Chapter 3- Synapses

Question 1

Automatic muscular responses to stimuli

Answer 1

Reflexes

Question 2

A circuit from sensory neuron to muscle response

Answer 2

Reflex arc

For example: in a leg flexion reflex, a sensory neuron excites a second neuron, which in turn excites a motor neuron, which excites a muscle.

Question 3

A cumulative effect of repeated stimuli within a brief time

Answer 3

Temporal summation

Sherrington found that a light pinch of the dogs foot did not evoke a reflex, but a few rapidly repeated pinches did. Surmised that a single pinch did not reach the threshold of excitation for the next neuron.

Question 4

Neuron that delivers transmission to another neuron

Answer 4

Presynaptic neuron

Question 5

Neuron that receives transmission from another neuron

Answer 5

Postsynaptic neuron

Question 6

Graded depolarization

Answer 6

Excitatory postsynaptic potential EPSP

Unlike action potentials, which are always depolarizations, graded potentials maybe either depolarizations (excitatory) or hyperpolarizations (inhibitory). A graded depolarization is known as an excitatory postsynaptic potential. Results from a flow of sodium ions into the neuron. If an EPSP does not cause the cell to reach its threshold, the depolarization decays quickly

Eccles I found that when he stimulated an axon twice, if the delay between EPSPs was short enough, the second EPSP added to what was left of the first one, producing temporal summation.

Question 7

Combination of effects of activity from two or more synapses onto a single neuron

Answer 7

Spatial summation

Sherrington began with a pinch too weak to elicit a reflex. He then pinched two points at once. Although neither pension loan produced a reflex, together they did. Concluded that pinching two points activated separate sensory neurons, whose axons converged onto a neuron in the spinal cord. Excitation from either sensory axon excited that spinal neuron on their own, but not enough to reach the threshold. A combination of excitations exceeded the threshold and produced an action potential.

Question 8

Temporary hyperpolarization of a membrane

Answer 8

Inhibitory postsynaptic potential IPSP

When Sherrington vigourously pinched a dogs foot, the flexor muscles of that leg contracted, and so did the extensor muscles of the other three legs. Also, the dog relaxed the extensor muscles of the stimulated leg and the flexor muscles of the other lakes. Sherrington’s explanation assumed certain connections in the spinal cord: a pinch on the foot sends a message along a sensory neuron to an interneuron in the spinal cord, which in turn excites the motor neurons connected to the flexor muscles of that leg. Surmised that the enter neuron also sends a message to block activity of motor neurons to the extensor muscles in the same leg and the flexor muscles of the three other legs.

At the synapse ease, input from an axon hyperpolarizes the postsynaptic cell. That is, it increases the negative charge within the cell, moving it further from the threshold and decreasing the probability of an action potential. This is called an inhibitory postsynaptic potential, or IPSP. Occurs when synaptic input selectively opens the gates for potassium ions to leave the cell carrying a positive charge with them or for chloride ions to enter the cell carrying a negative charge

Question 9

A periodic production of action potentials even without synaptic input

Answer 9

Spontaneous firing rate

When neurons have a spontaneous firing rate, the EPSPs increase the frequency of action potential’s above the spontaneous rate, whereas IPSPs decrease it

Question 10

A specialized gap as a point of communication between two neurons

Answer 10

Synapse

Question 11

How did Sherrington measure or study reflexes?

Answer 11

Sherrington strapped a dog into a harness above the ground and pinched one of the dogs feet. After a fraction of a second, the dog flexed or raised the pinched leg and extended the other legs. Sherrington found the same reflexive movements after he made a cut that disconnected the spinal cord from the brain

Question 12

What are three properties Sherrington observed of reflexes suggesting special processes at the junctions between neurons?

Answer 12

1. Reflexes are slower than conduction along an axon
2. Several weak stimuli presented at slightly different times or locations produce a stronger reflex then a single stimulus does
3. When one set of muscles becomes excited, a different set becomes relaxed

Question 13

What did Sherrington find when he measured the total distance that the impulse travels from skin receptor to spinal cord to muscle and calculated the speed at which the impulse must travel to produce the response?

Answer 13

He found that the speed of conjunction through the reflex arc buried but was never more than about 15 m/s. In contrast, previous research had measured action potential velocities along sensory or motor nerves at about 40 m/s. Concluded that some process was slowing conduction through the reflex, and he inferred that the delay must occur where one neuron communicates with another. This established the existence of synapses.

