Every breath you take…
It’s likely the only time you think about breathing is when you can’t (!) e.g. after a hard interval training session or when forgetting to breathe during a set of bench press. Breathing is a purely involuntary process which happens on average 12 times per minute and is controlled by the autonomic nervous system which ensures our bodies get a steady supply of oxygen 24/4. Chemoreceptors in the blood vessels detect levels of carbon dioxide in the blood and concentrations reach a critical level we breathe. Inhalation (breathing in) occurs when the diaphragm and intercostals muscles contract to expand the rib cage which results in air being drawn into our lungs – just like a set of bellows. Air passes down the pharynx, larynx, trachea, bronchus, bronchi and bronchioles before reaching the alveoli where the oxygen diffuses into the blood via microscopic blood vessels called capillaries to then be circulated around the body. Exhalation (breathing out) is the action of the diaphragm and intercostals relaxing back into their original resting position which drives air out of the lungs. We can also use the muscles of the abdomen to “squeeze” air out when we need to breathe out more forcefully than usual.
The heart of the matter…
Just like your car has a fuel pump, we have a blood pump called the myocardium or heart in English! The heart is a 4 chambered muscle which can be divided into 2 halves – the left side and the right side. The left side of the heart is responsible for the pumping of oxygenated blood around the body and the right hand side pumps deoxygenated blood. When describing the heart, left and right are reversed as if you were describing the heart of someone facing you. The upper chambers of the heart are the receiving chambers and are called the atria (atrium = 1) and the lower chambers of the heart are the ejecting chambers and are called ventricles.
Blood vessels called veins take blood towards the heart whilst arteries take blood away. Blood flows from atrium to ventricle and the back flow of blood is prevented by one-way valves called atrioventricular valves (AV valves for short). The average resting heart rate is 72 beats per minute and our heart rhythm is controlled by our biological pacemaker – a bundle of nerves called the sinoatrial node or SAN. The heart, like the lungs, is an involuntary organ under the control of the autonomic nervous system which responds to the demands of the body. If more oxygen is required, greater energy expenditure is necessary or if we are feeling stressed, the heart will speed up to match the body’s demands.
Blood pressure
Blood pressure describes the force that the blood exerts against the artery walls and is a major indicator of health. The harder your heart beats, the higher the blood volume or the greater the resistance to blood flow the higher the blood pressure will be. Your blood pressure is measured in millimetres of mercury (mmHg) and is divided into 2 readings – an upper figure called systolic blood pressure and a lower figure called diastolic blood pressure. Systolic blood pressure describes blood pressure as the heart is contracting (beating) whilst diastolic blood pressure describes blood pressure when the heart as relaxed. Blood pressure is measured using a sphygmomanometer or blood pressure cuff and the accepted norm is 140/80 mmHg. Readings below this are referred to as hypotension and anything above is hypertension and may need medical supervision. Hypertension puts significant stress on organs such as the kidneys and the heart and has numerous causes. Stress, excess dietary salt, sedentary lifestyle, smoking, obesity, blocked arteries and excess fluid retention can all contribute to elevated blood pressure but the good news is that exercise and a healthy diet can go a long way to keeping blood pressure levels normal. Because hyper tension has no external symptoms, it’s very important to include blood pressure checks on a regular basis to avoid any problems.
Keeping the cardiorespiratory system in good shape is as simple as exercising regularly, eating well, avoiding smoking and getting regular blood pressure checks. Keep following the advice in Ultrafit magazine and your heart and lungs should provide you with many years of trouble free service!
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