Multiple sclerosis (MS) is one of the better known diseases resulting from demyelination of axons (in MS, only CNS axons are affected). Some of the earliest symptoms of the disease are difficulty in focusing the eyes, such as in reading, and difficulty in maintaining balance, and frequently not being able to make adjustments in posture to avoid falling. How do these symptoms "fit" with what you
know about nerve impulses, myelin sheaths, and the location of gated ion channels in the membranes of axons?
What will be an ideal response?
Symptoms listed all involve loss of motor control. The CNS axons involved in initiating and controlling movement are generally myelinated, thus loss of myelination slows or eliminates conduction of action potentials in these cells. Early on, many signals arrive normally at spinal motor neurons to produce movement, but enough signals are missing to cause noticeable alterations in motor control.
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Select the correct statement about the neural mechanisms of respiratory control
A) The pons is thought to be instrumental in the smooth transition from inspiration to expiration. B) The dorsal respiratory group neurons depolarize in a rhythmic way to establish the pattern of breathing. C) The ventral respiratory group is contained within the pons. D) The pontine respirator group (PRG) continuously stimulates the medulla to provide inspiratory drive.
Sherry is not able to produce surfactant. In order to inhale a normal tidal volume, does her intrapleural pressure have to be higher or lower than for a healthy individual? Explain.
What will be an ideal response?
All of the following organelles play a part in synthesizing and processing proteins except which one?
A. Ribosomes B. Mitochondria C. Golgi complex D. Endoplasmic reticulum
A stressful situation would stimulate ________ gluconeogenesis.
A. decreased B. no change in C. increased