Question 14

What is the difference between temporal summation and spatial summation?

Answer 14

Temporal summation is the combination effects of quickly repeated stimulation at a single synapse. Spatial summation is the combined effects of several nearly simultaneous stimulations at several synapses onto one neuron

Question 15

What evidence lead Sherrington to conclude that transmission at a synapse is different from transmission along an axon?

Answer 15

Sherrington found that the velocity of conduction through a reflex arc was significantly slower than the velocity of an action potential along an axon. Therefore, some delay must occur at the junction between one neuron and the next.

Question 16

What was Sherrington as evidence for inhibition in the nervous system?

Answer 16

Sherrington found that a reflex that stimulates a flexor muscle prevents contraction of the extensor muscles of the same limb. He therefore inferred that an axon sending an excitatory message for the flexor muscle also sent an inhibitory message for the extensor muscle

Question 17

What ion gates in the membrane open during an EPSP? What the gates open during an IPSP?

Answer 17

During an EPSP, sodium gates open. During an IPSP, potassium or chloride gates open

Question 18

Can an inhibitory message flow along an axon?

Answer 18

No. Only action potential’s propagate along an axon. Inhibitory messages – IPSPs – decay over time and distance

Question 19

Describe the contributions of TR Elliot and O Loewi to the question of whether most synaptic transmission is electrically or chemically mediated

Answer 19

Sherrington originally inferred that synaptic transmission must be electrical.

In 1905, TR Elliott reported that applying the hormone adrenaline directly to the surface of the heart, the stomach, and the pupils produces the same affects as those of the sympathetic nervous system. He therefore suggested that the sympathetic nerves stimulate muscles by releasing adrenaline or a similar chemical. Sherrington’s prestige, however, was so great that his findings continued to be ignored.

O Loewi came up with an idea in the middle of the night and performed an experiment. He repeatedly stimulated a frogs Vegus nerve, thereby decreasing the heart rate. He then collected fluid from that heart, transferred it to a second frogs heart, and found that the second heart also decreased it’s rate of beating. He then stimulated the Excelerator nerve to the first frogs heart, increasing the heart rate. When he collected fluid from that hard and transferred it to the second from his heart, it’s heart rate increased. Therefore, stimulating one nerve released something that inhibited heart rate, and stimulating a different nerve release to something that increased heart rate. He then concluded that nerves send messages by releasing chemicals

Question 20

What was Loewi’s evidence that neurotransmission depends on the release of chemicals?

Answer 20

When he stimulated a nerve that increased or decreased a frogs heart rate, he could withdraw some fluid from the area around the heart, transfer it to another frogs heart, and thereby increase or decrease its rate also.

Question 21

What are six major events at a synapse?

Answer 21

1. The neuron synthesizes chemicals that serve as neurotransmitters. It synthesizes the smaller neurotransmitters in the axon terminals and neuropeptides in the cell body.
2. Action potentials travel down the axon. At the presynaptic terminal, an action potential enables calcium to enter the cell. Calcium releases neurotransmitters from the terminals and into the synaptic cleft, the space between the presynaptic and postsynaptic neurons
3. The released molecules diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neuron
4. The neurotransmitter molecules separate from their receptors
5. The neurotransmitter molecules maybe taking back into the presynaptic neuron for recycling or they may diffuse away
6. Some postsynaptic cells send reverse messages to control the for the release of neurotransmitter by presynaptic cells

Question 22

List the six major types of neurotransmitters

Answer 22

Amino acid’s, monoamine’s, acetylcholine, neuropeptides, purines, gases

Question 23

Chemicals released by neurons that affect other neurons

Answer 23

Neurotransmitters

Question 24

Acids containing an amine group NH2

Answer 24

Amino acids

Question 25

A chemical similar to an amino acid, except that it includes an N(CH3)3 group instead of an NH2 group

Answer 25

Acetylcholine

Question 26

Chemicals formed by a change in certain amino acids

Answer 26

Monoamines

Question 27

Chains of amino acids

Answer 27

Neuropeptides

Question 28

A category of chemicals including adenosine and several of its derivatives

Answer 28

Purines

Question 29

One of the categories of neurotransmitters, including nitric oxide and possibly others

Answer 29

Gases

Question 30

A gas released by many small local neurons (NO)

Answer 30

Nitric oxide

Question 31

What does a highly active brain area due to increase its blood supply?

