Control conditions from a normal nerve cell in response to a Depolarizing stim

Trace A represents a typical action potential recorded under control conditions from a normal nerve cell in response to a depolarizing stimulus. Which of the following perturbations would explain the conversion of the response shown in trace$$\mathrm{A}$$to the action potential shown in trace$$\mathrm{B}$$? a. Blockade of voltage-sensitive$$\mathrm{Na}+$$channels b. Blockade of voltage-sensitive$$\mathrm{K}+$$channels c. Blockade of Na-K “leak” channels d. Addition of the voltage-sensitive$$\mathrm{K}+$$channels at the top of action potential e. Addition of the voltage-sensitiveCa2+channels at the top of action potential

2. Similarities between smooth and cardiac muscle include which of the following?

a. Ability to contract in the absence of an action potential b. The sources ofCa2+ions for muscle contraction c. Presence of myosin light chain kinase d. Role of myosin kinase in muscle contraction e. Striated arrangement of the actin and myosin filaments

3. Which characteristic or component is shared by skeletal muscle and smooth muscle? a. Thick- and thin- filaments arranged in sarcomeres b. Presence of Troponin ic. Elevation of intracellularCa2+concentration for excitation-contraction coupling d. Spontaneous depolarization of the membrane potential e. High degree of electrical coupling between cells

4. Smooth muscle contraction is terminated by which of the following? a. Dephosphorylation of myosin kinase b. Dephosphorylation of myosin light chain c. Efflux ofCa2+ions across the plasma membrane d. Inhibition of myosin phosphatase e. Uptake ofCa2+ions into the sarcoplasmic reticulum 5. Excitation-contraction coupling is a process in which a skeletal muscle cell is stimulated to contract, and this process is followed by muscle cell relaxation. Which of the following order describes the correct order of the above events? 1. Action potential 2.Ca2+release into cytoplasm 3. Cross-bridge cycling 4. CytoplasmicCa2+removal

5. Depolarization of$$\mathrm{T}$$tubules a. 1-2-5-3-4 b. 1-5-2-3-4 • c. 5-4-3-1-2 d. 5-4-1-3-2 e. 4-5-1-3-2 6. Repeated stimulation of a skeletal muscle fiber causes a sustained contraction (tetanus). Accumulation of which solute in intracellular fluid is responsible for the tetanus? a. Adenosine triphosphate (ATP) b. K+ c.Na+d. Troponin e.Ca2+f. Calmodulin

7. In contraction of gastrointestinal smooth muscle, which of the following events occurs right after binding ofCa2+to calmodulin? a. increased intracellularCa2+concentration b. activation of myosin light chain kinase c. depolarization of the sarcolemmal membrane d. opening of ligand-gatedCa2+channels e.Ca2+-inducedCa2+release 8. Which autonomic receptor mediates secretion of epinephrine by the adrenal medulla? a. Cholinergic nicotinic receptor b. Adrenergic alpha 1 receptor c. Adrenergic beta 2 receptor d. Adrenergic beta 1 receptor e. Cholinergic muscarinic receptor

9. Which of the following statement is not true about autonomic nervous system? a. Sympathetic and parasympathetic nervous system are two groups of the autonomic nervous system b. Preganglionic nerve axon synapse with postganglionic nerve at ganglion c. Preganglionic nerve of sympathetic and parasympathetic release acetylcholine that binds nicotinic receptor on the ganglion d. Postganglionic nerve of sympathetic and parasympathetic release acetylcholine that binds muscarinic receptor on a target tissue e.

Adrenal medulla is part of sympathetic nervous system 10. Scientist is studying the properties of muscle tissue. They are able to examine a single sarcomere within a myocyte, as demonstrated in Figure A.

They then artificially induces the sarcomere to contract. When this occurs, which of the following sections (as identified by the correct letter in Figure A and correct name) will not decrease in length? a. Section C; A band b. Section C; H zone c. Section B; I band d.

Section D; I band e. Section B; A band 11. In skeletal muscle cells, which of the following has an ATPase activity? a. Myosin b. Actin c. Tropomyosin d. Troponin e. Titin 12. The diagram shows the length-tension relationship for a single sarcomere. Why is the tension development maximal between points$$\mathrm{B}$$and$$\mathrm{C}$$? a. Actin filaments are overlapping each other b. Myosin filaments are overlapping each other c. The myosin filament is at its minimal length d.

The$$\mathrm{Z}$$discs of the sarcomeres are far apart from each other ‘ e. There is optimal overlap between the actin and myosin filaments 13. Which of the following best describes an attribute of visceral smooth muscle not shared by skeletal muscle? a. Contraction is ATP dependent b. Can contract in the absence of action potential c. Does not contain actin filaments d. High rate of cross-bridge cycling e. Low maximal force of contraction

14. Targets of the autonomic nervous system include all of the following except a. cardiac muscle b. adrenal medulla c. skeletal muscle d. smooth muscle in hollow organs e. blood vessel