1. R.D. arrives in the emergency room feeling dizzy. He says he has difficulty standing up because he feels like fainting. Upon examination his blood pressure is found to be 85/60 mmHg. His blood pressure is too low. What type of drug should the physician prescribe to improve R.D.'s condition?
A sympatholytic agent such as a adrenergic-blocking agent
A sympathomimetic agent such as an adrenergic-agonist
2. Patient E.S. visits her physician and complains of problems with bladder control. She states that she frequently experiences urinating at inappropriate times. She seems to have lost control of bladder function. The physician determines that she sufffers from spasticity or involuntary contractions. What should be prescribed?
3. A friend of yours is involved in an accident. After the accident you notice that the pupils of his eyes are always constricted, his face flushed and there is never sweat on his brow, even on the hottest Houston summer days. What is the explanation for this condition.
The sacral segments of his spinal cord were damaged
The cervical or upper thoracic spinal cord was damaged
The lumbar spinal cord was damaged
This is incorrect. Factors that contribute to blood pressure include heart rate, cardiac output and resistance to blood flow (size of the blood vessels). All of these are controlled by the autonomic nervous system. Activation of the sympathetic nervous system results in an increase in all those contributing factors and, thus, increases blood pressure. A sympatholytic agent, such as a adrenergic-blocker, would prevent the sympathetic nervous system from exerting its actions on the heart and blood pressure.In fact, it could result in a further fall in blood pressure.
Correct! Because blood pressure is determined by contributions from heart rate, cardiac output and resistance to flow you would want to increase their contributions. These contributing factors are controlled by the autonomic nervous system. The sympathetic nervous system causes an increase in these factors. So, increasing heart rate, blood pressure and resistance results in an increase in blood pressure. That's why an agent that "minics" the actions of the sympathetic nervous system is the correct choice.
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Correct! Good job. You would want to prescribe an anticholinergic agent. The bladder is controlled by the autonomic nervous system. Postganglionic parasympathetic neurons innervate the wall of the bladder (detrusor muscle, trigone and sphincter). Stimulation results in contraction of the muscle and relaxation of the sphincter resulting in urination. An anticholinergic drug should reduce or eliminate the involuntary contractions.
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Sorry, this is incorrect. The bladder is controlled by a balance of activity in the autonomic nervous system. In the case of the bladder the sympathetic division of the autonomic nervous system innervates the bladder wall (detrusor muscle) and exerts an inhibitory influence. This inhibition can be overridden as a result of a full bladder. Blocking sympathetic influences would not alleviate the problem of involuntary contractions or a spastic bladder.
This is incorrect. The sacral segments of the spinal cord give rise to fibers of the parasympathetic nervous system. The parasympathetic nervous system does not innervate sweat glands or the blood vessels. Parasympathetic innervation to the eye will cause pupillary constriction when activated.
Excellent! The cervical and upper thoracic segments of the spinal cord give rise to sympathetic fibers that innervate the head. Among the actions of the sympathetic innervation to the head include stimulation of sweat glands, contriction of the cutaneous blood vessels and dilation of the pupils of the eye. Loss of this innervation is called Horner's Syndrome (your friend's injury) and results in: the inabilility to stimuate sweat glands; loss of tonic vasoconstrictor actions on the cutaneous blood vessels resulting in vasodilation and the flushed look; loss of dilating actions on the pupil of the eye.
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Sorry. You are right in determining that the lumbar region of the spinal cord gives rise to sympathetic fibers. However, these do not innervate the region of the head.