Test #2 Flashcards
Slow-twitch muscle fibers use ______ to especially enhance ATP production by ____
Myoglobin; oxidative phosphorylation
A toxin that blocks acetyl-choline gated sodium channels on skeletal muscle is likely to _____
Cause flaccid (floppy) paralysis of skeletal muscle
Put these events in chronological sequence for skeletal muscle:
- T tubules convey action potentials into the interior of the cell
- Acetylcholine binds to receptors on the sarcolemma
- Ca2+ is released from the sarcoplasmic reticulum
- Ca2+ ions bind to troponin, pulling on tropomyosin
2 –> 1 –> 3 –> 4
A drug that decreases the activity of myosin kinase has the potential to:
- Decrease blood pressure by causing vasodilation in patients with high BP
- Increase the rate of contractions to induce labor
- Increase rate of contractions in the large intestine
- Increase BP by causing vasoconstriction in patients with circulatory failure
Decrease blood pressure by causing vasodilation in patients with high BP
Paravalbumin is a protein that binds to calcium, removing it from the cytosol, in certain types of skeletal muscle, especially in birds or insects with high wing beat frequencies. What is an explanation of how this protein affects twitch speed?
It allows muscle to relax more quickly
What best describes the role of calcium in the excitation-contraction coupling reaction
Ca2+ will bind to troponin, which leads to a conformational shift in tropomyosin, allowing for actin and myosin to attach
What causes the myosin head to disconnect from actin
Binding of ATP
Compared to the interstitial fluid, the fluid in the t-tubules of skeletal muscle fibers
- has more potassium
- has more sodium
- has more calcium
- is identical
Is identical - t-tubules are filled with interstitial fluid
What causes the relaxation of smooth muscle?
Calcium removal from the cytosol, inhibition of myosin kinase, and activity of myosin phosphatase
The mechanism responsible for skeletal muscle fatigue appears to involve
Decreased effectiveness of action potentials along the t-tubules.
Neurotransmitters are typically released ______ into the synapse
From the pre-synaptic membrane of neurons
What does transduction in the olfactory system depend on?
Ligands binding to receptor neurons causing a graded and an action potential
Adrenergic receptors are known as either ____ or ____
Alpha or beta
Blood flow in a blood vessel can decrease (vasoconstriction) if that vessel has:
Alpha-adrenergic receptors
Touch neurons undergo graded depolarizations when
Mechanically-G Na+ channels are opened