Q&A Hero

Q: The main feature that distinguishes a neuron from other animal cells is that a neuron has: a. a larger nucleus. b. a distinctive shape. c. the ability to metabolize a variety of fuels. d. a high internal concentration of sodium ions.

Q: The endoplasmic reticulum is a: a. network of thin tubes that transport newly synthesized proteins. b. site where the cell synthesizes new protein molecules. c. structure that separates the inside of the cell from the outside. d. structure that contains the chromosomes.

Q: The sites at which the cell synthesizes new protein molecules are called: a. mitochondria. b. endoplasmic reticula. c. ribosomes. d. plasma membranes.

Q: Ribosomes are the part of a cell that: a. performs metabolic activities. b. breaks down harmful chemicals. c. transports proteins. d. synthesizes new proteins.

Q: Where do the metabolic activities occur that provide energy for all of the other activities of the cell? a. Mitochondria b. Ribosomes c. Lysosomes d. Golgi complexes

Q: Protein channels allow ____ to cross the cell membrane. a. large charged molecules b. small charged molecules c. large uncharged molecules d. small uncharged molecules

Q: Small, charged molecules can cross the cell membrane through: a. diffusion. b. ribosomes. c. mitochondria. d. protein channels.

Q: Which of the following is most likely to cross the cell membrane by simple diffusion? a. large proteins b. small, charged ions c. small, uncharged molecules d. large, charged ions

Q: The structure that contains the chromosomes is called the: a. endoplasmic reticulum. b. nucleus. c. mitochondrion. d. ribosome.

Q: Chemicals than cannot flow freely across a cell membrane enter a neuron through: a. a Golgi complex. b. specialized protein channels. c. the endoplasmic reticulum. d. gaps in the myelin sheath.

Q: Which chemicals flow most freely across a cell membrane? a. proteins, fats, and carbohydrates b. positively charged ions c. water, oxygen, and carbon dioxide d. calcium and magnesium

Q: Water, oxygen and ____ most freely flow across a cell membrane. a. calcium b. positively charged ions c. magnesium d. carbon dioxide

Q: What structure is composed of two layers of fat molecules that are free to flow around one another? a. the endoplasmic reticulum b. a ribosome c. a mitochondrion d. the membrane

Q: The ____ of neurons most strongly differentiate them from other cells in the body. a. temperature. b. shape. c. osmotic pressure. d. mitochondria.

Q: Neurons differ most strongly from other body cells in their: a. temperature. b. shape. c. osmotic pressure. d. mitochondria.

Q: The cell membrane is composed of two layers of: a. protein. b. fat. c. carbohydrate. d. plasma.

Q: Which of the following contributed most to Cajal's ability to find that neurons are separate from one another? a. Charles Sherrington's study of reflexes b. Camillo Golgi's cell staining method c. Perves & Hadley's dye injection method d. Galileo's invention of the telescope

Q: Prior to the work of Santiago Ramon y Cajal, what did many investigators believe? a. Nerves conducted impulses at the speed of light. b. Transmission across a synapse was just as fast as transmission along an axon. c. The tip of an axon physically merged with the next neuron. d. All neurons were of similar size and shape.

Q: Who was the first researcher to demonstrate that neurons are separate from one another? a. Curt P. Richter b. Santiago Ramon y Cajal c. Charles S. Sherrington d. Jose Delgado

Q: Santiago Ramon y Cajal demonstrated that: a. at rest, the neuron has a negative charge inside its membrane. b. neurons are separate from one another. c. neurons communicate at specialized junctions called synapses. d. action potentials follow the all-or-none law.

Q: What are the two kinds of cells in the nervous system? a. neurons and glia b. dendrites and axons c. ribosomes and lysosomes d. neurons and axons

Q: The two kinds of cells in the nervous system are: a. neurons and glia b. dendrites and axons c. ribosomes and lysosomes d. neurons and axons

Q: In a myelinated axon, sodium channels are absent in the nodes of Ranvier.

Q: Dendrites and cell bodies are capable of producing action potentials.

Q: Additional stimulation beyond the threshold of excitation will result in a greater depolarization of the membrane during an action potential.

Q: A prolonged increase in the permeability of the membrane to sodium ions would interfere with a neuron's ability to have an action potential.

Q: If a drug was given that temporarily inactivated the sodium-potassium pumps, action potentials would cease immediately.

Q: The sodium-potassium pump is what normally brings the membrane back to its original state of polarization after the peak of the action potential.

Q: Increasing the electrical gradient for potassium would reduce the tendency for potassium ions to exit the neuron.

Q: The difference in voltage in a resting neuron is called the resting potential.

Q: At rest, the inside of a neuron's membrane is more negative than the outside.

Q: The primary source of energy used by the brain is fat.

Q: One disadvantage of the blood-brain barrier is that it keeps out most forms of nutrition.

Q: The blood-brain barrier is made up of closely packed glial cells.

Q: Most chemicals can easily cross the cell membrane of a neuron.

