Chapter 4, Problem 3AYB

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 33.11 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 33.11 Effects of age and occupational noise exposure on hearing. The graph shows the threshold hearing capacities (in decibels) for sounds of different frequencies (given in hertz) in a 25-year-old carpenter (blue), a 50-year-old carpenter (red), and a 50-year-old who did not have any on-the-job noise exposure (brown). Which sound frequency was most easily detected by all three people?

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 33.11 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 33.11 Effects of age and occupational noise exposure on hearing. The graph shows the threshold hearing capacities (in decibels) for sounds of different frequencies (given in hertz) in a 25-year-old carpenter (blue), a 50-year-old carpenter (red), and a 50-year-old who did not have any on-the-job noise exposure (brown). How loud did a 1,000-hertz sound have to be for the 50-year-old carpenter to detect it?

What vibration-detecting systems are found in octopuses and insects?

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?

Like other nocturnal carnivores, the ferret shown in FIGURE 33.13 has light-reflecting material in its choroid. Explain why the presence of reflective material in this layer of the eye maximizes the degree to which light excites photoreceptors. Explain also why having reflective material in this layer causes the perceived image to be somewhat blurry. FIGURE 33.13 Eyeshine of a back-footed ferret A reflective layer in this nocturnal predators eyes enhances its night vision,

Watch this video (http://openstaxcollege.org/l/pupillary) to learn about the pupillary reflexes. The pupillary light reflex involves sensory input through the optic nerve and motor response through the oculomotor nerve to the ciliary ganglion, which projects to the circular fibers of the iris. As shown in this short animation, pupils will constrict to limit the amount of light falling on the retina under bright lighting conditions. What constitutes the afferent and efferent branches of the competing reflex (dilation)?

A satellite is launched into space, but explodes after exiting the Earth’s atmosphere. Which statement accurately reflects the observations made by an astronaut on a space walk outside the International Space Station during the explosion? The astronaut would see the explosion, but would not hear a boom The astronaut will not sense the explosion The astronaut will see the explosion, and then hear the boom The astronaut will feel the concussive force of the explosion, but will not see it.

An animal that navigates by the stars needs ________. a. an ability to sense Earths magnetic field b. pheromone receptors c. an internal clock d. an acute sense of hearing

Visual accommodation involves adjustment to the shape or position of the ___ . a. conjunctiva b. retina c. orbit d. lens