meow meow

4. Which of the following statement(s) apply to alpha motor neurons ? a. their axons leave the spinal cord via the dorsal nerve b. their axons are small and non myelimted and innervate intrafusal fibers c. their axons are huge and myelinated and innervate extrafusal fibers d. their are luge and myelinated innervate both intrafusal and extrafusal fibers

c. their axons are huge and myelinated and innervate extrafusal fibers

A motor unit consists of: a. an alpha motor unit and the extrafusal fibers that it innervates b. the combined intrafusal and extrafusal fibers of a given muscle c. an alpha and a gamma motor neuron d. a gamma motor neuron and the intrafusal fibers that it innervates

a. an alpha motor unit and the extrafusal fibers that it innervates

The end plate potential during muscle stimulation is depolarized to -15 mV. What is mechanism this? a. voltage-gated Na+ are activated b. acetylcholine receptors are equally permeable to both Na+ and K+ c. Ca2+ entry via activation of slow calcium channels d. the release of Ca2+ from the sarcoplasmic reticulum

b. acetylcholine receptors are equally permeable to both Na+ and K+

Botulina toxin is a potential weapon of mass destruction. What is it's effect and mechanism of action? a. paralysis by blocking acetylcholine receptors b. paralysis by inhibiting acetylcholinesterase c. paralysis by preventing acetylcholine release from motor nerve terminals d. paralysis by preventing Ca2+ release from the sarcoplasmic reticulum

c. paralysis by preventing acetylcholine release from motor nerve terminals

The release of Ca2+ from the sarcoplasmic reticulum (SR) of skeletal muscle is stimulated by: a. the activation of myosin light chain kinase b. voltage sensing elements in the transverse tubules that activate calcium release channels in the SR c. the formation of cross bridges between actin and myosin d. the hydrolysis of ATP

b. voltage sensing elements in the transverse tubules that activate calcium release channels in the SR (1/23)

The formation of cross bridges and contraction of smooth muscle is initiated by what sequence of events? a. Ca2+ released from the sarcoplasmic reticulum binds to troponin, permitting cross bridge formation b. Ca2+ entering across the cell membrane binds to troponin, permitting cross bridge formation c. Ca2+ binds to calmodulin in the cytosol, activating myosin light chain kinase d. the depolarization of the transverse tubules stimulated Ca2+ release from the sarcoplasmic reticulum

c. Ca2+ binds to calmodulin in the cytosol, activating myosin light chain kinase (1/23)

Motor neurons that stimulate jaw muscle are located in: a. dorsal nerve roots of the spinal nerves b. ventral nerve roots of the spinal nerves c. the fifth cranial nerve (trigeminal) d. post ganglionic cells of the sympathetic nervous system

c. the fifth cranial nerve (trigeminal)

What statement applies to alpha motor neurons that innervate muscles in the limbs and torso? a. they have large, myelinated axons that leave the spinal cord via the dorsal nerve roots b. they have large, myelinated axons that leave the spinal cord via the ventral nerve roots c. they have small myelinated axons that leave the spinal cord via the dorsal nerve roots d. they have large unmyelinated axons that leave the spinal cord via the ventral nerve roots

b. they have large, myelinated axons that leave the spinal cord via the ventral nerve roots

Which statement about the myoneural junction is false? a. the muscle fiber membrane is folded extensively to increase its surface area b. acetylcholine receptors are located in the muscle fiber membrane c. acetylcholine receptors are located in the membrane of the motor nerve ending d. the release of acetylcholine from the motor nerve is stimulated by the activation of voltage gated Ca2+ channels in the axon terminal

c. acetylcholine receptors are located in the membrane of the motor nerve ending (1/23)

The magnitude of the end plate potential (-15mV) is the result of: a. acetylcholine receptor being permeable to both Na+ and K+ b. the acetylcholine receptor being permeable to Na+ only c. the acetylcholine receptor being permeable to K+ only d. the acetylcholine receptor being permeable to neither Na+ or K+

a. acetylcholine receptor being permeable to both Na+ and K+

Which of the following processes utilizes electronic conduction of positive charge? a. the end plate potential b. acetylcholine vesicle release c. breakdown of acetycholine to acetate and choline d. activation of voltage gated Na+ channels near the motor end plate

d. activation of voltage gated Na+ channels near the motor end plate

The paralytic effect of curare results from: a. blockage of the acetylcholine receptor b. inhibition of acetylcholinesterase c. inhibition of acetylcholine vesicle release d. stimulation of acetylcholine vesicle release

