Midterm Study Questions Flashcards

Question

What are the roles of astrocytes and microglia?

Answer 1

Glial Cells Astrocyte - A star-shaped glial cell with numerous processes (extensions) that run in all directions. Microglial cells Also called microglia. Extremely small glial cells that remove cellular debris from injured or dead cells.

Answer 2

Synapse - The tiny gap between neurons where information is passed from one to the other. Studding the dendrites of many neurons are outgrowths called dendritic spines that, by effectively increasing the surface area of the dendrites, allow for extra synaptic contacts. Both the number and structure of dendritic spines may be rapidly altered by experience, such as training or exposure to sensory stimuli

Answer 3

Information is transmitted from the axon terminal of the presynaptic neuron to the receptive surface of the postsynaptic neuron through the synaptic cleft. The synaptic cleft is the gap of about 20–40 nanometers (nm) that separates the presynaptic and postsynaptic membranes. Presynaptic axon terminals contain numerous tiny spheres, called synaptic vesicles, each 30–140 nm in diameter. Each vesicle contains a specialized chemical substance, a neurotransmitter, which the neuron uses to communicate with postsynaptic neurons. In response to electrical activity in the axon, these vesicles fuse with the presynaptic membrane, releasing molecules of neurotransmitter into the cleft. After crossing the cleft, the released neurotransmitter interacts with postsynaptic receptors: specialized protein molecules that capture and react to molecules of the neurotransmitter.

Answer 4

a natural subdivision into a peripheral nervous system (all nervous system parts that are outside the bony skull and spinal column) and a central nervous system (CNS), consisting of the brain and spinal cord

Answer 5

Cranial nerves serve the sensory and motor systems of the head and neck. Three cranial nerves are exclusively sensory pathways to the brain: the olfactory, the optic and the nerve is concerned with hearing and balance. Five nerves are exclusively motor pathways from the brain: three nerve pathways innervate muscles to move the eye; one pathway controls neck muscles; and one controls the tongue. The remaining cranial nerves have both sensory and motor functions. One serves facial sensation and it controls chewing movements through other axons. Another set of nerves control facial muscles and receive taste sensation, there are nerves that receive sensation from the throat and control the muscles there. And the vagus (X) nerve extends far from the head, running to the heart, liver, and intestines

Answer 6

Spinal nerves–also called somatic nerves, connected to the spinal cord Each spinal nerve is the fusion of two distinct branches, or roots: 1. Dorsal (back) root–carries sensory information from the body to the spinal cord 2. Ventral (front) root–carries motor information from the spinal cord to the muscles

Answer 7

Each spinal nerve is the fusion of two distinct branches, or roots: 1. Dorsal (back) root–carries sensory information from the body to the spinal cord 2. Ventral (front) root–carries motor information from the spinal cord to the muscles

Answer 8

The autonomic nervous system has three major divisions: 1. Sympathetic nervous system 2. Parasympathetic nervous system 3. Enteric nervous system Sympathetic nervous system - A component of the autonomic nervous system that arises from the thoracic and lumbar spinal cord. In general, sympathetic activation prepares the body for action: blood pressure increases, the pupils of the eyes widen, and the heart quickens. This set of reactions is sometimes called simply the “ﬁght or ﬂight” response. Parasympathetic nervous system - A component of the autonomic nervous system that arises from both the cranial nerves and the sacral spinal cord. Generally helps the body to relax, recuperate, and prepare for future action, sometimes called the “rest and digest” response.

Answer 9

Neural tube - An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain. The walls of this neural tube are made of cells, and the interior is ﬁlled with ﬂuid. A few weeks after conception, the human neural tube begins to show three separate swellings at the head end: the forebrain (or prosencephalon), the midbrain (or mesencephalon), and the hindbrain (or rhombencephalon). About 50 days after conception, the forebrain and hindbrain have already developed clear subdivisions. At the very front of the developing brain is the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.

Answer 10

Meninges are the three protective sheets of tissue—dura mater, pia mater, and arachnoid—that surround the brain and spinal cord. Dura mater -The outermost of the three meninges that surround the brain and spinal cord. Pia mater - the innermost of the three meninges that surround the brain and spinal cord Arachnoid - The thin covering (one of the three meninges) of the brain that lies between the dura mater and pia mater.

Answer 11

An acute inﬂammation of the meninges, usually caused by a viral or bacterial infection. Potentially lethal medical emergency characterized in early stages by headache, fever, and stiff neck as the inﬂamed meninges press on the brain.

Answer 12

What is CSF? Cerebrospinal ﬂuid (CSF) - The ﬂuid that ﬁlls the cerebral ventricles. where is it made? Choroid plexus - A highly vascular portion of the lining of the ventricles that secretes cerebrospinal ﬂuid. Specialized membrane the lines the lateral ventricles produces CSF by ﬁltering blood. where does it flow? Ventricular system - A system of (CSF) ﬂuid-ﬁlled cavities inside the brain. The middle layer of Meninges call Arachnoid - suspends the brain in a bath of cerebrospinal ﬂuid (CSF). where is it re-absorbed? CSF is absorbed back into the circulatory system through: large veins beneath the top of the skull. Do we make what we need on a daily basis? First, it acts mechanically as a shock absorber for the brain: ﬂoating in CSF, the brain is protected from sudden movements of the head that would smash it against the inside of the skull. Second, CSF provides a medium for the exchange of materials, including nutrients, between

Answer 13

ventricular system - A system of ﬂuid-ﬁlled cavities inside the brain. The CSF circulating through the ventricular system has at least two main functions. First, it acts mechanically as a shock absorber for the brain: ﬂoating in CSF, the brain is protected from sudden movements of the head that would smash it against the inside of the skull. Second, CSF provides a medium for the exchange of materials, including nutrients, between blood vessels and brain tissue. lateral ventricle - A complexly shaped lateral portion of the ventricular system within each hemisphere of the brain. third ventricle - The midline ventricle that conducts cerebrospinal ﬂuid from the lateral ventricles to the fourth ventricle. fourth ventricle - The passageway within the pons that receives cerebrospinal ﬂuid from the third ventricle and releases it to surround the brain and spinal cord. It has three small openings allow CSF to exit the ventricular system and circulate over the outer surface of the brain and spinal cord.

Answer 14

Frontal lobe - The most anterior portion of the cerebral cortex. important for movement and high-level cognition Parietal lobe - Large regions of cortex lying between the frontal and occipital lobes of each cerebral hemisphere. It receives sensory information from the body and participate in spatial cognition. Temporal lobes - Large lateral cortical regions of each cerebral hemisphere, continuous with the parietal lobes posteriorly, and separated from the frontal lobe by the Sylvian fissure. Auditory information damage here can impair hearing the temporal lobes are also particularly associated with the sense of smell, and with aspects of learning and memory. Occipital lobes - Large regions of cortex covering much of the posterior part of each cerebral hemisphere. Receive and process information from the eyes, giving rise to the sense of vision.

