MUSCULAR SYSTEM Flashcards
What is the diaphragm and why is it an important muscle?
The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. It is important as the chief muscle of inhalation because it allows breathing to occur
What is curare?
A drug acting as a skeletal muscle blocker for surgeries and operations
Why is curare used for surgeries?
It promotes muscle relaxation and paralysis because ACh can’t bind to receptor sites as an effect, so muscle contraction is prevented
What is the sartorius? What is its function and location?
Sartorius is a long muscle that crosses obliquely (diagonal) over the anterior thigh; its origin is on ilium; inserts in the tibia. It flexes/abducts, laterally rotates thigh at hip
define the origins of muscles
the immobile or stationary part of the muscle (ie. clavicle)
what is the masseter and its function?
A chewing muscle that works synergistically with the temporalis muscle. It closes/retracts jaw.
what is the sternocleidomastoid ?
Two neck muscles running bilaterally each side of neck; extends obliquely from sternum and clavicle upward to mastoid process of temporal bone; during contraction, both muscles flex the head at the neck–contraction of one rotates head towards opposite side
What is the quadriceps femoris group and its’ function(s)?
Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius–muscles located on anterior thigh; they all insert on tibia; rectus femoris originates on ilium but all others originate on femur. Their goal is to extend leg at knee (femoris can flex at hip); lateralis common site for pediatric IM injections
What is the sliding filament theory?
The chemical process that makes muscles contract and move
What are the components of the sliding filament mechanism theory and their function(s)?
Actin and Tropomyosin-troponin complex are the thin filaments, with actin being a contractile protein also. Myosin is the thick filament, and the other contractile protein. They form cross-bridge.
Tropomysoin-troponin complex are inhibiting proteins. Actin and mysoin connect, form a bridge, then slide past one another.
What happens to muscles and its system as we age?
They lose mass, become small, weaker, dehydrated; motor neurons are lost to muscle atrophy; decreased muscle strength, slowing of reflexes
Define ACh and its function in the NMJ
ACh is a neurotransmitter that acts as a signal stimulant to initiate an impulse to the muscle membrane
What is cholinesterase and its relation to acetylcholine?
It is an enzyme; Cholinesterase destroys ACh after it has unbound from the receptor site.
What is recruitment?
The addition of motor units, which allows variety of force of contraction
Describe a consequence of recruitment.
Recruitment itself is a consequence; a consequence within recruitment is increased force of muscle contraction
Describe the ACh in the first 2 steps of information transfer in at the NMJ
- ACh introduced as chemical substance stored in vesicles found at a neuron’s ending
- Released ACh is released into synaptic cleft
What action do ACh take post-release to the synaptic cleft?
It diffuses across the space (cleft) and binds to the receptor sites on the muscle membrane
What role does calcium play in the sliding filement mechanism?
Ca, stored away in the SR away from the filaments, is released during muscle stimulation and floods the sarcomere, so it’s essential for cross-bridges (actin-myosin connection). It’s pumped back to SR during muscle relaxation.
What is Clostridium tetani (tetanus)?
A neurotoxin produced by bacteria that causes excessive motor neuron stimulation, followed by excessive release of ACh, and resulting in muscle spasms and tetanic contractions; i.e. “lockjaw”
Myalgia
Pain
What is Myasthenia gravis and effects?
A NMJ-effecting disease caused by damaged receptor sites (which cant effectively bind to receptors) on the muscle membrane. It effects muscle contraction, resulting in initial muscle weakness, then progressed respiratory issues
Because muscles require a rich ATP energy source, what is the 1st chemical to be broken down?
Creatine phosphate, which can also be used as an energy storage
What is the 2nd energy source/breakdown for ATP?
Glycolysis (anaerobic metabolism), which causes lactic acid build up
What is the 3rd ATP source for muscles?
Aerobic metabolism, which facilitates fat breakdown and ATP production for muscle contraction
