Ramon Y Cajal hypothesized long ago that the floor plate of the developing spinal cord exerts an attractive effect on developing commissural axons. Describe the explant co-culture experiment that confirmed Cajal hypothesis.

Ramon Y Cajal hypothesized long ago that the floor plate of the developing spinal cord exerts an attractive effect on developing commissural axons. Describe the explant co-culture experiment that confirmed Cajal hypothesis.

Biomedical Instrumentation Systems

1st Edition

ISBN:9781133478294

Author:Chatterjee

Publisher:Chatterjee

Chapter14: Instrumentation In Diagnostic Ultrasound

Section: Chapter Questions

Problem 10Q

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Occupational Hearing Loss Frequent exposure to loud noise of a particular pitch can cause loss of hair cells in the part of the cochlea that responds to that pitch. People who work with or around noisy machinery are at risk for such frequency-specific hearing loss. Taking precautions such as using ear plugs to reduce sound exposure is important. Noise-induced hearing loss can be prevented, but once it occurs it is irreversible because dead or damaged hair cells are not replaced. FIGURE 33.24 shows the threshold decibel levels at which sounds of different frequencies can be detected by an average 25-year-old carpenter, a 50-year-old carpenter, and a 50-year-old who has not been exposed to on-the-job noise. Sound frequencies are given in hertz (cycles per second). The more cycles per second, the higher the pitch. FIGURE 33.24 Effects of age aria occupational noise exposure. The graph shows the threshold hearing capacities fin decibels) for sounds of different frequencies (given in hertz) in a 25-year-okj carpenter (blue), a 50-year-old carpenter (red), and a 50-year-otd who did not have any on-the-job noise exposure (brown). 2. How loud did a 1,000-hertz sound have to be for the 50-year-old carpenter to detect it?
Occupational Hearing Loss Frequent exposure to loud noise of a particular pitch can cause loss of hair cells in the part of the cochlea that responds to that pitch. People who work with or around noisy machinery are at risk for such frequency-specific hearing loss. Taking precautions such as using ear plugs to reduce sound exposure is important. Noise-induced hearing loss can be prevented, but once it occurs it is irreversible because dead or damaged hair cells are not replaced. FIGURE 33.24 shows the threshold decibel levels at which sounds of different frequencies can be detected by an average 25-year-old carpenter, a 50-year-old carpenter, and a 50-year-old who has not been exposed to on-the-job noise. Sound frequencies are given in hertz (cycles per second). The more cycles per second, the higher the pitch. FIGURE 33.24 Effects of age aria occupational noise exposure. The graph shows the threshold hearing capacities fin decibels) for sounds of different frequencies (given in hertz) in a 25-year-okj carpenter (blue), a 50-year-old carpenter (red), and a 50-year-otd who did not have any on-the-job noise exposure (brown). 3. Which of the three people had the best hearing in the range of 4,000 to 6,000 hertz? Which had the worst?
Occupational Hearing Loss Frequent exposure to loud noise of a particular pitch can cause loss of hair cells in the part of the cochlea that responds to that pitch. People who work with or around noisy machinery are at risk for such frequency-specific hearing loss. Taking precautions such as using ear plugs to reduce sound exposure is important. Noise-induced hearing loss can be prevented, but once it occurs it is irreversible because dead or damaged hair cells are not replaced. FIGURE 33.24 shows the threshold decibel levels at which sounds of different frequencies can be detected by an average 25-year-old carpenter, a 50-year-old carpenter, and a 50-year-old who has not been exposed to on-the-job noise. Sound frequencies are given in hertz (cycles per second). The more cycles per second, the higher the pitch. FIGURE 33.24 Effects of age aria occupational noise exposure. The graph shows the threshold hearing capacities fin decibels) for sounds of different frequencies (given in hertz) in a 25-year-okj carpenter (blue), a 50-year-old carpenter (red), and a 50-year-otd who did not have any on-the-job noise exposure (brown). 4. Based on these data, would you conclude that the hearing decline in the 50-year-old carpenter was caused by age or by job-related noise exposure?
VISUALIZE Describe the action taking place at each of the numbered steps in the figure.
Occupational Hearing Loss Frequent exposure to loud noise of a particular pitch can cause loss of hair cells in the part of the cochlea that responds to that pitch. People who work with or around noisy machinery are at risk for such frequency-specific hearing loss. Taking precautions such as using ear plugs to reduce sound exposure is important. Noise-induced hearing loss can be prevented, but once it occurs it is irreversible because dead or damaged hair cells are not replaced. FIGURE 33.24 shows the threshold decibel levels at which sounds of different frequencies can be detected by an average 25-year-old carpenter, a 50-year-old carpenter, and a 50-year-old who has not been exposed to on-the-job noise. Sound frequencies are given in hertz (cycles per second), The more cycles per second, the higher the pitch. FIGURE 33.24 Effects of age aria occupational noise exposure. The graph shows the threshold hearing capacities fin decibels) for sounds of different frequencies (given in hertz) in a 25-year-okj carpenter (blue). a 50-year-old carpenter (red), arid a 50-year-ofd who did not have any on-the-job noise exposure (brown). 1. Which sound frequency was most easily detected by all three people?
Watch this video (http://openstaxcollege.org/l/2point) to see a quick demonstration of two-point discrimination. Touching a specialized caliper to the surface of the skin will measure the distance between two points that are perceived as distinct stimuli versus a single stimulus. The patient keeps their eyes closed while the examiner switches between using both points of the caliper or just one. The patient then must indicate whether one or two stimuli are in contact with the skin. Why is the distance between the caliper points closer on the fingertips as opposed to the palm of the hand? And what do you think the distance would be on the arm, or the shoulder?
Watch this video (http://openstaxcollege.org/l/DanielleReed) to learn about Dr. Danielle Reed of the Monell Chemical Senses Center in Philadelphia, PA, who became interested in science at an early age because of her sensory experiences. She recognized that her sense of taste was unique compared with other people she knew. Now, she studies the genetic differences between people and their sensitivities to taste stimuli. In the video, there is a brief image of a person sticking out their tongue, which has been covered with a colored dye. This is how Dr. Reed is able to visualize and count papillae on the surface of the tongue. People fall into two large groups known as tasters and non-tasters on the basis of the density of papillae on their tongue, which also indicates the number of taste buds. Non-tasters can taste food, but they are not as sensitive to certain tastes, such as bitterness. Dr. Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew. Are you very sensitive to tastes? Can you see any similarities among the members of your family?
Benign Paroxysmal Positional Vertigo is a disorder where some of the calcium carbonate crystals in the utricle migrate into the semicircular canals. Why does this condition cause periods of dizziness? The hair cells in the semicircular canals will be constantly activated The hair cells in the semicircular canals will now be stimulated by gravity The utricle will no longer recognize acceleration There will be too much volume in the semicircular canals for them to detect motion.