Weekly Quizes

The Nernst potential for sodium is____ mV, while the Nernst potential for potassium is ____mV. Therefore, the resting membrane potential of a neuron is closer to the Nernst potential for ______.

+60, -90, Potassium

Match the following to the area of the central nervous system it describes: 1. Descending neurons that travel from the cortex to the spinal cords motorneurons/interneurons. 2. Creates the "plan" (or motor image) for an intended motor pattern. 3. Origination of signals (i.e. action potentials) which will be sent to the spinal cord to activate motor neurons necessary for creating a movement. 4. Origination of signals which are involved in activating motor neurons required to support a desired movement (e.g. postural muscles).

1. Corticospinal tract 2. Premotor area 3. Primary motor cortex 4. Supplementary motor cortex

Name the cones that are being stimulated when looking at a white wall.

All of them

A patient sustained a head injury in an automobile accident. Although the use of his muscles returned, the individual could no longer ride a bike or type without watching the keyboard keys. What is a plausible site of damage?

Basal ganglia

Receptive aphasia is a condition where a patient can speak with normal syntax, rate, and intonation, but their words are nonsensical. While speaking or listening to others, they can hear clearly but cannot understand the words. Based on these symptoms, which of the following areas of the brain are likely to be affected?

Dominant Wernicke's area

The year is 2050 and you have been working for years in the field of membrane physiology. New life forms have recently been discovered at the bottom of the ocean whose tiny bodies contain unique ions that have not been identified in other organisms on earth. You are testing the theory that these unique creature's membranes operate using the same principles as human cell membranes. You have identified three unique charged ions, and calculated their Nernst Potentials & concentration gradients E+ concentrated in extracellular fluid with Nernst of +130, T+ concentrated in intracellular fluid with Nernst of -45, and J- concentrated in extracellular fluid with Nernst of -65. The cells produce an action potential with a resting potential of -25mV, threshold of -10mV, peak depolarization of +120, and hyperpolarization of -35. If your theory is correct, and the creature's membrane mechanics match our own, which ion is likely producing depolarization?

E+

_________is described as ion movement across a membrane that requires interaction with a protein.

Facilitated diffusion

While working as a research assistant in the area of rare biological toxins, you come across a toxin that binds to the Na+/K+ ATPase pump, causing a conformational change in the proteins of the pump. When bound to the toxin, the Na+/K+ ATPase pump is non-functional. Answer "true or false" to each of the following statements related to the plausibility of the outcomes in a neuron affected by this toxin, assuming that all Na+/K+ ATPase pumps in the neuron are rendered non-functional? True/False: The concentration of potassium inside the neuron would build up to a level far greater than is typically maintained.

False

True or False: The amygdala is the area of the brain responsible for recognizing people's faces.

False.

The ___________ equation calculates membrane potential of a cell considering the permeability and concentration gradients of multiple ions.

Goldman

What specific chemical binds to taste receptors to produce a 'sour' taste?

H+

what occurs when a nerve is heated?

Na+ channels close more quickly and nerve conduction velocity increases

During an action potential, which ion movement across the membrane is mostly responsible for cell depolarization?

Na+ entering the cell

The uninsulated portions of axon between myelinated sections are referred to as the ________________.

Nodes of ranvier

Another patient you had the opportunity to meet was also experiencing some unique symptoms. She could hear and understand words, but was unable to tell if the speaker was happy or sad. The voices she heard were without expression. Based on her symptoms, which area of the brain might be affected?

Non-dominant Wernicke's area

You are working in a research lab that measures the amplitude and duration of individual action potentials in motor neurons. During a routine data collection, you notice something unique about the pattern of action potentials for one of the subjects. They appear to have a prolonged hyperpolarization phase. Provide an explanation could indeed produce this change in the action potential pattern?

Once the repolarization phase has occurred, potassium ion channels remain open longer than expected.

What following could cause an inhibitory postsynaptic potential (IPSP)?

Opening of chloride channels in the postsynaptic membrane; Opening of potassium channels in the postsynaptic membrane.

