A&P I Chapter 12

The ________ nervous system is composed of the brain and spinal cord. A) autonomic B) peripheral C) central D) efferent E) afferent

The ________ nervous system controls the skeletal muscles. A) sympathetic B) parasympathetic C) afferent D) somatic E) autonomic

The part of the peripheral nervous system that carries sensory information to the CNS is designated A) motor. B) afferent. C) efferent. D) autonomic. E) somatic.

The efferent division of the peripheral nervous system innervates ________ cells. A) skeletal muscle B) smooth muscle C) heart muscle D) glandular

The nervous tissue outside of the central nervous system composes the ________ nervous system. A) somatic B) peripheral C) autonomic D) afferent E) parasympathetic

The ________ division of the peripheral nervous system brings sensory information to the central nervous system. A) somatic B) peripheral C) autonomic D) afferent E) parasympathetic

The ________ division of the nervous system carries motor commands to muscles and glands. A) spinal B) peripheral C) autonomic D) afferent E) efferent

The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity. A) somatic B) peripheral C) autonomic D) afferent E) motor

________ carry motor information to peripheral effectors. A) Unipolar neurons B) Efferent neurons C) Multipolar neurons D) Afferent neurons E) Interneurons

________ nerves are nerves that connect to the spinal cord. A) Spinal B) Cranial C) Afferent D) Multipolar E) Autonomic

________ nerves are nerves that connect to the brain. A) Spinal B) Unmyelinated C) Myelinated D) Cranial E) Interneural

The axoplasm of the axon contains which of the following? A) neurotubules B) mitochondria C) vesicles D) neurofibrils

Which of the following is not a recognized structural classification for neurons? A) anaxonic B) bipolar C) multipolar D) pseudopolar E) unipolar

The most abundant class of neuron in the central nervous system is A) anaxonic. B) bipolar. C) multipolar. D) pseudopolar. E) unipolar.

The cytoplasm that surrounds the nucleus of a neuron is called the A) protoplasm. B) nucleoplasm. C) sarcoplasm. D) neuroplasm. E) perikaryon.

Clusters of RER and free ribosomes in neurons are called A) neurofilaments. B) neurofibrils. C) perikaryon. D) Nissl bodies. E) microglia.

The axon is connected to the soma at the A) telodendria. B) synaptic terminal. C) collaterals. D) axon hillock. E) synapse.

Branches that may occur along an axon are called A) telodendria. B) synaptic terminals. C) collaterals. D) hillocks. E) synapses.

Axons terminate in a series of fine extensions known as A) telodendria. B) terminals. C) collaterals. D) dendrites. E) synapses.

The site of intercellular communication between a neuron and another cell is the A) telodendria. B) axolemma. C) collateral. D) hillock. E) synapse.

The rabies virus travels to the CNS via A) anterograde axoplasmic transport. B) retrograde axoplasmic transport. C) blood vessels. D) subcutaneous connective tissue. E) cerebrospinal fluid.

Neurons that are rare, small, and lack features that distinguish dendrites from axons are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

Neurons that have one axon and one dendrite, with the soma in between, are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

Neurons that have several dendrites and a single axon are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

Sensory neurons of the PNS are A) unipolar. B) bipolar. C) anaxonic. D) multipolar. E) tripolar.

Which of the following activities or sensations is/are not monitored by interoceptors? A) sight B) pain C) activities of the digestive system D) cardiovascular activities E) urinary activities

________ are the most numerous type of neuron in the CNS. A) Sensory neurons B) Motor neurons C) Unipolar neurons D) Bipolar neurons E) Interneurons

How does blocking retrograde axoplasmic transport in an axon affect the activity of a neuron? A) The neuron becomes unable to produce neurotransmitters. B) The neuron becomes unable to produce action potentials. C) The soma becomes unable to export products to the synaptic terminals. D) The soma becomes unable to respond to changes in the distal end of the axon. E) The neuron becomes unable to depolarize when stimulated.

