The Small Details
What are the two types of myofilaments that make up myofibrils?
Thin and thin myofilaments
The protein found in the thin myofilaments that physically blocks the myosin head from binding actin is called?
Tropomyosin
What is a muscle twitch?
A single muscle contraction-relaxation cycle.
What is the energy source for all muscles at rest and during mild exercise, moderate exercise, & heavy exercise?
(Glycogen, fatty acids, & glucose)
Fatty acids
Glycogen
Glucose
Which type of smooth muscle cells have little or no gap junctions?
(unitary or multiunit)
Multiunit smooth muscles
When sarcomere contracts, which of the following shortens: A bands, I bands, distance between Z lines.
I bands, distance between Z lines.
What is the role of calcium in muscle contraction?
Calcium binds to Troponin C causing conformational change to Troponin and tropomyosin which exposes the myosin binding site on actin thereby allowing myosin head to bind actin
If a skeletal muscle is stimulated and a second stimulus is applied before relaxation is complete, a second contraction, which develops a greater tension, is fused to the first contraction. This addition of two muscle contraction events is called what?
What is a twitch summation
What is it called when growth is due to increase in cell size
What is it called when growth is due to increase in cell numbers
(Hyperplasia, hypertrophic)
Hypertrophic
Hyperplasia
Which muscle uses a myosin-regulated mechanism in which myosin light chain kinase phosphorylates myosin light chains allowing myosin to form cross bridges with actin to initiate contraction.
Smooth muscle
What are the protein components of thin myofilaments & thick myofilaments?
Thin – Actin, tropomyosin, troponin,
Thick – myosin
Where is Ca2+ stored in the muscle cell?
Terminal cisternae of the sarcoplasmic reticulum
If the stimulus is repeated at a sufficiently high rate, the muscle will not relax between each stimulus but rather will remain in a contracted state what is this called?
tetanic contractions?
Unlike skeletal muscle, the voltage-gated calcium channels are not directly connected to calcium channels in the SR of cardiac muscle. Instead, calcium acts as a second messenger to open SR channels. What do you call this mechanism of action of calcium on muscle contraction?
Calcium-induced calcium release
(T/F) Smooth muscles do not contain thin filaments
false
Name the two binding sites on the myosin heads.
ATP binding site and actin
What are transverse tubules and what are their functions?
They are narrow membraneous tunnels (invaginations) formed from the sarcolemma and situated close to the terminal cisternae, and function to conduction action potentials into the cell to the initiate Ca2+ release
The staircase effect of successive increases in the strength of contraction following repeated stimulation of a muscle. This property is a characteristic of cardiac muscle. What is this called?
What is treppe
What is the structure in smooth muscle that is equivalent to the neuromuscular junction?
Varicosities
Skeletal muscles have stem cells that can fuse to damaged muscle cells and repair them or fuse to each other to form new muscle fibers. What are these called?
satellite cells
Binding of what molecule to the myosin head causes the breakage of the myosin-actin cross bridges.
ATP
In the activation of muscle contraction by nerve impulses, what division of the nervous system is involved, and what neurotransmitter is utilized?
Somatic motor, acetylcholine
What is it called when a muscle contracts with a shortening action?
What is it called when a muscle contracts while lengthening?
(Eccentric or Concentric)
Concentric
Eccentric
(Bonus question: are these Isometric or Isotonic?)
In skeletal muscle, calcium binds to troponin C to initiate contraction. What do calcium binds to in smooth muscles to initiate contraction?
Calmodulin
(T/F) Muscle contraction is fastest when the load is increased.
False.
More load=slower contraction