Mechanisms For Regulating Ventilation and Pulse Rates

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4.1 Explain The Mechanisms For Regulating Ventilation
and Pulse Rates
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This blog is discussing what is needed to regulate ventilation and pulse rates, it is a result of homeostasis of the cardiovascular system. Our heart rate can be increased due to the amount of adrenalin that is in the blood stream, it can also be increased from the nerves from the sympathetic nervous systems. This can also increase the stroke volume, the nerves are stimulated by an increase in the carbon dioxide levels in the blood stream. The rise in the level of carbon dioxide comes from the increased release of oxygen in the cells, the way in which this occurs is as follows. There is an increase of the CO2 levels in the blood stream, this is then picked up on by the chemoreceptrs on the cartoid body. The chemoreceptors then send impulses to the cardiac acceleratory centre, this is in the medulla part of the brain. From here the cardiac acceleratory centre then sends impulses by way of the sympathetic nervous system to the sino atrial node in the heart, this is the accelerator. This then causes the release of the hormone noradrenline at the sino atrial node, this is what makes the heart beat faster.
Our cardiac output can also decrease, this is done by nerves from the parasympathetic nervous system. The nervous are stimulated due to a fall in the level of carbon dioxide. This happens as follows, the level of CO2 drops in the blood stream, this is noted by the chemoreceptors that then send impulses to the cardiac inhibitory centre in the medulla. From there impulses are sent by way of the parasympathetic nervous system to the sino atrial node in the heart. This then results in the impulses releasing the hormone aceytlcholine at the sino atrial node, this hormone then decreases the heart beat and stroke volume.
The higher the CO2 in our body the more we breath in, but the lower the CO2 in the blood stream the less we breath in. We breath in more when we exercise because this is what increases our CO2 levels and we breath less when we are asleep because we are at rest and our CO2 levels are lower.
Overall if we have a high concentration level of CO2 levels in our system we breath in a lot more which increases our heart rate which could put to much pressure on our heart if it regularly happens, but if carried out as a regular but sensible programme then it can help strengthen the heart and help with our respiratory system, decreasing the risk of heart problems, strokes and respiratory problems.

Cardiac Output and Importance Of Value

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3.4 Calculate Cardiac Output and Discuss The
Importance Of Value
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This blog is looking at how to measure our cardio output and the importance of measuring it. Our cardiac output is the measurement of how much blood is pumped by each ventricle per minute, this can be measured by the formula cardiac output = stroke volume x heart rate. By using this formula I measured my cardiac output and the results were 80 x 70 = 5600 cm3 = 5.60 litres per minute.
At rest the normal rate of blood is 5 litres per minute, but during exercise it can be up to 30 litres per minute. Our cardiac output depends on how much blood is getting back to the right hand side of the heart, this is known as venous return. When our blood return increases due to exercise this is because of the myocardium contracting stronger, causing the stimulus that the muscle fibres to stretch.
If our heart rate is low it can cause to feel unwell and also give us indication that there isn't enough oxygen getting around the body. Some things we could end up with are low blood pressure, fainting spells, dizziness, feeling tired and sluggish, not getting enough nutrients into our body causing mal - nutrition and also we won't be able to get rid of the carbon dioxide out of our body which can cause us severe problems with our heart, lungs, respiratory system and all other parts of the body.
Another issue that could be picked up from measuring our cardiac output is if we have high blood pressure, are at risk of a stroke or a heart attack, it could also indicate if we are under stress or even just been exercising.
Overall measuring our cardiac output is important for many reasons and could prevent us from serious health problems or even death, so it is worth just having it taken every so often to ensure that things are alright because even though you think they are it isn't always he case, and as they say prevention is better than the cure.

The Electrical Activity Of The Heart

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Pictures from:- http://www.cdle.ca/

http://www.bioen.utah.edu/

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3.3 Explain The Electrical Activity Of The
Heart During A Heart Beat
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Our heart as a pace maker of it's own and this is what helps keep our heart beating at a regular rate. The natural pace maker is situated in the upper part of the right atrium and it is a group of specialised electrical cells known as the Sinus or Sino - Atrial node.
The electrical system Carry's sparks that stimulate the muscle wall of the four chambers of the heart, those being the left atrium, right atrium, left ventricle and right ventricle to contract and then empty, this is done in a certain sequence. The first parts of the heart to be stimulated is the upper parts and the atria, after this there is a small delay which allows the two atria to empty, then the two ventricles are stimulated.
For the stimulation to happen adrenaline needs to be built up causing the sinus node to increase the amount of sparks per minute, this then increases the heart rate, how much adrenaline is released is determined by our nervous system. Our heart beats on average 72 times a minute (heartsite web) and when we carry out exercise or are stressed then the sinus node speeds up, this also occurs when our body needs an extra boost of blood supply.
The way in which the electrical activity takes place in the heart is as follows. When the sino - atrial node fires the electrical impulse goes through both the left and right atrium, this then causes both chambers to contract. When this happens this activity on an ECG would be known as the 'P' wave. From here the impulse then goes to the atrio- ventricular node which is just above the ventricules, it is then held here shortly. The reason it is help is to allow the left and right atrium to carry on emptying there blood into the ventricles, on an ECG this would then show as the 'PR interval'. The atrio - ventricular node is then acting as a rest area which is delaying the stimulation of the ventricles whilst the two atria empty. Once the delay is over the impulse then travels through both the ventricles, this then causes them to contract and blood is then sent into the pulmonary artery and the aorta, this is shown as the 'QRS complex' on an ECG. Once the ventricles have then recovered from the impulse it generates an 'ST segment' and T wave on an ECG.
The thing that makes the heart make the 'Lub' sound is when the impulses are in the ventricular systole stage and the pressure of the blood is causing the ventricular valves to close, the valve is opened during atrial systole and when it makes the 'Dub' sound it is during the diastole stage and due to the pressure of the blood being so high in the arteries that it causes the semi lunar valve to shut, the semi - lunar opens during ventricular systole.
Overall again our heart with help from our nervous system is playing a major part in our body and it enables us to breath without having to think about doing it.

