TEST 6 Flashcards
The basic unit of contraction in a skeletal muscle is?
a) Myofibril
b) Sarcomere
c) Tendon
d) Myosin
Sarcomere
The ___________ is the contractile protein found in the thick filaments of a sarcomere.
a) Actin
b) Tropomyosin
c) Myosin
d) Troponin
Myosin
The _______ is a specialized endoplasmic reticulum found in skeletal muscle cells.
a) Sarcoplasmic reticulum
b) Golgi apparatus
c) Mitochondria
d) Nucleus
Sarcoplasmic reticulum
The _______ is a thin filament protein that covers the active sites on actin molecules in a relaxed muscle fiber.
a) Myosin
b) Tropomyosin
c) Troponin
d) Sarcomere
Tropomyosin
The __________ is the regulatory protein that binds calcium ions and initiates muscle contraction.
a) Actin
b) Tropomyosin
c) Myosin
d) Troponin
Troponin
The __________ is the region of a sarcomere where actin and myosin filaments overlap.
a) Z-line
b) M-line
c) H-zone
d) A-band
H-zone
The __________ is the protein that connects the Z-lines and helps stabilize the sarcomere during contraction.
a) Actin
b) Titin
c) Myosin
d) Nebulin
Titin
The __________ is the thin filament protein that anchors actin to the Z-line.
a) Tropomyosin
b) Myosin
c) Nebulin
d) Dystrophin
Tropomyosin
The __________ is the area in the center of the sarcomere that contains only myosin filaments.
a) I-band
b) H-zone
c) A-band
d) Z-line
H-zone
The __________ is the structure that connects the muscle to the bone.
a) Tendon
b) Ligament
c) Cartilage
d) Fascia
Tendon
The __________ is the neurotransmitter released by motor neurons to initiate muscle contraction.
a) Dopamine
b) Serotonin
c) Acetylcholine
d) Norepinephrine
Acetylcholine
The __________ is the structure where the motor neuron and muscle fiber meet.
a) Neuromuscular junction
b) Synaptic cleft
c) Sarcolemma
d) Sarcoplasmic reticulum
Neuromuscular junction
The __________ is the structural protein that surrounds individual muscle fibers.
a) Endomysium
b) Perimysium
c) Epimysium
d) Sarcolemma
Endomysium
The __________ is the plasma membrane of a muscle fiber.
a) Epimysium
b) Endomysium
c) Sarcolemma
d) Perimysium
Sarcolemma
The __________ is the functional unit of a muscle fiber.
a) Sarcomere
b) Myofibril
c) Sarcoplasm
d) T-tubule
Sarcomere
The __________ is the storage form of glucose in skeletal muscle.
a) Glycogen
b) Glucagon
c) Insulin
d) Glucose-6-phosphate
Glycogen
The __________ is the type of muscle fiber that is adapted for aerobic endurance activities.
a) Type I (slow-twitch)
b) Type IIa (fast-twitch oxidative)
c) Type IIb (fast-twitch glycolytic)
d) Type III (intermediate)
Type I (slow-twitch)
The __________ is the protein responsible for releasing calcium ions from the sarcoplasmic reticulum.
a) Actin
b) Tropomyosin
c) Myosin
d) Ryanodine receptor
Ryanodine receptor
The __________ is the energy molecule used by muscle fibers to power contraction.
a) ATP
b) ADP
c) AMP
d) GTP
ATP
The __________ is the enzyme that breaks down acetylcholine in the synaptic cleft.
a) Acetylcholinesterase
b) Monoamine oxidase
c) Cholinesterase
d) Adenosine triphosphatase (ATPase)
Acetylcholinesterase
The specific area on the muscle fiber where the motor neuron releases acetylcholine is known as the __________.
a) Sarcolemma
b) T-tubule
c) Sarcoplasmic reticulum
d) Synaptic cleft
Synaptic cleft
Acetylcholine binds to receptors on the __________, which triggers an electrical impulse in the muscle fiber.
a) Sarcolemma
b) T-tubule
c) Sarcoplasmic reticulum
d) Synaptic cleft
Sarcolemma
The electrical impulse generated in the muscle fiber travels deep into the muscle fiber via structures called __________.
