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Questions and Answers
What is the main function of cardiac muscle?
What is the main function of cardiac muscle?
Which property of muscles allows them to respond to stimuli?
Which property of muscles allows them to respond to stimuli?
What are the basic contractile units of a striated muscle cell called?
What are the basic contractile units of a striated muscle cell called?
Which type of muscle contraction involves a change in muscle length?
Which type of muscle contraction involves a change in muscle length?
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What is muscle tone primarily responsible for?
What is muscle tone primarily responsible for?
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The sliding filament theory describes the interaction between which components during contraction?
The sliding filament theory describes the interaction between which components during contraction?
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Which muscle type is responsible for involuntary movements in hollow organs?
Which muscle type is responsible for involuntary movements in hollow organs?
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What occurs during tetanus in muscle physiology?
What occurs during tetanus in muscle physiology?
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What is the role of the sarcoplasmic reticulum in muscle contraction?
What is the role of the sarcoplasmic reticulum in muscle contraction?
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What is the primary source of energy for muscular work?
What is the primary source of energy for muscular work?
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Study Notes
Physiology of Muscles
- Muscles are classified as skeletal, cardiac, and smooth muscle
- Skeletal muscle is voluntary, controlled consciously, and connects to bones for movement
- Cardiac muscle is involuntary, controlled by the autonomic nervous system, and has pacemaker cells
- Smooth muscle is involuntary, found in hollow organs, and regulates the movement of contents through the lumen
Muscle Functions and Properties
- Functions: Muscles cause movement, maintain posture, support internal organs, control openings (sphincters), and move contents through tubes (peristalsis)
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Properties:
- Excitability (respond to stimuli)
- Contractility (shorten and generate force)
- Extensibility (stretch without damage)
- Elasticity (return to original shape)
- Conductivity (conduct electrical impulses)
Muscle Structure
- Skeletal muscles are composed of muscle fibers bundled into fascicles
- T-tubules conduct impulses into fibers
- Sarcoplasmic reticulum stores and releases calcium for contraction
- Myofibrils contain actin (thin) and myosin (thick) filaments
Muscle Contraction
- Sarcomere: Basic contractile unit of a muscle cell
- Sliding filament theory: Actin and myosin filaments slide past each other during contraction, creating muscle shortening
- Neuromuscular Junction, Sliding Filament Theory, Contraction of Motor Units, are studied in lab work
- Types of muscle contraction: Isotonic (change in length under constant tension) and isometric (increase in tension without change in length)
- Muscle tone is the baseline tension that maintains posture and readiness
- Motor unit is a single motor neuron and the muscle fibers it controls
Muscle Fatigue
- Tetanus is a sustained muscle contraction caused by rapid stimulation
- Muscular work involves ATP-powered cycles of contraction and relaxation. Prolonged work leads to fatigue and oxygen debt.
- Muscle fatigue results from depletion of energy reserves (ATP, glycogen), accumulation of lactic acid, or impaired calcium release.
Muscle Fiber Types
- Type I (slow-twitch, red): fatigue-resistant, efficient in low-intensity activity
- Type IIa (fast oxidative): moderately resistant to fatigue
- Type IIb/IIx (fast glycolytic): powerful but fatigue quickly
Muscle Training
- Regular exercise increases muscle size, strength, endurance, and resistance to fatigue, and enhances overall metabolism, circulation, and lung efficiency
Muscle Proprioceptors
- Muscle spindles detect muscle length and changes in length
- Golgi tendon organs detect tension and protect muscles from excessive force
- Joint receptors provide information about joint angle and motion
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Description
Explore the essential concepts of muscle physiology, including the classification of muscles into skeletal, cardiac, and smooth types. Learn about their functions, properties, and underlying structure. This quiz covers key aspects to deepen your understanding of how muscles work in the human body.