The Heart Structure and The Cardiac Cycle

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3.2 Describe The Structure Of The Heart and Explain
The Cardiac Cycle
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This blog is going to discuss the structure of the heart and look at how the cardiac cycle works.In an adult our heart beats around 70 times a minute which on average is 100,000 beats a day and on average it pumps 100 millilitres of blood per beat around the body (biology reference web).
Our heart sits on the left centre of the chest and it is a lubricated sac known has the pericardium, and it consist of four chambers, the left ventricle, right ventricle, left atrium and the right atrium. Blood that is coming from the body goes through the superior vena cava which is located on the right side of the heart, this is carrying blood from the head and other parts of the body that are above the heart and also blood comes through the inferior vena cava. Blood going through the inferior vena cava is coming from parts of the body that are lower than the heart. Has the superior vena cava and the inferior vena cava enter the right atrium which is an upper chamber, they join together, the right atrium then acts as a receiving area for the blood that is entering the heart. From the right atrium the blood goes down to the lower chamber being the right ventricle, this is done via the tricuspid valve which is a one way valve. The reason it is a one way valve is because it stops the blood going back up when the ventricle contracts. From here the blood goes through the pulmonary valve, this is done when the contraction of the ventricle takes place, the pulmonary valve is also a one way valve, it then goes into the pulmonary artery that then leads the blood to the lungs. The blood that is sent to the lungs via the right side of the heart is returned to the heart by four pulmonary veins, these take the blood to the left atrium which is the other upper chamber. The blood from the left atrium then goes through the mitral valve and down to the left ventricle, the mitral valve works in the same way as the tricuspid valve as it stops the blood going back to the left atrium and the pulmonary veins when the ventricle contracts as it is also a one way valve.
When the left ventricle contracts the blood then goes through the aortic valve, which is again one way and then goes into the aorta which is the biggest artery in the body. The aorta which curves over the top of the heart as large arteries which lead of to the head, arms and upper chest.The lower part of the aorta goes through the lower part of the chest and stomach and arteries lead off from there carrying blood into the liver, spleen, intestine, kidneys and legs. The blood then goes through smaller arteries and capillaries and it then goes back to the heart through our veins. From the aorta is also two coronary arteries, these carry blood to the heart and are a part of the systemic circulation. The blood that as gone through the capillaries in the heart then goes back into the right side of the heart through veins and sits back in the right atrium.
The cardiac cycle begins when the heart is relaxed, blood that is in the veins is at an higher pressure than the atria, therefore the means the pressure is higher than that of the ventricles, this then means that blood goes from the veins to the atria and then to the ventricles. The atria is where the contraction of the heart begins, this is also known as systole. Contraction of the atria causes the an increase in pressure which pushes more blood to the ventricles, there is then a delay of around 0.1 second, after the delay the ventricles start to contract. Has the blood pressure increases and it becomes higher in the ventricle than in the atria the tricuspid and mitral valve close, however the contraction continues causing the pressure in the ventricles to build up more than in the pulmonary artery, which then causes the opening of the arterial valve letting blood flow into the arteries. Contraction in the ventricles carry's on causing the blood pressure in the pulmonary artery and the aorta to reach it's highest point, which is the systolic blood pressure rate. After this the blood pressure then falls gradually as the blood starts moving away from the heart and to the lungs, disatole occurs when the heart relaxes and blood pressure carry's on falling.
Overall the heart is a very unique structure and is a very important part of the body, in fact it is the main functioning part of the body and without it we no longer live. There are many parts of the heart even though it is only a small organ, as it is only about the size of a fist and is the shape of a pear, and it is hard to believe that it as 60,000 miles of vessels in it.