In a fatigue research laboratory, subjects were asked to maintain a maximal voluntary contraction. The research staff has been trained to verbally motivate the subject to ensure they reach and maintain maximal contraction. Upon conclusion of the study, researchers found that the inability to maintain contraction was strictly due to an accumulation of lactate and hydrogen ions in the contracting skeletal muscle. This is an example of

Peripheral Fatigue

Consider the plausible outcomes of a toxin that changes the protein structure of the sodium channels on the axons of motor neurons. These structural changes decouple the voltage at which the sodium activation and inactivation gates initiate their movements. Sodium activation gates are now activated at -50mV, and sodium inactivation gates are activated at +10mV. The rate of movement of the gates is not affected. Considering this scenario, indicate which of the following are plausible or not plausible. The toxin-affected motor neurons would have a decrease in the maximal frequency of action potential firing.

Plausible

Consider the plausible outcomes of a toxin that changes the protein structure of the sodium channels on the axons of motor neurons. These structural changes decouple the voltage at which the sodium activation and inactivation gates initiate their movements. Sodium activation gates are now activated at -50mV, and sodium inactivation gates are activated at +10mV. The rate of movement of the gates is not affected. Considering this scenario, indicate which of the following are plausible or not plausible. The amplitude of the action potentials in the toxin-affected neurons would be increased.

Plausible

Name an ion channel on the post-synaptic dendrites of an alpha motor neuron that could be opened by an inhibitory interneuron in a reflex pathway:___________

Potassium

During an action potential, which are the fastest gates to initially open or close?

Sodium activation gates

Summation at the axon hillock is determined by the sum of all the synaptic inputs to the soma & dendrites. The term used to describe the contribution of the same synapse firing multiple times in rapid succession is __________.

Temporal Summation

If the calculated Nernst Equation value is positive, which of the following could be true of the ion under consideration?

The ion is positive with a lower concentration inside the cell; or the ion is negative with a higher concentration inside the cell.

True or false: The neurotransmitter acetylcholine is released by the preganglionic neurons of both the sympathetic and the parasympathetic nervous systems.

True

While working as a research assistant in the area of rare biological toxins, you come across a toxin that binds to the Na+/K+ ATPase pump, causing a conformational change in the proteins of the pump. When bound to the toxin, the Na+/K+ ATPase pump is non-functional. Answer "true or false" to each of the following statements related to the plausibility of the outcomes in a neuron affected by this toxin, assuming that all Na+/K+ ATPase pumps in the neuron are rendered non-functional? True/False: The resting membrane potential of the neuron would become less negative (closer to zero).

True

Imagine a condition in which the number of functioning receptors on the dendrites and soma of a neuron have decreased due to damage. Which of the following treatment options would improve the transmission of the signal between the excitatory presynaptic terminals and the damaged post-synaptic neuron (i.e.: produce a larger graded potential in the damaged neuron)? a. A treatment that increased the number of calcium channels that open following each action potential (in the presynaptic axon terminals). b. A treatment that increased the amount of enzyme available to break down the neurotransmitter in the synaptic spaces. c. Infusion of a drug into the synaptic spaces that is an antagonist for the neurotransmitter. d. Only A and C. e. Only A and B.

a. A treatment that increased the number of calcium channels that open following each action potential (in the presynaptic axon terminals).

Which of the following describe a situation that would increase two point discrimination of a cutaneous sensory receptor? a. Decreased size of the receptive field of sensory receptors b. Decreased lateral inhibition of nearby sensory receptors c. Increased convergence of first order sensory neurons onto second order neurons d. Increased size of the receptive field of sensory receptors

a. Decreased size of the receptive field of sensory receptors

In rare situations, as a treatment for epilepsy and seizures, patients will have a corpus callosotomy. This is a procedure in which the corpus callosum is cut along a sagittal plane. Based on what you know about the brain, which of the following statements is FALSE of patients receiving a corpus callosotomy. a. Patients whose language and motor dominance are on different sides of the brain are likely to experience fewer symptoms related to language and movement than patients whose language and motor dominance are on the same side of the brain. b.Patients may experience a decrease in motor coordination between the right and left sides of the body. c. Patients whose dominant Wernicke's Area is on the left side may have trouble naming an object that they feel only with their left hand. d. All of the above e. None of the above

a. Patients whose language and motor dominance are on different sides of the brain are likely to experience fewer symptoms related to language and movement than patients whose language and motor dominance are on the same side of the brain.

what occurs when a nerve is cooled?

absolute refractory periods lengthen, and Na+ channels are open for longer

The supplementary motor area is involved with:

activation of postural support muscles

What determines the volume of the sound we perceive?

amplitude of the sound wave and efferent effects on outer hair cells

The location in a neuron where graded potentials become action potentials is referred to as the _____________

axon hillock

Which of the following characterizes the I band? a. Also known as the dark band b. Also known as the light band c. Composed of the entire length of the myosin d. Composed of the entire length of the actin e. Only B and D

b. Also known as the light band

Which of the following is true according to the Size Principle? a. When the brain sends a weak signal to the motor neuron cell bodies in the spinal cord, the largest motor units fire first. b. Small motor neurons require less positive charge to reach the threshold required to produce an action potential. c. Very small increases in force can be produced when both small and large motor units are stimulated simultaneously. d. Only A and B. e. Only A and C.

b. Small motor neurons require less positive charge to reach the threshold required to produce an action potential.

