22 a. the sarcoplasmic reticulum b. a difference in thickness of the sarcolemma
ID: 3483350 • Letter: 2
Question
22 a. the sarcoplasmic reticulum b. a difference in thickness of the sarcolemma The striations of skeletal muscles are produced, for the most part, by c. the arrangement of myofilaments d. the T tubules 123. Which of the following is NOT true of myofilaments a. made of protein b. contractile components of muscle c. present in skeletal muscle but absent in smooth muscle d. include thin and thick filaments If a drug is an anticholinesterase,what effect would this drug have on the contraction of skeletal muscle? a. enhanced contraction b. paralysis d. stimulation of smooth, but not skeletal muscle The effect of the neurotransmitter on the target cell is always excitatory: Is this description characteristic of the: a. somatic nervous system b. autonomic nervous system c. both somatic and autonomic nervous sytems 125. Neural pathways are found in spinal and cranial nerves: a. somatic nervous system b. autonomic nervous system c. both somatic and autonomic nervous sytems Is this description characteristic of 26. Effectors are glands and involuntary muscles: Is this description characteristic of: a. somatic nervous system b. autonomic nervous system c. both somatic and autonomic nervous sytems 127. Slower conduction of nerve impulses because fibers are typically thin and unmyelinated no glanglia present: Is this description characteristic of the: a. somatic nervous system b. autonomic nervous system c. both somatic and autonomic nervous sytems 128. Involved in reflex activities: Is this description characteristic of the: a. somatic nervous system 129. b. autonomic nervous system c. both somatic and autonomic nervous sytemsExplanation / Answer
Answer 122.
The striations of the skeletal muscles are formed by the sarcomere. The sarcomere is a contractile unit present in the muscle cell made up of actin and myosin myofibrils. So, the correct answer is option c.
Note that sarcoplasmic reticulum (option a) is the Smooth Endoplasmic Reticulum (SER) of the muscle cell. It is a calcium store. And sarcolemma (option b) is the liquid present in the SER. T-tubules (option d) are extensions of the cell membrane. All these do not have any role in formation of the striations. Striations are because of the myofibrils.
Answer 123.
The myofilaments are present in smooth as well as skeletal muscle. So, this option (c) is untrue.
The myofilaments are the proteins of the skeletal muscle (generally actin and myosin protein). So, option “a” is correct. These are responsible for contraction of the muscle. So, option b is also true. These can be thin, thick or intermediate. So, option d is also correct.
Answer 124.
Option b is the correct answer.
The anticholinesterase drugs prevent destruction of acetylcholine by the enzyme acetylcholinesterase in the nervous system. So, the activity of acetylcholine is not stopped. So, the muscle will continue contracting; it will be fatigued after sometime. Ultimately it will lead to paralysis. So, the correct answer is option b.
Answer 125.
The correct answer is option b.
This description is a characteristic of autonomic nervous system. This system regulates unconscious movements of our body.
The somatic nervous system regulates the voluntary movements of the body.
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