Elvis Presley died on August 16,1977. He was extremely overweight when he died.
ID: 3483205 • Letter: E
Question
Elvis Presley died on August 16,1977. He was extremely overweight when he died. He had a history of ingesting fatty foods including fried peanut butter and banana sandwiches. He also had a long list of prescription medications he was taking, some of which had cardiovascular or neurological effects. He died on the toilet while trying to defecate. The autopsy on Elvis Presley revealed that his rectum and colon were severely impacted with fecal material, but the cause of death was listed as cardiac arrhythmia. Which cranial nerve serves both the rectum and the heart? How could the normal function of that nerve have contributed to his death?
Explanation / Answer
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Vagus nerve
The vagus nerve , historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with parasympathetic control of the heart, lungs, and digestive tract. The vagus nerves are paired; however, they are normally referred to in the singular.
Function of vagus nerve
In the thorax and abdomen, the vagus nerve is the main parasympathetic outflow to the heart and gastro-intestinal organs.
The Heart
Cardiac branches arise in the thorax, conveying parasympathetic innervation to the sino-atrial and atrio-ventricular nodes of the heart .
These branches stimulate a reduction in the resting heart rate. They are constantly active, producing a rhythm of 60 – 80 beats per minute. If the vagus nerve was lesioned, the resting heart rate would be around 100 beats per minute.
Gastro-Intestinal System
The vagus nerve provides parasympathetic innervation to the majority of the abdominal organs. It sends branches to the oesophagus, stomach and most of the intestinal tract – up to the splenic flexure of the large colon.
The vagus nerve is to stimulate smooth muscle contraction and glandular secretions in these organs. For example, in the stomach, the vagus nerve increases the rate of gastric emptying, and stimulates acid production.
Case study solution
The vagus nerve (cranial nerve X) serves both the heart and the rectum.
Stimulation of the vagus can lead to cardiac arrhythmias. If Elvis had an impaction, that may have led to vagal nerve stimulation, an abnormal heart rhythm, and in combination with his already unhealthy diet, an infarction.
Some bacteria produce a toxin that causes a flaccid paralysis. Other bacteria produce a toxin that causes all of the skeletal muscles to contract at the same time.
A flaccid paralysis could be caused by a couple of mechanisms, most notably by the toxin molecule attaching to the Ca+ binding sites on the actin fibers. This would block the troponin/tropomyosin from being able to uncover the actin binding sites for the myosin heads. It could also block the ATP binding sites on the myosin heads. No ATP binding, no muscle contraction.
A tetanus paralysis could be caused by a toxin molecule blocking the action of the Ca+ pumps on the sarcoplasmic reticulum. This would lead to an excess of calcium in the muscle fibers, and so long as ATP is available, continuous contraction. It could also act as an acetylcholine synergist and continually stimulate the muscle cells through the motor end plates.
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