Refer to Figure 12-1 The structures labeled "1" are dendrites. Their membranes contain numerous chemically- gated ion channels. A) The first statement is true but the second statement is false. B) The first statement is false but the second statement is true. C) Both statements are true. D) Both statements are false.

Refer to Figure 12-1 The structure labeled "2" is a(n) A) neurofilament. B) dendrite. C) initial segment. D) perikaryon. E) axon.

Refer to Figure 12-1 Which type of membrane channels are found at label "3"? A) voltage-gated Na+ channels B) voltage-gated K+ channels C) chemically-gated Na+ and K+ channels D) voltage-gated Ca2+ channels E) both voltage-gated Na+ channels and voltage-gated K+ channels

Refer to Figure 12-1 Identify the structure labeled "4." A) synaptic terminals B) telodendria C) dendritic spines D) collateral branches E) axons

Refer to Figure 12-1 Identify the structure labeled "5." A) axons B) telodendria C) dendritic spines D) synaptic terminals E) collateral branch

Refer to Figure 12-1 What is contained inside the structure labeled "5"? A) neuroglia B) sodium ions C) acetylcholinesterase D) calcium ions E) neurotransmitter molecules

Refer to Figure 12-1 Which part(s) of the neuron can propagate an action potential? A) 1 B) 1 and 2 C) 2 and 3 D) 3

Refer to Figure 12-1 On which structure do most neuron to neuron communications occur? A) 2 B) 1 C) 3 D) 4 E) 5

________ monitor the position of skeletal muscles and joints. A) Proprioceptors B) Internoceptors C) Photoreceptors D) Exteroceptors E) Pressoreceptors

________ carry sensory information to the CNS. A) Motor neurons B) Efferent neurons C) Multipolar neurons D) Afferent neurons E) Interneurons

________ provide information about the external environment. A) Spinal nerves B) Anaxonic neurons C) Internoceptors D) Exteroceptors E) Proprioceptors

________ monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems. A) Spinal nerves B) Unipolar neurons C) Internoceptors D) Exteroceptors E) Proprioceptors

The plasma membrane of an axon is called the A) axon terminal. B) neurilemma. C) myelin sheath. D) sarcolemma. E) axolemma.

The basic functional unit of the nervous system is the A) neuron. B) axon. C) nerve. D) glial cell. E) receptor.

The most common neuron of the nervous system is the A) interneuron. B) externoceptor. C) bipolar neuron. D) unipolar neuron. E) microglial cell.

Most neurons lack ________ and so are permanently blocked from undergoing cell division. A) ribosomes B) endoplasmic reticula C) a nucleus D) centrioles E) cytoplasm

Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration. A) neural B) central C) peripheral D) Wallerian E) conduction

Which of the following is not a function of the neuroglia? A) support B) memory C) secretion of cerebrospinal fluid D) maintenance of blood-brain barrier E) phagocytosis

Which of the following is a type of glial cell found in the peripheral nervous system? A) astrocytes B) satellite cells C) oligodendrocytes D) microglia E) ependymal cells

The largest and most numerous of the glial cells in the central nervous system are the A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

Functions of astrocytes include all of the following except A) maintaining the blood-brain barrier. B) conducting action potentials. C) guiding neuron development. D) responding to neural tissue damage. E) forming a three-dimensional framework for the CNS.

________ account for roughly half of the volume of the nervous system. A) Axons B) Dendrites C) Neuroglia D) Synapses E) Efferent fibers

The neuroglial cells that participate in maintaining the blood-brain barrier are the A) astrocytes. B) ependymal cells. C) microglia. D) oligodendrocytes. E) Schwann cells.

The myelin sheath that covers many CNS axons is formed by A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

________ line the brain ventricles and spinal canal. A) Astrocytes B) Satellite cells C) Oligodendrocytes D) Microglia E) Ependymal cells

Small, wandering cells that engulf cell debris and pathogens in the CNS are called A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

The neurilemma of axons in the peripheral nervous system is formed by A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) Schwann cells.

