30 Questions
What is the primary purpose of muscles?
to contract for purposeful movement, manipulation of external objects, propulsion of contents through hollow internal organs, and emptying contents of certain organs to external environment
What type of muscle is found only in the heart?
Cardiac muscle
Which type of muscle is characterized by dark and light bands?
Striated muscle
What type of muscle is innervated by neurons in the autonomic nervous system?
Both cardiac and smooth muscle
Which type of muscle is connected to the bones?
Skeletal muscle
What is the main difference between skeletal muscle and cardiac muscle in terms of control?
Skeletal muscle is voluntary, while cardiac muscle is involuntary
What is the primary function of myofibrils in a muscle cell?
To contract and produce muscle force
What is the name of the functional unit of a myofibril, found between Z-lines?
Sarcomere
What is the role of the myosin subunit that binds actin?
Binding to actin
How do muscles grow?
By adding sarcomeres to the end of myofibrils
What is the composition of thin filaments?
Actin, troponin, and tropomyosin
What is the role of the myosin heads during muscle contraction?
To form cross bridges with actin
What is the structure of the backbone of an actin filament?
Two strands of actin twisted together
What is the role of tropomyosin in muscle contraction?
To cover actin binding sites when muscles are at rest
What is the function of troponin in muscle contraction?
To hold tropomyosin in place and block actin binding sites
What is the result of calcium binding to troponin?
The tropomyosin is shifted out of the way, exposing the actin binding sites
What is the function of the cross bridges in muscle contraction?
To form the connection between myosin and actin, bringing about contraction
What is the composition of the A band in a sarcomere?
All the thick filaments and some areas of the thin filaments
What is the main component of the H zone within the A band?
Myosin filaments
What happens to the length of the thick filaments during muscle contraction?
It remains the same
What happens to the actin binding sites when calcium is present?
They are uncovered by tropomyosin
What is the role of troponin in the absence of calcium?
It holds tropomyosin in place
What is the composition of the I band?
Only thin filaments
What is the role of the supporting protein that extends from the M lines to the Z lines?
It provides support to the sarcomeres
What surrounds individual muscle fibers?
Endomysium
What is the result of multiple myoblasts fusing together during development?
Formation of a muscle fiber with multiple nuclei
What is the function of satellite cells?
To differentiate into new muscle cells
Why do muscle cells have a large number of mitochondria?
To generate and use energy
What is the shape of a muscle fiber?
Cylindrical
What is the term for the process of myoblasts fusing to form myotubes?
Fusion of myoblasts
Test your knowledge of muscle types, including skeletal, smooth, and cardiac muscles, and how they function and work together. Learn about muscle contraction and relaxation, and the different types of metabolism.
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