Answer 31

In a highly active brain area, many stimulated neurons release nitric oxide, which dilates the blood vessels in the area and thereby increases blood flow to the area

Question 32

Describe the role of diet in the synthesis of neurotransmitters

Answer 32

Neurons synthesize nearly all transmitters from amino acids, which the body obtains from proteins in the diet. Acetylcholine is synthesized from choline, which is abundant in milk, eggs, and peanuts. The amino acids phenylalanine and tyro scene, present in proteins, are precursors of dopamine, norepinephrine, and epinephrin The amino acid tryptophan, the precursor to serotonin, crosses the blood-brain barrier buy a special transport system that shares with other large amino acids. The amount of tryptophan in the diet controls the amount of serotonin in the brain, so your serotonin levels rise after you eat foods rich are in tryptophan, such as soy, and fall after something low and tryptophan such as maize or American corn. However, tryptophan has to compete with other, more abundant large amino acids, such as phenylalanine, that share the same transport system. One way to increase tryptophan entry to the brain is to decrease consumption of phenylalanine. Another is to eat carbohydrates which increase the release of the hormone insulin, which takes several competing amino acids out of the bloodstream and into the body, thus decreasing the competition against tryptophan.

Question 33

Compounds that contain a catechol and an amine group

Answer 33

Catecholamines Epinephrine, norepinephrine, and dopamine are compounds known as catecholamines because they contain a catechol group and an amine group

Question 34

Name the three catecholamine neurotransmitters

Answer 34

Epinephrine, norepinephrine, and dopamine

Question 35

Tiny nearly spherical packets filled with neurotransmitter molecules

Answer 35

Vesicles Most neurotransmitters are synthesized in the presynaptic terminal, near the point of release. The presynaptic terminal stores high concentrations of neurotransmitter molecules in vesicles. Nitric oxide is an exception to this rule.

Question 36

Enzyme that converts catecholamines and serotonin into synaptically inactive forms

Answer 36

Monoamine oxidase MAO

Question 37

Describe the processes of transport, release, and diffusion of neurotransmitters

Answer 37

At the end of an axon, the action potential itself does not release the neurotransmitter. Rather, the Depol arise Asian opens voltage-independent calcium gates in the presynaptic terminal. After calcium enters the presynaptic terminal, it causes exocytosis – release of neurotransmitter in bursts from the presynaptic neuron into the synaptic cleft of that separates one neuron from another. After its release from the presynaptic cell, the neurotransmitter diffuses across the synaptic left to the postsynaptic membrane, where it attaches to a receptor. Although the brain as a whole uses many neurotransmitters, no single neuron releases them all. Although a neuron releases only a limited number of neurotransmitters, it may receive and respond to many neurotransmitters at different synapses.

Question 38

When the action potential reaches the presynaptic terminal, which ion must enter the presynaptic terminal to evoke release of the neurotransmitter?

Answer 38

Calcium

Question 39

Synaptic effects that depend on the rapid opening of some kind of gate in the membrane.

Answer 39

Ionotropic effects Begin quickly, sometimes within less than a millisecond after the transmitter attaches. The effects decay with a half-life of about 5 ms. They are well-suited to conveying visual information, auditory information, and anything else that needs to be updated as quickly as possible. Most of the brains excitatory ionotropic synapses use the neurotransmitter glutamate. Glutamate is the most abundant neurotransmitter in the nervous system. Most of the inhibitory ionotropic synapses use the neurotransmitter GABA or gamma-amino-butyric acid which opens chloride gates, enabling chloride ion's, with their negative charge, to cross the membrane into the cell more rapidly than usual. Glycine is another common inhibitory transmitter, found mostly in the spinal cord. Acetylcholine is excitatory in most cases.

Question 40

Ion channel that opens temporarily when a neurotransmitter binds to it

Answer 40

Transmitter-gated channel or ligand-gated channels A ligand is a chemical that binds to another chemical

Question 41

A sequence of metabolic reactions that produce slow and long-lasting effects at a synapse

Answer 41

Matabotropic effects Emerge 30 ms or more after the release of the neurotransmitter. Typically lasts up to a few seconds, but sometimes longer. Use many neurotransmitters, including dopamine, norepinephrine, and serotonin. Sometimes glutamate and GABA too. Better suited for more enduring effects such as taste, smell, and pain where the exact timing isn't important anyway. Also important for many aspects of arousal, attention, pleasure, and emotion.