In lab several weeks ago, you explored fatigue during prolonged muscle contractions. Many students chose to remove visual feedback from their subjects during a sub-maximal grip (20-40%max) in order to examine 'central fatigue.' Which of the following is the BEST explanation for why this experiment demonstrated central fatigue? a. Seeing visual feedback is motivating, and motivation overcomes central fatigue. When visual feedback is removed, the subject is less motivated to maintain grip force over time and force output is reduced. b. Thermoreceptors and chemoreceptors in the active muscle are sending afferent signals to the central nervous system, and these signals inhibit motor output. With visual feedback, the subject compensates for this inhibition by increasing effort. Without feedback, the subject grips at the same effort, grip force decreases over time, and the effect of this afferent inhibition can be observed. c. Maintaining grip force requires concentration, and when not looking at the screen, the subject becomes distracted. This results in a reduction in neural drive from the CNS. This lower CNS output results in less motor unit recruitment, which causes grip force to go down over time. d. The muscle fibers involved in this sub-maximal grip are highly fatiguable, and over time these motor units stop functioning and grip force decreases. When the subject is looking at the screen, they increase effort to recruit new motor units. When they are not looking at the screen, they do not notice that this muscle fatigue has occurred and grip force decreases.

b. Thermoreceptors and chemoreceptors in the active muscle are sending afferent signals to the central nervous system, and these signals inhibit motor output. With visual feedback, the subject compensates for this inhibition by increasing effort. Without feedback, the subject grips at the same effort, grip force decreases over time, and the effect of this afferent inhibition can be observed.

What determines the speed at which myosin heads produce cross-bridge cycling? a. The rate that the Na+/K+ ATPase pump on the sarcolemma works b. the isoform of myosin ATPase on the myosin head c. the rate that the Ca++ ATPase pump on the sarcoplasmic reticulum pumps Ca++ back into the SR d. All of the above

b. the isoform of myosin ATPase on the myosin head

Which is an appropriate name for the nerve fibers that carry sensory information for sensations such as tickle or slow aching pain? a. A γ b. Ia c. C d. Aβ

c. C

Which of the following is true regarding potassium channels during an action potential in a neuron? a. During the repolarization phase of an action potential, there is net potassium influx. b. The stimulus for the opening of potassium channels occurs at a different membrane potential than sodium channels, which is why they open later c. During the repolarization phase of an action potential, there is net potassium efflux. d. Only A and B e. Only B and C

c. During the repolarization phase of an action potential, there is net potassium efflux.

Which of the following are ligand-gated channels? a. The predominant (most common) type of sodium channels found along the axon of a neuron. b. Calcium channels found at the axon terminal of a neuron. c. Post-synaptic ion channels found on the soma of a neuron. d. All of the above e. only B & C

c. Post-synaptic ion channels found on the soma of a neuron.

Researchers are working to understand a rare disease that affects the ability of the muscles to contract. They have identified that the disease is caused by abnormal gene expression leading to a relatively large intracellular space between the T-tubules and the terminal cisternae in the triad, which causes an interruption in the connection between the dihydropyridine (DHP) receptor and the ryanodine calcium channel. Based on this description of the morphology underlying the disease, which of the following problems would you expect in excitation-contraction coupling? a. An action potential would not be able to be transmitted down the T-tubule. b. Re-uptake of calcium would be blocked, leading to an increase in intracellular calcium. c. The actin binding sites may continue to be blocked by tropomyosin even following an action potential along the sarcolemma. d. All of the above. e. Only B and C.

c. The actin binding sites may continue to be blocked by tropomyosin even following an action potential along the sarcolemma.

