2function Flashcards

Question

second messengers are also

Answer 1

thought to play a role in the manufacture and release of neurotransmitters and in intracellular movements and carbohydrate metabolism in the cerebrum — the largest part of the brain, consisting of two hemispheres. Second messengers also are involved in growth and development processes. In addition, the direct effects of second messengers on the genetic material of cells may lead to long-term alterations in cellular functioning and, ultimately, to changes in behavior.

Answer 2

acts through the well-known acetylcholine nicotinic receptor. This drug can act as both a stimulant and a sedative. Nicotine stimulates the adrenal glands, and the resulting discharge of epinephrine causes a “kick” — a sudden release of glucose paired with an increase in blood pressure, respiration, and heart rate. In addition, nicotine releases dopamine in the brain regions that control motivation, which is one reason that people continue to smoke.

Answer 3

Ethanol, the active ingredient in alcoholic beverages, is a seductive drug. At first, it reduces anxiety, tension, and behavioral inhibitions. In low doses, it may act as a stimulant, but at higher doses, it acts as a depressant. In both cases, it significantly alters mood and behavior. Too much alcohol can also cause heat loss and dehydration

Answer 4

The drug, which is easily absorbed into the bloodstream and the brain, affects several neurotransmitter systems. For example, alcohol’s interaction with the gamma-aminobutyric acid (GABA) receptor can calm anxiety, impair muscle control, and delay reaction time. At higher doses, alcohol also decreases the function of N-methyl-d-aspartate (NMDA) receptors, which recognize the neurotransmitter glutamate. This interaction can cloud thinking and eventually lead to coma

Answer 5

In radioactive tracing studies, scientists found that tetrahydrocannabinol (THC), the active ingredient in marijuana, binds to specific receptors called cannabinoid receptors, many of which coordinate movement. This may explain why people who drive after they smoke marijuana are impaired. The hippocampus, a structure involved with memory storage and learning, also contains many receptors for THC. This finding provides some insight into why heavy users or those intoxicated on marijuana have poor short-term memory and problems processing complex information.

Answer 6

Opiates increase the amount of dopamine released in the brain reward system and mimic the effects of endogenous opioids (opioid peptides).

Answer 7

Heroin injected into a vein reaches the brain in 15 to 20 seconds and binds to opiate receptors found in many brain regions, including the reward system. Activation of the receptors in the reward circuits causes a brief rush of intense euphoria, followed by a couple of hours of a relaxed, contented state.

Answer 8

In 2009, in the United States, an estimated 4.8 million | people age 12 and older had abused cocaine.

Answer 9

This class of drugs includes cocaine and amphetamines. The key biochemical factor underlying the reinforcing effects of psychostimulant drugs is their ability to greatly elevate the brain chemical dopamine in specific brain regions, such as the nucleus accumbens. Alterations in dopamine activity in the accumbens, induced by chronic cocaine intake, are thought to result in a progressively increasing motivation to take the drugs, eventually leading to addiction.

Answer 10

When mixed with alcohol, rohypnol can incapacitate victims and prevent them from resisting sexual assault. Rohypnol may be lethal when mixed with alcohol and other depressants.

Answer 11

aka ecstasy. a synthetic psychoactive drug with hallucinogenic and amphetamine-like properties. Users encounter problems similar to those found with the use of amphetamines and cocaine. Recent research also links chronic ecstasy use to long-term changes in those parts of the brain critical for thought, memory, and pleasure.

Answer 12

Since about 1990 in the United States, GHB has been abused for its euphoric, sedative, and anabolic (body-building) effects. It, too, has been associated with sexual assault.

Answer 13

Ketamine is another central nervous system depressant abused as a date-rape drug. Ketamine, or “Special K,” is a fast-acting general anesthetic. It has sedative, hypnotic, analgesic, and hallucinogenic properties. It is marketed in the United States and a number of foreign countries as a general anesthetic — a drug that brings about a reversible loss of consciousness — in both human and veterinary medical practice

