Unit 8 MSK pt. 1 Patho Flashcards
What is muscle fatigue and what can cause it?
A reversible condition in which an exercising muscle is no longer able to generate or sustain the expected power output.
Changes in Ca++ release from the sarcoplasmic reticulum may have a major impact on muscle function.
What is a Type 1 muscle fiber? (just definition)
A slow-twitch oxidative; Red muscle
What is a Type 2A muscle fiber? (just definition)
A fast-twitch oxidative-glycolytic; Red muscle
What is a Type 2 B/X muscle fiber? (just definition)
A fast-twitch glycolytic; white muscle
What are the characteristics of a Type 1 muscle fiber?
It is the slowest in development of maximum tension;
It is slow in Myosin ATPase activity;
It has the longest contraction duration;
fatigue resistance;
most used (Posture);
has numerous mitochondria
What are the characteristics of a Type 2A muscle fiber?
It is intermediate speed in development of maximum tension;
It is medium speed in Myosin ATPase activity;
It has a short contraction duration;
It is fatigue resistance;
Used in standing and walking;
has moderate mitochondria
What are the characteristics of a Type 2B/X muscle fiber?
It is the fastest in development in maximum tension;
It is fast in Myosin ATPase activity;
It has a short contraction duration;
It is easily fatigued;
Least used (Quick fine movements);
Few mitochondria
What does a motor unit consist of?
One motor neuron and all the muscle fibers it innervates
What are the three muscle types?
Skeletal
Cardiac
Smooth
What are that characteristics of skeletal muscles?
Skeletal muscles have large fibers, multinucleate cells that appear striped or striated under the microscope
What are the characteristics of Cardiac muscles?
Cardiac muscles fibers are also striated but they are smaller, branched, and uninucleate. Cells are joined in series by junctions called intercalated disk
What are the characteristics of Smooth muscle?
Smooth muscles fibers are small and lack striations
Skeletal muscles is composed of:
Connective tisse
Muscle fascicles
Blood vessels
Nerves
_______ are the basic functional unit of the muscle fiber.
Sarcomeres
What are each sarcomere composed of?
Contractile, structural, and accessory proteins.
Different components of the sarcomere are named based on their appearance under a light microscope and to name different areas and structures of the sarcomere
What are the contractile proteins?
Myosin and actin
What are the structural proteins?
M Line and Z disk
What are the Accessory Proteins?
Titin and Nebulin
These are giant accessory proteins. Titin spans the distance form one Z-disk to the neighboring M line. Nebulin, lying along thing filaments, attaches to a Z-disk but does not extend to the M-line
What do Titin and Nebulin do?
Titin provides elasticity and stabilizes myosin.
Nebulin help align actin
What are the components for the Myosin molecule?
Myosin tail, hinge region, and the myosin heads
What regulatory proteins are associated with the actin chain?
Tropomyosin and troponin
What are the roles of tropomyosin and troponin?
Tropomyosin covers the actin binding sites.
Troponin controls the positioning of tropomyosin over the binding site.
Describe the location and function of the T-tubule.
T-tubules allow action potential to move rapidly from cell surface to inferior to fiber to reach terminal cisternae simultaneously
What is the Sliding Filament?
With any contraction that takes place the myosin and actin do not change length but slide past each other
Muscle contracts——->Sarcomere shortens with contraction——> Muscle contraction: H zone and I band both shorten, while A band remains constant
What signal initiates the power stroke?
A calcium signal initiates the power stroke when myosin cross bridges swivel and push the actin filaments toward center of sarcomere.
How is ATP used during the contraction cycle?
ATP is used by myosin to convert energy into mechanical energy of crossbridge motion
Why does Rigor Mortis occur after death?
Metabolism stops and ATP supplies exhaust. Muscles are unable to to bind more ATP so they remain in a tightly bound rigor state, muscles freeze due to immovable cross bridges
The somatic motor division controls what?
Skeletal muscles