Functional Anatomy of a Sarcomere

These flashcards cover the key concepts and terminology related to the functional anatomy of a sarcomere, including the various types of filaments and important structural proteins.

H zone

Lighter stripe in the middle of the A band.

M line

Structure that bisects the H zone and A band.

Z disc

Structure that bisects the I band.

A band

Region in the sarcomere where thick filaments (myosin) are found.

I band

Region in the sarcomere where thick filaments are not present.

Sarcomere

Functional contractile unit of muscle, defined as the region between two Z discs.

Thin filament

Filament composed of actin; anchors to Z discs.

Thick filament (myosin)

Filament that runs the width of the A band and is composed of myosin.

Alpha-actinin

Protein that forms the Z discs and anchors thin filaments.

Desmin

Protein that holds adjacent thick filaments together.

Myomesin

Fine protein strands that form the M line in the sarcomere.

Elastic filaments (titin)

Giant protein that holds thick filaments in place and allows for extensibility and recoil.

Myosin

Protein that makes up the thick filaments, characterized by two heads and a long tail.