PART I: Neurons and the Nerve Impulse

Identify each of the labeled structures of the neuron below. A. B. C. D. E. F. G.

Identify each of the labeled structures of the neuron below. A. dendrites B. nucleus C. cell body D. axon E. axon endings F. nodes of Ranvier G. Schwann cells/myelin sheath

Fill in the blanks in the sentences below with the NAME of the STRUCTURE of a NEURON that provides the described FUNCTION. The of a neuron contains the DNA and is the control center of the cell. The of a neuron contains the nucleus and most of the cellular organelles.

Fill in the blanks in the sentences below with the NAME of the STRUCTURE of a NEURON that provides the described FUNCTION. The nucleus of a neuron contains the DNA and is the control center of the cell. The cell body of a neuron contains the nucleus and most of the cellular organelles.

Fill in the blanks in the sentence below with the NAME of the STRUCTURE of a NEURON that provides the described FUNCTION. Signals come in to the neuron through the, and travel out of the neuron along the, at the end of which the contact the next neuron in the communication chain.

Fill in the blanks in the sentence below with the NAME of the STRUCTURE of a NEURON that provides the described FUNCTION. Signals come in to the neuron through the dendrites, and travel out of the neuron along the axon, at the end of which the axon endings contact the next neuron in the communication chain.

Neurotransmitters are contained in that are located in the of a neuron. A. vesicles; axon endings B. axon endings; dendrites C. calcium ions (Ca 2+ ); synapses D. cell membranes; synaptic gaps

Neurotransmitters are that travel across a to another neuron. a. electrical signals; receptor b. electrical signals; synapse c. chemical signals; receptor d. chemical signals; synapse

Generally, neural impulses travel: A. electrically between and within each neuron B. chemically between and within each neuron. C. electrically between neurons and chemically within each neuron. D. chemically between neurons and electrically within each neuron.

Generally, neural impulses travel: A. electrically between and within each neuron B. chemically between and within each neuron. C. electrically between neurons and chemically within each neuron. D. chemically between neurons and electrically within each neuron. The ELECTRICAL SIGNAL of neurons is an action potential which travels WITHIN a single neuron from the dendrite and out along the axon. At the axon endings, this action potential activates the release of neurotransmitters, which are CHEMICAL SIGNALS, into the synapse BETWEEN two neurons.

Which of the following types of molecules are the major structural components of the cell membrane? a) phospholipids and cellulose b) nucleic acids and proteins c) phospholipids and proteins d) proteins and cellulose

Plasma membranes are selectively permeable. This statement means that a) No substances can enter or exit the cell through the plasma membrane. b) The plasma membrane allows some substances to enter or exit a cell more easily than others. c) All substances are able to enter or exit the cell through the plasma membrane. d) It is random chance whether a molecule can or cannot enter or exit the cell through the plasma membrane.

What kinds of molecules pass through the cell membrane most easily? a) ions b) small and hydrophobic c) large and hydrophobic d) small and polar e) large and polar

1. For each of following molecules, indicate whether it CAN or CANNOT pass through the phospholipid bilayer of the plasma membrane by simple diffusion. 2. Then, for EACH molecule EXPLAIN WHY it can or cannot pass through based upon the SIZE and CHARGE characteristics of the molecule. A. CO 2 : B. O 2 : C. H 2 O: D. C 6 H 12 O 6 : E. K + : F. Na + : G. Ca 2+ :

1. For each of following molecules, indicate whether it CAN or CANNOT pass through the phospholipid bilayer of the plasma membrane by simple diffusion. 2. Then, for EACH molecule EXPLAIN WHY it can or cannot pass through based upon the SIZE and CHARGE characteristics of the molecule. A. CO 2 : YES! It CAN! It s both SMALL and NONPOLAR (hydrophobic)! B. O 2 : YES! It CAN! It s both SMALL and NONPOLAR (hydrophobic)! C. H 2 O: WATER!!! NO! It CANNOT! Yes, it s SMALL, but it is POLAR (hydrophilic)! D. C 6 H 12 O 6 : GLUCOSE!!! NO! It CANNOT! It s both LARGE and POLAR (hydrophilic)! E. K + : NO! It CANNOT! Yes, it s SMALL, but it is an ION with a CHARGE (hydrophilic)! F. Na + : NO! It CANNOT! Yes, it s SMALL, but it is an ION with a CHARGE (hydrophilic)! G. Ca 2+ : NO! It CANNOT! Yes, it s SMALL, but it is an ION with a CHARGE (hydrophilic)!

Which of the following statements regarding diffusion is FALSE? a) Diffusion is a result of the thermal energy of atoms and molecules. b) Diffusion requires no input of energy into the system. c) Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. d) Diffusion occurs even after equilibrium is reached and no net change is apparent.