Answer 15

White matter - A shiny layer underneath the cortex that consists largely of axons with white myelin sheaths. Which consists mostly of ﬁber tracts. It gains its appearance from the whitish fatty myelin that ensheathes and insulates the axons of many neurons. White matter mostly transmits information. Gray matter - Areas of the brain that are dominated by cell bodies and are devoid of myelin. On the exterior is dominated more by nerve cell bodies and dendrites, which are devoid of myelin. A simple view is that gray matter primarily processes information,

Answer 16

The lumpy convolutions of the paired cerebral hemispheres are the result of elaborate folding together of a thick sheet of brain tissue called the cerebral cortex which is made up mostly of neurons and their ﬁbers. The resulting ridges of tissue, called gyri, are separated from each other by furrows called sulci. A ﬁssure is a deep sulcus

Answer 17

Sylvian ﬁssure Also called lateral sulcus. A deep ﬁssure that demarcates the temporal lobe. Central sulcus A ﬁssure that divides the frontal lobe from the parietal lobe. Longitudinal fissure – the fissure that runs from the back to the front

Answer 18

Postcentral gyrus - The strip of parietal cortex, just behind the central sulcus, that receives somatosensory information from the entire body. Precentral gyrus - The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control.

Answer 19

Limbic system - A loosely deﬁned, wide-spread group of brain nuclei that innervate each other to form a network. Curving through each hemisphere, alongside the basal ganglia. It is critical for emotion and learning. Limbic structures near the base of the brain, especially the hypothalamus, help to govern highly motivated behaviors, like sex and aggression, and regulate the hormonal systems of the body. Hippocampus - A medial temporal lobe structure that is important for learning and memory. Amygdala - A group of nuclei in the medial anterior part of the temporal lobe. It has several subdivisions with diverse functions such as emotional regulation and odor perception. Cingulate gyrus - A cortical portion of the limbic system, found in the frontal and parietal midline. Implicated in many cognitive functions, including the direction of attention. Mammillary bodies - are important for emotion, learning, and memory.

Answer 20

Basal ganglia - A group of forebrain nuclei, including caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres. The basal ganglia are very important in motor control. Striatum The caudate nucleus and putamen together. Thalamus - The brain regions that surround the third ventricle. Acts as a switchbox, directing almost all incoming sensory information to the appropriate regions of the cortex for further processing, and receiving instructions back from the cortex to control which sensory information is transmitted. Amygdala - A group of nuclei in the medial anterior part of the temporal lobe. It has several subdivisions with diverse functions such as emotional regulation and odor perception. Nucleus accumbens - A region of the forebrain that receives dopaminergic innervation from the ventral tegmental area.

Answer 21

Superior colliculi - Paired gray matter structures of the dorsal midbrain that receive visual information and are involved in direction of visual gaze and visual attention to intended stimuli. Inferior colliculi - Paired gray matter structures of the dorsal midbrain that receive auditory information.

Answer 22

Hypothalamus - Part of the diencephalon, lying ventral to the thalamus. It is packed with discrete nuclei involved in many vital functions, such as hunger, thirst, temperature regulation, sex, and many more. Furthermore, because the hypothalamus also controls the pituitary gland, it serves as the brain’s main interface with the hormonal systems of the body. Substantia nigra - A brainstem structure in humans that innervates the basal ganglia. Contains neurons that release the transmitter dopamine. Pituitary gland - Also called hypophysis. A small, complex endocrine gland located in a socket at the base of the skull. Includes anterior pituitary and posterior pituitary. Hormone secretion

Answer 23

Cerebellum - t is involved in the central regulation of movement. Has long been known to be crucial for motor coordination and control, but we now know it also participates in certain aspects of cognition, including learning. Pons - part of the brainstem connecting midbrain to medulla. Within the pons are important motor control and sensory nuclei, including several nuclei from which cranial nerves arise. Reticular formation -An extensive region of the brainstem that is involved in arousal (waking). Variety of behaviors, including sleep and arousal, temperature regulation, and motor control.

Answer 24

Anterior cerebral arteries - Two large arteries, arising from the carotids, that provide blood to the anterior poles and medial surfaces of the cerebral hemispheres. (stroke here would cause damage in movement and high-level cognition, receiving sensory information from the body and participate in spatial cognition.) Middle cerebral arteries - Two large arteries, arising from the carotids, that provide blood to most of the lateral surfaces of the cerebral hemispheres. (stroke here would can impair hearing, the sense of smell, and with aspects of learning and memory) Posterior cerebral arteries - Two large arteries, arising from the basilar artery, that provide blood to posterior aspects of the cerebral hemispheres, cerebellum, and brainstem. (stroke here would cause problems with motor coordination and control, important motor control and sensory nuclei, including several nuclei from which cranial nerves arise and heart problems and death)

Answer 25

magnetic resonance imaging (MRI) A noninvasive technique that uses magnetic energy to generate images that reveal some structural details in the living brain. MRI images are derived from radio frequency energy, the patient’s head is placed in the center of an extremely powerful circular magnet that causes all the protons in the brain’s tissues to line up in parallel, instead of in their usual random orientations. the protons are knocked over by a strong pulse of radio waves. When this pulse is turned off, the protons relax back to their original conﬁguration, emitting radio waves as they go. a powerful computer uses this density-based information to generate a detailed cross-sectional map of the brain With their higher resolution, MRI images can reveal subtle changes in the brain, such as the loss of myelin that is characteristic of multiple sclerosis

Answer 26

positron emission tomography (PET) A technique for examining brain function by combining tomography with injections of radioactive substances used by the brain. the objective is to obtain images of the brain’s activity rather than details of its structure, and it has proven to be very valuable for both experimental and medical purposes. we can generate metabolic maps of the brain that identify the regions that contribute to speciﬁc functions.

Answer 27

functional MRI (fMRI) Magnetic resonance imaging that detects changes in blood ﬂow and therefore identiﬁes regions of the brain that are particularly active during a given task. has revolutionized cognitive neuroscience research, producing images with reasonable speed and excellent sharpness uses high-powered, rapidly oscillating magnetic-ﬁeld gradients to detect small changes in brain metabolism, particularly the moment-to-moment use of oxygen scientists can use fMRI data to create computer-generated images that reﬂect the activity of different parts of the brain while people engage in various experimental tasks The detailed activity maps provided by fMRI reveal how networks of brain structures collaborate on complex cognitive processes. The fMRI image generally reﬂects synaptic inputs and local processing, rather than the production of neural impulses

Answer 28

sodium-potassium pump The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in. It pumps three sodium ions (Na+) out of the cell for every two K+ ions pumped in. The sodium-potassium (Na+-K+) pump continually pushes Na+ ions out and pulls K+ ions in. This ion pump requires considerable energy. How does the sodium-potassium pump causing a net buildup of negative charges inside the cell? The sodium-potassium pump causes a buildup of K+ ions inside the cell, but recall that at rest the membrane is much more permeable to K+ ions than Na+ ions. That means K+ ions will tend to leave the interior, down their concentration gradient, causing a net buildup of negative charges inside the cell.