a) Sarcomeres
b) Actin filaments
c) Myosin filaments
d) T-tubules
T-tubules
The presence of the electrical impulse in the T-tubules triggers the release of __________ from the sarcoplasmic reticulum.
a) Calcium ions
b) Sodium ions
c) Potassium ions
d) Chloride ions
Calcium ions
Calcium ions released from the sarcoplasmic reticulum bind to a regulatory protein called __________.
a) Actin
b) Tropomyosin
c) Myosin
d) Troponin
Troponin
The binding of calcium ions to troponin causes a conformational change, which allows __________ to interact with __________.
a) Actin; tropomyosin
b) Actin; myosin
c) Myosin; tropomyosin
d) Myosin; actin
Actin; myosin
The interaction between actin and myosin leads to the formation of cross-bridges, and subsequent __________ of the muscle fiber.
a) Relaxation
b) Contraction
c) Elongation
d) Shortening
Contraction
Acetylcholine is rapidly broken down by the enzyme acetylcholinesterase to terminate muscle stimulation at the neuromuscular junction. True or false?
True
The release of calcium ions from the sarcoplasmic reticulum is an essential step in muscle contraction. True or false?
True
T-tubules play a crucial role in transmitting the electrical signal from the motor neuron to the deep regions of the muscle fiber. True or false?
True
Troponin is a thin filament protein that directly interacts with myosin during muscle contraction. True or false?
False
The neuromuscular junction is responsible for transmitting sensory information from the muscle back to the central nervous system. True or false?
False
The binding of calcium ions to troponin causes tropomyosin to shift, exposing the active sites on actin for myosin binding. True or false?
True
The neuromuscular junction allows for precise control and coordination of muscle movements. True or false?
True
The neurotransmitter acetylcholine is released into the synaptic cleft by the muscle fiber. True or false?
False
The action potential generated by the motor neuron triggers the release of acetylcholine from the motor end plate. True or false?
True
The release of calcium ions from the sarcoplasmic reticulum is stimulated by the presence of acetylcholine at the neuromuscular junction. True or false?
False
The neuromuscular junction is a one-way communication system, with signals traveling only from the motor neuron to the muscle fiber. True or false?
True
The rise of intracellular calcium that blocks the actin and myosin results in a state of ____________
Rigor mortis
The autoimmune disorder where patient develops antibodies against acetylcholine receptors is called?
Myasthenia Gravis
Resting membrane potential refers to the electrical potential difference across the __________ of a neuron.
a) Cytoplasm
b) Cell membrane
c) Axon
d) Dendrites
Cell membrane
The resting membrane potential is typically around __________ millivolts in a neuron.
a) -70
b) -40
c) 0
d) +40
-70
The resting membrane potential is primarily maintained by the uneven distribution of __________ ions inside and outside the neuron.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Potassium (K+)
The movement of ions across the cell membrane is regulated by __________.
a) Neurotransmitters
b) Ion channels
c) Vesicles
d) Synapses
Ion channels
During the resting membrane potential, there is a higher concentration of __________ ions outside the neuron compared to inside.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Sodium (Na+)
The movement of potassium ions out of the cell is facilitated by __________ channels.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Potassium (K+)
The movement of sodium ions into the cell is regulated by __________ channels.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Sodium (Na+)
The resting membrane potential is a dynamic state and can change in response to various stimuli. True or false?
False
The sudden change in the electrical potential across the cell membrane, resulting in the generation of an action potential, is known as __________.
a) Repolarization
b) Hyperpolarization
c) Depolarization
d) Resting potential
Depolarization
Action potential is generated when the membrane potential reaches the __________ threshold.
a) Resting
b) Hyperpolarized
c) Depolarized
d) Repolarized
Resting
The rapid depolarization phase of the action potential is primarily caused by the influx of __________ ions.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Sodium (Na+)
The repolarization phase of the action potential is primarily caused by the efflux of __________ ions.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Potassium (K+)
The return of the membrane potential to its resting state is known as __________.
a) Repolarization
b) Hyperpolarization
c) Depolarization
d) Resting potential
Repolarization
The all-or-none principle states that once an action potential is initiated, it will propagate along the entire length of the __________.
a) Dendrites
b) Cell body
c) Axon
d) Synapse
Axon
The speed of action potential conduction can be increased by the presence of __________ along the axon.
a) Myelin sheath
b) Nodes of Ranvier
c) Neurotransmitters
d) Synaptic vesicles
Myelin sheath
Action potential propagation can occur in both directions along an axon. True or false?