Answer 14

``` Apolipoprotein E (apoE), which influences susceptibility for Alzheimer’s later in life, exists in three forms. The variant known as APOE epsilon 4 is clearly associated with enhanced risk. ```

Answer 15

These genes encode beta and gamma secretases, which cut amyloid peptide from a larger protein. The amyloid peptide is then released from the neuron into the space around synapses, where it can accumulate and form Alzheimer’s disease plaques. Amyloid-destroying enzymes, known as alpha secretases, break up the amyloid peptide, preventing amyloid accumulation.

Answer 16

affects neurons that control voluntary muscle movements such as walking. For reasons that are not completely understood, motor neurons in the brain and spinal cord begin to disintegrate. Because signals from the brain are not carried by these damaged nerves to the body, the muscles begin to weaken and deteriorate from the lack of stimulation and resulting disuse.

Answer 17

vaccines created from the patient’s own tumor combined with substances that boost the immune system or kill tumor cells

Answer 18

hone in on receptors on the surface of | the tumor cells

Answer 19

during which the | tumor’s blood supply is restricted

Answer 20

uses the body’s own immune system against the tumor

Answer 21

delivers bioengineered genes to the | cancer cells to kill them

Answer 22

targeted delivery of antibodies, toxins, or growth-inhibiting molecules that attach specifically to the tumor cells and interfere with their growth. A scorpion-derived toxin called chlorotoxin, which interferes with the spread of the tumor, has shown promise in clinical studies. This therapy extended life expectancy significantly

Answer 23

an autoimmune disease in which the body’s natural defenses attack the myelin sheath covering the axons of neurons in the central nervous system. While neuroscientists do not know what causes this autoimmune assault, they have discovered that the loss of myelin results in damage to the nerve fibers. In some instances, the damage may be so severe that the nerve fiber deteriorates.

Answer 24

Following loss of myelin, the axon’s sheath is either repaired or replaced by scars, or scleroses, of hardened patches of tissue. Scarring is usually associated with further degeneration of the nerve fibers. Areas of disease activity, called lesions or plaques, appear in multiple places within the central nervous system.

Answer 25

In 2009, about 2.5 million people worldwide became infected with human immunodeficiency virus (HIV); 33 million are now living with HIV.

Answer 26

part of the skull may be removed to allow the brain to swell, a procedure known as a decompressive craniectomy.

Answer 27

they can increase pressure as well as | contribute to the development of post-traumatic epilepsy.

Answer 28

refers to the loss of pain sensation.

Answer 29

Local anesthetics temporarily interrupt the action of all nerve fibers, including pain-carrying ones, by interfering with the actions of sodium channels.

Answer 30

Acetaminophen, the active ingredient in Tylenol, has analgesic properties but does not reduce inflammation.

Answer 31

nerve growth factor, a type of trophic factor. slows the destruction of neurons that use acetylcholine. also holds promise for slowing the memory deficits associated with normal aging.

Answer 32

Using antibodies that override the effect of Nogo-A, a protein that inhibits nerve regeneration, Swiss researchers succeeded in getting some nerves of damaged spinal cords to regrow in rats and monkeys. recently injured spinal cord injury patients are being treated with anti-Nogo-A antibodies in a clinical trial.

Answer 33

It is sometimes possible to trick the immune system into attacking those proteins that cause neurological diseases by “vaccinating” patients against them. Another new approach combines genetic engineering with immunology to engineer antibodies or fragments of antibodies that can bind to and alter the disease characteristics of specific proteins. These therapies could be delivered either as proteins or as genes.

Answer 34

Thousands of small-molecule drug candidates can be tested using high-throughput screening, during which hundreds or thousands of compounds are tested to find those with the desired cellular effect.

Answer 35

Our ability to learn and consciously remember everyday facts and events is called declarative memory.

Answer 36

signaling molecules released by the mesoderm turn on certain genes and turn off others, triggering some ectoderm cells to become nerve tissue in a process called neural induction. Subsequent signaling interactions further refine the nerve tissue into the basic categories of neurons or glia (support cells), then into subclasses of each cell type. The remaining cells of the ectoderm, which have not received the signaling molecules diffusing from the mesoderm, become skin.

Answer 37

a particular signaling molecule, called sonic hedgehog, is secreted from mesodermal tissue lying beneath the developing spinal cord. As a result, the adjacent nerve cells are converted into a specialized class of glia. Cells that are farther away, however, are exposed to lower concentrations of sonic hedgehog, so they become the motor neurons that control muscles. An even lower concentration promotes the formation of interneurons, which relay messages to other neurons, not muscles.

Answer 38