Answer 29

They are both passive graded potentials that effect the charge of the cell and impact if threshold is reached and action potential starts. Hyperpolarization An increase in membrane potential (the interior of the neuron becomes even more negative, relative to the outside) So if the neuron already has a resting membrane potential of, say, –60 mV, hyperpolarization makes it even farther from zero, maybe –70 mV Depolarization A reduction in membrane potential (the interior of the neuron becomes less negative). In other words, depolarization of a neuron brings its membrane potential closer to zero.

Answer 30

voltage-gated Na+ channel A Na+- selective channel that opens or closes in response to changes in the voltage of the local membrane potential; it mediates the action potential. It is a tubular, membrane-spanning protein, but its central Na+-selective pore is ordinarily closed. When the cell membrane becomes depolarized to threshold levels, the channel’s shape changes, opening the pore to allow Na+ ions through. the voltage-gated Na+ channel, is really quite a complicated machine. It monitors the axon’s polarity, and at threshold the channel changes its shape to open the pore, shutting down again just a millisecond later. The channel then “remembers” that it was recently open and refuses to open again for a short time. These properties produce and enforce the properties of the action potential.

Answer 31

nodes of Ranvier A gap between successive segments of the myelin sheath where the axon membrane is exposed. small gaps spaced about every millimeter along the axon saltatory conduction The form of conduction that is characteristic of myelinated axons, in which the action potential jumps from one node of Ranvier to the next. because the myelin insulation offers considerable resistance to the ﬂow of ionic currents across the membrane, the action potential jumps from node to node. The evolution of rapid saltatory conduction in vertebrates has given them a major behavioral advantage over invertebrates, in which axons are unmyelinated and mostly small in diameter, and thus slower in conduction.

Answer 32

tetrodotoxin (TTX) and saxitoxin (STX) selectively block voltage-gated sodium channels, thereby preventing the production of action potentials; paralysis and death rapidly follow. Tetrodotoxin A toxin from puffer ﬁsh ovaries that blocks the voltage-gated sodium channel, preventing action potential conduction. batrachotoxin, A toxin, secreted by poison arrow frogs, that selectively interferes with Na+ channels it forces Na+ channels to stay open, with lethal results.

Answer 33

A substance that binds to receptor molecules, such as those at the surface of the cell. Ligands fit receptors exactly and activate or block them: endogenous ligand Any substance, produced within the body, that selectively binds to the type of receptor that is under study. Endogenous ligands–neurotransmitters and hormones exogenous ligand Any substance, originating from outside the body, that selectively binds to the type of receptor that is under study. Exogenous ligands–drugs and toxins from outside the body

Answer 34

postsynaptic potential A local potential that is initiated by stimulation at a synapse, can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance. given neuron, receiving synapses from hundreds of other cells, is subject to hundreds or thousands of postsynaptic potentials. When integrated, this massive array of local potentials determines whether the neuron will reach threshold and therefore generate an action potential of its own. Synapses Cause Graded, Local changes in the Postsynaptic Membrane Potential

Answer 35

Transmitters bind to postsynaptic receptors and cause an EPSP or IPSP. EPSPs or IPSPs spread toward the postsynaptic axon hillock The IPSPs and EPSPs in the postsynaptic cell spread throughout its interior. If the integration of all the EPSPs and IPSPs depolarizes the axon hillock enough, the postsynaptic neuron will ﬁre an action potential of its own. excitatory postsynaptic potential (EPSP) A depolarizing potential in the postsynaptic neuron that is caused by excitatory connections. EPSPs increase the probability that the postsynaptic neuron will ﬁre an action potential. inhibitory postsynaptic potential (IPSP) A hyperpolarizing potential in the postsynaptic neuron that is caused by inhibitory connections. IPSPs decrease the probability that the postsynaptic neuron will ﬁre an action potential. When the inhibitory neuron is stimulated, the postsynaptic effect is an increase of the resting membrane potential. This hyperpolarization moves the cell membrane potential away from threshold—decreasing the probability that the neuron will ﬁre an action potential

Answer 36

postsynaptic potential A local potential that is initiated by stimulation at a synapse, can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance. A given neuron, receiving synapses from hundreds of other cells, is subject to hundreds or thousands of postsynaptic potentials. When integrated, this massive array of local potentials determines whether the neuron will reach threshold and therefore generate an action potential of its own. Generally, the combined effect of many excitatory synapses is needed to elicit an action potential in a postsynaptic neuron. the membrane response is passive a graded response - The greater the stimulus, the greater the response action potential The propagated electrical message of a neuron that travels along the axon to the presynaptic axon terminals. Stimulation of an excitatory presynaptic neuron causes it to produces an all-or-none action potential that spreads to the end of the axon, releasing transmitter. How is the action potential unlike the passive graded potentials the action potential is actively propagated (or regenerated) down the axon, through ionic mechanisms

Answer 37

Also called gap junction. The region between neurons where the presynaptic and postsynaptic membranes are so close that the action potential can jump to the postsynaptic membrane with-out ﬁrst being translated into a chemical message. the presynaptic membrane comes even closer to the postsynaptic membrane than it does at chemical synapses. At electrical synapses, the facing membranes of the two cells have relatively large channels arranged to allow ions to ﬂow from one neuron directly into the other. As a consequence, the electrical current that is associated with neural activity in one neuron can ﬂow directly across the gap junction to affect the other neuron. Transmission at these synapses closely resembles action potential conduction along the axon. Electrical synapses therefore work with practically no time delay, in contrast to chemical synapses, where the delay is on the order of a millisecond—slow in terms of neurons. Because of the speed of their transmission, electrical synapses are frequently found in neural circuits that mediate escape behaviors in invertebrates. They are also found where many ﬁbers must be activated

Answer 38

1. Action potential travels down the axon to the axon terminal. 2. Voltage-gated calcium channels open and calcium ions (Ca2+) enter. 3. Synaptic vesicles fuse with membrane and release transmitter into the cleft. 4. Transmitters bind to postsynaptic receptors and cause an EPSP or IPSP. 5. EPSPs or IPSPs spread toward the postsynaptic axon hillock. 6. Transmitter is inactivated or removed–action is brief. 7. Transmitter may activate presynaptic autoreceptors, decreasing release

Answer 39

Agonist A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter. Examples carine and nicotine antagonist A molecule, usually a drug, that interferes with or prevents the action of a transmitter.

