The Spleen
In the adult in good health under normal circumstances it cannot be felt. In general terms it consists of two parts, called the red and white pulp. The red pulp is concerned with the metabolism of red blood cells, while the white pulp is lymphoid tissue involved in the formation and regulation of the white cells responsible for our body's defences. It is in the spleen that white cells coming to the end of their days are broken down and their constituent parts recycled. This is one of the functions of the white pulp - and another is the storage and regeneration of platelets, the cells responsible for helping our blood to clot (see blood and circulation in the chest cavity section). The red pulp fulfils a similar function with regard to red blood cells; it patches up those which have suffered injury and returns them to the circulation, and removes those that are, as it were, beyond repair. It also acts as a reservoir for red blood cells. For many years physicians were puzzled about the function of the spleen, and it was thought that one function was to supply an instant source of blood and white cells in times of crisis. While there may be a hint of truth in this idea, the ongoing continuous day-to-day activities are much more important.
We can live without our spleens; many people do because they’ve had theirs removed either as a result of trauma (though it lies high up in the abdomen and underneath the ribs it is vulnerable to blows, and since it is fragile it readily ruptures. Being part of the circulation, when this happens it tends to bleed a lot, and therefore needs removal) or because it’s overactive, and removing too many red or white cells. Being without a spleen, however, makes us susceptible to certain infections, and precautions such as vaccination against pneumonia caused by the agent streptococcus pneumoniae are necessary.
|
