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.