Board Review Week 3 Test Good luck!!
B Amygdaloid nuclei and lumbar system After the destruction of amygdaloid nucleus and lumbar system, the normal fear reaction is often absent. Mammillary bodies are part of the Papez circuit (of limbic system). Stimulation and ablation experiments indicate that in addition to its role in olfaction, the limbic system is concerned with feeding behavior. Along with the hypothalamus, it is also concerned with sexual behavior, the emotion of rage and fear, and motivation. The functions of cerebral frontal lobes and cerebral motor cortex include initiating voluntary motor impulses for the movement of skeletal muscles, analyzing sensory experiences and providing responses relating to personality. The frontal lobes are also involved with responses related to memory, emotions, reasoning, judgment, planning and verbal communication. Lesions in cerebral frontal lobes and motor cortex may affect any or all of these functions. Removal or lesions of neocortex will inhibit sexual behavior.
C Meissner's corpuscles Meissner's corpuscles are specialized receptors that lie in the papillary dermis, perpendicular to the surface of the skin. They are primarily found in hairless skin, particularly the fingers and toes. The capsule of the corpuscle is an elongated cone, within which an unmyelinated nerve ending spirals to the tip of the cone. As in the Pacinian corpuscle, the unmyelinated nerve ending is enclosed by Schwann cells.
B Cholinergic sympathetic The term cholinergic is used to describe any physiologic or pharmacologic relationship that involves acetylcholine (ACh). For example, cholinergic nerve fibers synthesize and release ACh, cholinergic receptors complex with ACh or synthetic analogs of ACh, and cholinergic drugs chemically resemble ACh or interfere with its inactivation. A sympathetic nerve fiber is part of the sympathetic division of the autonomic nervous system. Autonomic control of the adrenal medulla involves single innervation via motor fibers of the sympathetic division of the autonomic nervous system (ANS). This unique arrangement of single innervation, rather than dual autonomic innervation through the two opposing ANS subdivisions requires sympathetic neurotransmission that is not dependent on norepinephrine (noradrenaline). The majority of postganglionic sympathetic fibers of the ANS release noradrenaline and are termed adrenergic , but the sympathetic preganglionic fibers that innervate the adrenal medulla release ACh, therefore, such fibers are designated as cholinergic sympathetic fibers. The adrenal medulla has its embryological origins as a sympathetic ganglion that migrates to a location on the superior aspect of the kidney, but retains its connection with the sympathetic preganglionic fiber. (In this regard the cholinergic sympathetic classification of the autonomic fiber controlling the adrenal medulla is not unusual since all preganglionic fibers, both sympathetic and parasympathetic, are classified as cholinergic sympathetic fibers.)
B Basement membrane Type IV collagen is amorphous. It is abundant in the basement membrane. Distribution of collagen in different tissues is enumerated as follows: Type I Skin, bone, tendons Type II Cartilage, vitreous humor Type III Blood vessels, skin, uterus Type IV Basement membrane Type V Interstitial tissue Type VII Dermal epidermal junction Type VIII Endothelium-descemet's membrane Type IX Cartilage Type X Cartilage Type XI Cartilage
D Oral Bioavailability (F) refers to the rate and extent to which a drug or a metabolite enters general circulation. From the bloodstream, the drug or metabolite is capable of reaching its site of action. Several variables affect bioavailability. For example, the formulation and pH of the drug can affect how rapidly the drug is absorbed through membranes. In addition, the route of administration influences bioavailability because bioavailability is determined by measuring either the amount of drug in circulation or the extent of the pharmacologic response produced by the drug. Either way, the route of administration plays a critical role. In theory, the intravenous (IV) and intra-arterial (IA) routes deliver 100% of the administered dose to the bloodstream (F = 1). Other parenteral routes such as the intramuscular (IM) or subcutaneous (SC) routes deliver somewhat less than 100% of the administered dose (F < 1) due to pharmacokinetic factors such as tissue binding and relatively slow tissue clearance by the lymphatic system. The inhalational route, due to the extensive surface area of the alveolar-capillary interface, can provide a relatively high bioavailability measurement, although not as great as that attained through direct introduction of drug into the bloodstream. The route yielding relatively low bioavailability—a distinct disadvantage—is the oral route. The low bioavailability of drug is due to the action of gastric enzymes, gastrointestinal motility, and extensive hepatic first-pass metabolism effects. First-pass effects refer to the rapid inactivation of a drug by hepatic enzymes (e.g. mixed function oxidases) and the rapid elimination of drug metabolites via the biliary route of excretion. Drug metabolism also occurs within the intestinal lumen, the intestinal mucosal cells, and the hepatic portal system, but the majority of first-pass effects are due to the action of hepatic enzymes. (Although inhalational drugs are not directly affected by hepatic first-pass effects, they are subject to lung first-pass effects, including metabolism and excretion.) Passage through general circulation or through the kidney does not contribute to first-pass effects in pharmacokinetics. Different routes of administration exhibit different advantages and disadvantages. The intravenous route delivers drug to the bloodstream nearly instantaneously as evidenced by the short time required to reach peak plasma concentration (Tmax) and maximal serum levels (Cmax). By contrast, the oral route requires a much longer time to reach Tmax and Cmax. The intravenous route provides precise control of dose via IV infusion and provides the means to deliver water-soluble drugs such as aminophylline in large volumes. A significant drawback to the rapid onset and distribution of drug through the IV route is the simple fact that the delivered dose is not retrievable should a dosage miscalculation or an unforeseen drug reaction occur. The enteral route, on the other hand, allows the retrieval of a portion of orally administered drug through induction of emesis or gastric lavage. In addition, orally administered drugs, because of their dosing convenience, are ideal for chronic outpatient use.
