The health and safety risks involved in this monitoring
There are many risks involved in using the blood pressure machine as if you don’t use it properly it could lead to an accident. A person should only take 3 readings on the blood pressure machine; we overcome this by letting everyone in the group take their blood pressure readings so that no one had to use it more than 3 times. The blood pressure shouldn’t be set to any more than 170 and we made sure this was carried out. Using the stethoscope you should also make sure that nobody fooled around with it as if someone is using it and somebody else shouts down it, it could lead to damage to their hearing. We also made sure that the person taking part had no heart problems ect.
Patterns and trends in the data and how this data falls within the expected norms
The normal range of blood pressure at rest is 120/80 mmHg and anything over this 140/90mmHg is seen as Hypertension (high blood pressure) our data at rest was 101/74 mmHg which falls below the expected norms. But it is not that low to cause problems. For the pulse rate the normal is about 70 BPM (beats per minute) at rest. Our data was again below this but not a big difference as it was 64 BPM.
On our graph you can see that the data for both the pulse rate and systolic blood pressure both raised after mild and strenuous exercise, but the diastolic pressure didn’t, this raised to 102 on the mild exercise but dropped to 86 at the strenuous exercise, which didn’t fall within the expected norms. As normally a person’s blood pressure is expected to rise during physical exertion which this did but then dropped sooner than expected.
The heart beats per minute and blood pressure increase during exercise and after as the body is doing more work which means that the muscles are doing more work, so they need the cells to produce more energy for this, in which oxygen is needed. The oxygen supply may not be sufficient enough to completely oxidize the food required to meet the energy demands of the body. So this means that more oxygen needs to be taken into the body so that breathing increases to do this and this means that the heart has to speed up its heart rate to pump the oxygenated blood to around the body and because there is more blood being pumped around quicker this means that the blood pressure rises too. The products of the aerobic stages for example lactic acid needs to be oxidized or converted back to carbon hydrate. So even after exercise the oxygen intake is still high.
The Cardiac cycle is the sequence of events in a heartbeat. This involves systole (contraction) and diastole (relaxation) of the atria and ventricles. The cycle has 4 stages, the atrial systole which is when both of the atria contracts which forces the blood they contain through the atrioventricular valves into both of the ventricles this only lasts for about 0.1 seconds. Next it is the Ventricular systole which is when both ventricles contract forcing the blood through to the pulmonary artery to the lungs and through to the aorta to the rest of the body. This takes about 0.3 seconds. This contraction of the ventricles also pushes the blood against the atrioventricular valves causing them to close. The entrances of the aorta and pulmonary arteries contain Semi lunar valves which during ventricular systole there is increased pressure which causes the Semi lunar valves to open. Next it is the atrial diastole which is when the atria relax even though the ventricles are still contracted; the blood enters the atria from the large veins coming from the body. Lastly it is the Ventricular diastole which is when the ventricles relax and become ready to fill with blood from the atria as the next cycle begins. The heart beat is heard as a result of the arrest of moving blood when the valves close.
The Cardiac impulse is the contractions of the heart muscle which is triggered off by electrical stimulus. The electrical impulse originates in a region of the right atrium called the sino-atrial (SA) node; the less technical word for this is the pacemaker. This electrical impulse spreads into the walls of the atria causing atrial systole (contractions) This electrical impulse is stopped from spreading to the ventricles by a fibrous ring of tissue, this is important as the atria and ventricles mustn’t contract together. This impulse is then picked up by the second node which is the Atrioventricular (AV) node which is another pacemaker situated in the wall of the right atrium. This electrical impulse is then conducted through the fibrous ring along the Bundle of his which divides into interventricular septum into the left and right bundle branches. This then passes through the ventricular myocardium along the finely branched network of Purkinje fibres which causes the ventricles to contract. This can be recorded by electrocardiography (ECG
Homeostatic mechanisms that regulate heart rate
Within the medulla there are two centres that are responsible for controlling the heart rate, the Cardio-acceleratory centre which is linked with the sympathetic nervous system to the SA node. When stimulated these can cause an increase to the heart rate. The Cardio-inhibitory centre is linked to the parasympathetic fibres within the vagus nerve, to the SA node and the Bundle of his stimulation from these nerves decreases the heart rate. Which of these centres stimulates the heart depends on the blood and for example the carbon dioxide concentration. Under conditions of exercise the carbon dioxide increases in our blood, receptors in the carotid artery detect these changes and sends messages to the Cardio-acceleratory centre which increases the heart rate. A fall in the carbon dioxide concentration means that the receptors in the carotid artery stimulate the Cardio-inhibitory centre which reduces the heart rate. There are several other things that control the hearts activity, such as Starlings law of the heart. This law states that the power of the cardiac is directly related to the length of the cardiac muscle fibres. If more blood enters the heart from the veins, the cardiac muscle fibres in the myocardium are stretched more with greater force.
