Q&A Hero

Q: Lacking sarcomeres, smooth muscle does not have Z lines, but it does have ____________________ containing the same protein constituent found in Z lines.

Q: The patellar tendon, or knee-jerk, reflex is a type of ____________________ reflex.

Q: The efferent neuron that innervates a muscle spindle's intrafusal fibers is known as a(n) ____________________ motor neuron.

Q: Premotor and supplementary motor areas, with input from the ____________________, plan the ____________________ motor command that is issued to the appropriate motor neurons by the primary motor cortex through a descending system.

Q: ____________________ movements are the most complex type of motor activity.

Q: Oxidative fibers have high ____________________ content, which is why they are also called ____________________ fibers.

Q: The local increase in inorganic phosphate from ____________________ breakdown is considered the primary cause of ____________________ fatigue.

Q: When the end product of glycolysis, pyruvate, cannot be further processed by oxidative phosphorylation, it is converted to ____________________.

Q: Oxidative phosphorylation takes place within the muscle ____________________ if sufficient oxygen is present.

Q: If the muscle fiber is stimulated so rapidly that it does not have a chance to relax at all between stimuli, a smooth, sustained contraction of maximal strength known as ____________________ occurs.

Q: A(n) ____________________ is a rigid structure capable of moving around a pivot point known as a(n) ____________________.

Q: With eccentric contractions, the muscle ____________________.

Q: In a(n) ____________________ contraction, the muscle is prevented from shortening, so tension develops at constant muscle length.

Q: The end of the muscle attached to the more stationary part of the skeleton is called the ____________________, and the end attached to the skeletal part that moves is the ____________________.

Q: The lateral sacs (alternatively known as terminal cisternae) store ____________________.

Q: At each junction of an A band and I band, the surface membrane dips into the muscle fiber to form a(n) ____________________.

Q: A single ____________________ pulls the thin filament inward only a small percentage of the total shortening distance.

Q: The H zone, in the center of the ____________________ where the thin filaments do not reach, becomes ____________________ as the thin filaments approach each other when they slide more deeply inward.

Q: ____________________ is a protein complex made of three polypeptide units: one binds to ____________________, one binds to actin, and a third can bind with Ca2+.

Q: The lighter area within the middle of the A band, where the thin filaments do not reach, is the ____________________.

Q: Discuss how botulinum toxin can be used beneficially.

Q: Discuss how organophosphates affect neuromuscular junctions.

Q: Discuss the most common motor-neuron disease.

Q: Give an exception to the general rule of dual reciprocal innervation by the autonomic nervous system.

Q: Describe sympathetic dominance.

Q: Figure 7-5Which number in the figure represents the release of acetylcholine (ACh) by exocytosis from a portion of the vesicles?a. 1b. 2c. 3d. 4e. 5f. 6

Q: Figure 7-5Which number in the figure represents an end-plate potential, where local current flows between the depolarized end plate and the adjacent membrane?a. 1b. 2c. 3d. 4e. 5f. 6

Q: Figure 7-5Which number in the figure represents a local action potential triggering the opening of voltage-gated Ca2+ channels and the subsequent entry of Ca2+ into the terminal button?a. 1b. 2c. 3d. 4e. 5f. 6

Q: Figure 7-5Which number in the figure shows ACh diffusing across the space separating the nerve and muscle cells and binding with receptor-channels specific for it on the motor end plate of the muscle cell membrane?a. 1b. 2c. 3d. 4e. 5f. 6

Q: Figure 7-5Which number in the figure represents motor neuron propagation?a. 1b. 2c. 3d. 4e. 5f. 6

Q: Myasthenia gravis is a(n) ____________________ condition in which the body erroneously produces antibodies against its motor end-plate ____________________ receptor-channels.

Q: Death from organophosphates results from ____________________ failure because the ____________________ remains in a depolarization block and cannot be stimulated to contract again.

Q: The muscle cell's electrical response is turned off by an enzyme in the motor end-plate membrane called ____________________.

Q: A neuromuscular junction is always ____________________ (an EPP), whereas a synapse may be excitatory (an EPSP) or inhibitory (an IPSP).

Q: An action potential in a motor neuron is ____________________ to the terminal button.

Q: ____________________ ions trigger the release of acetylcholine by exocytosis from a portion of the vesicles.

Q: Within a neuromuscular junction, the axon terminal splits into multiple fine branches, each of which ends in an enlarged knoblike structure called the ____________________.

Q: The function of the afferent neuron is to carry information about the external and internal environments to the ____________________.

Q: The somatic system is under ____________________ control, but much of skeletal muscle activity involving posture, balance, and stereotypical movements is coordinated ____________________.

Q: Areas of the brain that exert control over skeletal muscle movements include the motor regions of the cortex, the ____________________ nuclei, the ____________________, and the brain stem.

