Question 1

What kind of tactile receptor is stimulated by light,sustained touch?

Accepted Answer

Merkel's discs are responsible for light, sustained touch. Pacinian corpuscles respond to deep pressure and vibration, Ruffini endings respond to skin stretch, and Meissner's corpuscles respond to light touch and changes in textures. Dermatomes refer to a specific area of skin that is innervated by a single spinal nerve.

Question 2

How many tactile mechanoreceptors are estimated to be in a typical fingertip?

Accepted Answer

It is estimated that there are approximately 17,000 tactile mechanoreceptors in a typical fingertip.

Question 3

Within the eye,what innermost pigment layer contains nervous tissue?

Accepted Answer

The retina is the innermost layer of the eye and contains nervous tissue responsible for processing visual information. The vitreous humor is a gel-like substance that fills the space between the lens and the retina. The choroid is a layer located between the retina and the sclera, and it contains blood vessels that nourish the retina. The sclera is the outermost layer of the eye, and the cornea is the clear, dome-shaped tissue that covers the front of the eye.

Question 4

What photosensitive cells within the retina perceive colors?​

Accepted Answer

Cones are the photoreceptor cells in the retina that are responsible for color vision. Rods, on the other hand, are responsible for vision in low light conditions and do not perceive colors. Bipolar cells, horizontal cells, and ganglion cells are also important cells in the retina but do not perceive colors directly.

Question 5

What are rapidly adapting receptors called?

Accepted Answer

Rapidly adapting receptors are often referred to as phasic receptors because they respond quickly to changes in stimuli, but then quickly adapt and become less sensitive to sustained stimulation.

Question 6

What condition occurs when the lens of the eye loses elasticity and can no longer assume the spherical shape required to accommodate for near vision?

Accepted Answer

Presbyopia is the condition that occurs when the lens of the eye loses elasticity and can no longer assume the spherical shape required to accommodate for near vision. This typically occurs in individuals over the age of 40, and results in difficulty focusing on close objects. Myopia is nearsightedness, optomia is not a recognized medical condition, macular degeneration is a degenerative eye disease that affects the macula, and cataracts are characterized by clouding of the lens in the eye.

Question 7

What gland produces tears?

Accepted Answer

The lacrimal gland is responsible for producing tears.

Question 8

What happens when the radial muscle of the eye contracts or shortens?

Accepted Answer

The radial muscle of the eye is responsible for dilating the pupil, which means the size of the pupil increases when this muscle contracts or shortens.

Question 9

What kind of nerves carries subconscious input information?

Accepted Answer

Subconscious input information is carried by visceral afferent nerves, which transmit sensory signals from internal organs to the brainstem or spinal cord without conscious control or awareness.

Question 10

What nerve fibers constitute the "fast pain" pathway?

Accepted Answer

A-delta fibers are lightly myelinated, allowing for faster conduction of pain signals compared to unmyelinated C fibers which make up the slow pain pathway. A-alpha and A-beta fibers are not involved in pain transmission. B fibers are a type of autonomic nerve fiber and are not involved in the pain pathway.

Question 11

Some receptors diminish the extent of their depolarization despite sustained stimulus strength,a phenomenon called ____.

Accepted Answer

The phenomenon described in the question is called adaptation, where the receptors gradually reduce their response to a sustained stimulus. This allows the neural system to focus on new, potentially important stimuli.

Question 12

What is the fastest transmission rate of A-delta fibers?

Accepted Answer

A-delta fibers are a type of sensory nerve fiber that are myelinated and can transmit impulses at speeds up to 30 meters per second, making them faster than C fibers but slower than A-beta fibers.

Question 13

Nociceptors are sensitive to ____.

Accepted Answer

Nociceptors are specialized nerve endings that detect and transmit the sensation of pain to the central nervous system. They respond to noxious stimuli such as high temperature, pressure, and chemicals that can cause tissue damage. Therefore, the correct answer is C - pain.

Question 14

The strength of the lens depends on its shape,which in turn is regulated by what muscle?

Accepted Answer

The ciliary muscle plays a crucial role in regulating the shape of the lens. When the ciliary muscle contracts, it changes the shape of the lens and increases its refractive power. When the ciliary muscle relaxes, the lens becomes flatter and its refractive power decreases.

Question 15

During precortical processing of sensory input,some features of stimuli are accentuated and others are suppressed through ____.

Accepted Answer

Lateral inhibition is a mechanism in which adjacent neurons in the sensory system inhibit one another, enhancing the contrast between the activated neuron and its neighbors. This process is vital in the visual system for sharpening edges and improving visual acuity.

Question 16

How many categories of pain receptors are there?​

Accepted Answer

There are three main categories of pain receptors: mechanical, thermal, and chemical.

Question 17

The photoreceptors in the eye are sensitive only to wavelengths between ____.

Accepted Answer

The photoreceptors in the eye are only sensitive to wavelengths between 400 and 700 nanometers, which is the visible spectrum of light. This range includes the colors of the rainbow, with red being the longest wavelength and violet being the shortest.

Question 18

What painkilling and mood enhancing compounds are released during prolonged exercise,such as jogging?

Accepted Answer

Endorphins are released during prolonged exercise and have painkilling and mood enhancing effects.

Question 19

What is the photopigment in rods?

Accepted Answer

Rhodopsin is the photopigment found in the rods of the retina. It consists of a protein called opsin and a chromophore molecule, called 11-cis-retinal. When photons of light are absorbed by the 11-cis-retinal, it undergoes a chemical change that triggers a nerve impulse to the brain, allowing us to perceive images in low light conditions.

Question 20

What compound greatly sensitizes all nociceptors to noxious stimuli?

Accepted Answer

Prostaglandins greatly sensitize all nociceptors to noxious stimuli by increasing their responsiveness and lowering their activation threshold.

Quiz 6: The Peripheral Nervous System - Afferent Division - Special Senses