a condition in which the vision of one eye is greatly reduced because the eyes do not work well together; has the best outcome when it is started early in life, before the age of eight. During this period of time, visual experiences guide the development of the visual circuits. After the critical period comes to an end, the circuits cannot be easily modified.

Answer 39

researchers use a technique called microdialysis to measure the amount of a particular brain chemical found in a specified area of the brain

Answer 40

The study of the electrical properties of neurons is called | electrophysiology.

Answer 41

long-term potentiation, the | cellular event that makes learning and memory possible. the discovery of this relied on electrophysiology

Answer 42

Genetic linkage studies, which studied families and large groups of unrelated people diagnosed with specific conditions, made it possible to find the chromosomal location of many genes.

Answer 43

Newer techniques, called chromosome microarrays, look carefully at the overall chromosome makeup of a person and find out if segments of chromosomes, perhaps involving multiple genes, are missing (called deletions) or present in more than the usual amount (called duplications).

Answer 44

the gene that is altered in patients diagnosed with Huntington’s disease

Answer 45

causes inherited retinoblastoma

Answer 46

a rare, highly malignant, childhood eye tumor that can lead to blindness and death

Answer 47

X-linked gene DMD, responsible for Duchenne muscular dystrophy, a progressive muscle disease.

Answer 48

In some cases, mapping techniques have shown that one condition may actually be due to mutations in any one of a group of genes. This is the situation with a condition called Walker-Warburg syndrome, which causes severe problems involving the brain, eyes, and muscles, leading to death in infancy or early childhood. Thus far, at least five genes are known to be associated with this disease, with still others yet to be discovered.

Answer 49

scientists have identified a gene called LIS1 that helps tell the brain how to grow. People with mutations in the LIS1 gene have smoother brains than normal and may have seizures. In addition, severe intellectual disability is common. However, the parents of these individuals do not have mutations in their LIS1 genes, so there is a very low chance of other children of those parents having the same diagnosis.

Answer 50

This testing is expected to uncover the functional sequence of all 20,000 or more human genes (collectively called the exome) as well as the remaining associated DNA that is thought to influence or regulate these genes (together with the exome, this is called the genome) for each person studied. So far, such studies have revealed numerous types of genetic variants, making for more variability in human genes than initially recognized.

Answer 51

causes congenital intellectual disabilities along with certain abnormal facial features. Despite being a distinctive condition, Kabuki syndrome long escaped efforts to identify its genetic underpinnings.

Answer 52

Information from research in cats and monkeys has | improved the therapy for strabismus

Answer 53

over the course of the first hour or so of sleep, the brain progresses through a series of stages during which brain waves slow down. This period of slow wave sleep is accompanied by relaxation of the muscles and the eyes. Heart rate, blood pressure, and body temperature all fall.

Answer 54

- REM, characterized by neocortical EEG waves similar to those observed during waking. , accompanied by atonia (paralysis of the body's muscles) - active dreaming - men have erections - Heart rate, blood pressure, and body temperature become much more variable

Answer 55

Obstructive sleep apnea occurs as sleep deepens and the airway muscles in the throat relax to the point of collapse, closing the airway. The individual has difficulty breathing and wakes up without entering the deeper stages of slow wave sleep.

Answer 56

This condition can cause high blood pressure and may increase the risk of heart attack. Increased daytime sleepiness that results from sleep apnea can lead to an increased risk of daytime accidents, especially automobile accidents.

Answer 57

may include a variety of strategies to reduce airway collapse during sleep. Whereas simple things like losing weight, avoiding alcohol and sedating drugs prior to sleep, and avoiding sleeping on one’s back can sometimes help, most people with sleep apnea require devices that induce continuous positive airway pressure to keep the airway open. One such device is a small mask that fits over the nose to provide an airstream under pressure during sleep. In some cases, surgery is needed to correct the airway anatomy.

Answer 58

are intermittent jerks of the legs or arms that occur as the individual enters slow wave sleep. These movements can cause arousal from sleep. more common in people with Parkinson’s disease, and both can be treated with drugs for Parkinson’s or with a benzodiazepine called clonazepam.

Answer 59

related to periodic limb movements of sleep. occurs when muscles fail to become paralyzed during REM sleep, As a result, people literally act out their dreams by getting up and moving around. more common in people with Parkinson’s disease, and both can be treated with drugs for Parkinson’s or with a benzodiazepine called clonazepam.

Answer 60