Which of the following are true regarding the after-images you observed in the color after-image experiment? a. The same colors are seen due to photoreceptor fatigue b. The complimentary colors are seen due to photochemical remaining in the cones c. The complimentary colors are seen due to depletion of photochemical in the cones c. Both B and C d. None of the above

c. The complimentary colors are seen due to depletion of photochemical in the cones

An experimental drug is given to a group of patients, and among their reported side effects are an increase in sweating, and a rapid heart rate. Which of the following statements are plausible regarding this drug's effects? a. The drug could be an acetylcholine agonist acting on post-ganglionic receptors and target organs of the sympathetic and parasympathetic nervous system b. The drug could be an acetylcholine antagonist acting on post-ganglionic receptors and target organs of the sympathetic and parasympathetic nervous system c. The drug could act centrally to increase sympathetic outflow and decrease parasympathetic outflow d. Only A and C e. Only B and C

c. The drug could act centrally to increase sympathetic outflow and decrease parasympathetic outflow

Name one of the compounds that the enzyme Phosphodiesterase breaks down______

cAMP

When the G protein "Gs" is activated, which second messenger is affected ? ______________

cAMP

In g-protein coupled receptors, the second messenger for Gs is ____and the second messengers for Gq are ____ and ____ .

cAMP; IP3; DAG

In which of the following would the nerve conduction velocity be the greatest? a. A myelinated neuron 20um in diameter at 37C. b. An un-myelinated neuron 20um in diameter at 37C. c. A myelinated neuron 4um in diameter at 25C. d. A myelinated neuron 20um in diameter at 40C.

d. A myelinated neuron 20um in diameter at 40C.

ATPase is an enzyme that breaks down ATP into ADP and Pi. Which of the following statements about ATPase are accurate? a. It is present on the Na+/K+ pump on neuronal cell membranes and the Ca++ pump on the SR in muscle cells b. It is present on the myosin head and required for cross-bridge cycling c. ATP breakdown by ATPase is required to provide energy for active transport d. All of the above e. Only A and C

d. All of the above

An action potential: a. results from movement of Na+ and K+ ions across the neuron's membrane. b. is conducted without decrement (the strength of the signal remains the same throughout its path). c. is the event following depolarization to threshold. d. All of the above e. Only A and C

d. All of the above

Which of the following statements regarding the Na+/K+ ATPase pump are accurate? a. It is an example of active transport b. It helps return the cell membrane from hyperpolarization to resting potential c. It pumps 2 K+ into the cell for every 3 Na+ it pumps out of the cell d. All of the above e. only A & C

d. All of the above

G-protein coupled receptors can contribute to which of the following outcomes? a. Opening of ion channels. b. Activation of intracellular second messengers. c. Phosphorylation or activation of cellular proteins. d. All of the above. e. Only B and C.

d. All of the above.

For a normal resting neuron, in order for an action potential to be initiated at the axon hillock, which of the following must be true? a. A graded potential must reach threshold b. The electrical sum of all excitatory post-synaptic potentials must be more than the sum of all inhibitory post-synaptic potentials c. The membrane potential must become positive d. Only A and B e. All of the above

d. Only A and B

Which of the following is true of both the sense of taste and the sense of smell? a. Both rely on chemoreceptors b. The receptors generate action potentials along their own axons c. Both require an aqueous solution d. Only A and C e. All of the above

d. Only A and C

In the patellar tendon stretch reflex pathway, the Ia afferent sensory neuron synapses directly onto: a. an inhibitory interneuron b. the antagonist muscle α-motor neuron c. the agonist muscle α-motor neuron d. only A and C e. none of the above

d. only A and C

Rigor mortis is a condition that sets in shortly after death. The muscle are held in the same position they were in at the time of death (i.e. they are not able to relax). Using what you know about the role of ATP in muscle contraction (and relaxation), which of the following could contribute to why muscles take on a state of rigor mortis after death? a. Calcium remains in the sarcoplasm because ATP is required for calcium to be re-sequestered back into the SR. b. Cross-bridge cycling will occur continuously. c. The myosin heads cannot be released from the binding sites on the actin filaments without ATP. d. All of the above. e. A and C only.

e. A and C only.

Which of the following are factors that affect the speed of signal transmission? a. Complexity of processing b. Number of synapses c. Distance traveled d. Only A and B e. All of the above

e. All of the above

Which of the following neurotransmitters are released by post-ganglionic sympathetic fibers in at least one location in the body? a. Epinepherine b. Norepinepherine c. Acetylcholine d. Only A and B e. All of the above

e. All of the above

In lab this week, you explored the patellar tendon stretch reflex pathway. Based on your knowledge of the pathway, which of the following are plausible reasons why the Jendrassik maneuver might increase the magnitude of the patellar tendon stretch reflex? a. Increased firing rate of Ia afferents in response to a given strength of stimulus. b. A pronounced excitation of the alpha motor neuron innervating the hamstrings (antagonist) muscles due to an inhibition of the inhibitory interneuron. c. Reduced tonic contractile activity in the antagonist muscles, and therefore a more relaxed state. d. All of the above. e. Both A and C.

e. Both A and C.

