Combining Touch and Relaxation Skills for Cancer Care by Ann Carter

Author:Ann Carter
Language: eng
Format: epub
ISBN: 9780857013118
Publisher: Jessica Kingsley Publishers
Published: 2019-04-11T16:00:00+00:00

ANATOMY AND PHYSIOLOGY OF THE OLFACTORY (SMELL) SYSTEM

The nose has two functions – one is to warm and filter incoming air, and the other is to house the first part of the olfactory system. At the top of the nose, on each side, is an olfactory lobe that is about the size of an almond. These two small lobes are covered in single-cell sensory receptors that are attached to a sensory nerve. Aromas are detected when airborne aromatic molecules stimulate these sensory receptor cells. However, the sensory receptors are of different shapes, and in order to stimulate the sensory nerves, an aromatic molecule has to match the shape of a sensory receptor. Once there is a ‘lock and key’ connection, a nerve stimulus is created. If aromatic molecules cannot find a receptor cell with which they can ‘fit’, the aroma cannot be detected. The scope for detecting different odours in humans is extraordinary. Bushdid et al. (2014) report that the human nose can detect at least 1 trillion different odours. Interestingly, the olfactory cells are very sensitive and cease firing when over-stimulated.

The olfactory nerves lead from the olfactory lobes into part of the brain known as the olfactory bulb. The stimulus is then transmitted to the limbic system, which is the oldest part of the brain in evolutionary terms. Within the limbic system it is the amygdala and hippocampus that are responsible for the ‘smell’ memory and its link to the emotions.

Unless some form of physical impairment exists, most people have an ‘olfactory memory’. Betts (1996) has stated that the sense of smell is very successful at recalling emotions and memories, both positive and negative. If the recall of an aromatic memory is positive, it is likely to initiate pleasant emotions and images for the patient. If the recall of the aroma was not pleasing, or is associated with an unhappy event, the reverse, negative reaction is likely to be generated.

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