Exam 2 Flashcards by Sarah Anderson

What kind of neuron is efferent? (Unipolar, Bipolar, or Multipolar)

Multipolar

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True or False

Action potentials travel faster in thinned neurons

False

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How do signals spread through electrical synapses?

By diffusion of ions through gap junctions

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Match the channel type to its typical function in neurons: Ligand-Gated ion channels

Generation of graded potential

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Match the channel type to its typical function in neurons: Voltage-gated Potassium channels

Termination of action potential

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Match the channel type to its typical function in neurons: Voltage-gated Sodium channels

Generation of action potential

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Match the channel type to its typical function in neurons: Voltage-gated Calcium channels

Release of neurotransmitters

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Myelin speeds up signal transmission by…

Prevention of ion loss through the membrane

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Nicotine ______ acetylcholine receptors that are _____

Activates, ionotropic

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True/False

Neurotransmitters don’t get released into the cleft

TRUE, vesicles only open up and release the neurotransmitter but do not come out into the synaptic cleft, as they are larger than the width of the gap

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What is the mechanism of neurotransmitter uptake?

By sodium-coupled transport

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How can inhibition of acetylcholinesterase alleviate curare poisoning?

By increasing the concentration of acetylcholine, so it would displace curare

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Rest and digest are controlled by what specific nervous system?

Parasympathetic

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Parasympathetic responses are mediated by acetylcholine, which bind to _______ receptors on target organs.

Muscarinic

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Skeletal muscle acetylcholine receptors are _____ type

Nicotinic

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How are hydrophobic hormones carried through the blood?

Complexed with proteins

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What happens after water-soluble hormones bind to receptors?

Hormone-receptor complexes are taken into the cell

Signaling by the second messengers is initiated

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What is the specialized organ for detection of pheromones?

Vomeronasal organ

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Exocytosis of insulin is stimulated by ______

Calcium

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True/False

Upregulation of glucose transporters is stimulated by cystolic calcium increase

FALSE

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True/False

There is movement in isometric contraction

FALSE

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True/False

Passive force contributes to resistance in both stretching and compression

FALSE- it only contributes in stretching

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A twitch lasts longer than calcium elevation. The possible reason is that interaction between Troponin and calcium is characterized by what?

Low dissociation rate

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The processes that occur both in neurons and skeletal muscle cells include all except:

a) The ability to generate action potential
b) Fusion of vesicles with the plasma membrane
c) The presence of molecular motors
d) Participation of calcium in a critical function

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What property of a muscle is most critical for generation of small, precise movements?

Small motor units

What property of asynchronous muscles of flying insects is responsible for the high frequency of wing beat?

Activation by stretch

What is the direct function of calmodulin in the smooth muscle?

Activate an enzyme that activates myosin ATPase

What is the significance of the initial segment? What biochemical feature enables this task?

It's the site where action potential is initiated due to the high density of the voltage-gated channels.

What types of cells produce Myelin?

Oligodendrocytes in the brain and Schwann cells in the PNS

Why does myelin speed up signal propagation?

The time consuming process of action potential generation occurs only at specific points along the axon.

How is the neurotransmitter removed from the synaptic cleft?

- It can diffuse away from the synaptic cleft - It can be taken up by the presynaptic neuron for reuse - Enzymatically degraded

What channels are responsible for excitatory post-synaptic integration?

Na+ or nonspecific cations

What receptors affect stimulation of acetylcholine?

Muscarinic receptors

What type of neuron takes information from the sensory organs toward the CNS and what is their morphology?

Afferent (sensory) neurons, unipolar or bipolar

What type of neuron takes information from the CNS and sends it to muscles/glands? What is their morphology?

Efferent (motor), multipolar

What type of neuron takes information from the CNS and moves it around in the CNS?

Interneurons (multipolar or other morphology)

Where do action potentials in neurons originate?

Trigger zone

How can action potential be sped up?

Increasing axon diameter and/or insulating the axonal membrane

What are the Nodes of Ranvier?

Myelin free areas within myelinated neurons that allow ion exchange for action potential

True/False | The fastest neurons are myelinated

True

Which are faster, electrical synapse or chemical synapse? What is a drawback to this?

Electrical synapses are faster, but they allow little control over how the signal is processed

What is the main type of synapses?

Chemical

True/False | In electrical synapses, chemical signal is converted into electrical signal.

False, in chemical synapses, electrical synapses are converted into chemical signals.

What occurs when action potential arrives at the terminal?

Depolarization

A signal is interpreted as pain because...

It arrives at a special part of the brain

All of the following might in principle be considered for pain treatment except the one that just doesn’t make sense. Which one is that? a) Blockers of sodium channels b) Blockers of potassium channels c) Blockers of glutamate receptors d) Blockers of TRPV1

B) Blockers of potassium channels, because blocking potassium channels would stimulate depolarization and transmission of pain signals.

Frequency coding of nerve impulses has to do with....

Relative refractory period. Early during the relative refractory phase, only strong stimuli can produce another action potential, but weak stimuli have to wait longer, until the relative refractory period is almost over. Thus, strong stimulation will cause more rapidly repeating pulses

True/False | Pain is transmitted by efferent neurons

False, afferent

The refractive index of the eye lens is higher than that of the cornea; nevertheless, in terrestrial animals, cornea’s contribution to light refraction and focusing is greater than that of the lens. The main reason for that is:

The cornea faces air on one side

For every 10 dB, how much does loudness increase?