Structure Of Arteries, Veins and Capillaries

3.1 Describe The Structure Of Arteries, Veins and Capillaries
and Relate This To Their Function
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www.cardiologyassociates.net

www.klbschool.org.uk

www.webanatomy.net

www.revisionworld.com

This blog is looking at the structure of the arteries,veins and capillaries and looking at each relate to their function. Our arteries contain a thick wall, the outer wall contains smooth muscle fibres. These muscle fibres contract and relax by way of instruction from the sympathetic nervous system. The inner layer of the arteries is very thin and the tissue is called endothelinal tissue.
The function of the arteries is to move blood away from the heart, they also transport oxygenated blood only, except in the case of the pulmonary artery. Has our ventricles contract, blood goes into the arteries at a high rate, this then stretches the endothelium which is folded and also the elastic walls. Once the ventricles relax it causes the elastic recoil of the wall and that keeps our blood pressure up, so it is important that the arteries are stretchy to allow this action to happen.
The veins outer part have three layers of tissue, the tissue is thinner and less elastical than the arteries layers. The veins also have valves, the valves help in returning blood to the heart, they do this by stopping it going backwards.
The function of the veins is to transport blood to the heart and to also transport deoxygenated blood only, this isn't the case with the pulmonary vein. The veins need to be stronger and thicker to enable the pressure to be kept for the valves to work and for the blood to be transported back to the heart.
Our capillaries are very small blood vessels, they are around 5 - 20 micro metres (ivy-rose web) in diameter. There is capillaries in most of our organs and body tissues. The blood that flows in the capillaries comes from arterioles and are drawn out by venules. The walls aren't very thick, this is so things like water and glucose can be broken down quickly. The venules are even smaller vessels that take blood from the capillaries and to the veins. The function of the capillaries is to supply tissue with components which are carried by the blood. It also helps to get rid of waste from cells that are around, this is beside just moving blood around the body. The capillaries also help in the exchange of oxygen, carbon dioxide, water and salt between the body tissue and the blood. With the capillaries being so small the blood flows slowly, otherwise they wouldn't be able to take the pressure and with the blood flowing slowly it enables longer time for diffusion to take place.
Overall the arteries, veins and capillaries are all different in structure but they all aid in transporting blood around the body and in getting rid of waste.

Transportation Of Oxygen and Carbon Dioxide

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2.3 Explain The Transport Of Oxygen and Carbon Dioxide In The Blood
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The transport of oxygen and carbon dioxide is done via the cardiovascular system, capillaries, veins, arteries and vessels and also with help from red blood cells. To start with the blood is oxygenated in the lungs, the process of this taking place is as follows.
The right ventricle in the heart sends blood that is de - oxygenated to the lungs, in the lungs the carbon dioxide releases out of the blood and into the lungs and the oxygen that we breath in then combines with the haemoglobin in the blood, it then passes through the lung capillaries. From this the oxyhaemoglobin then goes to the heart this is done via way of the pulmonary vein, it then enters the systemic circulation by the aorta.
In our body tissue there is a low amount of oxygen, it also contains products that are waste, this being carbon dioxide. Due to the high amount of oxygen in the blood and the ow amount in the tissue, the high amount of carbon dioxide in the tissues breaks down into the blood plasma. Finally the blood from the tissues go back to the heart by way of the superior vena cava and the inferior vena cava, the process then stars again.
Overall there is several major parts of our system involved in this process and without each linking to each other via veins, capillaries, vessels and arteries the process wouldn't be able to take place.

Structure Of Red Blood Cells and Relation To Function

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2.2 Describe The Structure Of A Red Blood Cell and Explain How
It Relates To It's Function
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Red blood cells also known as erythrocytes play a large part in the body. There are around 4.5 - 5.8 million (ivy-rose web), of these cells in the body per micro litre of healthy blood and they last around 120 days. The purpose of red cells is to supply and transport oxygen and to also get rid of carbon dioxide. In order for this to happen the structure helps a lot.
The shape of a red blood cell is a biconcave disk, it as a sunken centre on both sides, this allows the cell to have a larger cell membrane surface which can be exposed to diffusing oxygen whilst it is travelling to the lungs. The structure also enables the cells to be more flexible when it comes to them passing through tight passages like the capillaries. This is because they are flexible, bendy and bounce about, the cells are around 7.8 micrometers (cell tissue suite web) in diameter.
The immature red blood cell contains a nucleus but the mature ones don't, they also don't have mitochondria or other organelles. However the red blood cells do contain hemoglobin, these are molecules of protein and iron. These help in the process of picking up oxygen and transporting it through the vessels of the lung sacs that are called alveoli.
Due to the red blood cells being carried around the body easily they are able to help keep their small energy needs by a form of anaerobic respiration and are also able to distribute oxygen effectively to areas that need it the most.
Red blood cells also have something called carbonic anhydrase, this is an enzyme, it makes carbon dioxide and water, it then catalyzes to make a molecule called bicarbonnate. This is able to dissolve a lot better than carbon dioxide in the fluid, meaning that a greater amount can be carried around without the need to be in the small red blood cells.
Overall without red blood cells the oxygen in our body wouldn't be able to circulate and we wouldn't be able to get rid of the carbon dioxide. There for they are a very important part of our blood and their structure helps a lot in the process they carry out.