a. blockage of the acetylcholine receptor

Acetylcholinesterase is located in what region of the myoneural junction? a. the motor nerve terminal b. the myelin sheath c. the post junctional (muscle fiber) membrane d. the sarcoplasmic reticulum

c. the post junctional (muscle fiber) membrane

A motor unit consists of: a. all of the skeletal muscle fibers in a given muscle b. individual skeletal muscle fibers in a given muscle c. an alpha motor neuron and the skeletal muscle fibers that it innervates d. the association ofa motor nerve ending and the membrane of a skeletal muscle fiber

c. an alpha motor neuron and the skeletal muscle fibers that it innervates

What kind of motor unit distribution would you expect to find in a muscle that can be finely controlled? a. relatively few motor units, each having a large number of type II (glycolytic) fibers b. relatively few motor units, each having a large number of type I (oxidative) fibers c. many motor units, each having a srnall number of type I fibers d. many motor units, each having a small number of type II fibers

c. many motor units, each having a srnall number of type I fibers

The release of Ca2+ by the sarcoplasmic reticulum of skeletal muscle is triggered by a. depolarization of the motor end plates b. conduction of the action potential away from the motor end plate c. depolarization of the transverse tubules as the result of the action potential d. the phosphorylation of the myosin light chains

c. depolarization of the transverse tubules as the result of the action potential

Cross bridge formation in skeletal muscle results from a. Ca2+ binding to the myosin filament b. Ca2+ binding to the actin filament c. Ca2+ binding to tropomyosin moves troponin from cross bridge formation sites on the actin filament d. Ca2+ binding to troponin moves tropomyosin from cross bridge formation sites on the actin filament

d. Ca2+ binding to troponin moves tropomyosin from cross bridge formation sites on the actin filament (1/23)

During what phase of cross bridge cycling is ATP hydrolyzed to ADP + Pi? a. cross bridge formation between actin and myosin b. during the power stroke where the cross bridges draw the Z bands closer together c. breaking and re-setting the cross bridges d. an ATP molecule must be hydrolyzed during each of the above steps

c. breaking and re-setting the cross bridges (1/23)

The voltage trace shown below is an example of a(n) _________ that might be located in the ________. a. slow response fiber, sinoatrial node b. fast response fiber, ventricular syncytium and Purkinje fibers c. fast response fiber, sinoatrial node d. EKG, the combined electrical activity of the entire heart

b. fast response fiber, ventricular syncytium and Purkinje fibers

During which of the numbered stages in the figure do the L-type Ca2+ channels remain open? a. 0, 1 b. 1, 2 c. 2, 3 d. 3, 4

c. 2, 3

"What statement best describes slow response fibers in the sinoatrial node: a. their resting potential (about -60 mV) is more depolarized than the fast response fibers b. they spontaneously depolarize as the result of the ""funny current"" (If) that becomes activated as the cells depolarize c. they are lacking fast Na+ channels d. all of the above"

d. all of the above

How does the excitation-contraction coupling of smooth muscle differ from that of skeletal or cardiac muscle? a. there is an increase in Ca2+ concentration in the cytosol b. Ca2+ binds to troponin to permit cross bridge formation in smooth muscle c. Ca2+ binds to calmodulin that activates myosin light chain kinase which phosphorylates myosin and permits cross bridge formation d. Ca2+ binds to calmodulin that causes tropomyosin to move away from cross bridge formation sites on the actin filaments

c. Ca2+ binds to calmodulin that activates myosin light chain kinase which phosphorylates myosin and permits cross bridge formation (1/23)

Which of the following statements applies specifically to multiunit smooth muscle? a. the fibers are connected by gap junctions and contract as a syncytium b. the fibers contract independently c. the fibers are innervated by post ganglionic fibers of the sympathetic nervous system d. the contractile proteins are actin and myosin

b. the fibers contract independently

In general, vascular smooth muscle will be stimulated by: a. norepinephrine acting on alpha1 receptors b. norepinephrine acting on alpha2 receptors c. acetylcholine acting on beta1 receptors d. acetylcholine acting on beta2 receptors

a. norepinephrine acting on alpha1 receptors

Intrafusal fibers are associated with: a. stretch receptors that return to the spinal cord via large, myelinated fibers in the dorsal nerve roots b. stretch receptors that return to the spinal cord via small, myelinated fibers in the dorsal nerve roots c. alpha motor neurons that leave the spinal cord via large myelinated fibers in the ventral nerve roots d. stretch receptors that return to the spinal cord via large, myelinated fibers in the ventral nerve roots

b. stretch receptors that return to the spinal cord via small, myelinated fibers in the dorsal nerve roots

