A & P Flashcards for Muscle Function
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Questions and Answers

The term central nervous system refers to _______.

brain and spinal cord.

A neuron that has as its primary function the job of connecting other neurons is called a(n) ________.

interneuron.

Saltatory conduction is made possible by ________.

myelin sheath.

Which of the following is NOT a chemical class of neurotransmitter?

<p>Nucleic acid (B)</p> Signup and view all the answers

Which of the following is false or incorrect?

<p>A nerve impulse occurs if the excitatory and inhibitory effects are equal. (C)</p> Signup and view all the answers

Select the correct statement regarding chemical synapses.

<p>The synaptic cleft uses the action potential to transmit a chemical signal to the postsynaptic cell. (C)</p> Signup and view all the answers

Which of the following correctly describes a graded potential?

<p>It can have amplitudes of various sizes. (A)</p> Signup and view all the answers

Schwann cells are functionally similar to ________.

<p>oligodendrocytes.</p> Signup and view all the answers

Immediately after an action potential has peaked, which of the following channels will open?

<p>Voltage-gated potassium channels (C)</p> Signup and view all the answers

An inhibitory postsynaptic potential (IPSP) is associated with ________.

<p>hyperpolarization.</p> Signup and view all the answers

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane?

<p>A single type of channel will open, permitting simultaneous flow of sodium and potassium.</p> Signup and view all the answers

When a sensory neuron is excited by some form of energy, the resulting graded potential is called a(n) ________.

<p>generator potential.</p> Signup and view all the answers

What is the role of tropomyosin in skeletal muscles?

<p>Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.</p> Signup and view all the answers

Which muscle cells have the greatest ability to regenerate?

<p>smooth</p> Signup and view all the answers

Most skeletal muscles contain ________.

<p>a mixture of fiber types</p> Signup and view all the answers

The strongest muscle contractions are normally achieved by _________.

<p>increasing the stimulation up to the maximal stimulus.</p> Signup and view all the answers

Which of the following would be recruited later in muscle stimulation when contractile strength increases?

<p>motor units with larger, less excitable neurons.</p> Signup and view all the answers

Which of the following is a factor that affects the velocity and duration of muscle contraction?

<p>load on the fiber.</p> Signup and view all the answers

Myoglobin _______.

<p>stores oxygen in muscle cells.</p> Signup and view all the answers

What structure in skeletal muscle cells functions in calcium storage?

<p>sarcoplasmic reticulum</p> Signup and view all the answers

What does excess postexercise oxygen consumption represent?

<p>the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually used.</p> Signup and view all the answers

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period.

<p>latent.</p> Signup and view all the answers

Creatine phosphate functions in the muscle cell by ________.

<p>storing energy that will be transferred to ADP to resynthesize ATP.</p> Signup and view all the answers

What is the primary function of wave summation?

<p>produce smooth, continuous muscle contraction.</p> Signup and view all the answers

During muscle contraction, myosin cross bridges attach to which active sites?

<p>actin filaments.</p> Signup and view all the answers

Which of the following surrounds an individual muscle cell?

<p>endomysium.</p> Signup and view all the answers

Rigor mortis occurs because ________.

<p>no ATP is available to release attached actin and myosin molecules.</p> Signup and view all the answers

The oxygen-binding protein found in muscle cells is ______.

<p>myoglobin.</p> Signup and view all the answers

The contractile units of skeletal muscles are _____.

<p>myofibrils.</p> Signup and view all the answers

Sarcomeres are functional units of _________ muscle.

<p>B and C only (cardiac and skeletal)</p> Signup and view all the answers

What is the functional role of the T tubules?

<p>enhance cellular communication during muscle contraction.</p> Signup and view all the answers

During vigorous exercise, the pyruvic acid is converted to ________.

<p>lactic acid.</p> Signup and view all the answers

When a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

<p>refractory period.</p> Signup and view all the answers

In an isotonic contraction, the muscle ________.

<p>changes in length and moves the 'load'.</p> Signup and view all the answers

Which of the following is the correct sequence of events for muscle contractions?

<p>motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments.</p> Signup and view all the answers

The mechanism of contraction in smooth muscles is different from skeletal muscle in that ______.

<p>the site of calcium binding site differs.</p> Signup and view all the answers

Which of the following describes the cells of unitary smooth muscle?

<p>they exhibit spontaneous action potentials.</p> Signup and view all the answers

Which of the following is true about smooth muscle?

<p>certain smooth muscle cells can actually divide to increase their numbers.</p> Signup and view all the answers

Smooth muscle is characterized by all of the following EXCEPT _________?