Answer 40

They are all exogenous ligands. Exogenous ligands–drugs and toxins from outside the body. curare An alkaloid neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle. molecules that interfere with or prevent the action of a transmitter—in the manner that curare or bungarotoxin blocks the action of ACh—are called antagonists. bungarotoxin A neurotoxin, isolated from the venom of the banded krait, that selectively blocks acetylcholine receptors. Antagonist A Nicotinic Acetylcholine (ACh) The two ligand-binding sites normally bind ACh molecules, but they also bind exogenous ligands like nicotine and other nicotinic drugs. Molecules such as nicotine that act like a transmitter at a receptor are called agonists of that transmitter.

Answer 41

The recognition of transmitter molecules by receptor molecules controls the opening of ion channels in two different ways. Ionotropic receptors Metabotropic receptors Ionotropic receptors open when bound by a transmitter (also called a ligand-gated ion channel). A receptor protein that includes an ion channel that is opened when the receptor is bound by an agonist. A directly control an ion channel. When bound by the transmitter, the ion channel opens and ions ﬂow across the membrane. Metabotropic receptors A receptor protein that does not contain an ion channel but may, when activated, use a G protein system to alter the functioning of the postsynaptic cell. Recognize the synaptic transmitter, but they do not directly control ion channels. Instead, they activate molecules known as G proteins.

Answer 42

``` A class of proteins that reside next to the intracellular portion of a receptor and that are activated when the receptor binds an appropriate ligand on the extracellular surface. Are proteins that bind the compounds guanosine diphosphate (GDP), guanosine triphosphate (GTP), and other guanine nucleotides. Sometimes the G protein itself acts to open ion channels, but in other cases the G protein activates another, internal chemical signal to affect ion channels.. ```

Answer 43

When a chemical transmitter such as ACh is released into the synaptic cleft, its postsynaptic action is not only prompt but usually very brief as well. This brevity ensures that the message is repeated faithfully. The prompt cessation of transmitter effects is achieved in one of two ways: Degradation. Transmitter can be rapidly broken down and thus inactivated by a special enzyme—a process known as degradation Reuptake. Alternatively, transmitter molecules may be rapidly cleared from the synaptic cleft by being taken up into the presynaptic terminal—a process known as reuptake.

Answer 44

1. Action potential travels down the axon to the axon terminal. 2. Depolarization of the presynaptic terminal leads to influx of Ca2+. 3. Ca2+ promotes exocytosis, the fusion of vesicles with the presynaptic membrane, which releases transmitter into the cleft. 4. The binding of transmitter to receptor molecules in the postsynaptic membrane opens channels, permitting ion flow and initiating an excitatory orinhibitory postsynaptic potential. 5. Excitatory or inhibitory postsynaptic potentials spread passively over dendrites and the cell body to the axon hillock. (EPSP or IPSP) 6. A. Enzyme present in the extracellular space breaks down excess transmitter. B. Reuptake of transmitter slows synaptic action and recycles transmitter for subsequent transmission. 7. Transmitter binds to autoreceptors in the presynaptic membrane.

Answer 45

neural chain A simple kind of neural circuit in which neurons are attached linearly, end-to-end. Circuits of Neurons: two kinds of processes 1. analog-like signals that vary in strength (such as graded potentials at synapses) 2. and digital-like, all-or-none signals (such as action potentials) that vary in frequency. Two other features that are common to many kinds of neural circuits: convergence and divergence divergence The phenomenon of neural connections in which one cell sends signals to many other cells. convergence The phenomenon of neural connections in which many cells send signals to a single cell.

Answer 46

* The substance exists in presynaptic axon terminals. * The presynaptic cell contains appropriate enzymes for synthesizing the substance. * The substance is released in signiﬁcant quantities when action potentials reach the terminals. * Speciﬁc receptors that recognize the released substance exist on the postsynaptic membrane. * Experimental application of the substance produces changes in postsynaptic cells. * Blocking release of the substance prevents presynaptic activity from affecting the postsynaptic cell.

Answer 47

Gamma-aminobutyric acid (GABA) (-Ve) (Na+) CATEGORY OF NEUROTRANSMITTER: amino acid RECEPTOR CATEGORY: ionotropic and metabotropic RECEPTOR SUBTYPES: GABAA (ionotropic) GABAB (metabotropic), GABAC (ionotropic) FUNCTION: GABAA receptors are inhibitory in many brain regions, reducing excitability and preventing seizure activity. GABAB receptors are also inhibitory, by a different mechanism. GABAC receptors produce sustained inhibition, and are found especially in the retina

Answer 48

Glutamate (+Ve) (Na+) CATEGORY OF NEUROTRANSMITTER: amino acid RECEPTOR CATEGORY: ionotropic and metabotropic glutamate receptors RECEPTOR SUBTYPES: AMPA, kainate, and NMDA receptors (ionotropic), mGluR’s (metabotropic glutamate receptors) FUNCTION: Glutamate is the most abundant of all neurotransmitters, and the most important excitatory transmitter. Glutamate receptors are crucial for excitatory signals, and NMDA receptors are especially implicated in learning and memory.

Answer 49

Acetylcholine (Ach) (+Ve) (Na+) CATEGORY OF NEUROTRANSMITTER: amine neurotransmitter, subtype: quaternary amines RECEPTOR CATEGORY: ionotropic and metabotropic RECEPTOR SUBTYPES: Muscarinic receptors (metabotropic), Nicotinic receptors (ionotropic) FUNCTION: Both are involved in cholinergic transmission in the cortex. OTHER FUNCTION: A neurotransmitter produced and released by parasympathetic system which uses acetylcholine, which to slow down activity and recover. Generally opposite effects then norepinephrine. Nicotinic receptors are crucial for muscle contraction.

Answer 50

Norepinephrine (NE) CATEGORY OF NEUROTRANSMITTER: amine neurotransmitter, subtype: monoamine RECEPTOR CATEGORY: metabotropic RECEPTOR SUBTYPES: α1, α2, β1, and β2 adrenoceptors (all metabotropic) FUNCTION: In the brain, NE transmission provides an alerting and arousing function. OTHER FUNCTION: Multiple effects in visceral organs; important part of sympathetic nervous system and “fight or flight” responses

Answer 51

Serotonin CATEGORY OF NEUROTRANSMITTER: amine neurotransmitter, subtype: monoamine subsubtype: Indoleamines RECEPTOR CATEGORY: metabotropic RECEPTOR SUBTYPES: 5-HT1 receptor family (5 members), 5-HT2 receptor family (3 members), 5-HT3 through 5-HT7 receptors, All but one subtype (5-HT3) metabotropic FUNCTION: May be involved in mood, sleep, and higher cognition. 5-HT3 receptors are particularly involved in nausea.

Answer 52

Dopamine (DA) CATEGORY OF NEUROTRANSMITTER: amine neurotransmitter, subtype: monoamine subsubtype: Catecholamine RECEPTOR CATEGORY: metabotropic RECEPTOR SUBTYPES: D1 through D5 receptors (all metabotropic), D6 and D7 probable FUNCTION: Found throughout the forebrain. Involved in complex behaviors, including motor function, reward, higher cognition.

Answer 53

neurotransmitters affect their targets by interacting with receptors, The transmitter molecule binds to the receptor, changing its shape to open an ion channel (as with fast, ionotropic receptors) or altering chemical reactions within the target cell (as with slow, metabotropic receptors) Receptors add an important layer of complexity in neural signaling, because any given transmitter may affect various kinds of receptors that differ from one another in structure

Answer 54

agonist A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, usually a neurotransmitter. antagonist A molecule, usually a drug, that interferes with or prevents the action of a transmitter.

Answer 55

ionotropic receptor A receptor protein that includes an ion channel that is opened when the receptor is bound by an agonist. metabotropic receptor A receptor protein that does not contain an ion channel but may, when activated, use a G protein system to open a nearby ion channel.

Answer 56