The dynamic stretch reflex is mediated by: a. autonomic nuclei in the medulla b. interneurons that connect stretch receptor neurons to alpha motor neurons c. a direct connection between stretch receptor neurons and alpha motor neurons d. a direct connection between stretch receptor neurons and gamma motor neurons

c. a direct connection between stretch receptor neurons and alpha motor neurons

Gamma motor neurons: a. leave the spinal cord via the ventral nerve b. innervate contractile ends of the intrafusal fibers c. are efferent d. all of the above

d. all of the above

Which of the following molecules fits into the helical groove of f-actin and when calcium concentration is low, prevents interaction of actin and myosin? a. troponin b. tropomyosin c. nebulin d. desmin e. light meromyosin

b. tropomyosin (1/23)

Smooth muscle differs from skeletal muscle in that only smooth muscle a. utilizes calcium during contraction b. contains actin c. contains myosin d. is mitotic e. has intercalated discs

a. utilizes calcium during contraction

A group of skeletal muscle fibers bound together by perimysium is known as a. myofiber b. myofibril c. myofilament d. fascicle e. whole muscle

d. fascicle

Which tissue is generally not innervated by the autonomic nervous system? a. smooth muscle of blood vessels b. smooth muscle of the digestive tube c. glands d. skeletal muscle of the biceps e. cardiac muscle

d. skeletal muscle of the biceps

During an action potential in a nerve cell the membrane potential becomes positive (to about +40 mV) for a brief (> 1 millisecond period). What is the basis for this? a. voltage-gated K+ channels rapidly open and then close b. the Na+ K+ pump is inhibited c. voltage-gated Na+ channels rapidly open and then close d. the Na+ and K+ permeability become equal

c. voltage-gated Na+ channels rapidly open and then close (1/23)

What is a common feature of voltage gated Na+, K+ and Ca2+ channels? a. the are all single polypeptides b. they are all made of four subunits, each having a group of 6 transmembrane domains that form a channel c. the have four clusters of six transmembrane domains, each forming a channel d. they have four clusters of six transmembrane domains that, combined, form a channel through the membrane

d. they have four clusters of six transmembrane domains that, combined, form a channel through the membrane

The rapid inactivation (closing) of a voltage-gated Na+ channel results from: a. a positively charge transmembrane domain that can change the open-closed state of the channel b. an extracellular domain that extend into the pore formed by the transmembrane domains of the channel c. a globular component at the amino terminal of the channel protein that can be drawn into the channel d. a single cluster of 6 transmembrane domains that forms a channel through the membrane

c. a globular component at the amino terminal of the channel protein that can be drawn into the channel

"Which ofthe following statements is in best agreement with the quote, temporomandibular pain dysfunction syndrome... appears to be related to defects in occlusion which interfere with neuromuscular coordination...""? a. stretch receptors are lacking in the jaw muscles b. stretch receptors in the jaw muscles are not connected to motor areas ofthe brain c. stretch receptors in the jaw muscles are connected to motor areas of the brain d. the output of stretch receptors in the jaw muscles does not change with defects in occlusion"

c. stretch receptors in the jaw muscles are connected to motor areas of the brain (maybe D? DM)

The release of Ca2+ from the sacroplasmic reticulum (SR) of skeletal muscle: a. is the direct result of the end plate potential propagating down the transverse tubules b. is mediated by Ca ATPase in the SR membrane— c. results from voltage activated Ca release channels locatcd in the SR membrane adjacent to the transverse tubules d. is the result of the dissociation of Ca from troponin

c. results from voltage activated Ca release channels locatcd in the SR membrane adjacent to the transverse tubules

Which of the following properties would you expect from a muscle that has a high percentage of large motor units with type IIb fibers? a. fine control and rapid fatigue b. strong contraction and rapid fatigue c. strong contraction and slow fatigue d. find control and slow mtigue

b. strong contraction and rapid fatigue

Intrafrsal fibers: a. provide most of the contractile strength ofa skeletal muscle b. are innervated by alpha motor neurons c. are innervated by stretch receptors that sense the length of the muscle. d. are themselves stretch receptors that sense the length of the muscle.

c. are innervated by stretch receptors that sense the length of the muscle.

