Gaseous Exchange 1.2

Blood flows into the lungs from around the body, it is carrying CO2 produced by respiration in the cells of the body CO2 passes from the blood into the avioli then breathed out of the body, O2 is breathed into the lungs it dissolves in the water lining, the alvioli from there it passes into the blood, blood carries O2 away from the lungs and every cell in the body.

The surface of alvioli is thin and moist it is like this is so that gases can pass through or be exchanged easily.

Alvioli are smaller than grains of salt there are about 300 million of these in our lungs, alviol have a very large surface area, plenty of room for gas exchange.

The surface of the alvioli are covered with capillaries, these are narrow blood vessels one cell thick, oxygen is passed from the alvioli into the blood stream which distributes it to the cell where it is used to unlock energy from the food, the blood carries carbon dioxide, a waste product from the oxygen filled food cells back to the capillaries, where it goes back through the walls of the avioli and is breathed out when you exhale as waste

Electrical Activity 3.3

The heart has a natural pacemaker that regulates the rate of the heart, it is in the upper part of the atrium and is a collection of specialised electrical cells known as the sino atrial (SA) node it generates a number of sparks per minute each spark travels across the electrical pathway and stimulates the muscle wall of the four chambers of the heart.

The SA node fires each electrical impulses that travel through the right and left atrium, this electrical activity cause the two upper chambers of the heart to contract, this electrical activity can be recorded as a P wave on a ECG, the electrical impulse then moves to an area called the AS (artio-ventricular) node, this node is above the ventricles, the electrical impulse is held for a brief period, This delay allows the right and left atrium to continue emptying the blood into the two ventricles, this delay is recorded as a PR interval, the AV node acts as a relay station delaying stimulation of the ventricles long enough to allow the two atrium to empty after this delay. The electrical impulse travels through both ventricles ( via specialised electrical pathways known as left and right bundle branches). The electrically stimulated ventricles contract and blood is pumped into the pulmonary artery and aorta, the electrical activity is recorded as QRS, the ventricles then recover and the electrical stimulation generates an ST segment and T wave on the ECG.

Exchanging oxygen and carbon dioxide 2.3

The primary function of the respiratory system is to exchange oxygen and carbon dioxide. when we breathe in the oxygen goes into our lungs and travels to the aveoli, in the layers of cells that line the aveoli are capillaries these are very small, they carry the oxygen we have breathed in passes into the capillaries, when this happens the unwanted carbon dioxide passes from the blood into the aveoli and then we expel this when we breathe out.
The oxygen rich blood which we have just breathed in travels from our lungs through the pulmonary veins and travels to the left side of the heart, from here it pumps it around the body.
The carbon dioxide rich blood then returns to the right side of the heart, through two large veins called the vena cava, when this happens the blood is pumped through the pulmonary artery back into the lungs. then the cycle begins again.
For all this to take place three processes are needed for the transfer of oxygen from the outside air to the blood in order for this to work in the system, they are known as vetilation, diffusion and perfusion.
Ventilation- is when we breathe in and oxygen goes into the lungs
Diffusion- is the spontaneous movement of the gases and this is done without any effort from the body
Perfusion- is when the cardiovascular system pumps the blood through the lungs

Effects of smoking on the body system 6.2

Nicotine in cigarettes is addictive and therefore is harmful and because of the nicotine addiction they continue to smoke, cigarettes contain well over 1000 different chemicals which can interfere with the body and put it under constant pressure.
Tar is also found in cigarettes, it is sticky and brown causes the discolouring of teeth, fingers and the lining of the lungs, the tar contains carcinogen benzoapyrene and this is linked with tumours in the lungs.
Carbon monoxide is also found in cigarettes, this is odourless and a type of gas, this gas can be fatal in large quantities as it takes oxygen from the blood, carbon monoxide binds with the haemoglobin better than oxygen and means less oxygen is reaching the heart, brain, muscles or other organs that require it, this then allows damage to occur.
Hydrogen cyanide is also found in cigarettes this affects the cilia hairs, these help clean the airways and remove unwanted substances and foreign bodies, hydrogen cyanide stops the lungs from doing this and allows the poisonous gas to build up in the lungs, there is a link to this also affecting the heart, which in turn can lead to heart disease and stroke.
Cigarettes also contain arsenic and lead these can affect passive smokers, they cause damage to the trachea and larynx it also damages the air sacs in the lungs and the lungs take years to recover.

