed in, at the Undergraduate Office (TM1-85), within ONE week of the date on which the practical is done. The report must represent your own work, and must not be written collaboratively. You must also not copy material from the internet, textbooks or elsewhere. An electronic version of this form is available on Weblearn.

NAMEID NUMBER GROUPDATE OF PRACTICAL
(i) Electrocardiography

Measurements at rest
Attach a print-out of the ECG recording with your subject at rest, showing the different features of the cardiac cycle labelled with the appropriate letters. (5 marks)

Briefly describe the functional significance of the features labelled in your diagram, in terms of both electrical changes occurring in the heart, and also the mechanical effects they give rise to (15 lines maximum 15 marks).

The waves seen on a normal ECG indicate the electrical activity that happens to the heart when it under-Goes cardiac action potentials. The 1st wave visible is called the P wave, this wave fires at the start of theSA node and represents the depolarization of the atrias muscle fibers. Between each wave there are  Intervals, the PR interval represents the travel time of electrical signals from the Sinus node through theAtrium to the AV node to the Purkinjie-His system to activate ventricular myocardial cells. The next Wave is called the QRS complex. This wave represents all ventricular muscle cell depolarizations and  Varies between each individual but usually lasts between 0.06-0.10s. The ST interval shows all of the Ventricular myocardium cells depolarizing. The QT interval is called the electrical systole of the Ventricles and lasts about 0.4s. Lastly the T wave represents the repolarization of the ventricles.

Calculate the following variables using the print-out of your ECG recording. Each variable should be measured on 3 cardiac cycles, and an average taken. The cardiac cycles from which the measurements were taken should be labelled on your print-out (as 1,2,3). Make sure you use the units specified in the Table. (5 marks)

VariableUnits123AverageCYCLE TIME1
ms0.91.11.01.0 HEART RATE2
BPM65797272P-R INTERVAL
ms0.30.20.20.23Q-T INTERVAL
ms0.40.60.60.53T-Q INTERVAL
ms0.30.30.40.331The time for a single complete cardiac cycle (express this in milliseconds - ms).
2Calculate as beats per minute (BPM) using the cycle times already calculated

Attach the printout(s) showing ECG during the Valsalva manoeuvre, and during deep breathing.
The Valsalva manoeuvre usually results in an increased heart rate (sometimes after an initial, smaller, decrease in heart rate). Investigate whether your results showed this effect, and explain the underlying physiological mechanisms (5 marks)

The increased pressure from the Valsalva manoeuvre  increase heart rate because the muscles feel an extra-Ordinary amount of pressure and the only way to relieve that pressure is by bring more oxygen and bloodTo the body, which is why most health professionals ask you to take a deep breath and release when thy do This technique so that the person doesnt pass out. The results showed this effect.

The effect of breathing on heart rate is known as sinus arrhythmia, but its magnitude differs considerably between individuals. Evaluate whether your results showed this effect, briefly explain the physiological mechanisms that underlie it, and suggest why it might improve respiratory function. (5 marks)
Physiologically respiration and cardiac function go hand in hand because oxygen is need to maintain Adequate blood flow throughout the body. Having lower blood pressure when exercising improves Respiratory function because the less oxygen a person has to expend during exercise leaves more oxygenReserves when the person is at rest. In the end my results indicated this effect.

Measurements during exercise
Attach the print-out of your ECG recording under exercise conditions. Calculate the following variables as before, but using the exercise ECG data. (5 marks)
VariableUnits123AverageCYCLE TIME
ms1.71.91.51.7HEART RATE
BPM122137108108P-R INTERVAL
ms0.10.070.09 0.087Q-T INTERVAL
ms0.20.10.10.13T-Q INTERVAL
ms0.060.050.050.053

Complete the following Table, inserting the words contracted or relaxed into the different boxes as appropriate

P-R intervalQ-T intervalT-Q intervalAtriaContractedRelaxed ContractedVentriclesRelaxedContracted Relaxed

Using the average figures from the first two Tables above, calculate the percentage change, in these three intervals, when going from the resting to the exercise state
P-RQ-TT-Q change37.824.5 16.1 (5 marks)

It is normally found that the T-Q interval is shortened to a relatively greater degree than are the other cardiac intervals, as heart rate increases. Evaluate whether your results show this, and suggest why this is beneficial to cardiovascular function  (5 lines maximum 5 marks)

My results show this function. The shortening the QT interval during exercise is beneficial to cardiovascular function because when a person is vigorously exercising heshe needs greater amounts of blood pumping to the throughout the system so it can reach the muscles. Which means that having a shorterQT interval allows the blood to exit the left ventricle sooner and into the aorta where the blood is then ejected to the entire body thereby bring more oxygen to the muscles.

(ii) Blood pressure measurements
Give the blood pressure measurements made under resting and exercise conditions. (5 marks)
(all readings as mm Hg)Right armLeft armSystolicDiastolicSystolicDiastolicAt rest14565167107After exercise10872127114

Define the terms cardiac output and total peripheral resistance. State the relationship between these two variables and blood pressure, in the form of an equation, and explain the physiological mechanisms that underlie the formula. (10 lines maximum 10 marks)

Cardiac output can be defined as the volume of blood flowing through either the systemic or the pulmonaryCircuit per minute and is often measure in liters per minute. Total peripheral resistance is defined as the  Resistance flow through a system of vessels.  In terms of an equation, blood pressure  cardiac output x Peripheral resistance. Physiologically, when cardiac output is increased, which is heart rate multiplied by Stoke volume, the capillary flow is increased. On the other hand when peripheral resistance is increased, Capillary flow decreases. Therefore, blood pressure is often increased when cardiac output is increased andPeripheral resistance is decreased.

Blood pressure measurements are generally higher during exercise than at rest, and during dynamic exercise like cycling systolic pressure usually increases more than diastolic. Do your measurements agree with these assertions Additionally, explain how changes in cardiac output and peripheral resistance during exercise combine to cause observed changes in both systolic and diastolic blood pressure. (10 lines maximum 10 marks)

My measurements do not agree with these assertions because both my left and right arm after exerciseIndicated a decrease in blood pressure, but both arms at rest showed an increase in blood pressure. As Mentioned before, the increase in blood pressure is attributed to two variables cardiac output and Peripheral resistance. When a person exercises their heart rate and stroke volume (volume of blood ejectedDuring systole) increase but resistance decreases. The width of vessels increases because blood and oxygen Need to be sent to the muscles so that the person can continue to exercise without falling over. Therefore, The combination of increased CO and decreased PR increase both the SBP and DBP during exercise becauseThe muscles need blood and oxygen to keep going, which in turn allows the individual to exercise longer.