What is the approximate threshold value for mammalian neurons?
-55 mV.
-80 mV.
+35 mV.
0 mV.
The Correct Answer is A
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV.
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
The correct answer is choice B. 3’ TCGATCGCA 5’.
In DNA, the nitrogenous bases adenine (A) and thymine (T) pair together, while cytosine © and guanine (G) pair together.
Therefore, the complementary strand of the given DNA sequence “5’ AGCTAGCGT 3’” would have the nitrogenous bases T, C, G, A, T, C, G, C and A in that order.
Additionally, the 5’ to 3’ direction of the complementary strand is opposite to that of the given strand.
Choice A. 3’ AGCTAGCGT 5’ is not correct because it is not complementary to the given strand.
Choice C. 5’ UCGAUCGCA 3’ is not correct because it contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Choice D. 3’ TCGUTCGCU 3’ is not correct because it also contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Correct Answer is D
Explanation
Testosterone is classified as an androgen hormone.
Androgens are a type of sex hormone that primarily regulates the development and maintenance of male characteristics, such as body hair growth, muscle mass, and deepening of the voice.
Testosterone is produced primarily in the testes in males and in smaller amounts in the ovaries and adrenal glands in females.
Option A, estrogen, is a female hormone that regulates the development of female sexual characteristics, such as breast growth and menstruation.
While estrogen and testosterone are both steroid hormones and can be converted to one another in the body, testosterone is not categorized as estrogen.
Option B, progestin, is a synthetic form of the hormone progesterone.
Progesterone is a female hormone that plays a role in the menstrual cycle and pregnancy.
Testosterone and progestin are not related, and testosterone is not categorized as progestin.
Option C, aldosterone, is a mineralocorticoid hormone that regulates salt and water balance in the body.
It is produced in the adrenal gland and plays a role in regulating blood pressure.
Testosterone and aldosterone are not related, and testosterone is not categorized as aldosterone.
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