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The H Zone
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What are the 3 sections along the length of sarcomere?
The three sections along the length of a sarcomere are the A band, the I band, and the H zone. The A band is the dark region in the center of the sarcomere that contains both thick and thin filaments, while the I band is the light region at the ends of the sarcomere that contains thin filaments only. The H zone is the region in the center of the sarcomere where only thick filaments are present.
What separates one sarcomere from the next?
actin
Does actin filaments extend the enyire length of a sarcomere?
Yes, it makes cool stuff
What is the dark staining area of a sarcomere?
It is a section of the Sarcomere that stretches from one end of the Myosin filament to the other, and also includes parts of the Actin filaments that overlaps it.
What is atrial depolarization?
Atrial depolarization is the first part of the cardiac cycle.Cardiac (and skeletal) muscle is made up of bundled stands of functional units called sarcomeres. Each sarcomere consists of two Z-disks, which mark the ends of each sarcomere, and alternating dark and light bands called A-bands and I-bands respectively. The I-band contains only actin (the main cytoskeletal protein in most cells) filaments whereas the A-band contains overlapping myosin (a "molecular motor" protein) and actin filaments in its periphery and only myosin filaments in the central region called the H-zone. The center of the H-zone is marked by an imaginary line (called the M-line) in which myosin extends in both directions. The sarcomere contracts inward toward the M-line. "Depolarization" occurs when an electrochemical event causes calcium cations to be released from a membranous network (similar to the the endoplasmic reticulum) called the sarcoplasmic reticulum and creates an action potential. The free Ca2+ binds to a specific troponin protein shifting a troponin/tropomyosin protein complex allowing the myosin head groups to bind to the actin filament. ATP hydrolysis causes conformational changes of the myosin filament which in effect "pulls" the actin filament toward the M-line of the sarcomere. The sarcomere can return to its resting potential by allowing potassium (K+) ions to flow out.
What are the 3 sections along the length of sarcomere?
The three sections along the length of a sarcomere are the A band, the I band, and the H zone. The A band is the dark region in the center of the sarcomere that contains both thick and thin filaments, while the I band is the light region at the ends of the sarcomere that contains thin filaments only. The H zone is the region in the center of the sarcomere where only thick filaments are present.
What is the H zone A band?
Within skeletal muscle there are muscle fibres... and within muscle fibres there are myofibrils... and within a myofibril there is a sarcomere.Within the sarcomere there are 2 types of bands:-Actin (light)-Myosin (dark)There are different striations of these bands, this is what makes up the muscle fibre:The A band is where actin & myosin overlapp- it contains both myosin & actinThe I band only contains actinThe H zone only contains myosinThe Z line is in the centre of each I band, and marks the start of a sarcomere
What is the zone of overlap?
The zone of overlap is the point where actin myofilaments overlay the myosin myofilaments as it (actin) gets pulled towards the m-line (mid-point of sarcomere). The zone of overlap increases during muscle contraction, resulting in the shortening of the muscle.
What separates one sarcomere from the next?
actin
What is one of the functional units of a myofibril?
sarcomere
When the sarcomere is at rest what is covering the active sites on actin?
Troponin
What region in a sarcomere does actin and myosin overlap?
z disc
What is a actin or myosin containing strucutre?
The basic unit of muscular contraction; the sarcomere.
Does actin filaments extend the enyire length of a sarcomere?
Yes, it makes cool stuff
What is the dark staining area of a sarcomere?
It is a section of the Sarcomere that stretches from one end of the Myosin filament to the other, and also includes parts of the Actin filaments that overlaps it.
What do sarcomere contain?
Sarcomeres are composed of actin (thin filaments) and myosin (thick filaments).
What is the protein filament that slides inward toward the middle of a sarcomere during a muscle contraction?
Actin
