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What is a Hemorrhoid?
What is a Hemorrhoid?
Hemorrhoids are masses of tissue within the anal canal that contain blood vessels. They also contain the supporting tissues made up of muscle fibers. The anal canal is classified as the last four centimeters between the rectum and the anus. The anus is the opening of the anal canal.
Hemorrhoids are not abnormal, though most people think this. They are present in everyone, but the problem occurs when these hemorrhoidal cushions enlarge. When these hemorrhoidal cushions enlarge, the can cause problems and are then considered abnormal or a disease.
Hemorrhoids become a problem in 4% of the general population. They are not partial to men or women, and normally prevale between 45 and 65 years of age.
Anatomy of Hemorrhoids
The blood vessels that supply blood to the anal canal descend from the rectum. The rectum is above the anal canal. This area contains a network of arteries that make the conditions perfect for hemorrhoids. This is also the reason that blood from hemorrhoids is a bright red, because it is fresh arterial blood rather than venous blood. This also is why bleeding from hemorrhoids can be very severe. The blood vessels that supply blood to the hemorrhoidal vessels pass through the tissue around the hemorrhoidal cushions.
The anal veins drain blood away from the canal and hemorrhoids. The veins drain in two directions; one drains upwards into the rectum, and the other downward through the skin surrounding the anus. The dentate line differentiates the transition from anoderm (anal skin) to the rectum lining.
Formation of Hemorrhoids
If the hemorrhoid forms at the top of the anal canal, or inside the anus, it is considered an internal hemorrhoid. If it originates near the anus in the anal canal, it is considered an external hemorrhoid. Technically, the difference between an internal and external hemorrhoid is if it is above or below the dentate line.
During the formation of internal hemorrhoids, the vessels of the hemorrhoidal cushions swell along with the supporting tissues. When these bulging cushions protrude into the anal canal, problems arise. No one knows exactly how external hemorrhoids form.
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What Causes Hemorrhoids?
No one really knows what exactly causes hemorrhoids to enlarge. However, there are a couple of theories that we will go over here.
Some of theses theories include an inadequate intake of fiber, prolonged sitting on the toilet, and chronic constipation. There is not very much experimental support to back up any of these theories. Pregnancy is a common cause of enlarged hemorrhoids, though the actual reason is not known. Another cause can be enlarged tumors in the pelvis. These tumors can cut off the veins draining the anal canal and cause enlarged hemorrhoids.
Another theory takes into consideration the pulling force of passing a stool. This would particularly be the case with a hard stool passing through the anal canal that drags the hemorrhoidal cushions downward. This relates to having an inadequate fiber intake.
Hemorrhoids are known to be more prevalent in the 45 to 65 age group. Another theory suggests that with age, or an aggravating condition, the supporting tissues that are responible for tying the hemorrhoids to the underlying muscle deteriorates. Over time this allows the hemorrhoidal tissue to slide down into the anal canal.
It is a physiological fact that enlarged hemorrhoids are associated with elevated pressure in the anal sphincter, the muscle surrounding the anal canal, and the hemorrhoids. The anal sphincter is the muscle area that allows us to control our bowel movements. We don’t know if the elevated pressure precedes the enlarged hemorrhoids, or if the enlarged hemorrhoids causes the elevated pressure. If it precedes the hemorrhoids, perhaps increased pressure during a bowel movement in the anal canal is the cause. This would greatly increase the pulling force of the stool as the theory states above.
Some also believe that there is a genetic predisposition for hemorrhoids. This predisposition could be weak rectal vein walls or valves. Others also believe that humans are more prone to hemorrhoids simply becuase of our erect posture. This naturally sends more blood to the rectal area making it easier for them to form.
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