Glial cells that surround the neurons in ganglia are A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

Damage to ependymal cells would most likely affect the A) formation of myelin sheaths. B) formation of cerebrospinal fluid. C) formation of ganglia. D) repair of axons. E) transport of neurotransmitters within axons.

When pressure is applied to neural tissue, all of the following effects are possible except A) a decrease in blood flow. B) a decrease in available oxygen. C) a change in neuron excitability. D) glial cells degenerate. E) neurons are triggered to divide.

In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by A) producing new axons. B) regenerating cell bodies for the neurons. C) forming a cellular cord that directs axonal regrowth. D) clearing away cellular debris. E) producing more satellite cells that fuse to form new axons.

The tiny gaps between adjacent Schwann cells are called A) neurillema. B) nodes of Ranvier. C) axolemma. D) terminals. E) vesicles.

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter. A) gray B) white C) neural D) brain E) ganglion

Regions of the CNS where neuron cell bodies dominate constitute the ________ matter. A) white B) gray C) neural D) brain E) ganglion

Which of the following is not a function of astrocytes? A) They create a three dimensional framework for the CNS. B) They maintain the blood-brain barrier. C) They guide neuron development. D) They rebuild injured neurons. E) They adjust the composition of the interstitial tissue.

All of the following cause demyelination except A) heavy-metal ion poisoning. B) diphtheria. C) multiple sclerosis. D) dopamine deficiency. E) All of these cause demyelination.

Which of the following can cause demyelination? A) arsenic poisoning B) diphtheria C) multiple sclerosis D) mercury exposure

Which of the following is not true regarding the establishment of a neuron's resting membrane potential? A) Chemical and electrical forces both favor sodium ions entering the cell. B) Electrical forces do not push sodium ions into the cell. C) The chemical gradient for potassium ions tends to drive them out of the cell. D) Ion pumps in the plasma membrane eject sodium ions as fast as they cross the membrane. E) Resting membrane permeability to Na+ is very low.

At the normal resting membrane potential of a typical neuron, its sodium-potassium exchange pump transports A) 1 intracellular sodium ion for 2 extracellular potassium ions. B) 2 intracellular sodium ions for 1 extracellular potassium ion. C) 3 intracellular sodium ions for 1 extracellular potassium ion. D) 3 intracellular sodium ions for 2 extracellular potassium ions. E) 3 extracellular sodium ions for 2 intracellular potassium ions.

Ion channels that are always open are called ________ channels. A) active B) gated C) leak D) regulated E) local

Opening of sodium channels in the axon membrane causes A) depolarization. B) repolarization. C) hyperpolarization. D) increased negative charge inside the membrane. E) inhibition.

Voltage-gated channels are present A) at the motor end plate. B) on the surface of dendrites. C) in the membrane that covers axons. D) on the soma of neurons. E) along the perikaryon of neurons.

The sodium-potassium ion exchange pump A) must reestablish ion concentrations after each action potential. B) transports sodium ions into the cell during depolarization. C) transports potassium ions out of the cell during repolarization. D) moves sodium and potassium opposite to the direction of their electrochemical gradients. E) depends on a hydrogen gradient for energy.

________ open or close in response to binding specific molecules. A) Leak channels B) Activated channels C) Chemically gated channels D) Voltage-gated channels E) Voltage-gated and chemically gated channels

________ channels open or close in response to physical distortion of the membrane surface. A) Voltage-gated B) Chemically gated C) Active D) Mechanically gated E) Leak

Any stimulus that opens a ________ ion channel will produce a graded potential. A) voltage-gated B) chemically gated C) sodium D) mechanically gated

If the permeability of a resting axon to sodium ion increases, A) the membrane potential will repolarize. B) the membrane potential will hyperpolarize. C) inward movement of sodium ion will increase. D) outward movement of sodium ion will decrease. E) inward movement of sodium will increase and the membrane will depolarize.