Question 42

A protein coupled to guanosine triphosphate GDP, an energy-storing molecule

Answer 42

G protein When a neurotransmitter attaches to a Matab tropic receptor, it bends the receptor protein that goes through the membrane of the cell. The other side of that receptor is attached to a G protein. Bending the receptor protein detaches that G protein, which is then free to take its energy elsewhere in the cell. The result of the G protein is increased concentration of a second messenger, such as cyclic adenosine monophosphate inside the cell. Just as the first messenger, the neurotransmitter, carries information to the postsynaptic cell, the second messenger communicates too many areas within the cell. It may open or close ion channels in the membrane or activate a portion of a chromosome.

Question 43

A chemical that, when activated by a neurotransmitter, initiates communication to many areas within the neuron

Answer 43

Second messenger

Question 44

Researchers often refer to neuropeptides as ________, because they have several properties that set them apart from other transmitters. What are five things that make neuropeptides different from other neurotransmitters?

Answer 44

Neuromodulators 1. Whereas the neuron synthesizes most other neurotransmitters in the presynaptic terminal, it's synthesizes neuropeptides in the cell body and then slowly transports them to other parts of the cell. 2. Whereas other neurotransmitters are released at the axon terminal, neuropeptides are released mainly by dendrites, and also by the cell body and the sides of the axon. 3. Whereas a single action potential can release other neurotransmitters, neuropeptide release requires repeated stimulation. However, after a few dendrites release a neuropeptide, the released chemical primes other nearby dendrites to release the same neuropeptide also, including dendrites of other cells. 4. Unlike other transmitters that are released immediately adjacent to their receptors, neuropeptides diffuse widely, affecting many neurons in the region of the brain. In that way they resemble hormones. 5. Whereas the duration of effects other neurotransmitters is generally less than a second to a few seconds, neuropeptides effects are long-lasting, in the range of 20 minutes or more. Neuropeptides are important for hunger, thirst, intense pain, and other long-term changes in behaviour and experience.

Question 45

A kind of neuron that releases huge amounts of GABA all at once, producing widespread inhibition

Answer 45

Neurogliaform cell An exception to the rule that a neuron delivers neuropeptides that diffuse to receptors throughout a wide area, but it delivers other transmitters only in small amounts directly adjacent to their receptors. The neuroglia form cell releases huge amounts of GABA all at once, forming a "cloud" that spreads to a large number of neurons in the area, producing widespread inhibition

Question 46

How do ionotropic and Matabotropic synapses differ in speed and duration of effects?

Answer 46

Ionotropic synapses act more quickly and more briefly

Question 47

What are second messengers, and which type of synapse relies on them?

Answer 47

At metabotropic synapses, the neurotransmitter attaches to its receptor and thereby releases a chemical, the second messenger, within the postsynaptic cell, which alters metabolism or gene expression of the postsynaptic cell

Question 48

How are neuropeptides special compared to other transmitters?

Answer 48

Neuropeptides are released only after prolonged stimulation, but when they are released, they are released in large amounts by all parts of the neuron, not just the axon terminal. Neuropeptides diffuse widely, producing long-lasting effects on many neurons

Question 49

Chemical that is secreted by cells in one part of the body and conveyed by the blood to influence other cells

Answer 49

Hormone

Question 50

Hormone-producing glands

Answer 50

Endocrine glands

Question 51

Hormones composed of long chains of amino acids

Answer 51

Protein hormones

Question 52

Hormones composed of short chains of amino acids

Answer 52

Peptide hormones

Question 53

An endocrine gland attached to the base of the hypothalamus

Answer 53

Pituitary gland

Question 54

Portion of the pituitary gland, composed of glandular tissue

Answer 54

Anterior pituitary Synthesizes six hormones, although the hypothalamus controls their release. The hypothalamus secretes releasing hormones, which flow through the blood to the anterior pituitary. There they stimulate or inhibit the release of the 6 hormones

Question 55

Portion of the pituitary gland, which releases hormones synthesized by the hypothalamus

Answer 55

Posterior pituitary The posterior pituitary is composed of neural tissue, and can be considered an extension of the hypothalamus. Neurons in the hypothalamus synthesize the hormones oxytocin and vasopressin which migrate down axons to the posterior pituitary. Later, the posterior pituitary releases these hormones into the blood

Question 56

Hormone released by posterior pituitary; important for sexual and parental behaviours

Answer 56

Oxytocin

Question 57

Hormone released by posterior pituitary; raises blood pressure and enables kidneys to conserve water

Answer 57

Vasopressin or antidiuretic hormone

Question 58

Hormone released by the hypothalamus that flows through the blood to the anterior pituitary

Answer 58

Releasing hormone

Question 59

What are the six hormones synthesized by the anterior pituitary and controlled by the hypothalamus?

