Have you ever stopped to consider the vital, ongoing functions of our body that tick away for us daily? We do not have to consciously mediate them; they moderate themselves outside the realm of our attention. Yet – without them – we would cease to live. The circulatory system is one of these.
Also dubbed the cardiovascular system or the vascular system, the circulatory system is an organ system that transports oxygen, nutrients and hormones within the blood via blood vessels around the body – vital components needed for homeostasis. Energy, growth and repair essentials are transported via its intricately designed network. Products of metabolism and respiration are also removed via this system.
The cardiovascular system is comprised of: The heart Let’s just take a moment to appreciate this awe-inspiring organ. Understanding it better can really broaden the perspective on its integral part in homeostasis in the body. Around the size of a fist, the heart beats around 100,000 times per day, pumping approximately eight pints of blood around the body, 24 hours a day. Here’s a run-down of its ongoing job sheet, structure and how it continues to go and go and go. • It pumps deoxygenated blood to the lungs where carbon dioxide (a waste product of metabolism) is unloaded (via the all-important alveoli) and oxygen is taken up. • The heart consists of four chambers: the two atria (upper chambers that receive blood) and ventricles (lower chambers that discharge blood). A wall of tissue separates the left and right sides. Each heartbeat has two parts: • diastole – atria contract and expel blood to relaxed ventricles • systole – ventricular contraction expels blood from the heart; atria relax, filling with blood again. (When taking blood pressure, this will be the TOP number indicating the pressure exerted by the blood on the artery walls.)Ultimately, heartbeat is maintained and influenced by the medulla. Located in the brainstem above the spinal cord, the medulla contains cell bodies for the autonomic nervous system – the sympathetic and parasympathetic nervous system. Heartbeat is directly controlled by our ‘fight/flight’ (sympathetic) nervous system and the vagus nerve. Sympathetic nerves leave the medulla, travelling down the spinal cord where they connect (synapse) with relatively short fibres that then synapse with the sympathetic ganglia. Fibres from the ganglia then travel to the heart and vasculature where they synapse and influence these structures. The parasympathetic nerves (vagus nerves, cranial nerve X. the ‘rest/digest’ system) exit the medulla as long fibres that synapse with short fibres within the heart or vascular tissue. The activity of the medullary neurons is modulated by input from sensors within the body and from other brain regions. Arteries These are muscular-lined blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. The largest and strongest of these is the aorta connected to the left ventricle. It receives blood immediately from the heart. The aorta branches into a network of smaller arteries that extend throughout the body. These smaller branches are arterioles (small branch of an artery leading to a capillary) and capillaries (connect arterioles to venules – the smallest of veins. Small enough to penetrate bodily tissues, they allow oxygen, waste products and nutrients to be exchanged between the tissues and the blood.). The pulmonary arteries are quite unique though. They carry deoxygenated blood from the right ventricle to the lungs under low pressure. Veins Veins are blood vessels that transport deoxygenated blood back from the organs and tissues of the body to the heart. Some contain valves to prevent backflow of blood. They often parallel the arteries of the body and possess similar names. Superficial veins reside in the layers just beneath the surface of the skin. Deep veins are located in and around muscles and bones. These veins are very important in return of blood to the heart – 90 per cent or so! Musculatures surround them to facilitate venous return flow by compressing and releasing during our movement. Short veins connect the superficial and deep veins.Blood Made mostly of plasma (and technically a tissue, being 80 per cent water and 20 per cent solid), blood contains three types of cells that circulate within it: • Platelets enable blood clotting, preventing blood from flowing from broken arteries, veins or capillaries. • Red blood cells carry oxygen and are the most plentiful. Most adults have approximately 35 trillion of them. We produce 2.4 billion red blood cells per second. They have a life span of 120 days. • White blood cells fight off infection and are vital to the immune system; they increase in number during such a process. They are also called leukocytes.
How can osteopathic technique assist the circulatory system? With appreciation of the circulatory system’s structure and function, osteopathic practitioners can use manual techniques in an effort to assist the homeostatic function of the cardiovascular system. In the presence of particular conditions, this may provide some relief of signs or symptoms. Muscle Energy Technique (MET) One of my personal favourites to use in the osteopathic treatment setting, this technique predominantly minimises discomfort for patients. The neural effects of muscular contraction are utilised to reduce muscle tightness (hypertonicity). Post isometric relaxation (i.e. relaxing after having contracted the affected muscle) is used to reduce tension in chronically tight and/or shortened musculature. Reciprocal inhibition is used to advantage in acute cases in application of this technique style. Remember the deep veins and how muscles assist venous return via their contraction? This is where MET really assists the circulatory system. Using MET (particularly in the lower limb) can help patients presenting with: • Fluid accumulation (secondary to congestive cardiac failure, portal hypertension results in increased intravascular pressure and interstitial fluid accumulation in tissues) • Muscular tear/joint sprain recovery (facilitate oedema return via venous system). Effleurage A French term meaning ‘to skim’ or ‘to touch lightly on’, effleurage is a gentle soft tissue massage style frequently seen in Swedish massage to promote relaxation and in the initial part of traditional massage treatments to ‘warm up’ the areas where techniques are to be applied. Its mild yet repetitive and frictional nature promotes increased blood flow to the area of application. The soothing sweeping strokes can also be performed from an inferior to superior, lateral to medial direction along the peripheries to encourage lymphatic and venous return. This can be a beneficial technique for patients with lymphoedema or with subacute joint sprain. Longitudinal massage can also be applied to benefit hypertonic tissue and emphasise venous return. Cross-fibre massage Similar to effleurage, cross-fibre massage involves applying pressure deeper and perpendicular to the direction of muscular fibres. This technique promotes increased blood flow in the superficial tissue. This technique can provide relief to chronic ischemic fatigue that is seen in patients who are sitting for long periods during the day at a desk. Capillaries typically pierce muscular tissue to give it blood supply. Overall, the human body is not designed to be sitting static for long periods; it benefits well during more dynamic activity due to increased blood flow! When required to maintain a position for an extended period (45 minutes to 1 hour plus), muscles become more hypertonic to hold this posture, as they fatigue. They essentially begin to cut off that capillary perfusion. HVLA High velocity low amplitude (often termed ‘cracking’ techniques) results in a mild neurovascular reaction after application. When applied to spinal and peripheral joints, HVLA can bring reparative factors within the blood to these locations that are part of the healing process. If you have a condition involving the cardiovascular or vascular system, please consult your osteopath prior to treatment. Take care everyone, Lenore
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