Two-fold

To what color is the eye most sensitive in daylight?

Green

What is the purpose of the ciliary muscle?

To change the shape of the lens

What physical quantity corresponds to sound pitch?

Frequency of sound waves

True/False | Opsins modify light absorption by retinal

True

Examples of exocrine secretion

Saliva, bile, tears

How does autocrine signaling contribute to tumor growth?

Tumor cells secrete EGF that stimulates their growth

Why does quorum sensing require low-affinity receptors?

To avoid saturation binding. If saturation is achieved, the cell can no longer detect concentration differences

Epithelial cells grown in culture release lactic acid and ammonia that inhibit cell growth. What type of signaling does this represent?

Quorum sensing

Why is ATP a suitable molecule to serve as an injury sensor?

Cells contain much higher concentration of ATP than do extracellular fluids, therefore injury causes it to come out.

Name at least two properties common to all hormones

Delivered through the blood, act at low concentrations, most secreted by specialized organs

What happens to hormone receptors after binding to a hormone?

Receptors are endocytosed and recycled back into the membrane

True or False | The rate of hormone removal is independent of its rate of infusion.

False, hormone removal rate is dependent on rate of infusion

What would happen if the affinity of the carrier protein for a hormone is too high?

The hormone would be unavailable to tissues

What would happen if the affinity of the carrier protein for hormone is too low?

Much of the hormone would be lost before it reached its target

What prominent tissue is unaffected by the autonomic nervous system?

Skeletal tissue

What is the difference between skeletal muscle fiber and myofibril?

Myofibrils are inside muscle fibers

Are motor neurons afferent or efferent?

Efferent

What is the end-plate potential?

Depolarization of the motor end plate caused by binding of the neurotransmitter

Which neurotransmitter produces end-plate potential?

Acetylcholine

“... inward Cl-current contributes to repolarization”. Why is it inward?

Depolarization shifts the equilibrium for chloride, creating an inward driving force

How is DHPR gated?

Voltage gated

Most of the fuel for slow-twitch fibers is delivered by...

Blood

What is the advantage of force control by motor unit recruitment?

Large range of forces are possible

What is the difference between passive and active tension in the muscle?

Active tension depends on myosin-actin interactions; passive tension is mostly due to titin and collagen. Its origin is the same as tension in a stretched rubber band.

How is ryanodine receptor gated in skeletal muscle?

Partly voltage-gated, partly ligand-gated

Why does isometric twitch start sooner than isotonic twitch?

Response in an isotonic twitch experiment starts only after active tension develops enough to exceed the load. Response in an isometric twitch is detectable as soon as myosin becomes active.

How does contraction of one insect muscle cause stretching of the other?

By being bound to the same thoracic structure

Would you expect a higher lactate dehydrogenase activity in fast-twitch or slow-twitch fibers?

Higher in the fast twitch fibers that depend on glycolysis.

How is it possible for Ca2+to depolarize the membrane in smooth muscle cells if its concentration is so low?

It takes only a micromolar increase

What in the skeletal muscle is analogous to varicosities?

Motor end-plate

Why do twitches in smooth muscles last longer?

The rate of Ca2+removal in smooth muscle is much slower

What is the difference between phasic and tonic smooth muscle?

Tonic muscle is usually in the contracted state; phasic muscle contracts only occasionally.

“Other smooth muscle cells do not generate action potentials at all.” What type of muscle could it possibly be?

Tonic

What are the two function of ATP in smooth muscle activation?

Phosphorylation of myosin light chain and force generation

What would be the effect of potassium channel blockers on smooth muscle activation?

More potassium would stay inside, and that would cause depolarization of the muscle and contraction

Is the receptor potential of agraded or of anaction type?

Graded

What is the basis of frequency coding?

Strong stimuli can overcome relative refractoriness faster

What is the morphological type of the primary pain-sensing neurons?

Pseudounipolar

Whattype of gating is used in TRPV1?

Ligand and temperature

What is the main target of local anesthetics?

Na channels

The two essential characteristics of a lens that determine its ability to form an image are...

Curvature and refractive index difference with the surrounding medium

What are the two elements of the eye that cause ray bending?

Cornea and lens

What biological property of the eye lens makes it bend the light?

High concentration of protein (crystallin)

What causes color blindness?

Defect in cones

What is the difference between farsightedness and presbyopia?

Farsightedness: short eyeball; presbyopia: stiff lens

Why is the theoretical vision acuity better in blue light than in red light?

Smallest resolvable distance is proportional to wavelength

How do fish get around the problem of weak refraction at the cornea?

By having a spherical lens with high refractive index

What happens at resonant frequency?

The amplitude of vibrations increases

What characteristic of the acoustic wave corresponds to loudness?

amplitude

Which parts of the basilar membrane respond to high-pitch sounds?

Near the base

What is the advantage for a moth to have low-sensitive A2 receptors?

They become activated only when a bat is near and induce a different type of escape behavior

What is the purpose of the lateral line?

Sensing vibrations of water created by predator, prey, or other fish in the same school