week 3 (nervous + special senses) Flashcards
(26 cards)
explain: types of refractory periods (2)
-
absolute
- another AP cannot happen
- Na+ already open so cannot open again to depol. -
relative
- needs a larger stim. to reach threshold
compare: electrical and chemical synapses
ELECTRICAL
- fast
- bi-directional
- excitatory
CHEMICAL
- slower
- uni-directional
- excitatory or inhibitory
question: how does AP freq. influence the amount of NT released in a chemical synapse?
- lower AP greq. = less synaptic vesicles releasing their contents into cleft to be bound to recep. (vv)
name: steps of a chemical synapse (ex. intracellular calcium)
- AP happens
- Ca+ voltage channels open
- Ca enters cell
- Ca signals vesicles
- Vesicles move to mem. and exocytosis
- NT from vesicle diffuses across cleft
- NT binds to receptor on postsynaptic cell
name: ways a chemical synaptic transmission is ended
- NT removed from cleft
⤷ degradation
⤷ reuptake into presynaptic cell
⤷ diffusion out of cleft + reuptake by nearby cells
define: excitatory NT vs inhibitory ones?
- excitatory -> depol. (EPSP)
⤷ more likely for AP generation - inhibitory -> hyperpol. (IPSP)
⤷ less likely for AP generation
name: excitatory and inhibitory NTs
EXCITATORY
- Ach
- glutamate
INHIBITORY
- GABA
- glycine
define: ionotropic vs metabotropic
- iono = ligand gated channels on postsyn. mem.
⤷ faster transmission - metabo = activates a signaling pathway (second messenger)
⤷ slower transmission
explain: effects of Ach, GABA, and endorphin on synapses
ACH
- affects excitatory control of skeletal musc
- caffeine, nicotine, nerve gas
GABA
- inhibitory in CNS
- inhibits anxiety
- alcohol, tranquilizers -> enhances GABA -> reduced anxiety
ENDORPHIN
- inhibitory in CNS
- opiates (agonists)
compare: branches of autonomc NS
SNS
- fight or flight
- active in stress
PSNS
- active at rest
ENS
- indep. of the other two systems
- affects digestion
question: relationship between SNS and PSNS?
- dual innervation in ANS
- innervate many of the same organs but usually have opposing effects
question: how does olfaction happen (general summary)?
- odorants dissolve in mucus
- bind to receptors
- if enough depol. + strong enough -> AP
question: does olfaction go through thalamus?
- no
- only sense to directly go to cerebral cortex
question: what is the vomeronasal organ?
- detects pheromones for animals
⤷ no human equivalent - pheromones don’t go to olfactory bulb
⤷ go through another structure that directs to amygdala -> hypothalamus
name: order of structures (steps) in olfactory system
odourant
odourant receptors
olfactory receptor cell
cribriform plate
interneuron of olfactory bulb
question: what type of neurons are olfactory receptor cells?
- bipolar neurons
explain: types of papillae (4)
- have pockets in taste buds
⤷ pockets hold taste receptors
-
vallate
- v shaped border
- posterior part of tongue -
fungiform
- mushroom shaped
- anterior 2/3 of tongue
- each have 1 - 8 taste buds
- receptors for pressure and temp -
filiform
- flame shaped
- across tongue
- rough surface to manipulate food
- no taste buds -
foliate
- leaf shaped
- lateral and posterior
- 1300 taste buds w/in the folds
question: how often are taste cells vs olfactory cells replaced?
- taste = 10 - 14 days
- olfactory = 30 days
explain: salty and sour taste vs sweet and bitter taste
SALTY SOUR
- ionotropic path
- salty = Na+
⤷ Na+ binds -> depol. -> Ca opens -> NT release
-
sour = H+
⤷ blocks K+ leaving -> depol. -> Ca opens -> NT release
SWEET BITTER
- metabotropic path
- sweet = activates G prot. called gustducin -> activates adenylyl cyclase -> ATP becomes cAMP secondary messenger -> closes K+ -> depol. -> Ca opens -> NT release
- bitter= activates G prot. (transducin) -> activates phopholipase C -> PIP2 becomes IP3 secondary messenger -> release of Ca from stores -> NT release
question: how is spice tasted?
- nociceptors
- pain receptors
- thermodetecting receptors
explain: movement of ear hair cells
DEPOL
- psi changes cause stereocilia to move
- opens mechno gated channels
⤷ allows Ca in -> NT release -> AP
- stereocilia move back -> closes K+ -> closes Ca -> less AP
name: order of structures in middle ear
canal
tympanic mem
ossicles (malleus, incus, stapes)
oval window
cochlea
round window
question: how is sound heard in the middle/inner ear?-
- vibrations move the basical membrane in the cochlea
- displaces stereocilia
- opens and closes channels
- sends AP -> sig. to brain
question: how do the utricle and saccule help with balance?
- head tilt -> otoliths pulled by gravity
- stereocilia bends with head tilt
⤷ sends sig. to brain that head is tilted -> allows balance to be maintained
