Skeletal
Smallest contractile unit:
A) Myofibrils
B) Muscle Fibers
C) Actin
D) Sarcomere
D) Sarcomere
Choose the best possible answer
What are the types of ion channels part of the neuromuscular junction? (2 pts) And what are examples of each?
Chemically gated (Ach)
Voltage gated (Na or K)
What pathway is primarily used for marathons?
Aerobic Pathway
What are 3 differences in skeletal vs smooth muscles
Fibers: Striated in skeletal, Non-striated in smooth
Skeletal: voluntary, striated fibers, multi nucleated
Smooth: Involuntary, non-straited fibers, uninucleated
What increases surface area and allows for rapid changes to membrane potentials deep into muscles?
T-tubules
What band gets shorter in contraction?
I band (and H zone)
What type of fibers are primarily used in marathons?
Slow oxidative fibers
Smooth muscle cells connected by_____
gap junctions
Which of the following is characteristic of skeletal and NOT smooth?
a) Ca2+ release from the sarcoplasmic reticulum
b) Formation of actin and myosin cross bridges
c) acetylcholine can stimulate contractions
d) sarcomeres
d) sarcomere
Smooth muscles do not have sarcomeres, they have a more random arrangement of actin and myosin filaments.
Which of the following structures interacts directly with ions to expose actin binding sites in contracting muscle?
A) Troponin
B) Tropomyosin
C) Actin
D) Myosin
A) Troponin
(Once bound to calcium ions, troponin facilitates the movement of tropomyosin away from actin binding sites, allowing myosin to bind and, ultimately, contract)
Part of cross bridge cycling
What is the factor that does NOT increase contraction duration
-Slow oxidative fibers
-Small Load
-Fast Glycolytic fibers
-Increased recruitment
-Fast Glycolytic fibers
True or False:
Smooth Muscle has a larger capacity for length/tension changes
True
Write the order for the smallest to the biggest unit of organization in skeletal muscle tissue
filament, myofibril, muscle fiber, fascicle
What causes voltage gated Ca 2+ channels to open?
Hint: part of Neuromuscular Junction process
an AP reaching the axon terminal
(Then, Ca 2+ entry causes ACh release from synaptic vesicles)
Which of the following happen as a result of anaerobic exercise?
A) Increases capillaries near muscle fibers
B) Increase the number of mitochondria
C) Increased muscle fiber size
D) A and B
E) All of the above
C - increase muscle fiber size
Increases capillaries near muscle fibers and increase number of mitochondria happen due to aerobic exercise.
What type of smooth muscle are eye muscles for pupils and focusing?
A) Skeletal Muscle
B) Multi Unit Smooth Muscle
C) Unitary Smooth Muscle
D) Striated Smooth Muscle
B) Multi Unit Smooth Muscle
Pay attention to the wording of the question , it says SMOOTH
Skeletal muscle relaxation occurs when
a ) Ca2+ ions are actively transported out of the sarcoplasmic reticulum
b) Ca2+ ions diffuse out of the sarcoplasmic reticulum
c) Ca2+ ions are actively transported into the sarcoplasmic reticulum
d) Ca2+ ions diffuse into the sarcoplasmic reticulum
c) Ca2+ ions are actively transported into the sarcoplasmic reticulum
How is ATP formed in direct phosphorylation? Name all components and enzyme involved (5 pts)
Coupled reaction of creatine phosphate and ADP. Creatine kinase is the enzyme that catalyzes this reaction to produce ATP and creatine.
What is Muscle Fatigue, and what causes it... explain?
-Physiologically unable to contract even though it still receives stimulus
-Causes are not formally understood.
It could be...
No major lack of ATP (think death/rigor mortis)
Ionic imbalances
Increased inorganic phosphate levels
Decreased ATP and increased Mg 2+
Decreased glycogen
Ca 2+ fluxes into the cell from SR and via caveolae what are the other steps that lead to cross bridge cycling? (3 pts)
Ca 2+ binds to calmodulin to activate it
Activated calmodulin activates MLCK
MLCK enzymes phosphorylate myosin head to activate it