Which of the following is not involved in creating the resting membrane potential of a neuron? A) diffusion of potassium ions out of the cell B) diffusion of sodium ions into the cell C) membrane permeability for sodium ions greater than potassium ions D) membrane permeability for potassium ions greater than sodium ions E) The interior of the plasma membrane has an excess of negative charges.

If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur except A) the intracellular concentration of potassium ions will increase. B) the neuron will slowly depolarize. C) the membrane will slowly lose its capacity to generate action potentials. D) the inside of the membrane will have a resting membrane potential that is more positive than normal. E) the intracellular concentration of sodium ions will increase.

Graded potentials A) produce an effect that increases with distance from the point of stimulation. B) produce an effect that spreads actively across the membrane surface. C) may be either a depolarization or a hyperpolarization. D) are often all-or-none. E) cause repolarization.

When potassium channels open and the ions diffuse through the membrane, A) the inside of the membrane will become more positive. B) the inside of the membrane will become more negative. C) there will be almost no effect on transmembrane potential. D) the membrane will become depolarized. E) the membrane will depolarize to threshold.

Ions can move across the plasma membrane in which of the following ways? A) through voltage-gated channels as in the action potential B) through passive or leak channels C) by ATP-dependent ion pumps like the sodium-potassium exchange pump D) through chemically gated channels as in neuromuscular transmission

Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have what effect? A) depolarize it B) hyperpolarize it C) increase the magnitude of the potassium equilibrium potential D) decrease the magnitude of the potassium equilibrium potential E) both hyperpolarize it and decrease the magnitude of the potassium equilibrium potential

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. A) inactivation B) ion C) swinging D) repolarization E) threshold

If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind? A) mechanically-regulated channel B) voltage-regulated sodium channel C) voltage-regulated calcium channel D) chemically-regulated potassium channel E) chemically-regulated sodium channel

A movement of charges in response to a potential difference is called A) current. B) depolarization. C) hyperpolarization. D) action potential. E) electricity.

The sum of the electrical and chemical forces acting on an ion is known as its A) permeability gradient. B) thermodynamic difference. C) electrochemical gradient. D) action potential. E) summation difference.

A shift of the resting transmembrane potential toward 0 mV is called A) potential difference. B) depolarization. C) hyperpolarization. D) polarization. E) repolarization.

The equilibrium potential of potassium is A) -90mV. B) -65mV. C) -70mV. D) +30mV. E) +66mV.

The equilibrium potential of sodium is A) -90mV. B) -65mV. C) -70mV. D) +30mV. E) +66mV.

The following are the main steps in the generation of an action potential. 1. Sodium channels are inactivated. 2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization. 3. Sodium channels regain their normal properties. 4. A graded depolarization brings an area of an excitable membrane to threshold. 5. A temporary hyperpolarization occurs. 6. Sodium channel activation occurs. 7. Sodium ions enter the cell and depolarization occurs. What is the proper sequence of these events? A) 4, 6, 7, 3, 2, 5, 1 B) 4, 6, 7, 1, 2, 3, 5 C) 6, 7, 4, 1, 2, 3, 5 D) 2, 4, 6, 7, 1, 3, 5 E) 4, 2, 5, 6, 7, 3, 1

The all-or-none principle states that A) all stimuli will produce identical action potentials. B) all stimuli great enough to bring the membrane to threshold will produce identical action potentials. C) the greater the magnitude of the stimuli, the greater the magnitude of the action potential. D) only sensory stimuli can activate action potentials. E) only motor stimuli can activate action potentials.

Which of the following statements about the action potential is false? A) The rapid depolarization phase is caused by the entry of potassium ions. B) During the repolarization phase, sodium channels close and potassium channels open. C) During the depolarization phase, membrane potential becomes positive. D) During the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane. E) Repolarization occurs as potassium ions leave the axon.

