Question

for each, what is the right answer?

30. When a neuron encodes the strength of a stimulus, it does so by changing A) the frequency of action potentials. B) the duration of each action potential C) the polarity of every alternate action potential. D) the size of each action potential E) the direction of the action potentials along the axon. 31. The relative refractory period of an axon begins with A) activation of chemically-gated K+ channels. B) increasing Na+ flux into the cell. C) increasing K+ flux into of the cell. D) re-activation and closure of voltage-gated Nat channels. E) very high Nat permeability across the membrane. 32. Cortical grey matter is NOT present in the A) Cerebellum C) Medulla oblongata B) Cerebrum D) Both (A) and (B) 33. The regions of exposed axon membrane that separate two adjacent Schwann cells on a neuron are called A) variations B) nodes of Ranvier C) synaptic membranes D) islets of Langerhans E) neuroglia 34. Shaking one's head "no" activates hair cells in the A) cochlea B) vestibule C) olfactory mucosa D) scalp E) semicircular canals 35. Which of the following statements about hormone activation/deactivation is true? A) Prohormones are inactive polypeptide hormones that must undergo peptide cleavage in the cells that secrete them in order to change into their active form. B) Conversion of T4 to T3 is an example of a step down reaction for thyroid hormones. C) Conversion of testosterone to DHT is an example of a step up reaction for androgens. D) Both (A) and (C) are correct. E) Both (B) and (C) are correct. 36. Which of the following statements about olfactory receptors is FALSE? A) When stimulated, they send impulses to the limbic system B) They can discriminate only among the four primary smells - sweet, sour, salty and bitter. C) They are stimulated by chemicals called odorants. D) They are free nerve endings. E) They are located in the nasal mucosa. 37. T F True (A) or False (B): The tympanic membrane separates an air-filled chamber from a fluid-filled chamber. 38. Among the steroid hormones, __ are directly synthesized from cholesterol, without first forming any other types of active steroid hormones as precursors. A) estrogens B) androesters C) corticoids D) progestins E) androgens

Answer 1

30. The neurons encode the strength of a stimuli based on the frequency of the action potential.

31. the relative refractory period of an axon begin with activation of voltage gated potassium channel.

32. the cortical grey matter is not present in medula oblangata.

33. the region of exposed axon membrane that seperates the two adjacent schwann cells on a neuron are called region of ranvier.

34. shaking of ones head "no" activates hair cell in the semicircular canals.

36. B is false

37. false

38.progestins