Redistributing blood during exercise 4.2

The vascular system can redistribute blood to those tissues with the greatest demand and away from areas that have less demand for oxygen, at rest 15-20% of circulating blood supplies skeletal muscles, during exercise this increases to 80-85% of cardiac output blood is taken away from major organs like the kidneys, liver, stomach etc, it is then redirected to the skin to promote heat loss following exercise the heart rate remains elevated before slowly recovering to a resting level.

Exercise places an increased demand on the cardiovascular system, oxygen demand by the muscle increases sharply, metabolic processes speed up and move waste (CO2) is created more nutrients are used and body temperature rises to preform as effectively as possible the cardiovascular system must regulate these changes and meet the bodies increasing demands.

The resting heart beats approximately 60-80 beats per minute in a adult, increasing to 110-130 beats during intense exercise.

Regulating Ventilation and Pulse rates 4.1

The blood pressure is normally measured via a sphygmomanometer blood pressure varies between systolic and diastolic pressure, systolic pressure is peak pressure in the arteries which occurs near the end of the cardiac cycle when ventricles are contracting, diastolic pressure is minimum pressure in the arteries which occurs near the beginning of the cardiac cycle, when ventricles are filled with blood an example of normal measured values for a resting healthy adult is 120 mmHg systolic and 80mmHg diastolic 120/80.
Blood pressure is a force exerted by circulating blood on the walls of blood vessels and is one of the principle vital signs during each heart beat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure, the mean blood pressure due to pumping of the heart and resistance blood vessels, decrease as the circulating blood moves away from the heart through arteries, the greatest decrease is in the small arteries and arterioles and continues to decrease as the blood flows through the capillaries and back to the heart through veins.
Blood pressure refers to the pressure measured on a persons upper arm, it is measured at the elbow at the brachial artery, this is the upper arms major blood vessel that carries blood away from the heart.
We can measure the pulse manually at the wrist this is done by placing two fingers and counting the beats per minute, other places we can find a pulse are the neck, the tops of our legs and foot. the reason we check the pulse is to detect the blood flow through the arteries, an abnormal reading could tell us that they are suufering from a blockage, which could eventually lead to a heart attack or stroke.
Our body's temperature needs to be kept at a certain level for the body to run efficiently. the bodies temperature can rise and fall due to the activities we are doing on a daily basis. this can be due to physical exercise, it is important that after our bodies have endured exercise, it goes back to normal, this is called homeostasis this allows the body to remain at the correct level. we take our temperature with a thermometer, this either place in the mouth or electronically in the ear this measures the core temperature,and usually used in a hospital. the thermometers placed in our mouths contains mercury, keeping a regular check on a persons temperature enables us to see if someones health is deteriorating.
We measure someones respiratory rate by watching the chest rise and fall, we count how many times this happens in a minute, this is best done without the patient knowing as they may try to breathe faster or slower. this helps us to find out if they are suffering from illnesses like Asthma, chronic obstructive pulmonary disease (COPD) and Emphysema. a normal reading is between 8-17 breathes per minute, anything higher or lower than this can indicate a persons deterioration.
Another way to find out if the lungs are working correctly is to take a peak flow reading, it measures the speed at which we exhale this is normally used in asthmatics to see how wide their bronchial tubes are, this read by blowing into a peak flow meter this is a long tube. we take the average reading from three blows and can indicate a problem when readings are to low or to high, a low reading in an asthmatic could indicate an attack and they need to use prescribed inhalers.
Chemorectors in the carotid arteries and aorta detect the levels of carbon dioxide in the blood, they monitor the concentration of hydrogen ions in the blood which increase the ph of the blood as a direct result of the carbon dioxide concentration the apneustic centre sends a nervous impulse to the intercostal muscles and diaghram via the phrenic nerve to increase breathing rates.

Cardiac Output 3.4

Cardiac output is the volume of blood pumped by the heart per min ( mL blood/min) cardiac output is a function of heart rate and stroke volume, the heart rate is simply the number of beats per minute, the stroke volume is the volume of blood in millitres (mL) pumped out of the heart with each beat.

Q=SVxHR (Q= cardiac output) ( SV=stroke volume) (HR=heart rate)

An average person has a resting heart rate of 70 beats per min and a resting stroke volume of 70mL per beat.

the total volume of blood in circulatory system of a average person is approx 5 litres (5000mL)

We measure a persons heart rate by counting the beats minute of the pulse. a pulse is where the vein crosses over a bone, for example in the wrist.

measuring cardiac output is very important as it allows us to know how healthy a heart is, if allows us to know if the heart is under stress or pressure, like heart failure.

