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Questions and Answers
The sliding filament model of contraction involves ________.
The sliding filament model of contraction involves ________.
actin and myosin sliding past each other and partially overlap
Identify the correct sequence of the following events.
Identify the correct sequence of the following events.
- The sarcomere shortens. (correct)
- Ca+ binds to troponin. (correct)
- ATP recharges the myosin head. (correct)
- Myosin generates a power stroke. (correct)
- Troponin removes tropomyosin from G actin. (correct)
- Myosin binds to actin. (correct)
Which type of muscle requires voluntary nervous stimulation for activation?
Which type of muscle requires voluntary nervous stimulation for activation?
Skeletal
The contractile, or functional, unit of a muscle fiber is __________.
The contractile, or functional, unit of a muscle fiber is __________.
Muscle tissue has all of the following properties EXCEPT________.
Muscle tissue has all of the following properties EXCEPT________.
What would result from a block in the release of neurotransmitters into a neuromuscular synapse?
What would result from a block in the release of neurotransmitters into a neuromuscular synapse?
What prevents ACh in the synaptic cleft from continuing to stimulate contraction after nervous stimulation stops?
What prevents ACh in the synaptic cleft from continuing to stimulate contraction after nervous stimulation stops?
What part of the sarcolemma contains acetylcholine receptors?
What part of the sarcolemma contains acetylcholine receptors?
One of the important functions of skeletal muscle contraction is the production of heat.
One of the important functions of skeletal muscle contraction is the production of heat.
The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.
What describes a fascicle?
What describes a fascicle?
The __________ shorten(s) during muscle contraction.
The __________ shorten(s) during muscle contraction.
What are the symptoms of curare poisoning?
What are the symptoms of curare poisoning?
Which of the following is most directly required to initiate the coupling of myosin to actin?
Which of the following is most directly required to initiate the coupling of myosin to actin?
When a sarcomere contracts and thin filaments move over thick filaments, you would expect to see ________.
When a sarcomere contracts and thin filaments move over thick filaments, you would expect to see ________.
What step precedes all of the other listed steps in muscle contraction?
What step precedes all of the other listed steps in muscle contraction?
Which term best identifies a muscle cell?
Which term best identifies a muscle cell?
Myoglobin ________.
Myoglobin ________.
The sliding filament model of contraction states that __________.
The sliding filament model of contraction states that __________.
A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell.
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Study Notes
Sliding Filament Model
- Actin and myosin filaments slide past each other during muscle contraction, resulting in partial overlap.
Sequence of Muscle Contraction Events
- Calcium ions (Ca+) bind to troponin.
- Troponin then removes tropomyosin from G-actin.
- Myosin binds to actin.
- Myosin generates a power stroke.
- Sarcomere shortens.
- ATP recharges the myosin head.
Skeletal Muscle Characteristics
- Requires voluntary stimulation from the nervous system for activation.
- Neuromuscular junction is the communication site between nerve fiber and muscle fiber.
- Sarcomere is the smallest functional unit of muscle, located between two Z discs.
Properties of Muscle Tissue
- Muscle tissue exhibits contractility, excitability, and extensibility.
- Secretion is NOT a property of muscle tissue.
Impact of Toxins
- Toxins blocking neurotransmitter release lead to muscle contraction loss due to lack of acetylcholine (ACh).
ACh Regulation
- Acetylcholinesterase degrades ACh in the synaptic cleft, ceasing stimulation of muscle contraction.
Muscle Structure
- Epimysium is a dense connective tissue around muscles, connecting tendons to bones or other muscles.
- A fascicle is a group of muscle fibers enclosed by perimysium.
Muscle Contraction Facts
- Skeletal muscle contractions produce heat.
- Actin is the primary protein in thin myofilaments.
Ion Permeability and Neurotransmitters
- Neurotransmitters modify muscle cell membrane ion permeability temporarily.
Sarcomere Changes During Contraction
- During contraction, the sarcomere shortens as actin slides over myosin, leading to smaller I bands.
Muscle Cell Types
- Muscle fibers are multinucleated cells formed by the fusion of skeletal muscle cells during development.
Myoglobin Function
- Myoglobin is a protein that stores oxygen within muscle cells, supporting aerobic metabolism.
Connective Tissue Layers
- Endomysium surrounds individual muscle cells, while perimysium encloses fascicles.
Cross-Bridge Formation
- Cross-bridges form between actin (thin filaments) and myosin (thick filaments) during contraction.
Muscle Tissue Types
- Skeletal muscle is voluntarily controlled.
- Cardiac muscle is involuntary and striated.
- Smooth muscle is involuntary and typically non-striated.
Sliding Filament Theory
- During contraction, thin myofilaments slide past thick myofilaments, leading to increased overlap between actin and myosin.
Resting Potential
- A resting potential arises due to ionic concentration differences across the cell membrane, crucial for nerve impulse transmission.
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