Muscular System 3 Flashcards
Define the Sliding Filament Model:
When a myofibril contracts, thin & thick filaments slide past each other within each sarcomere
What is the first step of the sliding filament theory?
ATP cocks a myosin head into an active position
breaks off a phosphate group from ATP
At the beginning of a muscle contraction, calcium ions are?
released from the myocyte’s sacroplasmic reticulum and binds to Troponin
When Calcium binds to Troponin it causes Tropomyosin to?
Tropomyosin to uncover tropomyosin binding sites
Myosin inserts its head into an ACTIN biding site
Describe the “power stroke”:
When the Myosin head uncocks
Moves into relaxed position
causes ACTIN & MYOSIN to move past each other
Additional ATP causes the Myosin to?
Myosin detaches from ACTIN binding site
How does ATP reactivate the free myosin head?
By breaking off a phosphate and cocks the head of the myosin
The ratchet-like-movement causes?
Thin filaments to slide past thick filaments
The sliding filament needs this to repeat the process?
Calcium in the sarcoplasm
How do Z-lines act when a sarcome contracts?
The z-lines move closer together
Multiple Sacromeres contracting causes?
The myofibril to contract
The myocyte contracts
Do Actin and Myosin become shorter?
NO, thick & thin filaments slide past each other
During Muscle Contraction what part of the myofiribril sorten?
The Sacromere
What are the 2 Contractile Proteins?
Myosin & Actin work to shorten the sacromere
What are the 2 Regulatory Proteins?
Troponin & Tropomyosin act as a switch to determine whether actin & myosin can bind and slide