<p>there are more thick filaments than thin filaments.</p> Signup and view all the answers

The ability of muscle to shorten forcibly when adequately stimulated is known as _______, and sets muscle apart from other tissue types.

<p>contractility.</p> Signup and view all the answers

Which of the following statements is true?

<p>striated muscle cells are long and cylindrical with many nuclei.</p> Signup and view all the answers

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is _______.

<p>glycolysis.</p> Signup and view all the answers

Muscle tone is ________.

<p>a state of sustained partial contraction.</p> Signup and view all the answers

The sliding filament model of contraction involves _________.

<p>actin and myosin sliding past each other and partially overlapping.</p> Signup and view all the answers

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

<p>acetylcholinesterase breaks apart the ACh.</p> Signup and view all the answers

Which of the following is the correct order for the phases of a muscle twitch?

<p>relaxation, contraction, latent.</p> Signup and view all the answers

What is the most distinguishing characteristic of muscle tissue?

<p>the ability to transform chemical energy into mechanical energy to move the body.</p> Signup and view all the answers

Of the following muscle types, which has the longest muscle cells and has obvious stripes called striations?

<p>skeletal muscles.</p> Signup and view all the answers

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________.

<p>no muscle tension could be generated.</p> Signup and view all the answers

What part of the sarcolemma contains acetylcholine receptors?

<p>motor end plate.</p> Signup and view all the answers

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of extensibility?

<p>elastin (thin) filaments.</p> Signup and view all the answers

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of excitability?

<p>acetylcholine receptors in the motor end plate.</p> Signup and view all the answers

Although all the anatomical parts of muscle work together to give it its characteristics, which of the following proteins listed below would be most associated with the characteristics of contractility?

<p>thick (myosin) filaments.</p> Signup and view all the answers

Oxygen-starved tissues can release chemical signals into the blood that can change the diameter of nearby blood vessels. Which muscle type is responsible for this vasodilation?

<p>smooth muscle.</p> Signup and view all the answers

Of the following items listed below, which is the best description for why skeletal muscle stores glycogen?

<p>skeletal muscle is a heavy consumer of energy.</p> Signup and view all the answers

During development embryonic cells will fuse to form muscle fibers. This will result in ________.

<p>multinucleated muscle fibers that can extend as long as 30 centimeters.</p> Signup and view all the answers

Approximately 80% of a muscle fiber's volume are the myofibrils. This characteristic reflects the muscle's ability to ________.

<p>produce movement through contractile force.</p> Signup and view all the answers

Troponin, a major protein in thin filaments, is a globular protein with three polypeptide subunits. Which of the following is NOT a function of the troponin?

<p>One subunit binds to potassium ions.</p> Signup and view all the answers

Curare is a poisonous plant extract. What do you think the symptoms of curare poisoning would look like?

<p>Curare will only affect muscles with ACh receptors, paralyzing them.</p> Signup and view all the answers

Myasthenia gravis is a disease that results in the loss of ACh receptors at muscle fibers. Which of the following is likely to be a symptom of myasthenia gravis?

<p>weakness of muscle.</p> Signup and view all the answers

Which of the following statements best illustrates the fact that skeletal muscle is voluntary muscle?

<p>skeletal muscle fibers are innervated by somatic motor neurons.</p> Signup and view all the answers

If a muscle fiber were to suddenly and permanently stop producing ATP, which of the following would you expect to happen?

<p>Myosin would be able to bind to the exposed binding sites on thin filaments but it would not be able to detach.</p> Signup and view all the answers

When a sarcomere contracts and thin filaments move over thick filaments, you would expect to see ________.

<p>the I bands to appear smaller.</p> Signup and view all the answers

Addition of more myoglobin to a muscle fiber would have the largest effect on ________.

<p>fast oxidative and slow oxidative fibers.</p> Signup and view all the answers

Exhaustion of glycogen storage within a muscle fiber would have the biggest effect on ________.

<p>fast glycolytic fibers.</p> Signup and view all the answers

Reduction in blood flow to a muscle fiber would have the greatest effect on ________.

<p>slow oxidative fibers.</p> Signup and view all the answers

A potential benefit of recruiting slow oxidative fibers for contraction before recruiting fast oxidative and fast glycolytic fibers might be _______.

<p>to allow for fine control with delicate contractile force with a small stimulus.</p> Signup and view all the answers

Addition of more mitochondria to a muscle fiber will have the greatest effect on ________.

<p>slow oxidative fibers.</p> Signup and view all the answers

If given the exact same amount of ATP, which of the three fiber types would be able to contract for the longest amount of time?

