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85 Cards in this Set
- Front
- Back
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The nerve cells that transfer information within the body are called...
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Neurons
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What are the two types of signals in communication by neurons?
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Long-distance electrical signals and short-distance chemical signals
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T/F: All of the information of the brain is transmitted through neurons as an electrical current, consisting of the movement of ions.
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True
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The three stages in information processing are...
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Sensory input, integration, and motor output
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What neurons (nerve cells) transmit information from eyes and other sensors that detect external stimuli or internal conditions (bp, muscle tension) to processing centers in the brain or ganglia?
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Sensory neurons
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T/F: After these sensory neurons do their jobs, neurons in the brain/ganglia analyze and interpret (integrate) the sensory input, taking into account the immediate context and the animal's experience.
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True
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Neurons that make only local connections are...
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Interneurons
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T/F: Motor output relies on neurons that extend out of the processing centers in bundles called "nerves" and generate output by triggering muscle or gland activity.
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True
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_ neurons transmit signals to muscle cells, causing them to contract.
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Motor
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In many animals, the neurons that carry out integration are organized in a _ _ _, which includes the brain and a longitudinal nerve cord.
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Central Nervous System
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The neurons that carry information into and out of the CNS constitute the...
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Peripheral nervous system
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The highly branched extensions of a neuron that receive signals from other neurons are called...
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Dendrites
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Most of a neuron's organelles, including its nucleus, are located in the...
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Cell body
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The long extension of a neuron that transmits signals to other cells is called an...
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Axon
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The cone-shaped region of an axon where it joins the cell body is called the...
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Axon hillock (typically the region where the signals that travel down the axon are generated)
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The junctions formed by a synaptic terminal and the dendrites of the receiving cell are called...
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Synapses
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The axon branches off into many branches onto the next cell called...
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Synaptic terminals
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The transmitting neuron releasing the neurotransmitters is called the _ cell, and the neuron, muscle, or gland that receives the signal is the _ cell.
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Presynaptic, postsynaptic
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Most neurons require supporting cells called...
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Glial cells (or glia)
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T/F: Changes in membrane potential act as signals, transmitting and processing information.
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True
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What is the membrane potential of a resting neuron called and what is it usually?
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The resting potential; -60 to -80 mV
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T/F: Converting chemical potential of ions like K+ and Na+ to electric potential involves ion channels, wherein any resulting net movement of positive or negative charge generates a voltage, or potential, across the membrane.
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True
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T/F: Because there are so many K+ ions in the resting neuron, they naturally flow outside of the neuron from the open potassium pumps. Thus, the many negative ions like Cl- remain within the neuron and cause the negative charge buildup, creating voltage.
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True
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The magnitude of the membrane voltage at equilibrium for a particular ion is called that ion's...
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Equilibrium potential or E(ion)
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At human body temperature (37C) and for an ion with a net charge of 1+ (like K+ or Na+), the Nernst equation is...
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E(ion) = 62*log([outsideion]/[insideion])
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T/F: When the E(ion) is negative, this indicates that K+ is at equilibrium when the inside of the membrane is 90 mV more negative than the outside.
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True
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Ion channels that open or close in response to stimuli are called...
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Gated ion channels
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The increase in the magnitude of the membrane potential (voltage) is called...
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Hyperpolarization
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The reduction in the magnitude of the membrane potential (voltage) is called...
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Depolarization (often involves gated SODIUM channels)
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Many of the ion channels in neurons are _ _ _ _, meaning they open or close in response to a change in the membrane potential.
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Voltage-gated ion channels
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When a depolarization lowers the magnitude of the voltage or membrane potential, voltage-gated ion channels for sodium open up and allow even more Na+ ions to enter, which causes further depolarization, and so on. These series of events which cause a massive change in membrane voltage are called...
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Action potentials
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T/F: Action potentials are the nerve impulses, or signals, that carry information along an axon.
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True
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Action potentials occur whenever a depolarization increases the membrane voltage to a particular value, called the...
