Every breath you take…
It’s likely the only time you think about breathing is when you can’t (!) for example, after a hard interval training session or if you ‘forget’ to breathe during a set of bench presses. Breathing is a purely involuntary process which happens on average 12 times per minute and is controlled by the autonomic nervous system.
In and out
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Inhalation (breathing in) occurs when the diaphragm and the intercostal muscles (these are found between the ribs and chest) contract to expand the rib cage – this 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 and is then 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 in plain English the heart. It has four chambers and is a muscle (cardiac muscle to be precise). It can be divided into two halves – the left side and the right side.
The left side of the heart is responsible for pumping 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 heart’s upper chambers 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. The back flow of blood is prevented by oneway valves called atrioventricular valves (AV valves for short). The average resting heart rate is 72 beats per minute. Our heart rhythm is controlled by our very own 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 speeds up to match the body’s demands.
“Blood vessels called veins take blood towards the heart whilst arteries take blood away”
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 two 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 is 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 hypertension 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 simple: exercise regularly, eat well, don’t smoke and get regular blood pressure checks. Do this and your heart and lungs will thank you by putting in years and years of trouble free service!