Smooth muscle in the gut forms a fimctional syncytium through electncal coupling of the muscle cells by gap junctions. Which of the following terms best describes this organization? a. multiunit b. single unit c. motor unit d. SI unit

b. single unit (not positive DM)

Which of the following statements explains why the membrane potential at the motor end plate depolarizes to -15 mV when stimulated by acetylcholine (ach)? a. The ach receptor is a channel that is selectively permeable to Na+ b. The ach receptor is a channel that is selectively permeable to K+. c. The ach receptor is a channel that is equally permeable to Na+ and K+ d. The ach receptor actively transports three Na+ out of the cell in exchange for two K+

c. The ach receptor is a channel that is equally permeable to Na+ and K+

The sensitivity of stretch receptors is regulated by which of the following? a. gamma motor neurons that innervate intrafusal fibers b. gamma motor neurons that innervate extrafusal fibers c. alpha motor neurons that innervate extrafusal fibers d. alpha motor neurons that innervate intrafusal fibers

a. gamma motor neurons that innervate intrafusal fibers

"The graph below is an action potential of a ventricular myocyte. What are the ionic bases for the electrical events at number 2 and at number 3? a. #2= increased Na+ permeability, #3= increase in K+ permeability b. #2= increased Ca2+ permeability, #3= increase in K+ permeability c. #2= increased Ca2+ permeability, #3= increase in Na+ permeability d. #2= increased K+ permeability, #3= increase in Ca2+ permeability"

"b. #2= increased Ca2+ permeability, #3= increase in K+ permeability"

The propagation of charge from the motor end plate that depolarizes voltage-gated Na+ channels in the surrounding muscle fiber membrane is rapid; however, it decays rapidly over distance. Which of the following terms describes this property? a. charge propagation b. the refractory period c. active transport d. capacitance

a. charge propagation

During skeletal muscle contraction all of the following occur EXCEPT one. one is the EXCEPTION? (potential delete) a. A-band decreases in width b. I-band decreases in width c. H-zone decreased in width d. Sarcomere length decreases in width

a. A-band decreases in width

Smooth muscle cells differ from skeletal muscle cell in that smooth muscle cells have which of the following? (potential delete) a. multiple nuclei b. are always under voluntary control c. use more energy rapidly d. use energy less rapidly

d. use energy less rapidly (not positive)

Groups of skeletal muscle cells surrounded by a perimysium are known as: a. fascicles b. myofilaments c. myofibrils d. muscles

a. fascicles

Cardiac muscle cells differ from skeletal muscle cells in that ONLY cardiac muscle cells a. contain more than one nucleus b. have transverse tubules entering at the Z-line level c. contain sarcomeres d. are Individually innervated

b. have transverse tubules entering at the Z-line level (pretty sure, DM if not)

The first molecule which changes conformation in response to calcium released from the sarcoplasmic reticulum is which of the following? a. calsequestrin b. troponin c. tropomyosm d. alpha-actinin e. myosin

b. troponin

Smooth muscle cells differ from cardiac muscle cells in that ONLY cardiac muscle cells (potential delete) a. are under voluntary control b. are connected by gap junctions c. store calcium in extracellular locations d. have sarcomeres

d. have sarcomeres

Calcium channel blockers would have which of the following effects on the heart? a. reduced Ca2+ entry during the cardiac action potential will increase Ca2+ release from the sarcoplasmic reticulum and strengthen the heart beat. b. reduced Ca2+ entry during the cardiac action potential will decrease Ca2* release from the sarcoplasmic reticulum, reducing the work and energy requirement of the heart c. reduced Ca2+ removal from the cytosol during repolarization of the ventricles a more depolarized membrane potential and faster heart rate

b. reduced Ca2+ entry during the cardiac action potential will decrease Ca2* release from the sarcoplasmic reticulum, reducing the work and energy requirement of the heart

Which of the following is true of motor neurons or the anterior horn of the spinal cord? a. multipolar b. dendrite enters CNS from the peripheral structures c. contain Nissl substance in the axon hillock d. are postganglionic neurons

a. multipolar

Myelin in the central nervous system is produced by which of the following cells? a. Schwann cells b. Oligodendrocytes c. Protoplasmic astrocytes d. Microglia

b. Oligodendrocytes

Which of the following regarding axons is correct? a. arise from multiple sites on the cell body ofa neuro b. contain Nissl c. conduct action potentials toward the cell body d. are less frequently myelinated than dendrites

d. are less frequently myelinated than dendrites

In myelinated neurons, the point at which the action potential is regenerated is known as which of the following? a. Mesaxon b. Cleft of Schmitt-Lantermann c. Axon hillock d. Gap junction e. Node of Ranvier

e. Node of Ranvier

Wllich of the following explains the mechanism of action of nitroglycerine when taken by a patient for relief of acute angina pectoralis? a. nitroglycerine provides a substrate for the formation of nitric oxide (NO) that dilates coronary blood vessels b. nitroglycerin stimulates phospholipase C to increase the Ca2+ release from the sarcoplasmic reticulum and strengthen the heartbeat c. nitroglycerine inhibits the Na+ - pump and to reduce removal from the cytosol of cardiac myocytes d. nitroglycerine inhibits cyclic GMP-specific phosphodiesterase

a. nitroglycerine provides a substrate for the formation of nitric oxide (NO) that dilates coronary blood vessels