``` peptide neurotransmitter (neuropeptide) A neurotransmitter consisting of a short chain of amino acids. - Functions: reward sensation, control of feeding, sexual behaviors, and social functions. - Examples: Opiates, Endorphins, Oxytocin ```

Answer 57

Drug molecules don’t seek out particular receptor molecules. A drug molecule that has more than one kind of action in the body exhibits this ﬂexibility because it affects more than one kind of receptor molecule. binding afﬁnity Also called simply afﬁnity. The propensity of molecules of a drug (or other ligand) to bind to receptors. The degree of chemical attraction between a ligand and a receptor efﬁcacy Also called intrinsic activity. The extent to which a drug activates a response when it binds to a receptor. After binding, the propensity of a ligand to activate the receptor to which it is bound is termed its efﬁcacy (or intrinsic activity): agonists have high efﬁcacy and antagonists have low efﬁcacy. Partial agonists are drugs that produce a middling response regardless of dose. So, it is a combination of affinity and efﬁcacy that determines the overall action of a drug that determine where it binds and what it does

Answer 58

A drug with high afﬁnity for a particular type of receptor will selectively bind to that type of receptor even at low doses, and it will stay bound for a relatively long time. Lower-afﬁnity drugs will bind fewer receptor molecules. If a particular drug has a low affinity for a receptor, then it will quickly uncouple from the receptor. If a drug has a high affinity for a receptor then the two will stay together for a longer time, and a lower concentration of drug will be sufficient to bind half the receptors.

Answer 59

study dose response curves A formal plot of a drug’s effects (on the y-axis) versus the dose given (on the x-axis). When plotted as a graph, the relationship between drug doses and observed effects is called a dose-response curve (DRC). Careful analysis of DRCs reveals many aspects of drugs’ activity and is one of the main tools for understanding pharmacodynamics. DRCs reveal the effective dose range of a drug and allow comparison of the potencies and efﬁcacies of different drugs

Answer 60

down-regulation A compensatory reduction in receptor availability at the synapses of a neuron. The effects of an agonist drug augment the effects of the endogenous ligand, enhancing the effect on the postsynaptic cell. The postsynaptic cell may respond by down-regulating (decreasing) the number of receptors it places into the synapse, in order to become less sensitive and more like the pre-drug state. up-regulation A compensatory increase in receptor availability at the synapses of a neuron. a competitive antagonist instead blocks an endogenous substance from having its usual effect, to which the postsynaptic cell may respond by up-regulating (increasing) the number of its receptors in order to become more sensitive and compensate for the lessened effect of the endogenous ligand.

Answer 61

Once established, drug tolerance is believed to be a major cause of withdrawal symptoms, the unpleasant sensations that occur when one stops using a drug. withdrawal symptoms uncomfortable symptoms that arises when a person stops taking a drug that he or she has used frequently, especially at high doses. Example cocaine withdrawal symptoms: initial agitation and powerful drug cravings, followed by depression and an inability to enjoy anything else in life. Cerebral glucose metabolism is decreased for months after cocaine use is discontinued and may contribute to that depression.

Answer 62

``` INGESTION Tablets and capsules Syrups Infusions and teas Suppositories EXAMPLES AND MECHANISMS Many sorts of drugs and remedies; depends on absorption by the gut, which is somewhat slower than most other routes TYPICAL SPEED OF EFFECTS Slow to moderate ```

Answer 63

``` INHALATION Smoking Nasal absorption Inhaled powders and sprays EXAMPLES AND MECHANISMS Nicotine, cocaine, organic solvents such as airplane glue and gasoline, also used for a variety of prescription drugs and hormone treatments. Inhalation methods take advantage of the rich vascularization of the nose and lungs to convey drugs directly into the bloodstream. TYPICAL SPEED OF EFFECTS Moderate to fast ```

