Muscles Flashcards
Which type of actin makes up the thin filaments in sarcomeres?
Double stranded, helical F-actin.
Which protein directly binds actin? Troponin or tropomyosin?
Tropomyosin.
In a relaxed state, is myosin bound to actin?
No. The binding site is covered by tropomyosin.
When does actin disassociate with myosin?
When ATP binds.
Where does the energy of the powerstroke come from?
The binding of actin and myosin which lowers them in energy.
What calks the myosin arm?
Hydrolysis of ATP.
If each myosin-actin cycle results in a displacement of 8 nm, how do we get muscle shortening of centimeters?
(1) Lots of sarcomeres in series will summate linearly.
(2) Many myosin-actin cycles occur during a single contraction
In smooth muscle, Ca binds to…
Calmodulin which then activates CaM Kinase.
Familial hypertrophic cardiomyopathy causes 50% of cardiac deaths in sports. What is the mutation in this disease?
Cardiac myosin heavy chain.
What 2 things are responsible for generating muscle tension?
Frequency of APs # of motor neurons recruited
What causes muscle fatigue?
- K+ buildup (quickly restored by k/na pump)
2. Pi + H+ buildup inhibit Ca release and binding.
Fast twitch muscles are _______ in color. They are located near ___________
More White in color than slow twitch. Located near glycogen stores. Do quick actions,
Slow twitch muscles are _______ in color. They are used for ___________
Red due to their myoglobin
Used for posture or sustained movement.
What happens when a person with malignant hyperthermia gets inhaled anesthetic? How do you treat it?
Ca is released constantly from the SR and causes muscle spasming and death.
Treat with dantrolene, which blocks Ca release