There are also the Baroreceptors which are receptors that are sensitive to the stretching in the walls of the aortic arch, carotid sinuses, venae cavae and the right atrium. The Baroreceptors detect any increases in blood pressure in any of the vessels. The Baroreceptors then transmit sensory impulses to the cardiac centres which decrease the cardiac activity appropriately.
Adrenalin in times of stress is secreted into the body by the Medullae of the adrenal glands. The adrenalin speeds up the heart beat by increasing the pacemaker’s excitability. A similar substance is used to decrease the heart rate is called noradrenalin, this is released onto the pacemaker by sympathetic (cardiac) nerve endings and the inhibitory parasympathetic (vagus nerve) releases acetylcholine onto the pacemaker resulting in the decreasing of the heart.
Other factors that regulate the heart rate are if there is a drop in oxygen or a rise in carbon dioxide affects the Cardio-acceleratory centre and results in an increase in heart rate. If there is a high concentration of potassium ions in the blood this interferes with the nerve impulses that control the pacemaker which causes the heart rate to slow down.
Blood pressure
Main factors that control blood pressure
Blood pressure is generated by the pumping of the ventricles. There are pressure sensitive devices called pressure transducers which are on long on the catheters in the heart. The pressure (the pressure is generated by the pumping action of the ventricles) in the left ventricle during systole usually rises to the maximum of 15.79 kpa, (120mmHg) and drops to zero during diastole. In the right ventricle it is usually lower; about 3.29 Kpa (25mmHg) the body must keep blood pressure inside strict limits. It must be high enough to push blood through the capillaries, but if it gets too high it would make the heart work unnecessarily hard and risk damage to the blood vessels. High blood pressure is a risk for Atherosclerosis which is hardening of the arteries. The normal reading for blood pressure is between 60 and 80 mmHg
A negative feedback system keeps the blood pressure in safe limits. The pressure of the blood is detected by the carotid sinus (Baroreceptors) which expand, and the stretch receptors in the artery walls inform the cardiovascular centre in the medulla. Signals from the medulla then lower the heart rate and vasodilatation of the vessels which lowers blood pressure or increases it according to the body’s requirements
Factors that may result in deviations of blood pressure readings from the expected norm
Factors that affect your blood pressure are things such as
- Smoking
- People with parents that suffer from high blood pressure can inherit it
- Medicines and oral contraception’s can interfere with readings
- Overweight people are at higher risk of having high blood pressure
- Pregnant women have higher blood pressure readings that are expected
- If a person is inactive and leads a life without exercise they are more prone to have high blood pressure
John’s ECG
A normal ECG has a p wave (atrial contraction) which is closely followed by a QRS (ventricles contracting) then a t wave and so on as the diagram shows you.
Johns ECG is defiantly different than this, he has up to three p waves before he has a QRS but this differs. The QRS is also not evenly spaced out and is not always followed by a t wave.
Conditions that might cause this
The reason why john’s ECG was how it is might be the influence of a heart block. A heart block is when sometimes the signal from the upper part of the heart to the lower is impaired or doesn’t transmit. A heart block doesn’t mean that the blood flow is blocked or the blood vessels. Heart block can be classified into 3 categories according to the level of impairment there is first second and third degree heart block.
I think that john is suffering from second degree heart block which is when some signals from the atria don’t reach the ventricles. This causes dropped beats on an ECG, and the p wave isn’t always followed by a QRS which is shown on johns ECG. This is caused because the ventricles were not activated properly. There are two types of second degree heart block in which I think that john has the type 1 as the electrical impulses are delayed resulting in on QRS and a repetition of p waves until a beat is dropped. This condition is not too serious but it can lead to needing a pacemaker and dizziness.
