18. The function of neurons is to
a. maintain a difference in electrical charge across the cell membrane
b. have specific ions cross the membrane through ion channels
c. maintain a membrane potential with charged ions on either side of the cell membrane
d. all of the above
D?
19. When an impulse moves down the axon,
a. sodium ions first rush out of the cell
b. a small part of the axon momentarily reverses its polarity
c. the resting potential of the cell does not change
d. potassium ions are pumped into the axon
Not sure...?
24. The brain stem is responsible for
a. directing information in the brain and secreting hormones
b. regulating vital functions and memory
c. motor processing and regulating homeostatic functions
d. sensory processing and regulating balance
I'm stuck between A and C
29. Thyroid hormones
a. stimulate cell metabolism and growth
b. slow growth of their target cells
c. stimulate synthesis of DNA
d. bind to receptor molecules on the target cell's surface
A?
Thanks
-MC
18. D
19. B
24. C
29. A
All of these are to the best of my knowledge, but I am pretty sure they are correct. Hope this helps!!
18. The correct answer is d. all of the above. Neurons function to maintain a difference in electrical charge (membrane potential) across the cell membrane. This is achieved by having specific ions cross the membrane through ion channels. These ions, such as sodium (Na+) and potassium (K+), contribute to the membrane potential and create a charged environment on either side of the cell membrane.
To arrive at the answer, you can eliminate options that do not correctly describe the function of neurons. Then, considering the role of neurons in maintaining the membrane potential and allowing charged ions to cross the membrane, you can conclude that all of the given options are valid functions of neurons.
19. The correct answer is b. a small part of the axon momentarily reverses its polarity. When an impulse, also known as an action potential, moves down the axon, it is a result of brief changes in ion concentrations and electrical potential across the membrane. These changes cause a small part of the axon, known as the action potential "wave," to reversibly change polarity.
To determine the correct answer, you need to understand the basic mechanisms of action potential propagation. Option a is incorrect because sodium ions (Na+) do not rush out of the cell; they actually rush into the cell during depolarization. Option c is incorrect because the resting potential of the cell does change during an action potential. Option d is incorrect because potassium ions (K+) are not pumped into the axon; they play a role in repolarization of the membrane after the action potential has passed.
24. The correct answer is c. motor processing and regulating homeostatic functions. The brain stem is responsible for various functions, including motor processing, which involves coordinating and controlling movement, and regulating homeostatic functions, such as breathing, heart rate, and blood pressure.
To determine the correct answer, you need to understand the functions associated with the brain stem. Option a is incorrect, as directing information in the brain and secreting hormones is primarily associated with other structures, such as the hypothalamus and pituitary gland. Option b is incorrect because while the brain stem does play a role in regulating vital functions, it is not directly involved in memory. Option d is incorrect because sensory processing and regulating balance are primarily associated with structures such as the cerebellum.
29. The correct answer is a. stimulate cell metabolism and growth. Thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3), play a vital role in regulating metabolism and promoting growth and development.
To determine the correct answer, you need to understand the basic functions of thyroid hormones. Option b is incorrect because thyroid hormones do not slow the growth of their target cells; they actually stimulate growth. Option c is incorrect because while thyroid hormones can influence DNA synthesis indirectly, they do not directly stimulate its synthesis. Option d is incorrect because thyroid hormones typically bind to intracellular receptors rather than receptor molecules on the cell surface.
I hope this explanation helps! Let me know if you have any further questions.