10 Touch and Pain Flashcards
(33 cards)
Q: What is the largest sense organ in the body?
A: The skin is the largest sense organ in the body.
Q: What are the two types of skin?
A: There are two types of skin: glabrous, found on the palms of hands and soles of feet, and hairy, found everywhere else on the body.
Q: Describe the physiology of skin sensation.
A: When a stimulus contacts the skin, receptors in the skin fire, and the signal travels to the brain via the spinal cord, ultimately reaching the somatosensory cortex on the opposite side of the body.
Q: What are the four senses associated with skin sensation?
A: The four senses associated with skin sensation are touch (mechanical stimuli), pain, body sense (proprioception), and temperature.
Q: What are the four types of tactile receptors in the skin?
A: The four types of tactile receptors are Merkel’s discs (fine details), Meissner corpuscles (flutter), Ruffini organs (stretching), and Pacinian corpuscles (vibration, fine texture).
Q: Why are there multiple types of tactile receptors?
A: Multiple types of tactile receptors allow for the detection of various types of information, and a single stimulus can activate many receptor systems.
Q: What is meant by receptive fields in the skin?
A: Receptive fields are the areas of skin that a particular cell receives information about. Pacinian corpuscles have larger receptive fields than Meissner’s corpuscles.
Q: What is two-point discrimination?
A: Two-point discrimination is the smallest separation of two separate but adjacent points of stimulation on the skin that produces two distinct impressions of touch.
Q: How does two-point discrimination vary across different areas of the body?
A: Two-point discrimination is most sensitive on the fingertips, with a threshold of around 2mm, while on the arm, it is around 3.5cm. This difference is due to the number of receptors and the amount of cortex in the somatosensory cortex.
Q: What is the homunculus?
A: The homunculus is a representation of the human body in the brain, with areas of the body that are most sensitive taking up the most space in the somatosensory area.
Q: What is the significance of fingertip sensitivity?
A: Fingertips have a high density of receptors, making them the “fovea” of the skin, and acuity can change with experience.
Q: What is the difference between active touch and passive touch?
A: Active touch involves active exploration of the environment, while passive touch occurs when the body is stationary.
Q: What are the advantages of active touch?
A: Active touch allows more parts of the body to contact the object, enables searching for the most diagnostic parts of the object, and engages kinesthetic senses.
Q: How do we perceive texture through touch?
A: We perceive texture through spatial cues (bumps and grooves when the finger is stationary or moving) and temporal cues (only when the finger moves across a surface).
Q: Which tactile receptors are involved in perceiving texture, and how can their function be impaired?
A: Pacinian corpuscles are involved in perceiving texture, especially through adaptation to high-frequency vibrations. Their function can be impaired by adaptation to these frequencies.
Q: What does the “What” and “Where” processing refer to in tactile perception?
A: “What” processing refers to identifying objects by touch, and “Where” processing refers to spatial processing of the location of objects.
Q: What is tactile agnosia?
A: Tactile agnosia is the inability to identify objects by touch, while spatial processing remains intact.
Q: What does tactile extinction involve?
A: Tactile extinction involves problems in object recognition by touch.
Q: What brain areas are active when processing “What” and “Where” tactile information?
A: “What” object processing activates the primary and secondary somatosensory cortex, while “Where” object processing activates the superior parietal areas.
Q: How do top-down influences affect touch perception?
A: Top-down influences require updating as the body moves, and the same sensation can be perceived differently based on emotional effects, expectations, and surprises.
Q: Why can’t you tickle yourself effectively?
A: You can’t tickle yourself effectively because you can predict the consequences of your own actions, making the sensation less ticklish.
Q: What is Aristotle’s illusion?
A: Aristotle’s illusion occurs when you cross your middle and index finger and run them down your nose, making you perceive two separate objects.
Q: What is the cutaneous rabbit illusion?
A: The cutaneous rabbit illusion is the perception of evenly spaced jumps when a stimulus involves widely repeated taps on the skin, leading to activity in the primary somatosensory cortex as if the intermediate points had been stimulated.
Q: What was the old view of pain?
A: The old view considered pain to be an overstimulation of any sensory system.