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Threshold (about -55 mV in humans)
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T/F: The frequency with which a neuron generates action potentials can vary in response to input.
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True
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The stage during action potentials when the positive sodium-channel feedback cycle brings membrane potential/voltage nearer and nearer to E(Na) is called the...
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Rising phase
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What two events prevent the membrane potential/voltage from actually reaching E(Na)?
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The fact that voltage-gated sodium channels inactivate soon after opening, and that most voltage-gated potassium channels open causing a rapid outflow of K+ ions, quickly bringing membrane potential/voltage back to E(K).
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What is the event on the previous card called?
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The falling phase
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What is the stage called when, immediately after the falling phase, the membrane's permeability to K+ is higher than at rest, until finally the voltage-gated channels close and the neuron is at resting potential again?
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The undershoot
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Sodium channels are inactivated during the falling phase and undershoot, so that if another depolarizing stimulus were to occur it couldn't trigger an action potential. What is this period, when a second action potential cannot be activated, called?
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The refractory period
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How does axon diameter affect the speed at which action potentials are conducted?
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The smaller the diameter, the more resistance there is. So the axon with the larger diameter will have the least resistance and the fastest action potential speed.
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What is the adaptation that allows fast conduction of action potentials in narrow axons?
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The myelin sheath, a layer of electric insulation that surrounds vertebrae axons
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Where/by what glia are myelin sheaths produced?
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Oligodendrocytes in the CNS and in Schwann cells in the PNS
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T/F: The insulation provided by the myelin sheath has the same effect as increasing the axon's diameter: it causes the depolarizing current associated with an action potential to spread farther along the interior of the axon, bringing more distant regions of the membrane to the threshold sooner.
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True
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What are the gaps in the myelin sheath called where voltage-gated sodium channels are restricted to?
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Nodes of Ranvier
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When the action potential is started in a myelinated axon (usually at the axon hillock) and transported to each node where the action potential is started again, this mechanism is called...
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Saltatory conduction
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T/F: Some synapses, called electrical synapses, contain gap junctions which do allow electrical current to flow directly from one neuron to another, but mostly action potentials don't go from cell to cell.
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True
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What are the synapses which involve the release of a chemical neurotransmitter by the presynaptic neuron?
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Chemical synapses
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At each terminal, the presynaptic neuron synthesizes the neurotransmitter and packages it in multiple membrane-bounded compartments called...
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Synaptic vesicles
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The narrow gap that separates the presynaptic neuron from the postsynaptic cell is called the...
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Synaptic cleft
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Describe how a neurotransmitter crosses the synaptic cleft.
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When an action potential arrives at the synaptic terminal, voltage-gated ion channels open causing Ca2+ to come in, and once this occurs the synaptic vesicles which carry the neurotransmitters fuse with the plasma membrane and the neurotransmitters go across the synaptic cleft. (then goes to ligand-gate ion channels in the postsynaptic cell where those channels are opened, creating postsynaptic potential)
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Because the depolarizations from the the postsynaptic voltage/potential bring the membrane potential toward threshold, they are called...
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Excitatory postsynaptic potentials
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Hyperpolarizations caused by the opening of ligand-gated ion channels which allow only K+ or Cl- to travel (initiated by different neurotransmitters) are called...
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Inhibitory postsynaptic potentials (because if it's hyperpolarization, action potientals from depolarization cannot occur and so this is INHIBITORY)
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T/F: Various mechanisms can remove neurotransmitters from the synaptic cleft including active transport back in to the presynaptic cell, hydrolysis by enzymes, etc.
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True
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T/F: Unlike action potentials, which are all-or-none events, post-synaptic potentials are graded; their magnitude varies with a number of factors, including the amount of neurotransmitter released by the presynaptic neuron.
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True
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T/F: Postsynaptic potentials usually do not regenerate as they spread along the membrane of a cell; they become smaller with distance from the synapse.
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True
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When two EPSPs occur at a single synapse in rapid succession, they can add together and are called...
