Multiple Choice
In the context of sliding filament theory, what is the functional unit of muscle contraction?
1
views
9. Muscle Tissue
Sliding Filament Theory and the Sacromere
Struggling with Anatomy & Physiology?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
In the sliding filament theory of skeletal muscle contraction, which structure actually shortens as the muscle contracts?
A
The A band shortens
B
The sarcomere (distance between Z discs) shortens
C
The thin (actin) filaments shorten
D
The thick (myosin) filaments shorten
Verified step by step guidance1
Understand the basic structure of a sarcomere, which is the functional unit of a skeletal muscle fiber, defined as the segment between two Z discs.
Recall that during muscle contraction, the sliding filament theory explains how thin (actin) and thick (myosin) filaments interact by sliding past each other without changing their individual lengths.
Identify that the A band corresponds to the length of the thick (myosin) filaments and remains constant during contraction because the myosin filaments do not shorten.
Recognize that the I band and H zone change in length as the thin filaments slide inward, causing the sarcomere itself to shorten.
Conclude that the actual structure that shortens during contraction is the sarcomere (the distance between Z discs), not the individual filaments or the A band.
6:26mWatch next
Master Sliding Filament Theory with a bite sized video explanation from Bruce Bryan
Start learningRelated Videos
Related Practice
Sliding Filament Theory and the Sacromere practice set
Problem sets built by lead tutorsExpert video explanations