Exam 2 Flashcards
What kind of neuron is efferent? (Unipolar, Bipolar, or Multipolar)
Multipolar
True or False
Action potentials travel faster in thinned neurons
False
How do signals spread through electrical synapses?
By diffusion of ions through gap junctions
Match the channel type to its typical function in neurons: Ligand-Gated ion channels
Generation of graded potential
Match the channel type to its typical function in neurons: Voltage-gated Potassium channels
Termination of action potential
Match the channel type to its typical function in neurons: Voltage-gated Sodium channels
Generation of action potential
Match the channel type to its typical function in neurons: Voltage-gated Calcium channels
Release of neurotransmitters
Myelin speeds up signal transmission by…
Prevention of ion loss through the membrane
Nicotine ______ acetylcholine receptors that are _____
Activates, ionotropic
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
What is the mechanism of neurotransmitter uptake?
By sodium-coupled transport
How can inhibition of acetylcholinesterase alleviate curare poisoning?
By increasing the concentration of acetylcholine, so it would displace curare
Rest and digest are controlled by what specific nervous system?
Parasympathetic
Parasympathetic responses are mediated by acetylcholine, which bind to _______ receptors on target organs.
Muscarinic
Skeletal muscle acetylcholine receptors are _____ type
Nicotinic
How are hydrophobic hormones carried through the blood?
Complexed with proteins
What happens after water-soluble hormones bind to receptors?
Hormone-receptor complexes are taken into the cell
Signaling by the second messengers is initiated
What is the specialized organ for detection of pheromones?
Vomeronasal organ
Exocytosis of insulin is stimulated by ______
Calcium
True/False
Upregulation of glucose transporters is stimulated by cystolic calcium increase
FALSE
True/False
There is movement in isometric contraction
FALSE
True/False
Passive force contributes to resistance in both stretching and compression
FALSE- it only contributes in stretching
A twitch lasts longer than calcium elevation. The possible reason is that interaction between Troponin and calcium is characterized by what?
Low dissociation rate
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
B
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
