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Why is it difficult to lift a heavy object when the elbow is at full extension?
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Ch. 11 The Muscular System
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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TOC.tableOfContents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Non è quello che usi tu?Cambia libro di testo
Capitolo 11, Problema 26
Why can a pennate muscle generate more tension than can a parallel muscle of the same size?
Guida verificata passo dopo passo1
Understand the basic difference in muscle fiber arrangement: a parallel muscle has fibers running parallel to the force-generating axis, while a pennate muscle has fibers arranged at an angle to this axis.
Recognize that the force a muscle can generate is proportional to its physiological cross-sectional area (PCSA), which accounts for the total area of all muscle fibers perpendicular to their length.
Note that in pennate muscles, because fibers are angled, more fibers can be packed into the same muscle volume compared to parallel muscles, increasing the PCSA.
Use the relationship that the total force generated by the muscle is the sum of the forces produced by all fibers, so a greater PCSA means greater total force despite the angle of fibers.
Conclude that although each fiber in a pennate muscle contributes less force along the muscle's line of action due to the angle, the increased number of fibers (and thus greater PCSA) allows the pennate muscle to generate more overall tension than a parallel muscle of the same size.
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Muscle Architecture
Muscle architecture refers to the arrangement of muscle fibers relative to the force-generating axis. Pennate muscles have fibers oriented at an angle to the tendon, allowing more fibers to pack into a given volume, while parallel muscles have fibers aligned along the force axis.
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Introduction to Muscles and Muscle Tissue Example 1
Physiological Cross-Sectional Area (PCSA)
PCSA is the total cross-sectional area of all muscle fibers perpendicular to their direction. Pennate muscles have a larger PCSA than parallel muscles of the same size, enabling them to generate greater force because tension is proportional to PCSA.
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02:33Anatomical Sections
Force Generation and Fiber Angle
In pennate muscles, fibers pull at an angle, so individual fiber force contributes less directly to tendon force. However, the increased number of fibers compensates for this, resulting in higher overall tension compared to parallel muscles where fibers pull directly along the tendon.
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14:36General Blood Vessel Structure
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