Sensory Physiology Flashcards
how is a physical stimulus converted into a response ?
stimulus -> receptor -> neuron -> CNS (receives, interprets and responds)
what are the 6 types of sensory receptors ?
- photoreceptors
- mechanoreceptors
- chemoreceptors
- nociceptors
- thermoreceptors
- osmoreceptors
what are nocireceptors ?
pain receptors
what are the classes of sensory receptors ?
complex and special
what are complex neural receptors ?
olfaction and somatic senses
what are the four special senses receptors ?
vision, hearing, balance and taste
difference between complex and special receptors ?
- special senses = separate from neutron but still need action potential
- complex receptors = must be sent to neutron and converted to action potentials
(only difference is the step is how receptor will release neurotransmitters; chemically gates Chanels opening up and ions are flying through it)
action potentials vs receptor potentials ?
- action potentials are all or none (once initiated, they will flow down the entire axon) *** once hits threshold action potential must occur
- receptor potentials are graded (they can differ in amplitude and dissipate over time and distance)
what type of frequencies of action potentials last longer ?
higher frequency (release of more neurotransmitters)
if a receptive field is more sensitive what does this mean ?
more senses present
where does smell senses occur (nerve and bulb)
cranial nerve 1 and olfactory bulb
about how many odor receptors do we have ?
about 350
what are the five taste sensations ?
sweet, sour, salty, bitter and umami
around how many taste buds do we have ?
2000-5000
how do we specifically taste our food ?
through taste cells “taste buds” that have flavour (each taste bud contains 50-150)
what are five important structures of the CNS for sensory physiology ?
- cerebrum
- cerebellum
- brain stem
- diencephalon
- spinal cord
what three parts make up the cerebrum ?
cortex, basal ganglia and limbic system (main part of brain)
what three parts make up the cerebrum ?
cortex, basal ganglia and limbic system (main part of brain)
what is the cerebellum responsible for ?
coordination of movement and different procceses
what three parts make up the cerebrum ?
medulla oblongata, pons, and midbrain
what four parts make up the diencephalon ?
thalamus, hypothalmus, pineal gland, pituitary gland
what are the four “lobes” of the brain ?
frontal, parietal, temporal, and occipital
what is the frontal lobe responsible for ?
movement and cognition
what is the parietal lobe responsible for ?
sensation
what is the temporal lobe responsible for ?
hearing and object perception
what is the occipital lobe responsible for ?
vision
what are the four somatic senses ?
- touch
- proprioception
- temperature
- nocieception
what is proprioception ?
awareness of body movement and location in space
how do mechanoreceptors differ ?
- adaptation rate
- receptive field size
what are the four adaptation rates ?
merkel’s disk, meissner’s corpuscle, ruffini’s ending and pacinian corpuscle
which two adaptation rates have small receptive fields ?
merkel’s disk and meissner’s corpuscle
what two adaptation rates have large receptive fields ?
ruffini’s ending and pacinian corpuscle
which two adaptation rates have slow adaptation ?
merkel’s disk and ruffini’s ending
which two adaptation rates have rapid adaptation ?
meissner’s corpuscle and paccinian corpuscle
regions with high tactile acuity have what size receptive fields ?
small
what is two-point discrimination ?
the smallest seperation between two points on the skin that is perceived as two points rather than one
large receptive fields are perceived as ______
one point
small receptive fields are perceived as ______
two points
between dorsal root and ventral root which is sensory and which is motor ?
sensory = dorsal
motor = ventral
what is the primary somatosensory cortex (S1) made up of ?
areas 3, 1 and 2 (located on the post central gyrus)
what is the primary motor cortex located on ?
the precentral gyrus
what is homunculus ?
homunculus represents either the motor or the sensory distribution along the cerebral cortex of the brain.
where are thermoreceptors found ?
in the brain
what are the three pain fiber types ?
beta, delta and C
describe alpha beta fiber type characteristics and associated stimuli ?
large, myelinated and mechanical stimuli (touch)
describe alpha delta fiber type characteristics and associated stimuli ?
small, myelinated and intense mechanical or mechanothermal stimuli, fast pain
describe C fiber type characteristics and associated stimuli ?
small, unmyelinated and heat, cold, slow pain
what has a higher threshold nociceptors or themoreceptors ?
nociceptors have higher than thermoreceptos
more pain = higher or lower threshold
higher threshold (higher pain tolerance)
name the 7 anatomy parts of the eye
- pupil
- cornea
- iris
- sclera
- conjunctive
- extraocular muscles
- optic nerve
what happens at the optic disk ?
no photoreceptors present therefore blind at this spot
what is the order of retinal processing cells ?
ganglion cells – bipolar cells – photoreceptors
what are the two types of photoreceptors ?
cones and rods
what are rods ?
highly sensitive to light and responsible for vision at low light levels (night vision)
what are cones ?
less sensitive to light, three types of cones; red blue and green (responsible for colour)
what happens to light transduction in the darkness ?
rods and cones are depolarized
what happens to light transduction in light stimulus ?
rods and cones are hyperpolarized
what happens to light transduction at recover phase ?
all channels are closed
what is the fovea ?
region of the highest visual acuity very small receptive field
which photoreceptors are selectively only present at the fovea ?
cones (for colour vision)
what are the four types of eye movement
- saccades
- smooth pursuit
- vestibule-ocular reflex
- vergence
what is saccades ?
rapid, jerky eye movements
what is smooth pursuit ?
smooth eye movement that keeps the image of a moving object of interest on the fovea
what is vestibule-ocular reflex ?
stabilizes the eye during a head movement
what is vergence ?
used when the object of interest is approaching or moving away
where do fibres from the nasal part of either eye cross over ?
at the optic chiasm
what is the order of the visual tract from back to eyes ?
primary visual cortez – optic tract – optic chiasm – optic nerve
what region of ear directs the sound into the ear ?
pinna or outer ear
which region of ear funnels and conducts the sound to the middle ear ?
ear canal
which region of ear separates the external ear from the middle ear
tympanic membrane
which region of ear transfers the sound from the external environment to the inner ear ?
small bones
what are the three little bones in ear called ?
malleus, incus and stapes
what do hair cells in ear do ?
depolarizes the nerve
what do fluid waves travel ?
basilar membrane
what does tonopoty mean ?
different cells responding to different frequencies
slow wave = what frequency ?
low frequency
what is the auditory pathway in the CNS ?
ears -> medulla -> midbrain -> thalamus -> auditory cortex
where do the nerves cross the body midline in the auditory pathway ?
medulla
where do projections to cerebellum come from ?
midbrain
what are the three types of hearing loss ?
conductive, sensorineural and central
what is sensorineural hearing loss ?
damage to structures of inner ear that affects hair cells, or to auditory nerve
what is conductive hearing loss ?
sound is unable to be transmitted through outer or middle ear
what is central conductive hearing loss ?
damage to auditory pathways upstream from cochlea (defect in CNS)
what does the cochlea in the ear do ?
It changes sounds into nerve messages and sends them to your brain.