False
The brief period following an action potential during which the neuron is temporarily unresponsive to further stimulation is known as the __________ period.
a) Refractory
b) Resting
c) Depolarization
d) Hyperpolarization
Refractory
Action potentials occur continuously in neurons, even during the resting state. True or false?
False
Saltatory conduction refers to the “jumping” of the action potential between __________ along a myelinated axon.
a) Neurotransmitters
b) Nodes of Ranvier
c) Synaptic vesicles
d) Dendrites
Nodes of Ranvier
The movement of ions during an action potential is primarily governed by the principles of __________.
a) Diffusion and osmosis
b) Active transport
c) Electrostatics and electrochemical gradients
d) Endocytosis and exocytosis
Electrostatics and electrochemical gradients
The __________ phase of the action potential involves a temporary hyperpolarization of the membrane potential.
a) Depolarization
b) Repolarization
c) Overshoot
d) Afterhyperpolarization
Afterhyperpolarization
The __________ is the critical voltage level that must be reached to trigger an action potential.
a) Threshold
b) Resting potential
c) Hyperpolarization
d) Repolarization
Threshold
Action potentials are typically longer in duration compared to the resting membrane potential. True or false?
False
The movement of ions during an action potential is primarily driven by __________.
a) Active transport pumps
b) Diffusion
c) Osmosis
d) Facilitated diffusion
Diffusion
The __________ is the time period during which a second action potential cannot be generated, regardless of the strength of the stimulus.
a) Absolute refractory period
b) Relative refractory period
c) Resting period
d) Threshold period
Absolute refractory period
The resting membrane potential of a neuron is maintained by the constant activity of sodium-potassium pumps. True or false?
True
The movement of ions during an action potential occurs due to changes in the __________.
a) Concentration gradient
b) Electrical gradient
c) Both concentration and electrical gradients
d) None of the above
Both concentration and electrical gradients
Action potentials can only occur in neurons and not in other types of cells. True or false?
False
The __________ period refers to the time during an action potential when the membrane potential is more negative than the resting potential.
a) Refractory
b) Resting
c) Depolarization
d) Hyperpolarization
Hyperpolarization
Voltage-gated sodium channels are responsible for the __________ phase of the action potential.
a) Depolarization
b) Repolarization
c) Hyperpolarization
d) Resting
Depolarization
Voltage-gated calcium channels play a crucial role in __________.
a) Muscle contraction
b) Neurotransmitter release
c) Resting membrane potential
d) Sodium-potassium pump activity
Neurotransmitter release
Voltage-gated potassium channels are responsible for the __________ phase of the action potential.
a) Depolarization
b) Repolarization
c) Hyperpolarization
d) Resting
Repolarization
Voltage-gated calcium channels are found in high concentrations in __________.
a) Muscle cells
b) Neurons
c) Both muscle cells and neurons
d) None of the above
Both muscle cells and neurons
Voltage-gated ion channels are membrane proteins that open or close in response to changes in membrane potential. True or false?
True
Voltage-gated sodium channels have two important gates called the __________ and __________ gates.
a) Activation; inactivation
b) Opening; closing
c) Resting; active
d) Hyperpolarization; depolarization
Activation; inactivation
The opening of voltage-gated potassium channels during an action potential allows for the efflux of __________ ions.
a) Sodium (Na+)
b) Potassium (K+)
c) Calcium (Ca2+)
d) Chloride (Cl-)
Potassium (K+)
L-type calcium channels are found in __________.
a) Skeletal muscle
b) Cardiac muscle
c) Smooth muscle
d) All of the above
All of the above
T-type calcium channels are often found in __________.
a) Neurons
b) Skeletal muscle
c) Cardiac muscle
d) Smooth muscle
Neurons
Voltage-gated calcium channels are primarily responsible for the generation of action potentials in neurons. True or false?
False
The opening of voltage-gated calcium channels triggers the release of __________ from intracellular stores in various cell types.
a) Neurotransmitters
b) Sodium ions
c) Potassium ions
d) Chloride ions
Neurotransmitters