The heart also has its own pacemaker which is connected to the SA node at the top of the heart.

Smoking and Lung cancer and heart disease 6.1

Smoking is perhaps the most potent factor for CHD in particular, cigarette smoke has approx 1,000 different chemicals and 60 are identified as being toxic, these toxins float within the blood and accelerate the hardening of the arteries, putting people at a greater risk of a heart attack and ultimately death - heart failure. cigarettes also contain a substance called nicotine that stimulates the heart to produce adrenaline, this causes the heart rate and blood pressure to increase and the heart works harder.
Smoking decreases the oxygen supply the heart and increases carbon dioxide and increases the possibility of a blood clot, increasing the blood pressure and heart rate as well as damage to the cells that line up on the coronary arteries as well as other blood vessels, CO2 is a poisonous gas that irreversibility combines with the haemoglobin in your red blood cells leaving you breathless.
CHD is a disease of the coronary arteries which branch from the aorta to supply the heart muscle, if atherosclerosis of these vessels occur ,then the heart has to work harder and blood pressure rises, this makes it difficult for the heart to receive extra nutrients and oxygen it requires, smoking increases the concentration of blood cholesterol which is a risk factor, risks increases with age and more men than women are at risk.
There is a clear link between smoking and coronary heart disease, however smoking remains a wide spread habit many smokers choose to ignore the link between smoking and coronary heart disease.

Tar is a sticky brown substance made up of many chemicals many of which are carcinogen (cancer producing) because tar is sticky it tends to accumulate and clog it stops the cilia from moving and allowing the build up of mucus, but persistent coughing can damage the delicate aveoli resulting in emphysema, this is a serious and chronic condition, tar builds up in the aveoli preventing gas exchange.
some of the irritants in smoke are dust and soot, other chemicals are ammonia and hydrogen cyanide, they all irritate the delicate mucus membranes lining the air passages this results in bronchitis (inflammation of the tube lining) this in turn can lead to pneumonia, some of the irritant chemicals are known to cause lung cancer. The heat from drawing on a cigarette burns away the cilia lining the trachea. Cancer is a disease and is formed by cell growth which can spread rapidly, lung cancer is when the uncontrolled cell begins in either lung, the usually healthy tissue is contaminated with the cancerous cells and they divide and form lumps known as tumours, the tumour grow and interfere with the function of the lungs providing oxygen into the blood stream. Lung cancer is the second most common cause of death in the UK.

Diet, Blood Pressure and 5.2

Peoples lifestyles and work pressures today means we can have bad diets and we don't tend to think about what we eat, we eat on the go and our bodies don't have a chance to digest the food properly.
We eat take aways and ready prepared meals many of the these contain saturated fats and sugars, we don't think of the huge risks when eating them, there have been lots of studies that suggest there is a link to high blood pressure and cholesterol this will eventually become heart disease.
If our diet contains loads of fat we become overweight or obese and these can lead to heart disease and heart attacks, these is because our arteries become clogged with fatty deposits and less blood flows around the body and the heart has to work harder, it finds it hard to cope with the demands made upon it.
Cholesterol is transported around the body in our blood stream, it is made up of fats and protein called lipoprotein. we need cholesterol in our body we use it in our digestive system to neutralise fats. the liver converts the high intake of fats, to much fat in our system raises our cholesterol and sticks to the side of the blood vessels causing plaque to build up, two thirds of adults have high cholesterol and this increases the risk of cardiovascular disease and angina.
If the fatty deposits break off and floats around the blood stream, one of the arteries can become blocked and cause a clot leading to a stroke or heart failure, doctors will prescibe statins to reduce the effects of cholesterol.

Circulatory Disease 5.1

The arteries have three layers that surround the lumen which becomes abraded and thinned in circulatory disease such as atherosclerosis, the middle layer is called the tunica media this becomes enlarged as cholesterol is sequested as the body tries to recover from damage, this layer is also the muscle layer that allows the artery to stretch and recoil around a pulse of blood leaving the heart during systole, this ability is reduced as the muscle deteriorates and finally the outer layer (tunica externa) loses it elastic properties, the overall effect is instead of a circular cross section you get a transverse section that is floppy.

This then severely restricts the flow of oxygen carrying blood to the myocardium.

An individual may develop a rupture of an atheromatous plaque at any stage this acute rupture may lead to an acute myocardial infarction (heart attack).

