A solution that has a lower solute concentration (and thus a higher water concen

Question

A solution that has a lower solute concentration (and thus a higher water concentration) than another solution is said to be iso-osmotic. hypo-osmotic hyperosmotic. hypertonic isotonic The following are the main steps in the generation of action potential sodium channels are inactivated voltage-regulated potassium channels open and potassium moves out of the cell initiating repolarization. Sodium channels regain their normal properties a graded depolarization brings an area of an excitable membrane to threshold. A temporary hyperpolarization occurs Sodium channel activation occurs Sodium ions enter the cell and depolarization occurs. The proper sequence of these events is: 4, 6, 7, 3, 2, 5, 1 4, 6, 7, 1, 2, 3, 5 6, 7, 4, 1, 2, 3, 5. 2, 4, .6, 7, 1, 2, 3, 5. 4, 2, 5, 6, 7, 3, 1. In a resting neuron, the plasma membrane is freely permeable to sodium ion. The concentration of sodium ion is grater inside the cell than outside. The plasma membrane is completely impermeable to sodium ion. The permeability of the plasma membrane to potassium ion is about 50 times greater than its permeability to sodium ion None of the above is true. Which of the following is NOT true of glial cells? They form myelin for axons. They regulate the composition of extracellular fluid in the CNS. They deliver fuel molecules to neurons and remove the waste products of metabolism. They are important for the growth and growth and development of the nervous system. There are fewer glial cells in the CNS than there are neurons.

Explanation / Answer

45. B. Hypo-osmotic

A solution is a mixture of solute and solvent.

Osmosis is the movement of water through the semipermeable membrane. Cells can lose or gain water from the surrounding through osmosis. Hypoosmotic is the solution that has a lower solute concentration than the another solution (Hypo is less).

46. C) 6,7,4,1,2,3,5

Membrane potential is the maintenance of voltage between inside and outside of the cell, in resting state it is -70 mV. Signals are transmitted from one neuron to other through neurotransmitters. The three parts of neuron are dendrites, cell body and axon, signals within a neuron is transmitted from dendrite to axon.

Dendrites have the receptors and the neurotranmitters bind to it and opens the voltage gated ion channel. The sodium channel open and it enters the cell, depolarisation occurs and the threshold otential is reached. Sodium channels are inactivated, voltage regulated potassium channels are open and intiates repolarisation. Sodium channels regain their normal properties. A temporary hyperpolarisation occurs.

47. F) None of the above is true

The resting membrane potential is -70mV. In a resting neuron, the sodium ions are more outside the cell and the potassium ions are more inside the cell. Membrane permeability of potassium is 100 times more than sodium ions.At rest, the cell membrane is not freely permeable to sodium ion.

48. E. there are fewer glial cells in the CNS than there are neurons

There are more glial cells than neurons in brain.

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