Answer 59

Adrenocorticotropic hormone ACTH, thyroid-stimulating hormone TSH, prolactin, somatotropin or growth hormone GH, gonadotropins (follicle-stimulating hormone FSH, and luteinizing hormone LH)

Question 60

Which part of the pituitary – anterior or posterior – is neural tissue, similar to the hypothalamus? Which part is glandular tissue and produces hormones that control the secretions by other endocrine organs?

Answer 60

The posterior pituitary is neural tissue, like the hypothalamus. The anterior pituitary is glandular tissue and produces hormones that control several other endocrine organs.

Question 61

In what way is a neuropeptide intermediate between other neurotransmitters and hormones?

Answer 61

Most neurotransmitters are released in small amounts close to their receptors. Neuropeptides are released into a brain area in larger amounts or not at all. When released, they diffuse more widely. Hormones are released into the blood for diffuse delivery throughout the body.

Question 62

Describe the similarities and differences between neurotransmitters and hormones.

Answer 62

Differences: a neurotransmitter is like a telephone signal – it conveys a message from the sender to the intended receiver. Hormones function more like a radio station – they convey a message to any receiver tuned in to the right station. Similarities: neuropeptides are similar to hormones because they both diffuse widely, affecting other parts of the body, except that neuropeptides diffuse only within the brain, and the blood doesn't carry them to other parts of the body like hormones.

Question 63

After acetylcholine activates a receptor, it is broken down by the enzyme ___________ into two fragments: acetate and choline. The choline diffuses back to the presynaptic neuron, which takes it up and reconnects it with acetate already in the cell to form acetylcholine again. Although this recycling process is highly efficient, it takes time, and the presynaptic neuron does not reabsorb every molecule it releases. A sufficiently rapid series of action potentials at any synapse can deplete the neurotransmitter faster than the presynaptic cell replenishes it, thus slowing or interrupting transmission

Answer 63

Acetylcholinesterase

Question 64

Reabsorption of a neurotransmitter by the presynaptic terminal

Answer 64

Reuptake

Question 65

Special membrane protein where reuptake occurs in the neurotransmitter

Answer 65

Transporter

Question 66

Enzyme that breaks down excess dopamine into inactive chemicals that cannot stimulate the dopamine receptors

Answer 66

COMT catechol-o-methyltransferase

Question 67

Receptors in many presynaptic terminals sensitive to the same transmitter they release. These receptors respond to the released transmitter by inhibiting further synthesis and release – they provide negative feedback

Answer 67

Autoreceptors

Question 68

Describe the two mechanisms for producing negative feedback

Answer 68

1. Many presynaptic terminals have receptors sensitive to the same transmitter they release. These receptors are known as autoreceptors – receptors that respond to the released transmitter by inhibiting further synthesis and release. They provide negative feedback. 2. Some postsynaptic neurons respond to stimulation by releasing special chemicals that travel back to the presynaptic terminal, where they inhibit for the release of the transmitter. Nitric oxide is one such transmitter. Two others are anandamide and 2-AG

Question 69

A direct contact of one neuron with another, enabling electrical transmission

Answer 69

Gap junction Fairly large pores of the membrane of wonder on lineup precisely with similar pores in the membrane of the other cell. These pores are large enough for sodium and other ions to pass readily, and unlike the other membrane channels we have considered, these pores remain open constantly. Whenever one of the neurons is depolarized, sodium ions from that cell can pass quickly into the other neurons and depolarize it too. As a result, the two neurons act almost as if they were in fact a single neuron.

Question 70

What happens to acetylcholine molecules after they stimulate a postsynaptic receptor?

Answer 70

The enzyme acetylcholinesterase breaks acetylcholine molecules into two smaller molecules, acetate and choline, which are then reabsorbed by the presynaptic terminal

Question 71

What happens to serotonin and catecholamine molecules after they stimulate a postsynaptic receptor?

Answer 71

Most serotonin and catecholamine molecules are reabsorbed by the presynaptic terminal. Some of their molecules are broken down into inactive chemicals, which they diffuse away.

Question 72

Why do our brains have receptors for plant chemicals?