<p>slow oxidative fibers.</p> Signup and view all the answers

The 100-meter dash is a quick and short run requiring explosive speed. Which of the following is the best explanation for why runners continue to breathe hard after running?

<p>The runner's use of stored oxygen, glucose, and creatine phosphate is being replenished and this requires a prolonged increase of oxygen intake.</p> Signup and view all the answers

Nerve impulses are sent to slow the heart's rate of contraction. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

<p>parasympathetic division.</p> Signup and view all the answers

Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

<p>sensory (afferent) division.</p> Signup and view all the answers

Nerve impulses leading to skeletal muscle carry information to direct movement. The nerve fibers sending these signals will most likely belong to which division of the nervous system?

<p>somatic nervous system.</p> Signup and view all the answers

Cranial nerve II, the optic nerve sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system?

<p>sensory (afferent) division.</p> Signup and view all the answers

The concentration of ions in the chemical environment surrounding the neurons must be tightly regulated. Which of the following cells is most responsible for this?

<p>astrocytes.</p> Signup and view all the answers

Some nerve fibers of the peripheral nervous system have the ability to regenerate after damage has occurred. Which of the following cells is most responsible for aiding this regulation?

<p>Schwann cells.</p> Signup and view all the answers

It is important for newly developed neurons to form synapses with other neurons. Which cells are most responsible for guiding the formation of these particular junctions?

<p>astrocytes.</p> Signup and view all the answers

Meningitis can be caused by infection of the central nervous system by bacteria. Which cells would be most responsible for removing the infection?

<p>microglia.</p> Signup and view all the answers

Like all cells, the neurons' internal organization dictates its function. Neurons have relatively many mitochondria, an extensive network of rough endoplasmic reticulum, and many clusters of ribosomes. These cellular features indicate all of the following EXCEPT ________.

<p>neurons have stable, relatively unchanging internal environments.</p> Signup and view all the answers

An action potential is regarded as an example of positive feedback. Which of the following examples below best illustrates the positive feedback aspect of an action potential?

<p>a threshold stimulus will cause the opening of voltage gated sodium ion channels that will cause further depolarizing stimulus. This stimulus will open still more voltage gated sodium ion channels.</p> Signup and view all the answers

The depolarization phase of an action potential is punctuated by the closing of the inactivation gates in the voltage gated sodium ion channels. All of the following are consequences of this inactivation except one. Choose the statement below that is not a consequence of the closing of inactivating gates.

<p>This allows for the efflux (diffusion out) of potassium ions, resulting in the repolarization of the cell.</p> Signup and view all the answers

During the release refractory period of an action potential, a larger than normal stimulus is needed to cause another action potential. This is due to the fact that ________.

<p>the voltage gated potassium ion channels remain open long enough to hyperpolarize the axon membrane.</p> Signup and view all the answers

If a postsynaptic neuron is stimulated to threshold by spatial summation this implies that ________.

<p>the postsynaptic cell has many synapses with many presynaptic neurons.</p> Signup and view all the answers

If a postsynaptic cell is stimulated to threshold by temporal summation this implies that __________.

<p>a presynaptic neuron is sending frequent EPSP.</p> Signup and view all the answers

When a neurotransmitter like acetylcholine is acting in an excitatory manner, which of the following is likely a result of the acetylcholine acting on the postsynaptic cell?

<p>chemically gated sodium channels will open.</p> Signup and view all the answers

When a neurotransmitter like GABA is acting in an inhibitory manner, which of the following is likely a result of the GABA acting on the postsynaptic cell?

<p>hyperpolarization of the postsynaptic cell membrane.</p> Signup and view all the answers

The effect of acetylcholine can be stimulating or inhibiting. Which of the following gives the best explanation for why this is so?

<p>different postsynaptic cells will have different receptors.</p> Signup and view all the answers

Which of the following is NOT a function of dendrites?

<p>generate nerve impulses and transmit them away from the cell body.</p> Signup and view all the answers

Which of the choices below describes the ANS?

<p>motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands.</p> Signup and view all the answers

These cells in the CNS have cilia that move in order to circulate cerebrospinal fluid.

<p>ependymal cells.</p> Signup and view all the answers

What does the central nervous system use to determine the strength of the stimulus?

<p>frequency of action potentials.</p> Signup and view all the answers

Bipolar neurons are commonly ________.

<p>found in the retina of the eye.</p> Signup and view all the answers

Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle?

<p>acetylcholine.</p> Signup and view all the answers

Which of the following describes the nervous system integrative function?

<p>analyzes sensory information, stores information, makes decisions.</p> Signup and view all the answers

The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ________.

