The enteric nervous system can control the smooth muscle and glands of the digestive tract independently of the brain and spinal cord.
Correct Answer
True
True. The enteric nervous system is a large network of neurons in the wall of the digestive tract that can regulate motility and secretion on its own, although the central nervous system can modify its activity.
Category: Organization of the Nervous System
Question 2
Sensation is the nervous system function in which sensory input is combined with memories, emotions and learning to produce a response.
Correct Answer
False
False. Combining sensory input with memories, emotions and learning is integration. Sensation is the receiving of information about the internal or external environment, and response is the resulting muscle or gland activity.
Category: Organization of the Nervous System
Question 3
Satellite cells are glial cells that surround neuron cell bodies within nuclei of the central nervous system.
Correct Answer
False
False. Satellite cells are peripheral nervous system glia. They surround and support neuron cell bodies in sensory and autonomic ganglia.
Category: Glial Cells
Question 4
Ependymal cells line the ventricles of the brain and use cilia to help move cerebrospinal fluid.
Correct Answer
True
True. Ependymal cells form the lining of the ventricles and central canal, help filter blood to produce cerebrospinal fluid, and beat their cilia to circulate it.
Category: Glial Cells
Question 5
Dendrites typically carry signals away from the cell body toward the axon terminals.
Correct Answer
False
False. Dendrites receive input from other neurons and carry it toward the cell body. The axon is the process that carries signals away from the cell body to its terminals.
Category: Neuron Structure
Question 6
In humans, unipolar neurons are sensory neurons whose cell bodies are located in ganglia.
Correct Answer
True
True. Human unipolar neurons, more precisely called pseudo-unipolar, are sensory neurons. Their single process splits into a peripheral branch and a central branch, and their cell bodies sit in ganglia outside the central nervous system.
Category: Neuron Structure
Question 7
Purkinje cells of the cerebellum are an example of bipolar neurons.
Correct Answer
False
False. Purkinje cells are multipolar neurons with an elaborately branched dendritic tree. Bipolar neurons are found mainly in the retina and the olfactory epithelium.
Category: Neuron Structure
Question 8
Action potentials are all-or-none, so a stronger stimulus increases how often they fire rather than how large they are.
Correct Answer
True
True. Once threshold is reached, an action potential always reaches about the same peak. Stimulus strength is encoded by the frequency of action potentials, not their size.
Category: Action Potential
Question 9
The sodium-potassium pump moves sodium ions into the cell and potassium ions out of the cell.
Correct Answer
False
False. The sodium-potassium pump uses ATP to move sodium out of the cell and potassium into it, against their concentration gradients, which maintains the gradients the resting potential depends on.
Category: Resting Membrane Potential
Question 10
The threshold for triggering an action potential in a typical neuron is about -55 mV.
Correct Answer
True
True. When a graded potential depolarizes the trigger zone from about -70 mV to about -55 mV, enough voltage-gated sodium channels open to start an action potential.
Category: Action Potential
Question 11
During the relative refractory period, a second action potential cannot be generated no matter how strong the stimulus is.
Correct Answer
False
False. During the relative refractory period a new action potential can be triggered, but it takes a stronger than normal stimulus because potassium is still flowing out. The period in which no stimulus can work is the absolute refractory period.
Category: Action Potential
Question 12
The brief hyperpolarization after an action potential occurs because voltage-gated potassium channels close slightly late.
Correct Answer
True
True. Voltage-gated potassium channels are slow to close, so potassium keeps leaving the cell for a moment after the membrane returns to rest, briefly making it more negative than -70 mV.
Category: Action Potential
Question 13
Continuous conduction along an unmyelinated axon is faster than saltatory conduction along a myelinated axon of the same diameter.
Correct Answer
False
False. Saltatory conduction in a myelinated axon is faster, because the action potential is regenerated only at the nodes of Ranvier rather than at every point along the membrane.
Category: Propagation
Question 14
Leakage channels open and close randomly and contribute to the resting membrane potential.
Correct Answer
True
True. Leakage channels are not gated by voltage, ligands or force. Their random opening, especially of potassium leakage channels, helps establish the negative resting potential.
Category: Ion Channels
Question 15
Mechanically gated channels open when a neurotransmitter binds to them.
Correct Answer
False
False. Mechanically gated channels open when the membrane is physically deformed, as by pressure or stretch. Channels that open when a neurotransmitter binds are ligand-gated channels.
Category: Ion Channels
Question 16
Spatial summation occurs when graded potentials from synapses at several different locations on a neuron add together.
Correct Answer
True
True. In spatial summation, simultaneous inputs at different sites combine. Temporal summation is the related process in which repeated inputs from one source add together over time.
Category: Synapses
Question 17
Electrical synapses transmit signals by releasing neurotransmitter molecules that diffuse across a synaptic cleft.
Correct Answer
False
False. At an electrical synapse the cells are directly connected, so ions flow from one cell into the next and depolarization spreads without a neurotransmitter. Neurotransmitter release across a cleft describes a chemical synapse.
Category: Synapses
Question 18
Neuropeptides such as substance P and the enkephalins are broken down in the synaptic cleft by peptidase enzymes.
Correct Answer
True
True. Neuropeptides are short chains of amino acids joined by peptide bonds, so their signal is ended by peptidases that cleave those bonds. Amino acid and biogenic amine neurotransmitters are cleared mainly by reuptake instead.
Category: Neurotransmitters
Question 19
Dopamine, norepinephrine and epinephrine are neuropeptides made of chains of amino acids joined by peptide bonds.
Correct Answer
False
False. Dopamine, norepinephrine and epinephrine are biogenic amines, each made from the single amino acid tyrosine. Neuropeptides such as enkephalins and substance P are amino acid chains.
Category: Neurotransmitters
Question 20
Nicotinic and muscarinic receptors are the two main classes of receptors for acetylcholine.
Correct Answer
True
True. Both bind acetylcholine and are named for the drugs nicotine and muscarine. Nicotinic receptors are cation channels that depolarize the cell, while muscarinic receptors work through G proteins.
Category: Neurotransmitters