Q: Schwann cells build the myelin sheaths in the periphery of the body.

Q: Oligodendrocytes in the periphery are specialized types of glia.

Q: Astrocytes remove waste material created when neurons die and control the amount of blood flow to each brain area.

Q: Glial cells transmit information across long distances.

Q: There are more glial cells than neurons in the human brain.

Q: Glial cells serve many functions.

Q: Neurons are distinguished from other cells by their shape.

Q: The greater the surface area of a dendrite, the more information it can receive from other neurons.

Q: The general rule among neurons is that the wider the branching, the fewer connections with other neurons.

Q: Neurons can have any number of dendrites, but no more than one axon.

Q: An efferent axon carries information away from a structure.

Q: An afferent axon brings information into a structure.

Q: Axons are covered with an insulating material called a myelin sheath.

Q: Neurons receive information and transmit it to other cells.

Q: A small gap is usually present between neurons.

Q: Dendrites contain the nuclei, ribosomes, mitochondria, and other structures found in most cells.

Q: Briefly describe the refractory period of a neuron.

Q: Briefly describe the function of voltage-gated channels.

Q: Why do neurons have a resting potential?

Q: Describe the aspects of the resting potential.

Q: Briefly describe how the brain transports essential chemicals.

Q: What is saltatory conduction?

Q: Briefly describe the all-or-none law of action potentials.

Q: What would happen to the resting potential if a neuron's membrane was always completely permeable to charged ions?

Q: The electrical gradient of a neuron membrane refers to what?

Q: Briefly describe the structure of the blood-brain barrier and why it is important.

Q: Briefly describe glial cells.

Q: List the parts of a neuron.

Q: A local neuron:a. has an axon approximately a meter long.b. conveys information to other neurons across great distances.c. is a small neuron with no axon or a very short one.d. has an axon with many branches far from the cell body.

Q: Which of the following is TRUE of local neurons? a. They exchange information with distant neurons. b. They abide by the all-or-none principle. c. The change in membrane potential increases as it travels. d. They have short dendrites and axons.

Q: Why are local neurons more difficult to study? a. There are so few of them that they are difficult to find. b. They are so small. c. They exist only in humans, so there are ethical considerations. d. They die if separated from other neurons.

Q: Which of the following describes the transmission of information in a local neuron? a. The signal decreases in strength as it travels. b. The signal increases in strength as it travels. c. The signal strength remains constant as it travels. d. Local neurons do not transmit any information.

Q: In what direction does a local neuron transmit information? a. through its dendrites to cell body to axon b. through its axon to cell body to dendrites c. only toward the cell body d. equally well in any direction

Q: Which of the following is NOT governed by the all-or-none law? a. unmyelinated axons b. myelinated axons c. motor neurons d. local neurons

Q: Multiple sclerosis is one of several:a. blood-brain disordersb. neuron diseasesc. demyelinating diseasesd. movement disorders

Q: In what way is a myelinated axon that has lost its myelin (through disease) different from an axon that was never myelinated? a. It has a smaller diameter. b. It lacks sodium gates along parts of its surface. c. It has a longer refractory period. d. It has a much higher threshold.

Q: What disease is related to the destruction of myelin sheaths?a. multiple sclerosisb. cystic fibrosisc. myasthenia gravisd. Parkinson's disease

Q: How does saltatory conduction affect energy use in a neuron?a. It eliminates the need for action potentials.b. It increases the duration of the refractory period.c. It reduces the frequency of action potentials.d. It reduces the work load for the sodium-potassium pump.

Q: Saltatory conduction ____ the velocity of action potentials and ____ the amount of energy used by the neuron. a. decreases; decreases b. decreases; increases c. increases; decreases d. increases; increases

Q: To what does saltatory conduction refer?a. the production of an action potential by the movement of sodium ionsb. the transmission of an impulse along a myelinated axonc. the transmission of impulses along dendritesd. the transmission of an impulse between one neuron and another

Q: In a myelinated axon, where are sodium gates abundant?a. in the areas covered by myelinb. at the nodes of Ranvierc. throughout the axond. only in the axon hillock

Q: The myelin sheath is interrupted periodically by short sections of axon called: a. axon gaps b. nodes of Cajal c. axon nodes d. nodes of Ranvier

Q: What are the nodes of Ranvier?a. gates in the membrane that admit all ions freelyb. gaps in the myelin sheathc. branching points in an axond. places where dendrites join the cell body

Q: If you were to stub your toe and feel the pressure a second or two before you feel the pain, then which of the following statements is most likely true?a. Pain sensitive neurons are large and myelinated.b. Pain sensitive neurons are longer.c. Pressure sensitive neurons are small and lightly myelinated.d. Pressure sensitive neurons are large and myelinated.

Q: The function of a myelin sheath is to: a. prevent action potentials from traveling in the wrong direction. b. increase the velocity of transmission along an axon. c. increase the magnitude of an action potential. d. provide a store of nutrients for the neuron.