Answer 64

``` PERIPHERAL INJECTION Subcutaneous Intramuscular Intraperitoneal (abdominal) Intravenous EXAMPLES AND MECHANISMS Nicotine, cocaine, organic solvents such as airplane glue and gasoline, also used for a variety of prescription drugs and hormone treatments. Inhalation methods take advantage of the rich vascularization of the nose and lungs to convey drugs directly into the bloodstream. TYPICAL SPEED OF EFFECTS Moderate to fast ```

Answer 65

CENTRAL INJECTION Intracerebroventricular (into ventricular system) Intrathecal (into spinwal CSF) Intrathecal (into spinwal CSF) Intracerebral (directly into a brain region) EXAMPLES AND MECHANISMS Central methods involve injection directly into the CNS; used in order to circumvent the blood-brain barrier, to rule out peripheral effects, or to directly affect a discrete brain location. TYPICAL SPEED OF EFFECTS Fast to very fast

Answer 66

pharmacokinetics Collective name for all the factors that affect the movement of a drug into, through, and out of the body. bioavailable Referring to a substance, usually a drug, that is present in the body in a form that is able to interact with physiological mechanisms. (free to act on the target tissue and therefore not bound to other proteins or in the process of being metabolized or excreted). The duration of a drug effect is largely determined by the manner in which the drug is metabolized and excreted from the body—via the kidneys, liver, lungs, and other routes. In some cases, the metabolites of drugs are themselves active; this biotransformation of drugs can be a source of unwanted side effects. biotransformation The process in which enzymes convert a drug into a metabolite that is itself active, possibly in ways that are substantially different from the actions of the original substance. Internal Drug depots Some drugs may be stored in depots (collecting in fat or bone, for example), only to reemerge and have physiological effects after long periods of time. blood-brain barrier The mechanisms that make the movement of substances from blood vessels into brain cells more difﬁcult than exchanges in other body organs, thus affording the brain greater protection from exposure to some substances found in the blood.

Answer 67

Illustrates presynaptic processes that are targeted by CNS drugs, with examples of each kind of drug. The most common presynaptic drug effects can be grouped into three main categories: effects on transmitter production, (1) Inhibition of transmitter synthesis (2) Blockade of axonal transport (3) Interference with the storage of transmitters effects on transmitter release (4) Prevention of synaptic transmission (5) Alteration of synaptic transmitter release (6) Alteration of transmitter release through modulation of presynaptic activity effects on transmitter clearance. (7) Inactivation of transmitter reuptake (8) Blockade of transmitter degradation

Answer 68

Another powerful way for drugs to affect synaptic transmission is to modify the ability of postsynaptic neurons to respond to neurotransmitters. Effects on Transmitter Receptors (1) Blockade of receptors (2) Activation of receptors Effects on Cellular Processes (3) Regulation of the number of postsynaptic receptors (4) Modulation of intracellular signals

Answer 69

autoreceptor A receptor for a synaptic transmitter that is located in the presynaptic membrane, telling the axon terminal how much transmitter has been released. They monitor how much transmitter they have released; it’s a kind of feedback system. Drugs that alter autoreceptor signals provide a false feedback signal, prompting the presynaptic cell to release more or less transmitter. transporters Specialized receptors in the presynaptic membrane that recognize neurotransmitter molecules and return to the presynaptic neuron for reuse.

Answer 70

Antipsychotic - A class of drugs that alleviate schizophrenia. Antidepressants - A class of drugs that relieve the symptoms of depression. Anxiolytics - A class of substances that are used to combat anxiety. Benzodiazepine agonists - A class of antianxiety drugs that bind to sites on GABAA receptors. Nowadays, the safest and most speciﬁc anxiolytics are the benzodiazepine agonists. Endogenous opiates - peptides produced in the body that bind to opioid receptors and relieve pain–are also addictive. There are 3 types. Alcohol - The frontal lobes are the most affected by chronic alcohol use, yet some effects are reversible.Periodic overconsumption, or bingeing, may cause brain damage and reduces neurogenesis. Tetrahydrocannabinol (THC) - the beneﬁcial effects of marijuana: relieving pain, lowering blood pressure, combating nausea, lowering eye pressure in glaucoma, and so on. Nicotine - Increases heart rate, blood pressure, hydrochloric acid secretion, and bowel activity. A compound found in plants, including tobacco, that acts as an agonist on a large class of cholinergic receptors. Cocaine - A drug of abuse, derived from the coca plant, that acts by potentiating catecholamine stimulation. Amphetamine - A molecule that resembles the structure of the catecholamine transmitters and enhances their activity. Over the short term, amphetamine causes increased vigor and stamina, wakefulness, decreased appetite, and feelings of euphoria. Hallucinogens - A class of drugs that alter sensory perception and produce peculiar experiences. Anxiolytics - A class of substances that are used to combat anxiety. Depressants - drugs that depress or reduce nervous system activity. Stimulants- Stimulants are excitatory. They therefore have an alerting, activating effect.

Answer 71

antipsychotics - neuroleptics - typical neuroleptics - atypical neuroleptics Neuroleptics are a class of antipsychotic drugs, traditionally dopamine receptor blockers. Typical neuroleptics are selective dopamine D2 antagonists. Atypical neuroleptics block serotonin receptors and may reduce negative symptoms of schizophrenia.receptors

Answer 72

They are all antidepressants, which is a class of drugs that relieve the symptoms of depression.Increasing synaptic monoamine availability appears to be a key activity of all antidepressants. ``` monoamine oxidase (MAO) MAOs break down monoamine neurotransmitters at axon terminals, thereby reducing transmitter activity. By blocking this process, MAO inhibitors allow monoamine neurotransmitters to accumulate at synapses, with an associated improvement in mood. ``` tricyclic antidepressants tricyclics block the reuptake of neurotransmitters into presynaptic axon terminals. selective serotonin reuptake inhibitor (SSRI) A drug that blocks the reuptake of transmitter at serotonergic synapses. these drugs alleviate depression by selectively allowing serotonin to accumulate in synapses.

Answer 73

``` anxiolytics A class of substances that are used to combat anxiety. Sometimes also called tranquilizers, anxiolytics belong to the general category of depressants: A class of drugs that act to reduce neural activity. ``` Barbiturate (“downers”) A powerful sedative anxiolytic derived from barbituric acid, with dangerous addiction and overdose potential. were originally developed to reduce anxiety, promote sleep, and prevent epileptic seizures. They are still used for those purposes but are also addictive and easily overdosed, often fatally. benzodiazepine agonists A class of antianxiety drugs that bind to speciﬁc sites on GABAA receptors and enhance the activity of GABA. Because GABAA receptors are inhibitory, benzodiazepines help GABA to produce larger inhibitory postsynaptic potentials than would be caused by GABA alone. This has the end result of reducing the excitability of neurons. Benzodiazepine agonists act on GABAA receptors and enhance the inhibitory effects of GABA. Nowadays, the safest and most speciﬁc anxiolytics are the benzodiazepine agonists, and they are among the most heavily prescribed drugs.

Answer 74

GABAA receptors have several different binding sites—some that facilitate and some that inhibit the effect of GABA therefore, many different drugs can interact with this receptor complex. For example, benzodiazepines bind to a unique modulatory site on the receptor complex that is distant from where GABA itself binds. The benzodiazepine-binding site is thus an orphan receptor—a receptor for which an endogenous ligand has not been conclusively identiﬁed—and the hunt for its endogenous ligand has been intense. Allopregnanolone, a steroid derived from the hormone progesterone, acts on yet another site on the GABAA receptor. Allopregnanolone is elevated during stress and has a calming effect. Alcohol ingestion also increases brain concentrations of allopregnanolone, so this steroid may mediate some of the calming inﬂuence of alcohol. Several other progesterone-like neurosteroids (steroids produced in the brain) may act on GABAA receptors to produce anxiolytic, analgesic, and anticonvulsant effects.

