BIOS 276 Multiple Choice Exam 2
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57 Terms
If two excitatory postsynaptlc potentials (EPSPs) occur at the same synapse in rapid succession before the first response fully dissipates, what type of summation is occurring?
Temporal summation
3 multiple choice options
What neurotransmitter is responsible for synaptic transmission at the vertebrate neuromuscular junction?
Acetylcholine
3 multiple choice options
What is the specialized term for an EPSP occuring at the vertebrate neuromusculuar junction?
Endplate potential (EPP)
3 multiple choice options
What best describes the receptors that respond to acetylcholine at the neuromuscular junction?
They are ligand-gated ion channels that open when acetylcholine binds to them
3 multiple choice options
The reversal potential of the ACh receptor at the neuromuscular junction is:
Midway between ENa+ and EK+ due to equal permeability to Na+ and K+
3 multiple choice options
What does the term "quantum" refer to in the context of Katz's quantal hypothesis?
The amount of neurotransmitter released from a synaptic vesicle to generate one miniature postsynaptic response
3 multiple choice options
What is the role of Ca++ in neurotransmitter release at the synaptic terminal?
Calcium entry into the presynaptic terminal triggers the fusion of synaptic vesicles with the membrane, releasing neurotransmitters.
3 multiple choice options
Where are Voltage-gated Ca++ channels located in a motor neuron?
Axon terminal boutons
3 multiple choice options
What is the role of synapsin in synaptic vesicle function?
Synapsin binds vesicles to actin filaments, anchoring them in place within the axon terminal.
3 multiple choice options
What is the role of SNARE proteins in neurotransmitter release?
SNARE proteins are responsible for the docking of vesicles at the presynaptic membrane and promoting vesicle fusion.
3 multiple choice options
What are the two major types of lonotroplc glutamate receptors?
AMPA and NMDA
3 multiple choice options
What role do AMPA receptors play In NMDA receptor activation?
They are a potential source of the initial depolarization needed to remove the Mg++ block
3 multiple choice options
What is the function of the autoinhibitory domain in CaMKII?
It blocks the catalytic domain to keep the enzyme inactive under basal conditions
3 multiple choice options
What typically happens when GABA or glycine binds to their receptors on neurons?
Cl- conductance increases
3 multiple choice options
Why is CREB necessary to induce late long-term potentiation (LTP)?
CREB stimulates the synthesis of proteins that support the maintenance of synaptic strength
3 multiple choice options
Which protein primarily makes up the thin filaments in a sarcomere?
Actin
3 multiple choice options
What is the I-band in a sarcomere?
The region containing only actin filaments
3 multiple choice options
How does Ca++ initiatemuscle contraction?
By binding to troponin, which pulls on tropomyosin and exposes myosin-binding sites.
3 multiple choice options
What is the role of T-tubules in excitation-contraction coupling?
They conduct the muscle action potential from the surface membrane to the sarcoplasmicreticulum
3 multiple choice options
What is the role of the ryanodine receptor in muscle contraction?
It transports calcium into the sarcoplasm when activated by the DHPS receptor
3 multiple choice options
Which cells in the retina are responsible for TRANSDUCING (converting) light into cellular voltage changes?
Photoreceptors
3 multiple choice options
The two main types of photoreceptor cells in the retina are:
Rods and cones
3 multiple choice options
Rods are specialized for:
Detecting dim light and night vision
3 multiple choice options
What is the ligand that opens Na+ channels in photoreceptors?
Cyclic guanine monophosphate (cGMP)
3 multiple choice options
What happens to the membrane potential of a photoreceptor in response to light?
The membrane hyperpolarizes
3 multiple choice options
What is the role of transducin in the phototransduction cascade?
It activates phosphodiesterase, which lowers cGMP levels
3 multiple choice options
Which cell types in the retina transmit information via action potentials?
Ganglion Cells only
3 multiple choice options
An "on-center, off-surround" receptive field responds BEST when:
The entire center is illuminated and the surround remains dark
3 multiple choice options
What is the primary difference between excitatory and inhibitory synapses made by photoreceptor cells on bipolar cells?