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Temporal summation
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EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron can also add together in an effect called...
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Spatial summation
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T/F: Through spatial and temporal summation, several ESPSs can depolarize the membrane at the axon hillock to the theshold, causing the postsynaptic neuron to produce an action potential.
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True (summation can also occur in ISPSs, inhibiting summation)
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T/F: At some postsynaptic cells there are not ligand-gated ion channels, but rather receptor proteins that activate a signal transduction pathway involving a second messenger
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True
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T/F: The most common form of a neurotransmitter, acetylcholine, acts as an EPSP in all muscle cells causing quicker contraction, except in the heart where it acts as an IPSP reducing the rate of heart contraction.
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True
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T/F: Dopamine and serotonin (biogenic amines) are released at many sites in the brain and affect sleep, mood, attention, and learning.
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True
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The two amino acids that serve as the major neurotransmitters in the vertebrae CNS are...
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Gamma-aminobutyric acid (GABA, inhibitory by means of Cl-) and glutamate (always excitatory)
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Short chains of amino acids that serve as neurotransmitters that operate via signal transduction pathways are called...
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Neuropeptides (substance P for pain, and endorphins which decrease pain)
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---Chapter 49: What three anterior bulges become evident in all vertebrates as the embryo develops?
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The forebrain, midbrain, and hindbrain
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The midbrain and hindbrain eventually form the..,
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Brainstem (hindbrain also gives rise to cerebellum)
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What region of the forebrain gives rise to the cerebrum?
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The telencephalon
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What is the outer portion of the cerebrum called which opens and extends to make this the largest part of the brain?
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The cerebral cortex
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What structures arise from the diencephalon from the forebrain?
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The thalamus, hypothalamus, and epithalamus
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What does the brainstem consist of?
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The midbrain, the pons, and the medulla oblongata (commonly just called the medulla)
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What is the main function of the medulla and pons?
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To transfer information from the PNS to the midbrain or forebrain
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T/F: Most axons carrying signals about movement cross the medulla from one side of the CNS to the other, so the right side of the brain controls much of the movement of the left side of the body, and vice versa.
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True
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T/F: In mammals, the forebrain/cerebrum controls vision, but the midbrain controls things like the peripheral vision reflex: the head turns toward an object approaching from the side without the brain having formed an image of the object.
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True
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T/F: Signals from the brainstem affect attention, alertness, appetite, and motivation.
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True
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Arousal and sleep are controlled by both...
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The brain stem and the cerebrum
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One such regulator of arousal/sleep is the _ _, a diffuse network of neurons in the core of the brainstem.
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Reticular formation
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What does the reticular formation do?
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It determines which incoming information reaches the cerebral cortex (acts as a sensory filter)
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T/F: COOLEST FACT EVER; Dolphins sleep with only one brain hemisphere at a time, with one eye open and one eye closed, so that they can swim while sleeping and rise to the surface for air.
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True
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What part of the brain coordinates movement and balance?
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The cerebellum (hand eye coordination, mostly movements, monitors cerebrum's motor commands)
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What part of the diencephalon includes the pineal gland and contains one of several clusters of capillaries that generate cerebrospinal fluid from blood?
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The epithalamus
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The main, initial input for sensory information which sorts this information out and sends it to respective parts of the cerebrum is the...
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Thalamus
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A molecular mechanism that directs periodic gene expression and cellular activity is a...
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Biological clock
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In mammals, circadian rhythms are coordinated and initiated by a group of neurons in the hypothalamus called the...
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Superchiasmatic nucleus
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What are the three main parts of the cerebrum?
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The outer gray matter cerebral cortex (perception, voluntary movement, learning), the inner white matter, and the basal nuclei deep within the white matter
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What is the thick band of axons which enable the right and left cerebral cortex to communicate called?
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The corpus callosum
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The outermost part of the cerebral cortex forms the _, six parallel layers of neurons arranged tangential to the brain surface.
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Neocortex
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