Questions and Answers
What are the two main divisions of the skeletal system and what do they include?
The two main divisions are the axial skeleton, which includes the skull, ribcage, and vertebrae, and the appendicular skeleton, which consists of the pelvic girdle and upper and lower appendages.
Describe the role of tendons and ligaments in relation to muscles and bones.
Tendons connect muscles to bones, allowing for movement, while ligaments connect bones to other bones, providing stability to joints.
What is the structure of a sarcomere and its significance in muscle contraction?
A sarcomere consists of Z discs, A bands, I bands, and H zones, and it is the smallest contractile unit of muscle that shortens during contraction to generate force.
What is the Sliding Filament Theory and how does it explain muscle contraction?
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Explain the role of calcium in muscle fiber activation.
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What are the three types of skeletal muscle fibers, and how do they differ in terms of contraction speed and fatigue resistance?
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How do anaerobic and aerobic muscle contractions differ in energy production?
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What is an action potential and its role in muscle contraction?
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Describe the organization of muscle tissue from the largest entity to the smallest.
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What mnemonic can help remember the number of vertebrae in each section of the vertebral column?
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Study Notes
The Skeletal System
- Comprised of two main sections: Axial Skeleton (skull, ribcage, vertebrae including sacrum and coccyx) and Appendicular Skeleton (pelvic girdle, upper and lower limbs).
- Functions of bones include providing shape and support to the body.
- Synovial Joints are primary movement joints, containing joint capsule filled with synovial fluid.
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Vertebral Column consists of:
- 7 Cervical vertebrae
- 12 Thoracic vertebrae
- 5 Lumbar vertebrae
- 1 Sacrum and 1 Coccyx
- Mnemonic for Vertebral Column: "Crunchy Breakfast @ 7am, Tasty Lunch @ 12pm, Light Dinner @ 5pm" aids in recalling the number of vertebrae in each section.
The Muscular System
- Tendons connect muscles to bones, while ligaments connect bones to other bones; 'L' in ligament helps remember its connection between similar structures (bone to bone).
- Muscle tissue organization ranges from largest to smallest:
- Muscle
- Fascicle – a bundle of muscle fibers
- Muscle Fiber – a single muscle cell made of myofibrils
- Sarcomere – smallest contractile unit containing actin and myosin
- Myofilament
- Fascia is a connective tissue layer that separates muscle layers; Epimysium (surrounds the entire muscle), Perimysium (surrounds muscle fiber bundles), Endomysium (surrounds individual muscle fibers).
- A Motor Unit consists of one nerve and the muscle fibers it innervates, with all fibers contracting simultaneously.
Muscle Physiology
- Components of a Sarcomere:
- Z Disc/Line – defines the boundaries and shortens during contraction.
- A Band – length of myosin, remains unchanged during contraction.
- I Band – contains only actin (thin filaments).
- H Zone – contains only myosin (thick filaments).
- Sliding Filament Theory explains muscle contraction as proteins sliding over each other to generate movement.
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Action Potential initiates muscle contraction by signaling release of acetylcholine at the neuromuscular junction.
- Multiple action potentials can fuse for increased force.
- All or Nothing principle indicates muscle fibers either fully contract or do not contract at all.
Activation of a Muscle Fiber
- Steps to activate a muscle fiber:
- An action potential is generated.
- Signal travels down the nerve to the neuromuscular junction.
- Travels along t-tubules, causing calcium to be released from the sarcoplasmic reticulum.
- Calcium binds to troponin, which then displaces tropomyosin away from actin binding sites.
- Myosin binds to actin, forming a cross bridge.
Skeletal Muscle Types
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Type I – Slow Twitch
- Contraction Speed: Slow
- Energy Source: Aerobic Metabolism
- Fatigue Resistance: High, suitable for prolonged activity.
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Type IIa – Fast Oxidative Glycolytic
- Contraction Speed: Faster than Type I, slower than Type IIx
- Energy Source: Mixed (primarily aerobic, but can use anaerobic)
- Fatigue Resistance: Moderate.
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Type IIx – Fast Glycolytic
- Contraction Speed: Fastest
- Energy Source: Primarily anaerobic glycolysis
- Fatigue Resistance: Low, fatigue quickly due to reliance on anaerobic pathways.
Muscle Contraction Types
- Aerobic Contraction: Requires sufficient oxygen for energy, ideal for lower-intensity, sustained activities.
- Anaerobic Contraction: Utilizes stored energy without oxygen; occurs during short bursts of high-intensity activities.
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Description
Test your knowledge on the skeletal system, including the axial and appendicular skeleton. Explore the functions of bones, different types of joints, and the vertebral column. This quiz will help reinforce your understanding of essential anatomical structures.