Structure of Arteries Veins and Capillaries 3.1

Arteries



Arteries are blood vessels that carry blood away from the heart, they vary in size depending on where they are in the body and how far away from the heart they are, the structure of the artery is three layers of tissue

Tunica Adventria - outer fiberous layer

Tunica Media - middle layer of smooth muscle and tissue

Tunica Intima - inner lining of endothelium

In the large arteries you will find tunica media consists of more elastic tissue and less smooth muscle, to allow them to stretch more each time the heart pumps blood into them, they then return to their original shape, they push the flow of blood when the ventricles are relaxed and the heart is refilling, the smaller the arteries get the more smooth muscle they contain they cannot stretch as much as the larger arteries, the smaller arteries are known as arterioles.



Veins



Veins are blood vessels that carry deoxygenated blood back to the heart, the walls are thinner than the arteries, but they still have the same three layers, they have less elastic tissue and muscle, some veins have valves (these can be found in the legs) to ensure the flow of blood travels to the heart and not backwards, the smaller veins that are furthest away from the heart are called venules, the blood pressure is lower in the veins compared to that in the arteries so no pulse can be felt.

Capillaries

Capillaries are the smallest of the blood vessels in the body, the structure consists of one layer of endotheliac cells, water and other small molecules can push through this wall, capillaries act as a link between the arteries and veins, they have no valves or pulse.

Describe the structure of a Red Blood cell 2.2

Red blood cells have a unique apperance they look like doughnuts because they are thinner in the centre and thicker around the edges, they are flexible wjth the ability to twist and bend through blood vessels, red blood cells are about 1/25,000 of an inch in size, they are made in red bone marrow, in infants every bone produces red blood cells but in an adult red blood cells are produced in the thoracic bones, vertebrae, cranial bones and the ends of the femur and humerus bones, red blood cells live for approx 120 days they have a high surface area to allow maximum diffusion of gases.
Red blood cells make up 40% of the bloods volume they contain haemoglobin a protein that gives blood its red color and enables it to carry oxygen from the lungs and deliver it to all body tissues, when the number of red blood cells is to low anemia) it carries less oxygen and we feel fatigued and waek, when the red blood cells are to high (polycythemia) blood becomes too thick which causes the blod to clot and increases the risk of heart attack and strokes.

Components of Plasma 2.1

Plasma is the liquid component of blood in which the red blood cells, white blood cells and platelets are suspended, it constitutes more than half of the blood volume and consists mostly of water, dissolved salts (electrolytes) and proteins, the major protein in plasma is albumin, albumin helps keep fluid from leaking out of vessels and into tissues, albumin binds and carries substances like hormones and certain drugs, other proteins in plasma include antibodies (immumoglobulin) which actively defend the body against viruses, bacteria and cancer cells and clotting factors which control bleeding.
Plasma has many functions it acts as a reservior that can replenish insufficent water or absorb excess water from tissues, plasma also prevents blood vessels from collapsing and clogging and help maintain blood pressure and circulation throughout the body, plasma circulation also plays a role in regulating body temperture by carrying heat generated in core body tissues through areas that lose heat more readily, like the head, arms and legs.

Describe the role of the Nervous System 1.3

The nervous system has two parts the sympathetic and parasympathetic they both supply the same organs but cause opposite effects, this is because the neuro transmitters are different.
The sympathetic are called the "fight or flight" system, they prepare the body for emergencies, it shuts down the blood supply to the muscles and increases blood pressure, heart rate and breathing which tends to allows us to cope with stressful situations.
The parasympathetic nervous system maintains and refreshes energy it directs blood to the digestive tract and makes us actively digest food. it also maintains Blood pressure heart rate and breathing rate.
Breathing is an involuntary process (we don't think about doing it) like many involuntary processes it is controlled by the medulla oblongata which is situated in the brain and its nerves are part of the autonomic nervous system.
The respiratory centre transmits regular impulses to the diaphragm intercostal muscles to cause inhalation and sends signals to the respiratory centre to cause exhalation, the negative feedback system prevents damage to the lungs.
Ventilation is also under voluntary control from the cortex, it allows you to hold your breath for a few seconds but if you hold your breath to long carbon dioxide builds up in the blood to a dangerous level, it forces us to exhale and gasp for breath.

