10 Questions
Which structures are found in the sarcoplasm of a muscle fiber?
Myofibrils and Z-lines
What is the unit of myofibril called?
Sarcomere
What is the function of transverse tubules in a muscle fiber?
To transmit action potentials
What is the name of the band that bisects the A band in a myofibril?
H band
What is the shape of a muscle fiber?
Cylindrical
Which of the following is NOT found in the sarcoplasm of a muscle fiber?
Transverse tubules
What is the function of longitudinal tubules in a muscle fiber?
To transmit nerve impulses
What is the role of the Z-line in a myofibril?
To anchor the myofilaments
What is the H band in a myofibril composed of?
Thick myofilaments
What are the two types of myofilaments found in a myofibril?
Actin and myosin
Study Notes
Muscle Fiber Structure
- The sarcoplasm of a muscle fiber contains myofibrils, mitochondria, sarcoplasmic reticulum, and transverse tubules.
Myofibril Structure
- A unit of myofibril is called a sarcomere.
- The M line bisects the A band in a myofibril.
Muscle Fiber Shape
- Muscle fibers are long, multinucleated, and cylindrical in shape.
Transverse Tubules
- Transverse tubules (T-tubules) are involved in the transmission of action potentials from the muscle fiber surface to the sarcoplasmic reticulum.
Longitudinal Tubules
- Longitudinal tubules are not found in muscle fibers; instead, smooth endoplasmic reticulum is present.
Z-line Function
- The Z-line marks the boundary of a sarcomere and acts as an anchor for the myofilaments.
H Band Composition
- The H band is composed of thick myofilaments (myosin).
Myofilaments
- There are two types of myofilaments found in a myofibril: thick myofilaments (myosin) and thin myofilaments (actin).
Test your knowledge on the physiologic anatomy of muscle, excitation contraction coupling, and the different types of muscle contractions. Dive into the composition of muscle fibers, the role of sarcolemma and sarcoplasm, and understand the mechanisms behind muscle contraction.
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