Answer 72

Nearly all neurotransmitters and hormones are the same in humans as in other species. So if a plant evolves a chemical to attract bees, repel caterpillars, or whatever, that chemical is likely to affect humans also

Question 73

A drug that blocks a neurotransmitter

Answer 73

Antagonist

Question 74

A drug that mimics or increases the effects of a neurotransmitter

Answer 74

Agonist

Question 75

When a drug has the capacity to bind to a receptor, like a key into a lock. A drugs tendency to bind to a receptor

Answer 75

Affinity

Question 76

A drugs tendency to activate the receptor

Answer 76

Efficacy

Question 77

What are six ways that drugs influence synaptic activity?

Answer 77

A drug can increase or decrease the synthesis of the neurotransmitter, cause it to leak from its vesicles, increase its release, decrease its reuptake, block it's breakdown into inactive chemicals, or act on the postsynaptic receptors

Question 78

Is a drug with high affinity and low efficacy and agonist or an antagonist?

Answer 78

It is an antagonist because, by occupying the receptor, it blocks out the neurotransmitter

Question 79

A drug that binds to a receptor but fails to stimulate it has a high ______ but low ______

Answer 79

High affinity, low efficacy

Question 80

What is the common mechanism of action of nearly all abused drugs?

Answer 80

Abused drugs share certain effects on dopamine and norepinephrine synapses

Question 81

Behaviour that is reinforced by electrical stimulation of a brain area

Answer 81

Self-stimulation of the brain For example: researchers olds and Milner placed rats in boxes where they could press a lever to produce electrical self-stimulation of the brain. With electrodes in the septum and certain other places, rats sometimes pressed as often as 2000 times per hour.

Question 82

Brain area that is rich in dopamine and is central to the brain's reinforcement system

Answer 82

Nucleus accumbens Central to reinforcing experiences of all types: sexual excitement, the taste of sugar, imagining something pleasant activates it, gambling for habitual gamblers, video game playing for habitual video game players.

Question 83

Describe the two components of reinforcement according to psychologists

Answer 83

Wanting and liking Ordinarily, you want something that you like, but wanting or motivation is not always the same as liking or pleasure. For example, you might want medicine but not enjoy it or you know you would enjoy a fattening dessert, but you don't want it. Research in rats shows that small parts of the nucleus accumbens respond to pleasure/liking, but larger areas respond to motivation or wanting. Addictive drugs strongly activate the nucleus accumbens by releasing dopamine and norepinephrine. People addicted to a drug show an overwhelming, all-consuming drive to obtain the drug, even though it no longer provides much pleasure. This could be because of the larger area that response to motivation or wanting, even though that was addicted to drugs may no longer like it.

Question 84

Drugs that increase excitement, alertness, and activity while elevating mood and decreasing fatigue

Answer 84

Stimulant drugs

Question 85

A drug that blocks reuptake of dopamine and other neurotransmitters

Answer 85

Amphetamine

Question 86

A drug that blocks reuptake of dopamine

Answer 86

Cocaine

Question 87

A protein that is reabsorbed at the presynaptic terminal. Amphetamine and cocaine inhibit the transporter, thus decreasing reuptake and prolonging the effects of released dopamine. Thus, stimulant drugs increase the accumulation of dopamine in the synaptic cleft it.

Answer 87

Dopamine transporter

Question 88

What do drug use, sex, gambling, and video game playing have in common?

Answer 88

They increase the release of dopamine in the nucleus accumbens

Question 89

Stimulant drug prescribed for ADHD that increases the stimulation of dopamine synapses by blocking the reuptake of dopamine by the presynaptic neuron

Answer 89

Methylphenidate or Ritalin

Question 90

How do amphetamine and cocaine influence dopamine synapses?

Answer 90

They interfere with reuptake of release dopamine

Question 91

Why is methylphenidate generally less disruptive to behaviour than cocaine is despite the drugs' similar mechanisms?

