18. The most common neuron type in human beings and the major neuron type in the CNS is - structurally classified as: T a) Únipolar neuronsT + b) bipolar neuronsT + ) multipolar neuronsT + d)...

please answer 18,19,20,

Extracted text: 18. The most common neuron type in human beings and the major neuron type in the CNS is - structurally classified as: T a) Únipolar neuronsT + b) bipolar neuronsT + ) multipolar neuronsT + d) pseudounipolar neurons T 19. Which of the following statements are correct with regard to electrical activity of neurons. T - a) Resting membranes will have a potential difference across them of about -70 mV.T + b) Ohm's law states that current is directly proportional to voltage and inversely proportional - to resistance. T + c) In the body, electrical currents reflect the flow of ions, rather than free electrons, across cellular membranes. T + d) lons move along electrochemical gradients which is a combination of chemical gradients in which ions move from area of high to areas of low concentration and electrical gradients in which ions move to an area of opposite electrical charge. T + e) All of the above (a, b, c and d) are correct. T 20. Which of the following statements about membrane permeability are correct? T + a) The resting membrane of neurons is about 75 times more permeable to K+ than Na+.T + b) The resting membrane of neurons is impermeable to large, negatively charges cytoplasmic - proteins. T + ) Gradients necessary for ion diffusion are maintained by active transport processes that pump 3 Na+ ions out of the cell and 2 K+ ions into the cell. T + d) Depolarization is a reduction in membrane potential. T + e) All of the above (a, b, c and d) are correct. T