Describe the structure of the heart and explain the cardiac cycle 3.2

The heart is a pump made of four chambers, it is situated more to the left in the chest. it is a hollow muscular organ about the size of a fist. it beats constantly from birth to death and works harder than any other muscle in the body.
The heart is divided into two lobes, this is to stop oxygen rich blood from mixing with blood than contains carbon dioxide.
the heart and blood vessels comprise the cardio vascular system which circulates blood and oxygen around the body, the heart pumps around 5 litres of blood a minute and beats 100,000 times a day, it does this constantly and automatically.
Blood that contains CO2 returns to the heart after circulating around the body, the right side of the heart consists of the right atrium and right ventricle these collects and pumps the blood through the pulmonary arteries the lungs refresh the blood with a new supply of O2. Oxygen rich blood enters the left side of the heart the left atrium and left ventricle and is pumped through the aorta to the body, to supply the tissues with oxygen.
four valves in the heart keeps the blood moving around the body the correct way the tricusid valve, mistral valve pulmonary and aortic valve, they open only one way each valve opens and closes once per heart beat, the heart relaxes and contracts. the contraction is called systole and relaxed is diastole, in systole the right ventricle contracts and forces blood into the lungs and body the right ventricle contracts slightly before the left ventricle allowing the blood out of the atrium (LUB) into the ventricular then the artial ventricle node transmits an impulse to each ventricle making it contract. the ventricles then relax diastole and are filled with blood from the upper chambers (DUB), into the left and right atrium, the cycle then repeats.
the heart also receives blood from the coronary arteries these are on the surface of the heart and branch into smaller capillaries, the heart also has electrical wiring called the sinoatrial node (SA Node) to keep it beating, electrical impulses begin high in the right atrium and travel through specialized pathways to the ventricles telling the heart to pump this helps keep the heart beating in a normal regular rhythm this in turn keeps blood circulating, the continous exchange of oxygen rich blood and blood with carbon dioxide is what keeps us alive.

Structure of the respiratory system 1.1

We breath through our nose this as a mucus membrane, cilia and mucus lines the walls of the nose to trap dust and pathogens in the air as it passes through the nasal cavity and helps warm and humidify the air.
The air then enters the mouth this is made up of bone, muscle and tissue, saliva that contains enzymes to break down particles is found here, the mouth enables us to inhale and exhale air.
The larynx is next this is lined with epithelial tissue and is only one cell thick, it also includes the epiglottis, thyroid, the larynx shares a passage way with the digestive system, the larynx protects the trachea from foreign bodies and particles and to assist in warming and humidifying air as it passes through.
After the larynx the air goes into the lungs, the lungs consists of 90% air and 10% hard tissue. the right lungs as three lobes and the left lung as two lobes this is because the heart is more to the left side of the chest, the lungs are in the chest and are large organs. they take up most of the room in the chest, the ribcage protects the lungs, the average length of a lung is between 10" and 12" the role of the lungs is very important they allow the air (O2) that we have breathed in to be transported into the blood stream, which is then carried around the body to cells and helps get rid of waste gases carbon dioxide (CO2).
The oxygen then goes into the bronchus, these are attached to both lungs, they are small tubes which have smaller tubes attached called bronchioles, the inside walls of the bronchioles are lined with cilated columnar mucus membrane, the oxygen is transported to these via the aveoli that are connected to the bronchus, aveoli are very small sacs that are filled with air and each set of lungs contains approx 600 million of theses spongy sacs and are surrounded with capillaries, the function of the aveoli is to diffuse the inhaled oxygen through the capillaries and into the arterial blood. whilst this is going on the waste rich blood comes from the veins letting the CO2 into the aveoli, the CO2 goes the same way out when we exhale.
The diaphragm is large and dome shaped, it is a sheet of muscle and lies across the bottom of the chest cavity. the job of the diaphragm is to assist in the pumping out CO2 from the lungs and drawing in oxygen. the diaphragm works by contracting and relaxing, when we breathe in this is when it contracts allowing oxygen to be drawn in and when we breathe out it relaxes allowing carbon dioxide to be let out of the lungs.
The oropharynx is a tube that goes from the mouth separated by the palate then joins the pharynx leading to the trachea, it works with the mouth where air is inhaled carrying it from the mouth down to the oesophagus and the air then goes into the larynx trachea and lungs. the trachea is about 10" long and 2-5 Cm's in diameter it is an incomplete cartilage and extends from the larynx to the carina. the function of the trachea is to keep the airways open, this is helped by incomplete catilage rings, the rings enable the changes to happen when air is passed through it, therefore preventing a breakdown in the process of respiration.