Chapter 10 Flashcards
Smooth Muscle
Found in the walls of all hollow organs (GI tract, the urinary system and the uterus)
What does skeletal muscles use for movement?
The framework of the bones of the skeleton
How are skeletal muscles attached?
Skeletal muscles attach at each end to two different bones
How are muscles attached?
Muscles are attached to bones by tendons
Tendons
Strong connective tissue formed primarily of collagen
Point of origin
Point where the muscle attaches on the bone closer to the center of the body Stays in place when contraction occurs
Point of insertion
Brought closer to the point of origin during contraction Point more distant from the center of the body
Why are different muscles needed to move a joint?
Muscles can only contract so different muscles are necessary for flexion and extension of a joint
Antagonistic
Muscles that are responsible for movement in opposite directions
Synergistic
Muscles that move a joint in the same direction
Myofibril that generate contractions
Polymerized actin and myosin
Actin polymerizes to form
Thin filaments
Thin filaments
Attach to eachZ line and overlap with thick filaments in the middle of each sacromere
Myosin polymerizes to from
Thick filaments
Thick filaments
Are not attached to the Z lines
When does contraction occur in the Myofiber?
When thin and thick filaments slide across each other
How is filament sliding powered?
ATP hydrolysis; myosin is an enzyme which uses energy of the ATP to create movement
Filament sliding step 1
(1) Binding of the myosin head to a myosin binding site on actin (cross bridge formation) Myosin has ADP and P1 bound
Filament sliding step 2
The power stroke; myosin head moves to a low-energy conformation, and pulls the actin chain toward the center of the sacromere. ADP is released
Filament sliding step 3
Binding of a new ATP molecule necessary for release of actin by the myosin head
Filament sliding step 4
ATP hydrolysis occurs immediately and the myosin head is cocked. Another cycle beings when the myosin head binds to a new binding site on the thin filament
Troponin-tropopomyosin complex
Prevents contraction when Ca2+is not present
Tropomyosin
A long fibrous protein that winds around the actin polymer, blocking all the myosin binding sites
Troop in
Globular protein bounds to tropomyosin that can bind Ca2+