Which of the following statements regarding diffusion is FALSE? a) Diffusion is a result of the thermal energy of atoms and molecules. b) Diffusion requires no input of energy into the system. c) Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. d) Diffusion occurs even after equilibrium is reached and no net change is apparent. Statement c above is FALSE: In reality diffusion occurs when particles spread from areas where they are MORE concentrated to areas where they are LESS concentrated, in other words from HIGH to LOW concentration.

Water moves in and out of cells by the process of a) Passive diffusion b) Osmosis c) Active transport d) Phagocytosis

When two aqueous solutions that differ in solute concentration are placed on either side of a semi- permeable membrane and osmosis is allowed to take place, the water will a) exhibit a net movement to the side with lower free water concentration. b) exhibit a net movement to the side with higher free water concentration. c) exhibit a net movement to the side with lower solute concentration. d) exhibit an equal movement in both directions across the membrane.

The diagram to the right represents a plant cell in distilled water as seen with a compound light microscope. Which diagram below best represents the appearance of that cell after it has been placed in a 15% salt solution for two minutes? A. 1 B. 2 C. 3 D. 4

The diagram to the right represents a plant cell in distilled water as seen with a compound light microscope. Which diagram below best represents the appearance of that cell after it has been placed in a 15% salt solution for two minutes? This is a high salt concentration solution, therefore a hypertonic solution. Water will move OUT of the cell, causing it to shrink within its plasma membrane, but the cell wall (a rigid structure) will maintain it s shape, a situation shown in (3) below. A. 1 B. 2 C. 3 D. 4

Which of the following statements regarding active transport is FALSE? a) Active transport uses ATP as an energy source. b) Active transport can move a solute against its concentration gradient. c) Active transport requires the cell to expend energy. d) Active transport is driven by the potential energy represented by a concentration gradient.

Which of the following statements regarding active transport is FALSE? a) Active transport uses ATP as an energy source. b) Active transport can move a solute against its concentration gradient. c) Active transport requires the cell to expend energy. d) Active transport is driven by the potential energy represented by a concentration gradient. ATP is an energy source that drives active transport, active transport can move a solute against its concentration gradient (meaning move it from LOW to HIGH concentration), and requires the cell to expend energy (usually in the form of ATP). Only d is FALSE.

Which of the following statements about the sodium- potassium pump (SHOWN BELOW) is FALSE? a) Sodium ions in the cytoplasm and an ATP molecule bind to the carrier protein on the cytoplasmic side of the cell membrane. b) ATP is broken down into ADP and potassium to supply the energy. c) The carrier protein changes shape as it transports ions from the cytoplasm to the extracellular fluid. d) The ions from inside the cell are transported across the cell membrane. e) The ions are then released into the extracellular fluid outside the cell.

The sodium- potassium pump (SHOWN BELOW) functions to move a) 2 sodium ions out of the cell and 3 potassium ions into the cell. b) 2 sodium ions into of the cell and 3 potassium ions out of the cell. c) 3 sodium ions out of the cell and 2 potassium ions into the cell. d) 3 sodium ions into of the cell and 2 potassium ions out of the cell.

The function of the sodium- potassium establishes two concentration gradients across the plasma membrane of neuron, such that sodium ion concentration is high the cell and potassium ion concentration is high the cell. a) inside; inside b) inside; outside c) outside; inside d) outside; outside

The function of the sodium- potassium establishes the resting membrane potential of a neuron, in which the outside of the cell has a charge, and the inside of the cell has a charge. a. positive; positive b. positive; negative c. negative; positive d. negative; negative

Identify each of the labeled phases of an action potential of a neuron as shown in the graph to the right. A. B. C. D. E.

Identify each of the labeled phases of an action potential of a neuron as shown in the graph to the right. A. Resting Membrane Potential B. Depolarization C. Repolarization D. Hyperpolarization or Undershoot E. Threshold

The part of the curve labeled A is MOST DIRECTLY the result of the activity of a) the sodium- potassium pump. b) voltage- gated Na + channels. c) ligand- gated ion channels. d) voltage- gated K + channels. e) voltage- gated Ca 2+ channels.

The part of the curve labeled B is MOST DIRECTLY the result of the activity of a) the sodium- potassium pump. b) voltage- gated Na + channels. c) ligand- gated ion channels. d) voltage- gated K + channels. e) voltage- gated Ca 2+ channels.

The part of the curve labeled C is MOST DIRECTLY the result of the activity of a) the sodium- potassium pump. b) voltage- gated Na + channels. c) ligand- gated ion channels. d) voltage- gated K + channels. e) voltage- gated Ca 2+ channels.

The part of the curve labeled D is MOST DIRECTLY the result of the activity of a) the sodium- potassium pump. b) voltage- gated Na + channels. c) ligand- gated ion channels. d) voltage- gated K + channels. e) voltage- gated Ca 2+ channels.

