Day 2 Flashcards
What is the sarcoplasm?
It is the cytoplasm of a muscle cell
What does the sarcoplasm contain?
Glycosomes and myoglobin
What does a muscle cell contain?
Myofibrils, sarcoplasmic reticulum, and T tubules
What are myofibril’s made up of?
Sarcomeres
What are myofibrils?
They are rod like structures that run parallel to the length of the muscle fiber
What are Sarcomeres?
They are the contractile units
What is a Sarcomere composed of?
Myofilaments and contractile proteins
What are the two types of microfilaments?
Thick( myosin) and Thin(actin)
What are striations made out of?
A repeating series of dark, (A) bands and light( I) bands
Where are stations found in?
They are evident along the length of each myofibril
The A band has a lighter midsection called the what?
The H zone
The H zone is bisected by the what
The M line
The I band has a midline interruption called the what?
The Z disc
A sarcomere is the region of what?
Of a myofibril between two successive Z discs
What do thick filaments contain?
Bundled myosin molecules
What does a myosin molecule consist of?
Six polypeptide chains with a rod like tail and globular heads attached via a flexible hinge
What do Thin filaments contain?
Actin molecules
What does Actin have?
Has a kidney shaped polypeptide sub units called globular Actin
What does globular Actin have?
Myosin binding site
G Acton, sub units polymerize Into what?
Long actin filaments called filamentous
What do two intertwined F Actin filaments form?
Forms the backbone of each thin filament
Thin filaments contain the regulatory proteins called what
Tropomyosin and troponin
Elastic filaments are composed of what
Giant protein Titin
Elastic filaments extends from what to what?
The Z disc to the thick filament
What is the role of elastic filaments?
Maintains the organization of the A band
What does dystrophin link?
The thin filament to the integral proteins of the sarcolemma
Describe the sarcoplasmic reticulum
It is a smooth endoplasmic reticulum
What does the sarcoplasmic rectum regulate?
Regulates the intercellular levels of ionic calcium
What does the sarcoplasmic recticulum store?
It stores calcium
When does the sarcoplasmic rectum release the calcium?
When the muscle fiber is stimulated to contract
What are T tubules?
They are investigations of the sarcolemma that run deep into the cell between the terminal cisterns
What does T tubules increase?
It increases the muscle fibers surface area
What does T tubules allow?
It allows change in the membrane potential to rapidly penetrate deep into the muscle fiber
What are triads?
They are groupings of three membrane structures
Name the three membrane structures that make up a triad
Terminal cistern, T tubules, and terminal cistern
What does contraction refer to in the sliding filament model?
It refers to the active shed of myosin cross bridges
What are cross bridges?
Force generating sites
What does the sliding filament model state during contraction?
It states that the thin filaments slide past the thick ones so that the Actin and myosin filaments overlap to a greater degree
What occurs to the thick and the thin filaments during contraction of the sliding filament model?
Neither of them change Length during contraction
Skeletal muscle contractions are what?
Voluntary
What do skeletal muscle contractions require?
Requires activation of motor neurons in the spinal cord