Contraction of smooth muscle is initiated by which of the following' a. Ca2+ binding to troponin removes tropomyosin from cross bridge forming sites along the actin filaments b. binding to calmodulin removes tropomyosin from cross bridge forming sites along the actin filaments c. binding to calmodulin activates myosin light chain kinase d. Ca2+ binding to myosin light chains initiates cross bridge formation

c. binding to calmodulin activates myosin light chain kinase

Skeletal, cardiac and smooth muscle all have which ofthe following in common? a. ATP hydrolysis occurs during cross bridge formation b. ATP hydrolysis occurs during the power stroke of the cross bridges c. ATP hydrolysis occurs when cross bridges are broken and reset d. ATP is hydrolyzed during each of the above processes

c. ATP hydrolysis occurs when cross bridges are broken and reset (not sure DM)

"The term ""alpha"" with regards to a motor neuron refers to what property? a. it exits the spinal cord via the ventral nerve root b. it forms myoneural junctions with numerous skeletal muscle fibers c. its axons are large, myelinated and conduct action potentials rapidly d. it relies on glycolytic ATP production and fatigues-rapidly"

c. its axons are large, myelinated and conduct action potentials rapidly

Troponin is a calcium binding protein: a. on the myosin filament that forms cross bridges with actin b. that is responsible for movrng tropomyosin so cross bridges between actin and myosin can c. in the sarcoplasmic reticulum d. in the cytosol

b. that is responsible for movrng tropomyosin so cross bridges between actin and myosin can

Because of the action of Na+ K+ pump, what are the relative concentrations of Na+ and K+ in the cytosol compared to that of the extracellular fluid (ECF) a. [Na+] and [K+] are both greater in the cytosol than in the extracellular fluid b. [K+] in the cytosol is higher than in the ECF while [Na+] in the cytosol is lower than the ECF c. [K+] in the cytosol is lower than in the ECF while [Na+] in the cytosol is higher than the ECF d. [Na+] and [K+] in the cytosol are both less than that in the extracellular fluid

b. [K+] in the cytosol is higher than in the ECF while [Na+] in the cytosol is lower than the ECF

"What is meant by the term ""equilibrium potential for K+?"" a. it is the voltage across the membrane when the [Na+] and [K+] in the cytosol are the same b. it is the condition where the voltage across the membrane is 0 mV c. it is the condition where the concentration and electrical gradients for K+ across the membrane are balanced, about -90 mV d. it is the condition where the concentration and electrical gradients for K+ across the membrane are balanced, about +60 mV"

c. it is the condition where the concentration and electrical gradients for K+ across the membrane are balanced, about -90 mV (1/23)

"The ""P"" element of an ion channel is a. positively charged transmembrane domain that can change the open-closed state of the channel b. an extracellular domain that extends into the pore formed by the transmembrane domains of the channel c. a globular component at the amino terminal of the channel protein that can be drawn into the channel closing it d. a single cluster of 6 transmembrane domains that forms a channel through the membrane"

b. an extracellular domain that extends into the pore formed by the transmembrane domains of the channel

The resting potential across the cell membrane is closest to what value? a. 0 mV b. the equilibrium potential for K+ (Ek) c. the equilibrium potential for Na+ (Ena) d. 120 V

b. the equilibrium potential for K+ (Ek) (1/23)

The transmembrane region of membrane proteins are mostly in the __________ configuration. a. beta pleated sheet b. alpha helix c. random coil d. denatured

b. alpha helix

The spontaneous repolarization of axon membrane following an action potential is due to: a. inhibition of the Na+/K+ pump b. closing of voltage gated K+ channels c. inactivation of voltage gated gated Na+ channels d. inhibition of nicotinic channels by acetylcholine

c. inactivation of voltage gated gated Na+ channels (1/23)

Transport across a membrane by K+ channels or glut proteins is: (potential delete) a. passive diffusion b. facilitated diffusion c. co-transport d. active transport

b. facilitated diffusion

Viagra acts by inhibiting what enzyme? a. muscarinic receptors b. phospholipase A c. phosphodiesterase 5 (hydrolyzes cGMP to GMP) d. NO synthetase e. nicotinic receptors

c. phosphodiesterase 5 (hydrolyzes cGMP to GMP)