Answer 75

Alcohol up-regulates (increases) the number of receptors for GABA. depressants: drugs that depress or reduce nervous system activity The psychoactive effect of alcohol in the nervous system is biphasic: an initial stimulant phase is followed by a more prolonged depressant phase. Alcohol activates the GABAA receptor–coupled chloride channel, thereby increasing postsynaptic inhibition. This action contributes to social disinhibition, as well as the impairment of motor coordination that occurs after a few drinks. Alcohol also affects other transmitters. For example, low doses of alcohol stimulate dopamine pathways, and the resulting increase in dopamine may be related to the slightly euphoric feelings that many people experience when having a drink. Chronic abuse of alcohol damages neurons. Cells of the superior frontal cortex, Purkinje cells of the cerebellum, and hippocampal pyramidal cells show particularly prominent pathological changes. \ The frontal lobes—especially the superior frontal association cortex—are the brain areas that are most affected by chronic alcohol use. Fetal Alcohol Spectrum Disorder - A disorder, including intellectual disability and characteristic facial anomalies, that affects children exposed to too much alcohol (through maternal ingestion) during fetal development. bingeing—may cause brain damage. After only 4 days of bingeing on alcohol, rats exhibit neural degeneration in several areas of the brain. Damage is especially evident in the olfactory bulbs and in limbic structures connected with the hippocampus, and it is associated with impairments of cognitive ability. Alcohol bingeing also signiﬁcantly reduces the rate of neurogenesis—the formation of new neurons—in the adult hippocampus.

Answer 76

``` WHAT DO OPIATES DO? Opiates are anxiolytics. Anxiolytics are a class of substances that are used to combat anxiety. Anxiolytics belong to the general category of depressants: drugs that depress or reduce nervous system activity. ``` Opiates anxiety-ﬁghting properties come at the cost of intoxication, addiction potential, and neuropsychological impairment with long-term abuse, so they are not suitable for therapeutic use. HOW AND WHERE TO THEY WORK The opiates morphine, heroin, and codeine bind to speciﬁc receptors—opioid receptors. Opioid receptors are found in the limbic and hypothalamic areas of the brain, and they are particularly rich in the locus coeruleus and in the periaqueductal gray—the gray matter that surrounds the aqueduct in the brainstem. Endogenous opiates–peptides produced in the body that bind to opioid receptors and relieve pain–are also addictive. The three kinds are enkephalins, endorphins, and dynorphins. EXAMPLES OF OPIATES - Morphine - Heroin - Codeine - endogenous opioids - enkephalins - endorphins - dynorphins

Answer 77

What is the active ingredient in marijuana? Marijuana is derived from Cannabis sativa–its active ingredient is Δ9-tetrahydrocannabinol (THC) Where does this compound work in the brain? As was the case with opiates and benzodiazepines, researchers found that the brain contains cannabinoid receptors that mediate the effects of compounds like THC. Cannabinoid receptors are concentrated in the substantia nigra, the hippocampus, the cerebellar cortex, and the cerebral cortex; other regions, such as the brainstem, show few of these receptors.

Answer 78

How does it influence behavior? The subjective experience of marijuana use is quite variable among individuals: relaxation and mood alteration are the most frequent effects, but stimulation, hallucination, and paranoia also occur in some cases. Sustained use of marijuana can cause addiction and accelerated cognitive decline, and frequent smoking of marijuana, as with tobacco, can contribute to respiratory diseases. Adolescents who use marijuana are more likely to develop psychosis in adulthood * Altered memory formation * Appetite stimulation * Reduced pain sensitivity * Protection from excitotoxic brain damage

Answer 79

What neurotransmitter has been identified as endogenous neurotransmitter for cannabinoid receptors? endocannabinoid An endogenous ligand of cannabinoid receptors; thus, an analog of marijuana that is produced by the brain. The most studied endocannabinoid is anandamide, which has diverse functional effects, including alterations of memory formation, appetite stimulation, reduced sensitivity to pain, and protection from excitotoxic brain damage. Anandamide - An endogenous substance that binds the cannabinoid receptor molecule.

Answer 80

Stimulants are excitatory. They therefore have an alerting, activating effect. Many naturally occurring and artiﬁcial stimulants are widely used. Nicotine BEHAVIOR EFFECTS Nicotine in-creases heart rate, blood pressure, secretion of hydrochloric acid in the stomach, and intestinal activity. In the short run, these effects make tobacco use pleasurable. Smoking and nicotine exposure in adolescence has a lasting impact on attention and cognitive development, NEUROTRANSMISSION Acts as an agonist on a large class of cholinergic receptors. Acts as an agonist on nicotinic ACh receptors in the ventral tegmental area

Answer 81

Stimulants are excitatory. They therefore have an alerting, activating effect. Many naturally occurring and artiﬁcial stimulants are widely used. Cocaine BEHAVIOR EFFECTS either chewed or brewed as a tea—to increase endurance, alleviate hunger, and promote a sense of well-being. This use of coca leaves does not seem to cause problems. Heavy cocaine use raises the risk of serious side effects like stroke, psychosis, loss of gray matter, and severe mood disturbances. chronic cocaine use can provoke symptoms similar to psychosis. NEUROTRANSMISSION Like other psychostimulants, cocaine acts by blocking monoamine transporters, especially those for dopamine, slowing reuptake of the transmitters and therefore boosting their effects. Increases catecholamine stimulation blocks monoamine transporters

Answer 82

Stimulants are excitatory. They therefore have an alerting, activating effect. Many naturally occurring and artiﬁcial stimulants are widely used. Amphetamine and the even more potent methamphetamine (“meth” or “speed”) BEHAVIOR EFFECTS Over the short term, amphetamine causes increased vigor and stamina, wakefulness, decreased appetite, and feelings of euphoria. Addiction and tolerance to amphetamine and methamphetamine develops rapidly, requiring ever larger doses leading to sleeplessness, severe weight loss, and general deterioration of mental and physical condition. Prolonged use of amphetamine may lead to symptoms that closely resemble those of paranoid schizophrenia: compulsive, agitated behavior and irrational suspicious-ness. NEUROTRANSMISSION cause the release of these transmitters from presynaptic terminals even in the absence of action potentials, and when action potentials do reach the axon terminals, amphetamine also potentiates the subsequent release of transmitter. Once transmitter has been released, amphetamine further enhances activity in two ways: (1) by blocking the reuptake of catecholamines into the presynaptic terminal and (2) by providing an alternative target for the enzyme (monoamine oxidase) that normally inactivates them.

Answer 83

``` hallucinogens A class of drugs that alter sensory perception and produce peculiar experiences. ``` BEHAVIOR EFFECTS alter or distort existing perceptions The effects are predominantly visual. Users often see fantastic images with intense colors, and they are often aware that these strangely altered perceptions are not real events. NEUROTRANSMISSION Hallucinogenic agents are diverse in their neural actions. But many act as serotonin receptor agonists or partial agonists.

