BMS 300- Exam 2 Quizzes

What would the equilibrium potential be for K+ if there were equal concentration inside and outside the cell?

0

Vagus stuff

Acetylcholine

All or nothing

Action Potential

Unmyelinated axons

Action potentials propagate at 1 m/s (slow)

K+ leak channels

Always open

What is an equilibrium potential?

An equilibrium potential is when the electrical gradient is equal and opposite to the chemical gradient.

Dorsal column medial lemniscus

Ascend the spinal cord in the dorsal columns

Cells that maintain the extracellular environment in the central nervous system by pumping sodium and potassium ions and mopping up excess neurotransmitter are:

Astrocytes

What are the 3 types of glia and where are they found?

Astrocytes and Oligodendrocytes are found in the CNS. Schwann cells are found in the PNS.

Location of the output region of a sensory neuron

CNS

The Nernst potential equation depends on:

Charge on ions Concentration of ions outside the cell Concentration of ions inside the cell Temperature

Axon

Conductile Region characterized by volatage gated channels

What sensation types are carried by DCML pathway? What about the spinothalamic tract?

DCML carries proprioception and fine touch sense. The spinothalamic tract carries pain, pressure, and temperature sense.

Membranes that are "leaky" due to a large number of K+ leak channels or the opening on Cl- channels has what effect on membrane resistance?

Decreases

In a descending pathway, neurons cross the midline at the...

Decussation of the pyramids

Input, Conductile, and Output regions

Dendrite, Axon, Terminal

Graded

EPSP

The ion that is responsible for vesicular release at the axon terminal is:

Extracellular Ca2+

T or F: Action potentials can add together to make stronger action potentials.

False

T or F: Voltage and membrane resistance are inversely proportional to eachother.

False

T or F: An adequate amount of negative charge must arrive at the trigger zone in order to reach threshold.

False We want positive charge to reach the trigger zone

T or F: Only the dendrite or input region of a neuron has ion channels.

False, there are ion channels throughout the axon and in the axon terminal as well.

Number of action potentials per second

Frequency coding

When ______ binds to enough ligand-gated ionotropic channels, Cl- becomes the ion with the dominant permeability.

GABA

Collection of neuronal cell bodies in the PNS

Ganglion

In the knee jerk reflex (patellar tendon)arc described in lecture, where do we find a graded generator potential?

Graded generator potentials are excitatory potentials in sensory receptors. Only the stretch receptor on the primary sensory afferent.

Dendrite

Input region Charactarized by ligand gated channels

What channel is responsible for setting the resting membrane potential?

K+ leak channel

Internodal region

Lacks voltage gated Na+ and K+ channels

A neuron has K+ leak channels that are always open. If this is the case, why is there much more K+ inside of the cell (~100 mM) versus outside of the cell (~10 mM)?

Large anions create an electrical gradient that pulls on K+ in the cell, working opposite the chemical concentration gradient.

Post-synaptic membranes are enriched with _________ channels. In the spinal cord, the neurotransmitter glycine may bind to these channels, causing an ______ due to __________ influx.

Ligand-gated, IPSP, anion

SNAP-25

Membrane associated protein tied into the membrane by fatty acids

What are aspects that affect the propagation velocity?

Membrane capacitance Electromagnetic field

Which are true about muscle cells?

Multinucleated Contain t-tubules The plasma membrane is called the sacrolemma The sarcoplasmic reticulum contains a high concentration of Ca2+

If the inside of the neuron were positive, the electrical driving force on sodium would be...

Na+ is positive. If the inside of the neuron is positive the electrical driving force on sodium will be out of the neuron.

In resting condition, _________ is high outside the cell and ________ is high inside the cell.

Na+, K+

Bundle of conductile regions in the PNS

Nerves

Where the neuron innervates the muscle fiber

Neuromuscular Junction

For an excitatory synapse _________________ is released from the presynaptic cell and binds to ligand-gated ionotropic channels in the postsynaptic cell. This allows for ___________ ions to enter the postsynaptic cell.

Neurotransmitter, Na+

Collection of neuronal cell bodies in the CNS

Nucleus

If the resting membrane potential of a cell was +70 mv, the electrical driving force on sodium would be...

Out of the neuron

Axon Terminal

Output Region characterized by SNARE proteins

Location of the conductile region of a sensory neuron

PNS

When gated Na+ channels close, what ion is responsible for bringing the membrane back to resting membrane potential?

