Skeletal Muscle - Trachte Flashcards
What causes the power stroke of muscle contraction?
Phosphate release from the myosin head
What action allows the myosin head to relax in a low energy conformation?
binding of ATP
What action allows the myosin head to cock into the right position so that it can attach to the actin?
ATP is cleaved into ADP and Pi, they both remained attached a that point.
What is the state of the muscle fibers if actin and myosin are interacting without ATP
If actin and myosin are allowed to interact in the absence of ATP, the actin & myosin remain attached (rigor mortis)
Describe amyotropic lateral sclerosis (ALS)
Lou Gehrig’s disease
Degeneration of motor neurons
What disease is caused by autoimmune antibodies against calcium channels in motor neurons - results in inability to release ACh?
Lambert-Eaton Syndrome
What does botulism do?
Botulism prevents acetylcholine release by cleaving synaptic associated proteins (SNAPs)
What disease is caused by autoimmune antobdoies against nicotinic receptors in skeletal muscle?
Myasthenia gravis
<p>
| What is the cause of malignant hyperthermia?</p>
<p>
| mutation of the ryanodine receptor allowing for the excessive release of Calcium -usually triggered by anesthesia</p>
What causes Duchenne’s muscular dystrophy?
A mutation in dystrophin (a skeletal muscle support protein)
Why is the heart an exception as far as the length between actin and myosin?
In cardiac tissue the actin and myosin will be more squished together because you rely on the filling of the heart with blood to get maximum efficiency
General Description of Type 1 fibers:
Slow Twitch
The distinction in these muscles is a slower myosin ATPase enzyme
These are in high proportions in distance runners or in postural muscles such as the soleus
They contain a lot of myoglobin, resulting in the designation “red fibers”
They need the myoglobin because they require lots of oxygen to maintain contractions
General Description of Type 2 fibers:
Fast twitch
These are in high proportions in extraocular muscles of the eye
They have a faster myosin ATPase
They are termed white fibers (less myoglobin)
These muscles are adapted for anaerobic metabolism
What are concentric vs eccentric contractions?
Concentric
Muscle contracts resulting in shortening
Typical biceps curl in weightlifting
Eccentric
Muscle lengthens while attempting to shorten
Run down a hill
Much more damage to muscle with this type of contraction (really sore afterwards)
How does cardiac muscle differ from skeletal muscle?
Cardiac muscle has autorythmicity
- does NOT require innervation to contract
- innervation simply slows or accelerates the contraction
Cardiac muscle is more dependent on Calcium-induced calcium release to elevate intracellular calcium concentrations
