Podcast
Questions and Answers
Which of the following is NOT a component of the axial skeleton?
Which of the following is NOT a component of the axial skeleton?
- Vertebral column
- Shoulder girdle (correct)
- Sternum
- Ribs
What percentage range does skeletal muscle contribute to total body weight?
What percentage range does skeletal muscle contribute to total body weight?
- 40-50% (correct)
- 60-70%
- 10-20%
- 20-30%
Which of the following is NOT a primary function of skeletal muscle?
Which of the following is NOT a primary function of skeletal muscle?
- Postural support and breathing
- Heat production during cold stress
- Nutrient storage (correct)
- Force production for locomotion
In the sliding filament model of muscle contraction, what happens to the I-band and H-zone as the sarcomere shortens?
In the sliding filament model of muscle contraction, what happens to the I-band and H-zone as the sarcomere shortens?
What is the approximate water content of skeletal muscle?
What is the approximate water content of skeletal muscle?
Which two myofilaments account for approximately 85% of the myofibrillar complex?
Which two myofilaments account for approximately 85% of the myofibrillar complex?
Which of the following represents the correct order of muscle structure from largest to smallest?
Which of the following represents the correct order of muscle structure from largest to smallest?
Which term is NOT used as a synonym for a muscle fiber?
Which term is NOT used as a synonym for a muscle fiber?
Which connective tissue layer directly surrounds individual muscle fibers?
Which connective tissue layer directly surrounds individual muscle fibers?
What is the functional consequence of the continuity between muscle connective tissues and the tendon?
What is the functional consequence of the continuity between muscle connective tissues and the tendon?
During excitation-contraction coupling, what is the primary role of the sarcoplasmic reticulum (SR)?
During excitation-contraction coupling, what is the primary role of the sarcoplasmic reticulum (SR)?
What event directly triggers the binding of myosin to actin, initiating the power stroke?
What event directly triggers the binding of myosin to actin, initiating the power stroke?
Which of the following is the correct sequence of events in excitation-contraction coupling?
Which of the following is the correct sequence of events in excitation-contraction coupling?
If a toxin blocked the release of acetylcholine at the neuromuscular junction, what immediate effect would this have on muscle contraction?
If a toxin blocked the release of acetylcholine at the neuromuscular junction, what immediate effect would this have on muscle contraction?
What structural adaptation ensures the coordinated contraction of a muscle fiber upon receiving a nerve impulse?
What structural adaptation ensures the coordinated contraction of a muscle fiber upon receiving a nerve impulse?
How does the arrangement of epimysium, perimysium, and endomysium contribute to muscle function during exercise?
How does the arrangement of epimysium, perimysium, and endomysium contribute to muscle function during exercise?
Flashcards
Axial vs. Appendicular Skeleton
Axial vs. Appendicular Skeleton
The skeletal system, divided into two main parts.
Muscle Function
Muscle Function
Muscles pull on bones, creating movement.
Skeletal muscle functions
Skeletal muscle functions
Provide force for movement, posture, breathing, heat, and glucose disposal.
Sarcomere
Sarcomere
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Sliding Filament Model
Sliding Filament Model
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Myofilaments
Myofilaments
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Fascicle
Fascicle
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Muscle Structure Hierarchy
Muscle Structure Hierarchy
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Epimysium
Epimysium
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Perimysium
Perimysium
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Endomysium
Endomysium
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Tendon
Tendon
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Crossbridge Formation
Crossbridge Formation
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Action Potential (AP)
Action Potential (AP)
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Acetylcholine (Ach)
Acetylcholine (Ach)
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Excitation-Contraction Coupling
Excitation-Contraction Coupling
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Study Notes
- Human body consists of over 400 skeletal muscles
- Skeletal muscles make up 40-50% of total body weight
Skeletal Muscle Function
- Muscle shortening (contraction) pulls on bony levers to cause movement
- Force production for locomotion
- Postural support & breathing
- Heat production during cold stress
- Major site of glucose disposal
Skeletal Muscle Structure
- Striated
- Multi-nucleated
- Sarcomeres are functional units
- Each muscle consists of thousands of cylindrical cells called fibers that lie parallel to each other.
Muscle Composition
- Water content is 75% (sarcoplasm)
- Protein content is 20% (actin, myosin)
- Salts and other substances make up 5%
Myofilaments
- Consist of actin and myosin
- They account for ~85% of the myofibrillar complex
- Other proteins either serve a structural function or affect protein filament interaction during muscle action
- These include Tropomyosin, troponin, titin, α-actinin, β-actinin, M protein, and C protein
Muscle Cell Organization
- Muscle > fascicle > muscle fiber > myofibril > myofilaments
- Muscle fiber = muscle cell = myocyte = myofiber
- A single multinucleated muscle fiber contains myofibrils that lie parallel to the fiber's long axis
- Myofibrils contain smaller subunits called myofilaments, which lie parallel to the myofibril
Fascia Layers
- The body's skeletal muscles contain various wrappings of fibrous connective tissue (fascia)
- Epimysium is the outer layer of connective tissue
- Perimysium surrounds each fasciculus, or group of fibers
- Endomysium surrounds individual fibers
- Connective tissue is continuous with the tendon
- The tendon intermeshes with collagenous fibers of bone periosteum
- Tension developed in a muscle fiber is transmitted directly to the tendon & bone
Sliding Filament Model of Muscle Contraction
- Myofilaments (actin & myosin) slide past each other towards the center of the sarcomere
- Sarcomere shortens as the Z-line moves towards the center of the sarcomere
- Filaments overlap more, causing the disappearance of the I-band and H-zone
Axial vs Appendicular Skeleton
- Axial skeleton consists of the skull, vertebral column (C1-coccyx), ribs, and sternum
- Appendicular skeleton consists of the shoulder girdle; bones of the arms, wrists, hands, and pelvic girdle; and bones of the legs, ankles, and feet
Excitation-Contraction Coupling (Overview)
- Action Potential (AP) starts in the axon terminal
- Acetylcholine (Ach) is released
- Ach binds to receptors on the sarcolemma
- AP travels to T-tubules
- Sarcoplasmic reticulum(SR) releases Ca2+
- Calcium binds to Troponin causing Tropomyosin to shift
- Myosin binds to the active site to form crossbridge
- Power stroke & sliding of filaments occurs
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Description
Overview of skeletal muscle functions including locomotion, posture, breathing, and heat production. Details the striated structure, sarcomere units, and fiber composition. Covers myofilaments, actin, myosin, and regulatory proteins.