Answer 91

The effects of a methylphenidate pill develop and decline in the brain much more slowly than do those of cocaine

Question 92

Describe the differences between the effects of amphetamines, cocaine, and methylphenidate

Answer 92

Both amphetamine and cocaine stimulate dopamine synapses in the nucleus accumbens and elsewhere by increasing the presence of dopamine in the presynaptic terminal. Amphetamine and cocaine inhibit the transporter, thus decreasing reuptake and prolonging the effects of release dopamine. Amphetamine has similar effects on the serotonin and norepinephrine transporters , And methamphetamine has affect similar to those of amphetamine but stronger. Low-dose is of these drugs in hands attention, and low doses of amphetamine are sometimes used as a treatment for attention deficit disorder. However, higher doses of stimulant drugs impair attention and learning. Methylphenidate or Ritalin, like cocaine, blocks three uptake of dopamine in the same way at the same brain receptors. The differences between the drugs relate to dose and time course. Cocaine users typically sniff it or injected to produce a rapid rush of affect on the brain. People taking methylphenidate pills experience a gradual increase in the drugs concentration over an hour or more, followed by a slow decline. Therefore, methylphenidate does not produce the sudden rush of excitement that is common with cocaine

Question 93

A stimulant drug that stimulates certain acetylcholine receptors

Answer 93

Nicotine A compound present in tobacco. Stimulates a family of acetylcholine receptors known as nicotinic receptors. These receptors are abundant on neurons that release dopamine in the nucleus accumbens, so nicotine increases dopamine release there. Nicotine increases dopamine release in mostly the same cells that cocaine stimulates One consequence of repeated exposure to nicotine is that receptors in the nucleus accumbens become more sensitive to nicotine and less responsive than usual to other kinds of reinforcement

Question 94

Drugs derived from the opium poppy

Answer 94

Opiate drugs Familiar opiates include morphine, heroin, and methadone. Opiates relax people, decrease their attention to real world problems, and decrease their sensitivity to pain. Opiates relieve pain by acting on receptors in the brain – endorphins indirectly activate dopamine release. Endorphin synapses inhibit neurons that release GABA, a transmitter that inhibits the firing of dopamine neurons. By inhibiting at inhibitor, the net effect is to increase dopamine release. Endorphins also have reinforcing effects independent of dopamine

Question 95

Chemicals found in marijuana leaves that have been used medically to relieve pain or nausea, to combat glaucoma, and to increase appetite

Answer 95

THC or tetrahydrocannabinol or cannabinoids Common psychological effects include an intensification of sensory experience and an illusion that time has slowed down. Studies have reported impairments of memory and cognition, especially in new users and heavy users. Cannabinoid receptors are located on the presynaptic neuron. When certain neurons are depolarized, they release anandamide or 2-AG as retrograde transmitters that travel back to the incoming axons and inhibit for the release of either glutamate or GABA. Just like these two brain chemicals, the cannabinoids in marijuana attach to the same presynaptic receptors telling them that the cell got their message, and to stop sending it. The chemicals in marijuana decrease both excitatory and inhibitory messages from many neurons.

Question 96

What are two chemicals that bind to cannabinoid receptors?

Answer 96

Anandamide and 2-AG

Question 97

Drugs that distort perception

Answer 97

Hallucinogenic drugs

Question 98

Many hallucinogenic drugs, such as LSD or lysergic acid diethylamide, chemically resemble _______

Answer 98

Serotonin They attach to serotonin type 2A receptors and provide stimulation at inappropriate times or for longer than usual durations The drug MDMA or ecstasy is a stimulant at low doses, increasing the release of dopamine and producing effects similar to amphetamine or cocaine. At higher doses, it also releases serotonin, altering perception and cognition like hallucinogenic drugs. Repeated large injections of MDMA damage neurons that contain serotonin

Question 99

How does nicotine affect dopamine synapses?

Answer 99

Nicotine excites acetylcholine receptors on neurons that release dopamine and thereby increases dopamine release

Question 100

How do opiates influence dopamine synapses?

Answer 100

Opiates stimulate endorphin synapses, which inhibit neurons that inhibit release of dopamine. By inhibiting an inhibitor, opiates increase the release of dopamine

Question 101

What are the effects of cannabinoids on neurons?

Answer 101

Cannabinoids released by the post synaptic neuron attach to receptors on presynaptic neurons, where they inhibit further release of both glutamate and GABA

Question 102

If incoming serotonin axons were destroyed, LSD would still have its full effects. However, if incoming dopamine axons were destroyed, amphetamine and cocaine would lose their effects. Explain the difference

Answer 102

Amphetamines and cocaine act by increasing the net release of dopamine and other transmitters. If those neurons were damaged, amphetamines and cocaine would be ineffective. In contrast, LSD directly stimulates the receptor on the postsynaptic membrane

Question 103

The habitual use of alcohol despite medical or social harm

Answer 103

Alcohol dependence or alcoholism

Question 104

Alcohol abuse with gradual onset; only a weak genetic predisposition

Answer 104

Type I or type A alcoholism

Question 105

Alcohol abuse with rapid onset and a strong genetic basis

Answer 105

Type II or type B alcoholism

Question 106

How does alcohol affect neurons?