<p>absolute refractory period.</p> Signup and view all the answers

Which of the following is NOT a characteristic of neurons?

<p>they are mitotic.</p> Signup and view all the answers

Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials?

<p>voltage-gated channel.</p> Signup and view all the answers

Loss of function in the enzyme acetylcholine esterase would result in which of the following?

<p>inability to destroy and remove acetylcholine from the synaptic cleft.</p> Signup and view all the answers

Which of the following is NOT a function of the autonomic nervous system?

<p>innervation of skeletal muscles.</p> Signup and view all the answers

Collections of nerve cell bodies outside the central nervous system are called ________.

<p>ganglia.</p> Signup and view all the answers

Study Notes

Muscle Contraction and Mechanics

  • Tropomyosin inhibits contraction by blocking myosin binding sites on actin.
  • Skeletal muscles consist of a mixture of fiber types, allowing for varied functions.
  • Strongest contractions occur through maximal stimulus and increased stimulation frequency.
  • Myoglobin stores oxygen within muscle cells, vital for aerobic respiration.
  • Muscle contraction related to myosin cross bridges attaches to actin filaments.
  • Calcium storage in skeletal muscle cells is managed by the sarcoplasmic reticulum.
  • Muscle fibers demonstrate contractility, defining their unique capabilities compared to other tissues.

Muscle Fiber Types and Regeneration

  • Smooth muscle cells possess the highest regenerative capability compared to skeletal and cardiac muscle.
  • Fast glycolytic fibers are most affected by exhaustion of glycogen storage, highlighting their reliance on glucose.
  • Slow oxidative fibers are enhanced by additional mitochondria, increasing endurance and energy production.

Muscle Activity and Fatigue

  • Anaerobic metabolism leads to lactic acid production when oxygen is scarce.
  • Muscle tone corresponds to a state of sustained partial contraction, essential for maintaining posture.
  • Excess postexercise oxygen consumption accounts for the oxygen deficit after activity, necessary for recovery processes.

Nervous System Control of Muscle

  • Motor units with larger neurons are recruited for stronger stimulation.
  • Activation of acetylcholine receptors leads to muscle contraction through chemically gated channels.
  • The latency period follows stimulus arrival, involving neurotransmitter release and transmission across synapses.
  • Curare poison mimics acetylcholine and causes paralysis by blocking receptor sites without activating them.
  • Myasthenia gravis illustrates an autoimmune response leading to weakened muscles due to loss of ACh receptors.

Neuron Structure and Function

  • Neurons exhibit features like many mitochondria and extensive endoplasmic reticulum, indicating high energy demands.
  • Dendrites receive signals but do not generate impulses away from the cell body.
  • Interneurons act primarily to connect other neurons within the nervous system.
  • Graded potentials vary in amplitude and are crucial for neuron communication.

Synaptic Transmission and Neurotransmitters

  • Acetylcholine functions as an excitatory neurotransmitter for skeletal muscles.
  • GABA induces hyperpolarization in postsynaptic cells, serving an inhibitory role.
  • Chemical synapses transmit signals across a synaptic cleft, utilizing action potentials to send neurotransmitters.
  • Saltatory conduction occurs due to the presence of myelin sheath, facilitating rapid signal transmission.

Ion Channel Dynamics

  • Voltage-gated sodium channels open in response to depolarization, driving action potential propagation.
  • Potassium channels open immediately after an action potential peaks, promoting repolarization.

Central Nervous System and Support Cells

  • Astrocytes regulate the chemical environment for optimal neuron function and guide synapse formation.
  • Microglia act as immune cells within the CNS, responding to infectious agents or damage.
  • Ependymal cells produce and circulate cerebrospinal fluid, vital for the CNS's protective environment.

Sympathetic vs Parasympathetic Responses

  • Parasympathetic impulses slow heart rates, highlighting the balancing act of the autonomic nervous system.
  • Sensory (afferent) division neurons convey information about environmental stimuli to the CNS.

Muscle Fiber Characteristics

  • Striated muscle fibers are identified by their long, cylindrical shape with multiple nuclei, primarily found in skeletal muscle.
  • Elasticity in muscle fibers is attributed to thin (elastin) filaments, while thick (myosin) filaments relate to contractility characteristics.

Neurotransmitter Characteristics

  • The effects of neurotransmitters like acetylcholine can vary depending on the receptor type present in the postsynaptic cell, leading to either excitation or inhibition.

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Test your knowledge on muscle function with this set of flashcards. Explore key concepts related to tropomyosin, muscle regeneration, and fiber types in skeletal muscles. Perfect for students in Anatomy and Physiology!

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