How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate? A) It would last indefinitely. B) It would be much briefer. C) It would be basically unaffected.

During repolarization of a neuron A) sodium ions move out of the cell. B) potassium ions move out of the cell. C) potassium ions move into the cell. D) both sodium and potassium ions move into the cell. E) sodium ions move into the cell.

How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron? A) The neuron will only be able to hyperpolarize. B) The neuron will depolarize more rapidly. C) Action potentials will lack a repolarization phase. D) The neuron will automatically and repeatedly produce graded potentials. E) The neuron will only be capable of producing graded potentials.

A threshold stimulus is the A) depolarization necessary to cause an action potential. B) peak of an action potential. C) hyperpolarization of an axon. D) resting membrane potential. E) electrical current that crosses the synaptic cleft.

Which of the following is true about threshold for an action potential? A) It is more positive than the resting membrane potential. B) Voltage-gated potassium channels begin to close. C) Voltage-gated potassium channels begin to open. D) The membrane begins to hyperpolarize. E) Threshold for a typical neuron is approximately -30 mV.

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? A) Neurons would depolarize more rapidly. B) Action potentials would lack a repolarization phase. C) The absolute refractory period would be shorter than normal. D) The axon would be unable to generate action potentials. E) None, because the chemically gated sodium channels would still function.

Use Figure 12-2 to answer the following questions: What is occurring at the area labeled #4? A) An inhibitory stimulus has occurred. B) Chemically gated potassium channels have opened. C) Excessive potassium has diffused out causing hyperpolarization. D) Sodium ions have been pumped out of the neuron. E) Excessive depolarization of the axon has occurred.

Use Figure 12-2 to answer the following questions: What is occurring in the area between #2 and #3? A) An excitatory graded potential is occurring. B) Potassium ions are entering the axon and causing depolarization. C) Chemically gated sodium channels are open and sodium is diffusing into the axon. D) Sodium ions are entering the axon and causing depolarization. E) Repolarization of the axon due to sodium ions leaving the axon is occurring.

Use Figure 12-2 to answer the following questions: Which area of the graph shows when chemically gated sodium channels are open? A) 3 B) 1 C) 2 D) 5 E) 4

Use Figure 12-2 to answer the following questions: Which area of the graph shows when voltage-gated sodium channels are open? A) 2 B) 4 C) 1 D) 5 E) 3

Use Figure 12-2 to answer the following questions: Which area of the graph shows when potassium channels open? A) 1 B) 2 C) 3 D) 4

Use Figure 12-2 to answer the following questions: In which area of the graph do you see a sudden rush of sodium ions into the neuron? A) 1 B) 2 C) 3 D) 4

Use Figure 12-2 to answer the following questions: Which area of the graph shows when membrane potential approaches the potassium equilibrium potential? A) 1 B) 2 C) 3 D) 4

Use Figure 12-2 to answer the following questions: Which point of the graph shows when potassium ion outflow exceeds sodium ion inflow? A) 1 B) 2 C) 3 D) 4

Use Figure 12-2 to answer the following questions: When is the neuron in the relative refractory period? A) 1 B) 2 C) 3 D) 4

Rapid impulse conduction from "node" to "node" is called A) spatial propagation. B) saltatory propagation. C) divergent propagation. D) synaptic transmission. E) continuous propagation.

Which of the following does not influence the time necessary for a nerve impulse to be transmitted? A) length of the axon B) presence or absence of a myelin sheath C) diameter of the axon D) presence or absence of nodes E) whether or not the impulse begins in the CNS

Which of the following types of nerve fiber possesses the fastest speed of impulse propagation? A) type A B) type B C) type C D) type D E) type E

Type ________ fibers have the largest diameter axons. A) S B) F C) A D) B E) C

Sensory information from skeletal muscles travels over ________ fibers. A) type A B) type B C) type C D) type D E) type E

In which of the following would the rate of impulse conduction be the greatest? A) a myelinated fiber of 10-μm diameter B) a nonmyelinated fiber of 20-μm diameter C) a myelinated fiber of 1-μm diameter D) a nonmyelinated fiber of 10-μm diameter E) It would be the same in all because of the all-or-none principle.