Answer 106

Alcohol affects neurons in several ways. It facilitates response at the GABA receptor, the brains main inhibitory site. It also blocks activity at the glutamate receptors, the brains main excitatory site. Both the GABA effect and glutamate effect lead to a decrease in brain activity. Alcohol also increases stimulation at dopamine receptors in the nucleus accumbens.

Question 107

Which type of alcoholism – type I or type II – has a stronger genetic basis? Which type has earlier onset?

Answer 107

Type II has a stronger genetic basis and earlier onset

Question 108

Name at least two ways a gene could influence alcoholism

Answer 108

Genes can influence alcoholism by producing less sensitive dopamine receptors, faster breakdown of dopamine by the enzyme COMT, greater risk-taking behavior, and altered responses to stress. Of course, other possibility is not mentioned in this section also exist.

Question 109

Describe three findings common in the sons of alcoholics

Answer 109

1. Sons of alcoholics show less than average intoxication after drinking a moderate amount of alcohol. Presumably, someone who begins to feel tipsy after a drink or two stops, whereas one who holds his liquor well continues drinking, perhaps enough to impair judgement 2. Alcohol decreases stress for most people, but it decreases it even more for sons of alcoholics 3. Sons of alcoholics have some brain peculiarities, including a smaller than normal amygdala in the right hemisphere.

Question 110

What are two ways sons of alcoholics different behaviorally, on average, from sons of nonalcoholics?

Answer 110

Sons of alcoholics show less intoxication, including less body sway, after drinking a moderate amount of alcohol. They also show greater relief from stress after drinking alcohol

Question 111

Decrease of the effects of addiction

Answer 111

Tolerance

Question 112

Effects of drug cessation

Answer 112

Withdrawal Symptoms after someone quit heroin or other opiates include anxiety, sweating, vomiting, and diarrhea. Symptoms of alcohol withdrawal include irritability, fatigue, shaking, sweating, and nausea – sometimes progresses to hallucinations, convulsions, fever, and cardiovascular problems

Question 113

Someone who is quitting an addictive substance for the first time is strongly counseled not to try it again. Why?

Answer 113

Taking an addictive drug during the withdrawal is likely to lead to a habit of using the drug to relieve other kinds of distress

Question 114

When addiction develops, how does the nucleus accumbens change its response to the addictive activity and to other reinforcements?

Answer 114

The nucleus accumbens becomes selectively sensitized, increasing its response to the addictive activity and decreasing its response to other reinforcing activities

Question 115

Drug that antagonizes the effects of acetaldehyde hydrogenase by binding to its copper ion

Answer 115

Antabuse or disulfram It's use causes people to become sick when consuming alcohol. Studies find that Antabuse is moderately effective. When it works, it's supplements the alcoholics own commitment to stop drinking. By taking a daily pill and imagining the illness that could follow a drink of alcohol, the person reaffirms a decision to abstain. Those who drink in spite of taking the pill become ill, but often they quit taking the pill instead of quitting alcohol. Another medication, naloxone blocks opiate receptors and thereby decreases the pleasure from alcohol. Both medications work best with people who are strongly motivated to quit, and are more effective for type II alcoholics with a family history of alcoholism

Question 116

Drugs similar to heroin and morphine that is taken orally

Answer 116

Methadone Methadone taken orally gradually enters the blood and then the brain, so it's effects rise slowly, avoiding the rush experience. Because it is metabolized slowly, the withdrawal symptoms are also gradual. Furthermore, the user avoid the risk of injection with a possibly infected needle. These drugs do not end the addiction, they merely satisfy the cravings in a less dangerous way

Question 117

Methadone users who try taking heroin experience little effect from it. Why?

Answer 117

Because methadone is already occupying the endorphin receptors, heroin cannot add much stimulation to them

Question 118

Who would be likely to drink more alcohol – someone who metabolizes acetaldehyde acetic acid rapidly or one who metabolizes it slowly?

Answer 118

People who metabolize it rapidly would be more likely to drink alcohol because they suffer fewer unpleasant effects

Question 119

How does Antabuse work?

Answer 119

Antabuse blocks the enzyme that converts acetaldehyde to acetic acid and therefore makes people sick if they drink alcohol. Potentially, it could teach people anniversary into alcohol, but more often, it works as a way for the person to make a daily recommitment to abstain from drinking.