the switching mechanisms controlling the transitions into sleep, particularly REM sleep, do not work properly.People with narcolepsy have sleep attacks during the day, in which they suddenly fall asleep.

Answer 61

the suprachiasmatic nucleus provides signals to an adjacent brain area, called the subparaventricular nucleus, which in turn contacts the dorsomedial nucleus of the hypothalamus. The dorsomedial nucleus then contacts the ventrolateral preoptic nucleus and the orexin neurons in the lateral hypothalamus. It is these neurons that directly regulate sleep and arousal.

Answer 62

sends messages to muscles so that we may | respond to sensory information

Answer 63

- glucocorticoid that promotes energy replenishment and efficient cardiovascular function. - Cortisol levels, which vary naturally over a 24-hour period, peak in the body in the early-morning hours just before waking. This hormone helps produce a wake-up signal, turning on appetite and physical activity

Answer 64

When we have new experiences, information initially enters working memory, a transient form of declarative memory.

Answer 65

a form of declarative knowledge | that includes general facts and data

Answer 66

Our memories of specific personal experiences that occurred at a particular place and time are called episodic memories.

Answer 67

Nondeclarative knowledge, the knowledge of how to do something, often called procedural memory, is expressed in skilled behavior and learned habits.

Answer 68

In addition, cAMP activates another molecule, called cAMP-response element binding protein (CREB). CREB operates within the nucleus of the neuron to activate a series of genes, many of which direct protein synthesis. Among the proteins produced are neurotrophins, which result in growth of the synapse and an increase in the neuron’s responsiveness to stimulation.

Answer 69

language disorders

Answer 70

a syndrome in which speech production abilities are impaired. Speech output is slow and halting, requires effort, and often lacks complexity in word or sentence structure. Although speaking is impaired, nonfluent aphasics still comprehend heard speech, although structurally complex sentences may be poorly understood.

Answer 71

comprehension of heard speech is impaired. Speech output, although of normal fluency and speed, is often riddled with errors in sound and word selection and tends to be unintelligible gibberish. Wernicke’s aphasics can often comprehend bits and pieces of a spoken utterance, as well as isolated words.

Answer 72

a profound inability to comprehend auditory speech on any level. patients with word deafness are functionally deaf for speech, lacking the ability to comprehend even single words, despite being able to hear sound and even identify the emotional quality of speech or the gender of the speaker.

Answer 73

is thought to help the systems for speech recognition and speech production communicate with each other. This circuit is involved in speech development and is thought to support verbal short-term memory.

Answer 74

scientists have discovered that the adult brain continually generates new nerve cells — a process known as neurogenesis. Interestingly, one of the most active regions for neurogenesis in the brain, the hippocampus, is also an area heavily involved in learning and memory.

Answer 75

The brain possesses the ability to modify neural connections to better cope with new circumstances.

Answer 76

Growth cones, enlargements on the axon’s tip, actively explore the environment as they seek out their precise destination. Researchers have discovered many special molecules that help guide growth cones. Some molecules lie on the cells that growth cones contact, whereas others are released from sources found near the growth cone. The growth cones, in turn, bear molecules that serve as receptors for the environmental cues. The binding of particular signals with receptors tells the growth cone whether to move forward, stop, recoil, or change direction.

Answer 77

In between the myelin are gaps, called nodes of Ranvier, that are not covered in myelin. The electrical signal moves faster over the insulated portion, jumping from one node to another. This phenomenon, known as saltatory conduction (the word “saltatory” means “to jump”), is responsible for the rapid transmission of electrical signals.

Answer 78

the wrapping of axons by extensions of glia, increases the speed at which signals may be sent from one neuron to another by a factor of up to 100x. This advantage is due to how the sheath is wrapped. The process of myelination occurs throughout the lifespan.

Answer 79

the paring down of connections occurs in large part during critical periods in early postnatal life. During these moments in time, the developing nervous system must obtain certain critical experiences, such as sensory, movement, or emotional input, to mature properly. Such periods are characterized by high learning rates as well as enduring consequences for neuronal connectivity. It is important to note that there are multiple critical periods, organized sequentially, as individual brain functions are established.

Answer 80

Experience-expectant plasticity refers to the integration of environmental stimuli into the normal patterns of development. Certain environmental exposures during limited critical, or sensitive, periods of development are essential for healthy maturation.

Answer 81

the continuing process of the creation and organization of neuron connections that occurs as a result of a person's life experiences