Potassium (K+)

What two ions are responsible for establishing an equilibrium between the electrical and chemical gradients?

Potassium (K+) Anions

Upper Motor Neuron

Pre-central gyrus

At rest, the membrane potential is maintained near -70 mV. In order to fire an action potential, enough positive charge has to enter the cell to reach threshold ( around -55mV). What is true regarding the amount and form of that positive charge?

Proportionally, very little Na+ has to enter the cell in order to achieve threshold and therefore an action potential.

The fast axoplasmic transport includes proteins from the __________ and transported on ___________. The slow axoplasmic transport includes proteins from the ____________.

RER, microtubules, cytoplasm

The opening of axon membrane voltage-gated potassium channels is responsible for which part of the action potential?

Repolarization of the axon

Imagine we create a mutant mouse that lacks voltage-gated potassium channels. Which of the following would occur?

Repolarization would occur less quickly. Without the voltage-gated potassium channels, the only way for the cell to repolarize is through the potassium leak channels. However, there are not as many leak channels and the process would be much slower.

Primary Afferent

Sensory Ganglia

EPSPs from numerous synaptic sites providing the necessary charge to bring the membrane potential to threshold is an example of:

Spatial Summation

Capacitor

Storage of charge across a non-conducting medium

Generator potentials are initiated by the opening of:

Stretch activated channels

Site where neurons communicate with eachother

Synapse

Spinothalamic tract

Synapses on a second order neuron in the dorsal horn

According to the SNARE hypothesis, Ca2+ binds to ______________ which is the calcium sensor.

Synaptotagmin

Tertiary Sensory Afferent

Thalamic Relay Nucleus

Which of the following is correct when describing ion distributions in neurons?

The concentration of Na+ is higher in the extracellular space in the cytoplasm

During reciprocal inhibition, the inhibitory interneuron synapses on a lower motor neuron (LMN) that then sends inhibitory information to what muscle group?

The opposing muscle group

What is true about threshold?

The rate of Na+ influx is equal to the rate of K+ efflux

The resting membrane potential is approximately:

The resting potential is -70 mv, meaning the inside of the cell is negative relative to the outside.

Which is not true about muscle cells?

The sarcoplasmic reticulum and the t-tubules are physically fused with one another

At chemical synapses, _________ primarily dictates the postsynaptic response.

The type of receptor that binds the neurotransmitter always dictates the response.

Which are true about myelinating glial cells?

They provide insulation They physically surround neurons

Where did transmembrane channels in the axon terminal come from?

They were synthesized on bound ribosomes in the cell body and carried via fast axoplasmic transport

Bundle of conductile regions in the CNS

Tracts

Syntaxin

Transmembrane

Ca2+ binds to ____________________, which rolls __________________ out of the way. This allows myosin to bind the myosin binding sites located on the actin thin filaments.

Troponin C, tropomyosin

T or F: A motor unit is defined as a lower motor neuron and the group of muscle fibers it innervates.

True

T or F: All good primary sensory afferents leave their cell bodies outside the central nervous system in a dorsal root ganglion and do not cross the midline.

True

T or F: Myelin reduces membrane capacitance by increasing the thickness of the membrane and thus increasing the separation of cations and anions.

True

T or F: The membrane potential seeks the equilibrium potential of the ion whose permeability is dominant.

True

A protease, which is an enzyme that destroys peptide bonds, is added to the axoplasm. Its effect is to remove the inactivation gates on VG sodium channels. Without the ball and chain, what would the effect be on the membrane potential?

Upon stimulation, the membrane would deploarize but would take much longer to repolarize back to resting potential.

At the regions called Nodes of Ranvier are what channels exclusively located?

VG K+ channels VG Na+ channels

During depolarization, the dominant channel that is open is the ____________ channels . During repolarization, the dominant channel that is open is the ____________ channels.