The minimum stimulus required to trigger an action potential is known as the A) threshold. B) all-or-none response. C) potential. D) incentive. E) summation.

The ________ principle states that the size and speed of the action potential are independent of the stimulus strength. A) threshold B) all-or-none C) summation D) polarization E) potential

The period during which an excitable membrane cannot respond to further stimulation is the ________ period. A) relative refractory B) absolute refractory C) resting D) lag E) stationary

The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period. A) relative refractory B) absolute refractory C) resting D) lag E) stationary

The presence of ________ dramatically increases the speed at which an action potential moves along an axon. A) a capsule B) plasma protein C) neurilemma D) glial cells E) myelin

Below are the events that occur during continuous propagation of action potential. Select the correct order in which the events occur. 1. Adjacent membrane segment depolarizes. 2. Local current spreads to adjacent voltage gated channel. 3. Threshold is met. 4. Local current develops due to sodium moving in the cytosol. A) 2,4,3,1 B) 2,4,1,3 C) 4,2,3,1 D) 4,2,1,3 E) 1,4,2,3

A neuron that receives neurotransmitter from another neuron is called A) the presynaptic neuron. B) the motor neuron. C) an oligodendrocyte. D) a satellite cell. E) the postsynaptic neuron.

Which type of synapse is most common in the nervous system? A) chemical B) electrical C) mechanical D) processing E) radiative

The ion that triggers the release of acetylcholine into the synaptic cleft is A) sodium. B) potassium. C) calcium. D) chloride. E) magnesium.

Cholinergic synapses release the neurotransmitter A) norepinephrine. B) adrenalin. C) serotonin. D) acetylcholine. E) GABA.

The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events? 1. Chemically-gated sodium channels on the postsynaptic membrane are activated. 2. Calcium ions enter the synaptic terminal. 3. Acetylcholinesterase hydrolyzes acetylcholine. 4. An action potential depolarizes the synaptic terminal at the presynaptic membrane. 5. The pre-synaptic terminal reabsorbs choline. 6. Acetylcholine is released from storage vesicles by exocytosis. 7. Acetylcholine binds to receptors on the postsynaptic membrane. 8. Calcium ions are removed from the cytoplasm of the pre- synaptic terminal. A) 4, 2, 6, 7, 8, 5, 3, 1 B) 4, 2, 6, 7, 1, 8, 3, 5 C) 2, 4, 6, 7, 1, 8, 3, 5 D) 2, 5, 4, 6, 7, 1, 8, 3 E) 6, 4, 2, 7, 1, 8, 3, 5

If the chemically gated sodium channels in the postsynaptic membrane were completely blocked, A) synaptic transmission would fail. B) release of neurotransmitter would stop. C) smaller action potentials would result. D) the presynaptic membrane would be unable to reach threshold. E) the presynaptic neuron would release a different neurotransmitter.

The effect that a neurotransmitter has on the postsynaptic membrane depends on the A) frequency of neurotransmitter release. B) nature of the neurotransmitter. C) characteristics of the receptors. D) quantity of neurotransmitters released.

When cholinergic receptors are stimulated, A) sodium ions enter the postsynaptic neuron. B) sodium ions leave the postsynaptic neuron. C) chloride ions enter the postsynaptic neuron. D) chloride ions leave the postsynaptic neuron. E) norepinephrine deactivates acetylcholine.

What triggers the release of acetylcholine from a synaptic terminal? A) release of calcium ions from the synaptic vesicles B) graded potentials in the synaptic terminal C) synaptic vesicles fuse to dendrites D) diffusion of sodium ions out of the synaptic terminal E) diffusion of calcium ions into the synaptic terminal

At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane. A) electrical B) cell C) chemical D) osmotic E) gap