The postsynaptic receptors on bipolar cells
3 multiple choice options
The cone photoreceptors are uniformly distributed across the retina to impart a complete sense of color
False
1 multiple choice option
Which of the following occurs when multiple postsynaptic potentials arrive at the same time from different locations on the neuron and are added together?
Spatial summation
3 multiple choice options
If a single quantum of neurotransmitter is spontaneously released at the neuromuscular junction, you will record a(n) __________in the muscle cell
MEPP
3 multiple choice options
Which protein acts as the calcium sensor for synaptic vesicle fusion in neurotransmitter release?
Synaptotagmin
3 multiple choice options
What is the reversal potential of a receptor that is permeable to both Na⁺ and K⁺?
A value midway between the Na⁺ and K⁺ equilibrium potentials (-15 mV)
3 multiple choice options
Which protein binds Ca++ to initiate skeletal muscle contraction by causing a
conformational change that moves tropomyosin away from myosin-binding sites?
Troponin
3 multiple choice options
Long term potentiation arises from_________stimulation, and __________ activity
High frequency, CaMKII
3 multiple choice options
LTD is driven by low-frequency stimulation and the preferential activation of:
Protein phosphatase
3 multiple choice options
What triggers the release of calcium from the sarcoplasmic reticulum during muscle stimulation?
The action potential traveling down T-tubules
3 multiple choice options
Which enzyme is activated by transducin to convert cGMP to 5'-GMP in the phototransduction cascade?
Phosphodiesterase (PDE)
3 multiple choice options
What part of the eye contains predominantly cone photoreceptors?
Fovea
3 multiple choice options
In the on-center circuit, what is the result of the photoreceptor's hyperpolarization?
Decreased release of inhibitory neurotransmitter
3 multiple choice options
The lateral geniculate nucleus (LGN) receives input from retinal ganglion cells, projects to the primary visual cortex, and is organized into 4 layers receiving binocular input
False
1 multiple choice option
How is orientation specificity organized in the visual cortex?
In columns, where cells along a perpendicular electrode penetration share the same orientation preference
3 multiple choice options
How do end-stopped cells respond to light in their receptive field?
They respond to motion and bars of light with the correct orientation and appropriate length
3 multiple choice options
Retinal ganglion cell axons in the nasal half of the retina of each eye:
Cross over to the contralateral side of the brain
3 multiple choice options
How many types of cone photopigments are there in humans?
3
3 multiple choice options
What is the light-absorbing photopigment found in rod cells?
Rhodopsin
3 multiple choice options
What is a receptive field in the visual system?
The circular area of visual space that influences a single ganglion cell's activity
3 multiple choice options
What is associative strengthening?
Strengthening of a synapse when it fires simultaneously with a strongly stimulated synapse
3 multiple choice options
What happens to AMPA receptors during LTP?
Their single-channel conductance increases, and more are recruited to the synaptic membrane
3 multiple choice options
What is the name of the region in the sarcomere that contains only thick filaments and no thin filaments?
H-zone
3 multiple choice options
Which protein primarily makes up the thick filaments in a sarcomere?
Myosin
3 multiple choice options
What is the role of the ryanodine receptor in muscle contraction?
It transports calcium into the sarcoplasm when activated by the DHPS receptor.
3 multiple choice options
What is the neuromuscular junction?
A synapse between a motor neuron and a skeletal muscle fiber
3 multiple choice options
What is the quantal hypothesis proposed by Katz?
The concept that the endplate potential is the result of simultaneous release of many "quanta" or vesicles containing acetylcholine
3 multiple choice options
Retinal ganglion cell axons from the temporal half of the retina of each eye:
Remain on the ipsilateral side of the brain
3 multiple choice options
True or False: Each layer of the LGN contains neurons that are exclusively innervated by either the left
or right eye but not both.
True
1 multiple choice option
Note 
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