bio 361 Flashcards
final exam
nuclei
groupings of cell bodies in brain
tracts
groupings of axons in brain
which two neurotransmitters are used in sensitization
serotonin then glutamate
Which 2 receptors are in long-term potentiation
AMPA, NMDA
Sensitization Pathway
- facilitating neuron releases serotonin
- seretonin binds to a receptor
- activates AC
- cAMP
- PKA
- inactivates K+ channels (K cannot leave cell)
- increase membrane potential
- more likely to fire in the future
long-term potentiation pathway
- high glutamate release from pre-syn-neuron
- large influx of Na through AMPA receptor
- membrane potential rises, Mg pops off of NMDA receptor
- Ca enters through NMDA receptor
- phosphorylates AMPA, increasing affinity for glutamate
- increase glutamate secretion in future from presynaptic neuron
4 ventricles of brain
Lateral ventricles (big), 3rd, 4th, central canal
gray matter
regions of CNS containing cell bodies, non myelinated axons, dendrites
white matter
regions of CNS containing myelinated axons
dual innervation
organs receive input from both systems
parasympathetic neurotransmitter
Ach
sympathetic neurotransmitter
NE
muscle Ach receptor name
nicotinic Ach receptors
ionotropic transduction
directly open ligand gated ion channel
metabotropic transduction
channel changes shape - g protein pathway
discrimination
tell difference
sensitivity
lowest stimuli to chance AP frequency
polymodal receptor
responds to several different stimuli
teleoreceptors
detect distant stimuli
externoreceptors
external stimuli
Interoreceptors
stimuli inside body
labelled line theory
- each receptor cell connects to a specific sensory area in cortex
- cortex interprets any signal in that area as coming from the same stimuli
receptive field
region where specific stimulus elicits greatest AP change
dynamic range
range of stimulus that can be detected (eg frequency range)
tonic receptors
produce AP as long as stimuli is present
phasic receptors
produce AP only at start, end : readily adapt
static pressure receptors
produce AP whenever stimulus is present (tonic)
dynamic pressure receptors
produce AP only at start, end (phasic)
model of phasic response
- neuron in myelin
- deform skin, deform myelin, deform channel, depolarization
- myelin redistributes load, preventing further APs (while stimulus is constant)
- if you stop pushing, myelin pulls, another AP
hair cell pathway
- oval window
- waves in perilymph
- basilar membrane vibrates
- outer hair cells contract
- inner hair cells’ stereocilia move towards kinocilium
- K channels open, K goes in (dep)
- glutamate released to afferent neuron
encoding frequency
- location of hair cell dep. on cochlea
- high freq. near oval window - thin, stiff
- low freq. distal end - flexible, wide
Olfactory pathway
- odorant binds to receptor, conf. change
- Golf activated
- activates AC
- ATP -> cAMP
- cAMP directly opens cation channel
- Ca and Na enter
- Ca opens Cl channel, Cl leaves
- big dep. causes VG Na channels to open, causing AP
dampening olfaction pathway
- 4 WAYS
- very strong smell - lots of Ca enters
1) Ca binds to CALMODULIN - Ca-calmodulin complex decreases cAMP affinity of Ca/Na channel
2) Ca-calmodulin complex activates Cam Kinase ll which decreases activity of CA (turning ATP to cAMP)
3) ___ phosphorylates PDE to activate production of AMP from cAMP (degrades cAMP)
4) G-protein receptor kinase (GPK) decreases odorant receptor affinity
tasting salty pathway
- Na enters
- Ca enters
- release glutamate
tasting sour pathway
-H+ binds K channel, blocking it
- K does not leave cell
- Ca enters
release glutamate
tasting bitter pathway
- tastant binds receptor
- transducin activated
- activates PLC
- PIP2 -> IP3
- IP3 opens Ca channel
- dep, release glutamate
tasting sweet pathway
- tastant binds receptor
- gusducin activated
- activates AC
- ATP -> cAMP
- activates PKA
- closes K+ channels, K cannot leave
- Ca enters
- release glutamate
photopigment
chromophore + opsin
- changes conformation when it absorbs light
chromophore
converts from cis to trans
opsin
determines which
rhabdomeric photoreception pathway
- light hits 11-cis retinal, changes it to all-trans retinal
- opsin is activated, activates Gq -protein
- G protein activates PLC
- PLC converts PIP 2 to DAG
- DAG activates Na/Ca channel to open, causing dep.
ciliary photoreception pathway
- light hits 11-cis retinal, changes it to all trans retinal
- opsin is activates, activates transducin
- transducin activates PDE
- PDE converts cGMP to GMP
- lack of cGMP causes blocking of Na channel, causing hyperpolarization
how to detect a colour
- 3 types of cones (BGR)
- each come maximally absorbs a different wavelength
- brain compares the RATIO between the absorbance of each of the photoreceptors to estimate the wavelength (colour)
which type of shift causes trouble in discriminating colour
one bell curve moving closer to the others
- comparison is harder and harder as the wavelengths look more similar..
rod properties
- high photopigment
- high sensitivity
- low discrimination
- best in low light
- CONVERGENCE (more likely to pick up tiny amount of light)
cones
- low photopigment
- low sensitivity
- high discrimination
- best in high light
- PARALLEL
phasic muscle cells
- twitch
- one cell innervated by one neuron
tonic muscle cells
one muscle is innervated by several motor axons
cross bridge cycling “pathway”
- ATP binds to myosin head
- Myosin head detaches from actin
- ATP -> ADP + Pi
- myosin now in rest phase
- myosin head extends and bings to actin
- P is lost while myosin head performs power stroke
- myosin bound to ADP and actin
- ADP is lost and myosin is bound to actin still
duty cycle
ratio of cross-bridge time:cross-bridge cycle time
- low if spend less time attached
skeletal muscle contraction “pathway”
- Ach binds receptor - Na dep - AP
- propagates through t-tubules
- DHPR on sarcomere changes conformation
- Physically pulls open RyR receptor on SR
- Ca goes into cytosol
- Ca binds to troponin
- Ca-troponin complex binds tropomyosin
- tropomyosin moves off actin binding site
- myosin head can now bind
- (SERCA on SR is pumping Ca back into SR)
factors affecting force of skeletal contraction
1) optimal length
2) frequency of stimulation
3) fiber type
4) arrangement of fibers
tetanus
maintained contraction due to overlapping APs
cardiac muscle contraction “pathway”
- Ach binds receptor - Na dep - AP
- propagates through t-tubules
- DHPR on sarcomere opens
- Ca comes in from extracellular
- dep causes Ryr to open, Ca goes into cytoplasm from SR
- Ca binds to troponin
- Ca-troponin complex binds tropomyosin
- tropomyosin moves off actin binding site
- myosin head can now bind
- (SERCA on SR is pumping Ca back into SR)
cardiac action potential steps
0) Na channels open
1) Na channels