In lab this week, you stimulated the median nerve at a variety of intensities and observed the resultant m-wave amplitude. Increasing the current (i.e. stimulus intensity) delivered to a whole nerve that innervates skeletal muscle increased the m-wave amplitude by: a. Increasing the number of α -motor neurons that transmit action potentials. b. Increasing the strength of the action potentials fired by α-motor neurons. c. Increasing the number of muscle cells that are activated. d. All of the above. e. Both A and C.

e. Both A and C.

Which of the following is an accurate description of how graded potentials lead to an action potential? a. Graded potentials typically occur in the axon. b. Action potentials typically occur in the soma. c. Summation of graded potentials typically occurs in the axon. d. Only A and C. e. None of the above.

e. None of the above.

The force of muscle contraction is physiologically controlled by varying which of the following? a. Motor unit recruitment. b. Frequency of stimulation. c. Nerve action potential amplitude. d. All of the above. e. Only A and B.

e. Only A and B.

Which of the following are true about rods and cones? a. Rods are the photoreceptors in the eye most responsible for vision in dim light, night vision, and seeing black and white images. b. Cones are the predominant photoreceptors in the periphery of the retina. c. The colors we see are dependent on the type of cones stimulated d. All of the above e. Only A and C

e. Only A and C

Which of the following are true regarding length/tension relationships in muscle? a. In the sarcomere, the maximal tension occurs at normal resting length b. In the whole muscle, maximal passive tension occurs at ½ normal length c. In the whole muscle, maximal active tension occurs at normal resting length d. All of the above e. Only A and C

e. Only A and C

Which of the following are true about the sodium-potassium (Na+/K+) ATPase pump? a. It uses active transport to move ions against their electrochemical gradient. b. It pumps more potassium out of the cell than sodium into the cell. c. It contributes to maintenance of the resting membrane potential of a cell. d. All of the above. e. Only A and C.

e. Only A and C.

If the equilibrium potential (Nernst potential) for an ion is negative, which of the following could be true of that ion? a. Ion is positive with a higher concentration outside the cell b. Ion is positive with a higher concentration inside the cell c. Ion is negative with a higher concentration outside the cell d. Only A and C e. Only B and C

e. Only B and C

You touch the skin with two points of a caliper 13 mm apart, and the subject is able to perceive both points. Which of the following are possible explanations? a. The two points of the calipers were within two different receptive fields, and both primary sensory neurons converged onto the same secondary sensory neuron b. The two points of the caliper were in overlapping receptive fields and lateral inhibition allowed both points to be distinguished c. The two points of the calipers were within two different receptive fields, and both primary sensory neurons converged onto separate secondary sensory neurons. d. Only A and B e. Only B and C

e. Only B and C

What part of the brain is damaged/non-operational in a person with 'face blindness?'__________

fusiform gyrus

What is the name of the neurotransmitter released by photoreceptors to transmit the signal to the bipolar cells of the retina?

glutamate

What is the name of the neurotransmitter released by photoreceptors to transmit the signal to the bipolar cells of the retina?_________

glutamate

Myelin sheaths that surround nerve axons allow for...

increased nerve conduction velocity and saltatory conduction

What effect does the GαS (G alpha "s" subunit) have on cAMP?

increases cAMP production by increasing adenylate cyclase activity

What type of muscle contraction occurs when cross bridge cycling is occurring but the whole muscle is not changing length?

isometric

area of the brain that olfactory processing connects with

limbic system and hippocampus

What classification of receptor is used in the sense of hearing?

mechanoreceptor

Spatial summation refers to:

multiple graded potentials originating from different locations simultaneously.

What type of receptor is found on the post-ganglionic neurons of the sympathetic nervous system?

nicotinic cholinergic

The ________ refractory period is the time period when it will require a much stronger stimulus to illicit an action potential and corresponds with the _______ phase of an action potential.

relative; hyperpolarization

why does the parasympathetic nervous system is faster to respond than the sympathetic nervous system?

the parasympathetic nervous system has long preganglionic myelinated neurons