Q: Motor-neuron axon terminals release ____________________, which brings about excitation and contraction of the innervated muscle cells.

Q: Motor neurons, whose axons constitute the somatic nervous system, supply ____________________ muscles and bring about movement.

Q: Nicotinic receptors are found on the ____________________ cell bodies in all autonomic ganglia.

Q: The parasympathetic system promotes ____________________ bodily functions while slowing down those activities that are enhanced by the sympathetic system.

Q: Sympathetic stimulation ____________________ the heart rate, whereas parasympathetic stimulation ____________________ it.

Q: Autonomic efferent output regulates ____________________ activities such as circulation and digestion.

Q: Many autonomic fibers release ____________________ along with the classical neurotransmitters.

Q: Most sympathetic postganglionic fibers are called ____________________ fibers because they release noradrenaline, commonly known as norepinephrine.

Q: The sympathetic nervous system originates in the ____________________ regions of the spinal cord and has short cholinergic preganglionic fibers and ____________________ adrenergic postganglionic fibers.

Q: Parasympathetic preganglionic fibers are longer than sympathetic ____________________ fibers.

Q: Long postganglionic fibers originate in the ____________________ chain and end on the ____________________ organs.

Q: The sympathetic ganglion chain is also called the sympathetic ____________________.

Q: Sympathetic nerve fibers originate in the ____________________ horn of the thoracic and lumbar regions of the spinal cord.

Q: Each autonomic nerve pathway extending from the CNS to an innervated organ is a(n) ____________________ chain.

Q: Skeletal muscle is innervated by the ____________________ nervous system, the branch of the ____________________ division subject to voluntary control.

Q: The agonist curare irreversibly binds to the Ach receptor-channels on the motor end plate. a. True b. False

Q: By removing relaxation-inducing ACh from the sensory end plate, AChE permits the choice of allowing relaxation to take place or keeping the contraction going, depending on the body's needs. a. True b. False

Q: The muscle cell's electrical response is turned off by an enzyme in the motor end-plate membrane, acetylcholinesterase (AChE), which inactivates ACh. a. True b. False

Q: The motor end-plate region undergoes a threshold potential, so an action potential is initiated at this site. a. True b. False

Q: The end-plate potential (EPP) is a graded potential similar to an EPSP, except that an EPP is much larger. a. True b. False

Q: Nerve and muscle cells do not come into direct contact at a neuromuscular junction. a. True b. False

Q: The specialized underlying portion of the muscle cell membrane is called the sensory end plate. a. True b. False

Q: Within a neuromuscular junction, the axon terminal splits into multiple fine branches, each of which ends in an enlarged knoblike structure called the terminal button. a. True b. False

Q: The result of infection with poliovirus is paralysis of the muscles innervated by the affected neurons. a. True b. False

Q: Amyotrophic lateral sclerosis (ALS) is also known as polio. a. True b. False

Q: Motor neurons are considered the final common pathway because the only way any other parts of the nervous system can influence skeletal muscle activity is by acting on these motor neurons. a. True b. False

Q: Unlike the two-neuron chain of autonomic nerve fibers, the axon of a motor neuron is continuous from its origin in the CNS to its ending on skeletal muscle. a. True b. False

Q: The pons within the brain stem is the region most directly responsible for autonomic output. a. True b. False

Q: An antagonist binds with the receptor, preventing the neurotransmitter from binding and causing a response, yet the antagonist itself produces no response. a. True b. False

Q: Nicotinic receptors are activated by the tobacco plant derivative nicotine, whereas muscarinic receptors are activated by the mushroom poison muscarine. a. True b. False

Q: Dual innervation of organs with nerve fibers whose actions oppose each other enables precise control over an organ's activity, like having both an accelerator and a brake to control the speed of a car. a. True b. False

Q: Most visceral organs are innervated by only parasympathetic nerve fibers. a. True b. False

Q: Unlike autonomic efferent output, visceral efferent output operates within the realm of consciousness and voluntary control. a. True b. False

Q: Norepinephrine serves as a neurotransmitter in the CNS and is released from the adrenal medulla as a hormone as well. a. True b. False

Q: Sympathetic and parasympathetic postganglionic fibers release the same neurotransmitter, acetylcholine (ACh). a. True b. False

Q: Very short preganglionic fibers end on the cells of an organ itself. a. True b. False

Q: Long postganglionic fibers originate in the ganglion chain and end on the effector organs. a. True b. False

Q: The peripheral nervous system has two subdivisions: the sympathetic and the parasympathetic nervous systems. a. True b. False

Q: Almost all neurally controlled effector organ responses are directly mediated by one of two neurotransmitters: acetylcholine or norepinephrine. a. True b. False

Q: Cardiac muscle, smooth muscle, most exocrine glands, some endocrine glands, and adipose tissue are innervated by the autonomic nervous system, the involuntary branch of the peripheral efferent division. a. True b. False