Which of the following does NOT occur in or immediately prior to a muscle contraction? action potential in motor neuron acetylcholine released into synaptic cleft temporary localized changes in the membrane potential of the sarcolemma and t-tubules sacroplasmic recticulum releases acetylcholine active sites on actin molecules are exposed During contraction of a muscle, calcium ions bind to the _______." actin and myosin filaments troponin molecule tropomyosin molecule sarcoplasmic reticulum sarcolemma Which of the following is NOT a role of ionic calcium in muscle contraction? triggers neurotransmitter secretion binds with troponin removes contraction inhibitor spreads the depolarization from the neuromuscular junction to the T-tubules
Anatomy and Physiology of Special Sensory Organs
Sensory organs can be labeled as special sensory structures that permit sight, hearing, odor, and flavor. Sensory structures permitting proprioception, touch, thermal, and pain perception can be classified as more advanced sensory organs. The sensory neurons are trained to find out modifications in the external and internal conditions so that a person's body can react to that change. A stimulus is the first signal that is recognized by any sensory receptor of the body. Stimulus is an impulse generated when there is a change in the surroundings of a person. For example, a heated environment will alert the brain through the thermal sensory organs and generate a reflex accordingly.
Sensory Receptors
The human sensory system is one of the most complex and highly evolved structures, which processes a myriad of incoming messages. This well-coordinated system helps an organism or individual to respond to external stimuli, appropriately. The sensory receptors are an important part of the sensory system. These receptors are specialized epidermal cells that respond to external environmental stimuli. These receptors consist of structural and support cells that form the peripheral unit of the receptor and the neural dendrites which receive and detect the external stimuli.
Which of the following does NOT occur in or immediately prior to a muscle contraction?
- action potential in motor neuron
- acetylcholine released into synaptic cleft
- temporary localized changes in the membrane potential of the sarcolemma and t-tubules
- sacroplasmic recticulum releases acetylcholine
- active sites on actin molecules are exposed
During contraction of a muscle, calcium ions bind to the _______."
- actin and myosin filaments
- troponin molecule
- tropomyosin molecule
- sarcoplasmic reticulum
- sarcolemma
Which of the following is NOT a role of ionic calcium in muscle contraction?
- triggers neurotransmitter secretion
- binds with troponin
- removes contraction inhibitor
- spreads the depolarization from the neuromuscular junction to the T-tubules
The role of tropomyosin in a muscle cell is to ____.
- all to cell to relax by blocking the binding sites on actin
- facilitate the formation of cross-bridges between actin and myosin
Interactions between thick and thin filaments during muscle contraction occur in which sequence?
- "attach to actin, detach from actin, pivot in powerstroke, return or recock"
- "attach to actin, pivot in powerstroke, detach from actin, return or recock"
- "attach to actin, pivot in powerstroke, return or recock, detach from actin"
- "detach from actin,pivot in powerstroke, attach to actin, return or recock"
What is the role of calcium pump in muscle contractions?
- pump calcium out of the sarcoplasmic reticulum against its concentration gradient to initiate contractions
- remove calcium from the fluid surrounding the myofibrils to end contractions
- pump calcium into the muscle cell to stimulate the release of acetylcholine
Rigor mortis demonstrates that skeletal muscle tissue
- normally requires energy to end as well as to start a contraction
- can survive and function for some time after the heart stops beating
- "maintains powerful contractions even with no ATP, until autolysis occurs"
- all of the above
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