Which of the following statements about is TRUE about the phase of the curve labeled B? a) The cell membrane of the neuron is becoming repolarized. b) K + ions are moving out of the cell as voltage- gated K + - channels open. c) Na + ions are moving into the cell as voltage- gated Na + - channels open. d) The sodium- potassium pump stops functioning because the carrier protein becomes denatured. e) None of the above.

Which of the following statements about is TRUE about the phase of the curve labeled C? a) The cell membrane of the neuron is becoming repolarized. b) K + ions are moving out of the cell as voltage- gated K + - channels open. c) Most of the voltage- gated Na + channels are closed. d) The outside of the cell membrane now has a positive charge (+) while the inside has a negative charge (- ) e) All of the above.

Once an action potential has been fired, the neuron cannot fire again until: a) the resting membrane potential has been restored. b) the rising phase of the action potential has reached its peak. c) the reuptake of neurotransmitters has been blocked. d) the direction of the nerve impulse within the axon has been reversed.

The chemical signaling of neurons, provided by the action of neurotransmitters, is depicted in the figure below. Arrange the following in the proper order in which they occur at the pre- synaptic side of a neuromuscular junction. 1. Calcium ions enter the pre- synaptic cell via voltage- gated calcium channels. 2. An action potential arrives at the pre- synaptic axon terminal. 3. Neurotransmitter is released into the synapse. A) 1, 2, 3 B) 2, 1, 3 C) 2, 3, 1 D) 3, 2, 1 E) 3, 1, 2

The chemical signaling of neurons, provided by the action of neurotransmitters, is depicted in the figure below. Arrange the following in the proper order in which they occur at the postsynaptic side of a excitatory synapse. 1. The neurotransmitter binds to its matching, specific ligand- gated ion- channel on the membrane of the postsynaptic neuron. 2. An action potential is propagated along the postsynaptic neuron s axon 3. Depolarization of the postsynaptic membrane. 4. Sodium ions move into the postsynaptic cell. A) 1, 2, 3, 4 B) 2, 1, 3, 4 C) 4, 2, 3, 1 D) 1, 4, 3, 2 E) 3, 1, 2, 4

PUTTING IT ALL TOGETHER!!!! List the following in order of their occurrence: A. An action potential travels along axon of the pre- synaptic neuron. B. An action potential is propagated along the postsynaptic neuron s axon. C. The neurotransmitter crosses the synaptic gap and binds with its matching ligand- gated ion channel on the membrane of the postsynaptic neuron. D. Sodium ions move into the postsynaptic cell. E. Calcium ions enter the pre- synaptic cell via voltage- gated calcium channels. F. The action potential arrives at the pre- synaptic axon endings. G. Neurotransmitter is released into the synapse. H. Depolarization of the postsynaptic membrane.

PUTTING IT ALL TOGETHER!!!! List the following in order of their occurrence: A. An action potential travels along axon of the pre- synaptic neuron. B. An action potential is propagated along the postsynaptic neuron s axon. C. The neurotransmitter crosses the synaptic gap and binds with its matching ligand- gated ion channel on the membrane of the postsynaptic neuron. D. Sodium ions move into the postsynaptic cell. E. Calcium ions enter the pre- synaptic cell via voltage- gated calcium channels. F. The action potential arrives at the pre- synaptic axon endings. G. Neurotransmitter is released into the synapse. H. Depolarization of the postsynaptic membrane. A, F, E, G, C, D, H, B

PUTTING IT ALL TOGETHER!!!! OR, REARRANGING THEM TO BE IN ORDER. 1. An action potential travels along axon of the pre- synaptic neuron. 2. The action potential arrives at the pre- synaptic axon endings. 3. Calcium ions enter the pre- synaptic cell via voltage- gated calcium channels. 4. Neurotransmitter is released into the synapse. 5. The neurotransmitter crosses the synaptic gap and binds with its matching ligand- gated ion channel on the membrane of the postsynaptic neuron. 6. Sodium ions move into the postsynaptic cell. 7. Depolarization of the postsynaptic membrane. 8. An action potential is propagated along the postsynaptic neuron s axon.

The process by which neurotransmitter molecules detach from a postsynaptic neuron are reabsorbed by a pre- synaptic neuron so they can be recycled and used again. A. axon terminals B. synaptic transmission C. reuptake D. diffusion

Which of the following mechanisms can serve to remove neurotransmitter from the synaptic cleft? A) Reuptake by the axon terminus of the pre- synaptic cell B) Breakdown by enzymes C) Diffusion away from the synaptic cleft D) All of the above

Which of the following mechanisms can serve to remove neurotransmitter from the synaptic cleft? A) Reuptake by the axon terminus of the pre- synaptic cell B) Breakdown by enzymes C) Diffusion away from the synaptic cleft D)All of the above