Module 7 Flashcards
Define sensory receptor
receptors that detect environmental stimuli and convert information into action potentials
Define adequate stimulus
the form of environmental stimulus to which the sensory receptor is most sensitive
List 4 characteristics of generator potentials
generally depolarizing; caused by increased permeability to Na+ ions; local and do not propagate down the neuron (more like an EPSP); proportional to strength of stimulus
List 4 kinds of environmental stimuli and an example of each
mechanical (touch, pressure, vibration, proprioception, sound); chemical (taste, pain, odor); electromagnetic (light); other (gravity, motion, acceleration, heat)
Define cutaneous receptors
sensory receptors in the skin
Name the receptor sensitive to fine touch and vibration
hair follicle receptors
Name the receptor that responds to pain and temperature (hot and cold)
free nerve endings
Name the receptor that detects low-frequency vibrations (30-40 cycles/sec) and touch
meissner’s corpuscles
Name the receptor that detects only touch
ruffini’s corpuscles
Name the receptor that detects high-frequency vibrations (250-300 cycles/sec) and touch
pacinian corpuscles
Name all receptors that detect touch
hair follicle receptors (fine touch), Meissner’s corpuscles, Ruffini’s corpuscles, Pacinian corpuscles
Name all receptors that detect vibrations
meissner’s corpuscles (low-frequency), pacinian corpuscles (high-frequency)
Name the receptors that detect proprioception (limb position and movement)
muscle spindles and Golgi tendon organs
Define receptive field of a neuron
the area on the surface of the skin where an adequate stimulus will activate a particular receptor to fire an action potential in the neuron; any stimulus applied outside the receptor field will not generate an action potential
Name two major ascending sensory pathways
the spinothalamic (anterolateral) tract; the dorsal column, medial lemniscal system
Describe the pathway of the spinothalamic (anterolateral) tract
info from 1st order neuron (sensory) enters spinal cord, synapses with 2nd order neuron, crosses to contralateral side, ascends to thalamus, synapses with 3rd order neuron, travels to somatosensory cortex
Name the types of information transmitted by the spinothalamic (anterolateral) tract
pain, temperature, crude touch
Describe the pathway of the dorsal column, medial lemniscal system
info from 1st order neuron (sensory) enters spinal cord, travels up cord, synapses with 2nd order neuron in upper spinal cord, crosses to contralateral side, ascends to thalamus, synapses with 3rd order neuron, travels to somatosensory cortex
Name the types of information transmitted by the dorsal column, medial lemniscal system
fine detailed touch, proprioception (muscle sense), vibration
Describe where the primary somatosensory cortex is located
on the parietal lobe, on the postcentral gyrus behind the central sulcus
Describe the organization of the somatosensory homunculus, medial to lateral on the cortex
genitals, foot, leg, back, head, arm, forearm, hand, fingers, thumb, eye, nose, face, lips, tongue, pharynx
Name the three most sensitive parts of the body (largest areas on somatosensory homunculus)
the hand, tongue and lips
List the cell types in the retina
rod cells, cone cells, bipolar cells, ganglion cells, horizontal cells, and amacrine cells
List functional characteristics of rod cells
extremely sensitive to light, function best under low light, contain one type of photopigment, do not detect light, in region of retina outside and around the fovea
List functional characteristics of cone cells
function best under bright light, ideal for detecting detail, three different types each with a different photopigment, each sensitive to one primary colour, located in region of the fovea in large concentrations
Describe how light is tranduced by the retina into action potentials
light strikes retina, hyperpolarizes rod and cone cells to shut them off, inhibitory neurotransmitter stops being released, bipolar cells depolarize spontaneously and activate, may lead to action potential in ganglion cells
List four types of eye movements
saccades; smooth pursuit; vestibular ocular reflex (VOR); vergences
Describe saccades with an example
rapid, jerky movements of the eye, used to rapidly move the eye to the object of interest (ex. reading words on a page)
Describe smooth pursuit with an example
smooth movement of the eyes made to keep a moving object of interest focused on the fovea (ex. following flight of a bird with head still)
Describe vestibular ocular reflex (VOR) with an example
an eye movement made when you focus your attention on an object then move your head back and forth or shake it up and down (ex. looking at someone while agreeing or disagreeing)
Describe vergences with an example
eye movements made when an object of interest is approaching or moving away from you; when moving away, eyes diverge; when moving closer, eyes converge (ex. staring at pencil moving away and toward face)
Describe where different frequencies of sound will stimulate hair cells in the cochlea
high frequencies near oval window (narrow and thick, tight tension) and low frequencies at apex (top) of cochlea (wide and thin, loose tension)
Describe how sound is transduced into action potentials
basilar membrane vibrates, hair cells are bent, causing ion channels to open and depolarization of cells, release of neurotransmitter, excites neurons in auditory nerve, fires action potentials
List the major functions of the vestibular system
maintaining balance, equilibrium, and postural reflexes, by detecting linear and rotational motion
Name the movement detected by the semicircular canal receptors
detect rotational or angular accelerations of the head (three of them, each detect movement in one plane of motion)
Name the two movements detected by the otolith organs
linear acceleration/deceleration in the vertical plane (saccule) and the horizontal plane (utricle)
Describe how angular motion of the head is transduced into action potentials
body accelerates, otolith crystals lag behind and seem to move in opposite direction, bends cilia of hair cells, causes increase in frequency of action potentials
Describe how hair cells perform their function
at rest, release small resting level of neurotransmitter which fires action potentials; when small stereocilia bend towards large kinocilium, release more neurotransmitter = more action potentials; when stereocilia bend away from kinocilium, release less neurotransmitter = less action potentials