VG Na+, VG Na+

Lower Motor Neuron

Ventral Horn

The channel that delivers positive charge to the narrow gap between the T-tubule membrane and the sarcoplasmic reticulum is:

Voltage Gated Na+ channel

_____________ nerves carry information ___________ the brain.

afferent, toward efferent, away from

Generator potentials produced in the input region of sensory neurons:

are graded with the strength of the stimulus

To clear neurotransmitter from the synaptic cleft in the central nervous system, there are cells that contain transmembrane proteins that simultaneously bind Na + and the neurotransmitter glutamate. This transmembrane protein then simultaneously transports them into the cell's cytoplasm. The cell type where you would expect to find such transporters would be the:

astrocyte

In regards to the spinothalamic tract, where does the second order neuron cross the midline?

at the brainstem

Protein syntesis occurs in the:

cell body

Third order neuron

cell body in the thalamic relay nucleus, axon extends up to the somatosensory cortex

Santiago Roman y Cajal

cellularist

Cell body

characterized by protein synthesis organelles

When measurements are taken along an unmyelinated axon where the voltage gated channels are clustered at one site, we see a decrease in voltage as we move down the axon. Why do we see this decrease?

charge leaves through K+ leak channels

Radioactive amino acids incorporated into the proteins were rejected into the retina of a rabbit. After measuring the radioactivity and distance after a couple of experiments, two moving peaks were observed. The first peak moved 0.5-2 mm/day indicating that those are _________________ proteins which took up the radioactive AA whereas the second peak moved 200-400 mm/day indicating that those are _________________ proteins which took up the radioactive AA.

cytoplasmic, transmembrane

Na+ ions pass through their voltage gated channels and causes a conformational change in the _____________________. The conformational change allows for the ryanodine receptors to become unplugged and Ca2+ can now leave the _____________________.

dihydropyradine receptor, sarcoplasmic reticulum

The tendon tap reflex can be elicited by a stretch in a muscle. What is the order of information flow from the primary sensory afferent to the lower motor neuron?

dorsal root, dorsal root ganglion, dorsal horn, ventral horn

Clusters of neuron cell bodies in PNS

ganglia

In the functional classification of the neuron, neurons with their cell bodies in the dorsal root ganglion have their input regions in the:

gray matter of the spinal cord peripheral nervous system

What is true about Action Potentials?

information is coded through the frequency of Action Potentials they always have the same amplitude and duration

Slow axon-axoplasmic transport of cytoplasmic proteins is a result of:

intermittent fast transport

At chemical synapses, neurotransmitter predominantly opens _____________ in the ___________.

ligand gated channels, postsynaptic element

A hyperpolarized cell can be generated when:

ligand-gated ionotrophic channels for Cl- open

If you have a lesion affecting the entire left side of the spinal cord, as is the case with Brown Sequard Syndrome, what symptoms would you expect to see?

loss of proprioception on the left loss of pain on the right

You would predict that electrical stimulation of two neighboring neurons in the right precentral gyrus would cause:

muscle contraction in widely different areas of the left side of the body

The concentric rings formed by oligodendrocytes are called:

myelin

Collections of neuron conductile regions in the PNS

nerves

Clusters of neuron cell bodies in CNS

nuclei

Schwann cells are located in the ____________ and oligodendrocytes are found in the ____________.

peripheral nervous system (PNS) central nervous system (CNS)

Cell bodies of efferent neurons are found in the:

precentral gyrus ventral horn of the spinal cord

There is a type of toxin found in the liver of the puffer fish that prevents the opening of voltage-gated Na+ channels in neurons. The effect of this toxin is to:

prevents the initiation of the action potential

Action potentials will pass much more _________ along a myelinated axon, as opposed to an unmyelinated axon. This is because myelin ______________ membrane resistance.

rapidly, increases

Camillo Golgi

recitalist

What are functions of Astrocytes?

regulate extracellular K+ concentrations clear out excess amounts od neurotransmitters surround the synaptic cleft between neurons

The chemical connection between the output and input regions of two neurons is called a __________.

synapse

Osmium is a heavy metal used in tissue staining. It binds to lipids and turns black. Which of the following would expect to be stained the LEAST?

the cerebral cortex the dorsal root ganglion

Proteins are transported via axoplasmic transport at slow rates (0.5 to 2 mm per day) and fast rates (200 to 400 mm per day). The difference in transport rate directly results from:

the difference in the time spent per day in transport by kinesin on microtubules

The point at which K+ efflux equals Na+ influx is known as:

threshold

Collections of neuron conductile regions in the CNS

tracts

Molecules transported in the fast phase of axoplasmic transport are:

transported in vesicles synthesized on rough ER

For a disease where only motor neurons (somatic efferent neurons) die, you would expect to observe neuronal cell death in the:

ventral horn of the spinal cord