Answer 84

LSD lysergic acid diethylamide (acid) BEHAVIOR EFFECTS . they alter or distort existing perceptions The effects are predominantly visual. Users often see fantastic images with intense colors, and they are often aware that these strangely altered perceptions are not real events. Flash Backs NEUROTRANSMISSION Act as serotonin receptor agonists or partial agonists. act on serotonin receptors, probably evoking visual phenomena by activating 5HT2A receptors in visual cortex.

Answer 85

MDMA Also called Ecstasy BEHAVIOR EFFECTS positive emotions, empathy, euphoria, a sense of wellbeing, and colorful visual phenomena NEUROTRANSMISSION Major actions of MDMA in the brain include an increase in the release of serotonin, stimulation of 5HT2A receptors, and changes in the levels of dopamine and certain hormones, such as prolactin. Several possible psychiatric and cognitive consequences of chronic MDMA use have been described, including memory disturbances and depression. However, shorter-term MDMA treatment is also being studied in clinical settings, as a possible therapy for treatment-resistant posttraumatic stress disorder.

Answer 86

THE PHYSICAL DEPENDENCE MODEL sometimes called the withdrawal avoidance model, argues that people keep taking drugs in order to avoid unpleasant withdrawal symptoms. The speciﬁc withdrawal symptoms depend on the drug, but they are often the opposite of the effects produced by the drug itself. The model does a good job of explaining why addicts will go to great lengths to obtain their addicted drug, but it has an important shortcoming: it can’t explain how the addiction gets established in the ﬁrst place. Why do some people, but not all, start to abuse a drug before physical dependence (tolerance) has ever developed? And how is it that some people can become addicted to some drugs even in the absence of clear physical withdrawal symptoms

Answer 87

THE POSITIVE REWARD MODEL people get started with drug abuse, and become addicted, because the abused drug provides powerful reinforcement. Many addictive drugs cause the release of dopamine in the nucleus accumbens, just like more-conventional rewards such as food, sex, or winning money. dopamine released from axons originating from the ventral tegmental area (VTA), part of the mesolimbocortical dopaminergic pathway, has been widely implicated in the perception of reward. Then the addictive power of drugs may come from their artiﬁcial stimulation of this pathway. When the drug hijacks this system, providing unnaturally powerful reinforcement, the user learns to associate the drug-taking behavior with that pleasure and begins seeking out drugs more and more until life’s other pleasures fade into the background.

Answer 88

THE MORAL MODEL simply blame the substance abuser for a failure of moral character or a lack of self-control. However, the “Just Say No” campaign championed by former U.S. First Lady Nancy Reagan in the 1980s did not appear to signiﬁcantly reduce drug abuse.

Answer 89

THE DISEASE MODEL According to the disease model, the person who abuses drugs requires medical treatment rather than moral exhortation or punishment. However, the term disease is usually reserved for a state in which we can identify an abnormal physical or biochemical condition that initiates the problem. No abnormal physical or biochemical condition has been found in the case of drug addiction, and the disease model is mute with respect to initial development of addiction, although mounting evidence suggests that some people are genetically more susceptible to addiction than others. Nevertheless, this model continues to appeal to many, and an intensive effort is under way to identify the physiological “switch” that establishes addiction after exposure to a drug.

Answer 90

Many addictive drugs cause the release of dopamine in the nucleus accumbens, just like more-conventional rewards such as food, sex, or winning money. interestingly, dopamine release is also linked to pathological gambling. As we mentioned previously, dopamine released from axons originating from the ventral tegmental area (VTA), part of the mesolimbocortical dopaminergic pathway, has been widely implicated in the perception of reward. Then the addictive power of drugs may come from their artiﬁcial stimulation of this pathway. When the drug hijacks this system, providing unnaturally powerful reinforcement, the user learns to associate the drug-taking behavior with that pleasure and begins seeking out drugs more and more until life’s other pleasures fade into the background. These higher-order cognitive aspects of addiction depend on glutamatergic inputs from the prefrontal cortex, integrating aspects of memory, attention, and self-control to regulate the functioning of the dopamine reward system. Cocaine produces long-lasting changes in dopaminergic circuitry, as well as other neurotransmitter systems in the nucleus accumbens, which seems to further augment the pleasure associated with drugs while decreasing the pleasure experienced from other behaviors. The drug’s “pathological” reinforcement of associated behaviors leads to exclusive, compulsive drug seeking. If natural activities like conversation, eating, and even sex no longer provide appreciable pleasure, addicts may seek drugs as the only source of pleasure available to them.

Answer 91

The individual and environmental factors that account for this differential susceptibility are the subject of active investigation; they fall into several general categories: - Biological factors - Sex is a signiﬁcant variable; males are more likely to abuse drugs than are females. There is also evidence for genetic predisposition. - Family situation - Family breakup, a poor relationship with parents, or the presence of an antisocial sibling are associated with drug abuse. - Personal characteristics - Certain traits, such as aggressiveness and poor emotional control, are especially associated with drug abuse. Strong educational goals and maturity are associated with lower likelihood of drug abuse. Environmental factors - A high prevalence of drug use in the community, and especially in the peer group, predisposes an individual toward drug abuse.

Answer 92

Any circumstance that upsets homeostatic balance. Examples include exposure to extreme cold or heat or an array of threatening psychological states. Natural response to threat. Can be positive or negative, short term or chronic.

Answer 93

Less receptive binding to dopamine when stressed which limit happiness potential, Stress can unravel chromosomes, block artery’s, cause ulcers, decrece immune system functioning, cause weight gain (particularly in the abdomen, shorten telomeres, shrink the hippocampus, decrece memory, limit branching of neurons and kill brain cells.

Answer 94

Hormones that are the back bones of stress response: adrenalin (epinaphernan), gucalcorticoides.

Answer 95

Survival necessity. It increases functioning of things we might need in an emergency.

Answer 96

Stress in the hierarchy in baboons: higher in the hierarchy the lower the stress, and it impacts the health of the low rankers. British government study.

Answer 97

shrink the hippocampus, decreesed memory, limit branching of neurons and kill brain cells.

Answer 98

Less receptive binding to dopamine when stressed which limit happiness potential

Answer 99

The babies born during the time have a higher staticall average of health problems, reaction to stress, and psychological problems

Answer 100

The ones who died where the most aggressive. The lack of aggression in the troop lowered the amount of socially stressful situations and thus the groups stress as a hole went down, and stayed down as they now have a culture that is relatively peaceful and so new conform.

Answer 101

applying a hyperpolarizing stimulus to the membrane produces an immediate response that passively follows the stimulus pulse (FIGURE 3.5B; the distortions at the beginning and end of the neuron’s response are caused by the membrane’s ability to store electricity, known as capacitance). The greater the stimulus, the greater the response; so the neuron’s change in potential is called a graded response.