B Delusions A delusion is an idea that is not fixed in reality. A hallucination is a perception without a stimulus. Depression involves a depressed mood and lack of interest in life. Euphoria is an elevated mood. Delirium involves confusion and disorientation.
C Respect her decision if she can demonstrate and communicate ability to reason • Competence is a legal term, capacity is a medical term. Physicians are often called on to make a determination of a patient's capacity to make medical decisions. The patient's primary care provider is an ideal person to make the assessment as they have background knowledge of the patient's educational level, values, and medical history. • A psychiatrist may be needed if overlying psychiatric problems make it difficult to determine capacity for judgment or ability to reason. Courts make the ultimate determination of competence, although there is usually concordance with the medical determination of capacity. Only lack of competence has legal ramifications, however. • A bedside mental status examination may help to determine capacity, but in and of itself does not determine competence. If the patient is deemed to have the capacity to make her own decisions, it may be detrimental to encourage family member involvement in the decision making process. • Adult protective services are usually called to investigate cases of abuse or neglect, not issues of capacity or competence. If still unclear, a psychiatrist or ethics board consultation could be utilized to help determine the patient's capacity to make her own decisions. • Four main criteria should be used to determine a patient's capacity to make medical decisions. • They can demonstrate understanding of the treatment options. • They can demonstrate understanding of how the different options affect their own individual situation. • 3) They can demonstrate ability to reason with the above information, using either evidence based in fact, or personal beliefs rooted in their value system. • 4) They are able to demonstrate 1-3 and can communicate a choice.
A Frontal lobe The brain, or cerebrum, is divided into two hemispheres: the right hemisphere and the left hemisphere. Connecting the two hemispheres are the corpus callosum, anterior commissure, hippocampal commissure, posterior commissure, and the habenular commissure. The outermost portion of the brain, characterized by convolutions and grooves, is the cerebral cortex of which the right hemisphere controls the motor and sensory processes of the left side of the body and the left hemisphere controls the right side of the body (contralateral control). The cerebral cortex may be anatomically divided into four lobes: the frontal, parietal, temporal and occipital lobes. The frontal lobe is responsible for planning and for motor functions. Specifically, the area within the frontal lobe that controls voluntary body movements is called the motor cortex. Thus, frontal lobe is the correct answer to the question. The parietal lobe is largely concerned with somatic sensation (somatosensory cortex), the occipital lobe with vision, and the temporal lobe with audition as well as other functions. Thus, in the above question, these are incorrect answers. The limbic lobe is a ring of cortical structures surrounding the central core of the brain and is itself encircled by the frontal, parietal, temporal and occipital lobes. It is part of the limbic system which is generally associated with emotion, learning and memory. As it is not associated with motor function, limbic lobe is an incorrect answer.
D Spleen Based upon their ultrastructural characteristics, capillary endothelia may be described as being continuous, fenestrated or discontinuous (sinusoidal). Discontinuous capillaries characteristically have larger diameter and more irregularly shaped lumen than that of other capillaries. Furthermore, these large diameter capillaries may have gaps between endothelial cells and have sparse or absent basal lamina underlying the endothelium. These types of capillaries are common to the spleen, but are also found in the liver and in bone marrow.
B Anti-idiotype Each immunoglobulin consists of light chains and heavy chains. Isotypic differences are those between types such as IgG and IgM, and allotypes are allelic variants in the individual C genes of antibodies. Idiotypes are antigenic determinants of the variable regions linked to the specificity towards the antigen. Long ago it was shown that the heterogeneity and average affinity of antibodies increase with time in response to an antigen. The population of idiotypes produced during an immune response evolves so that the response is more specific and more effective. The study of idiotypes is essential for the analysis of the genetic origin of variability.
A Drug A Dose-response curves that show the interaction between an agonist drug and an antagonist drug are those that compare the ED50 of the agonist alone with the ED50 of the agonist after an antagonist is added. In both the Drug A and Drug B graphs, it can be seen that the ED50 (median effective dose) of the agonist drug has increased from approximately 20 mg to approximately 50 mg. This increase in the median effective dose is due to the pharmacologic antagonism between agonist and antagonist as both drugs attempt to bind the same pharmacologic receptor. A drug response is related to the number of complexes formed between receptor and agonist. An agonist exhibits affinity plus efficacy whereas an antagonist shows affinity for a receptor, or the ability to form a complex with it, but possesses no intrinsic activity, or efficacy. The noncompetitive nature of pharmacologic antagonism is seen in the graph of Drug A in which the potency and the efficacy of the agonist are both decreased. This type of interaction shows a sigmoid ED50 curve displaced downwards and to the right. The median effective dose increases from 20 mg to 50 mg, indicating a loss of agonist potency. In other words, more drug is required to bind available receptors and evoke a particular response. The maximal drug response, however, cannot be restored, no matter how high the dose of agonist drug administered. This decrease in effectiveness is visible graphically as a shift downwards in the ED50 curve and is typical of the irreversible competition occurring between an agonist drug and a noncompetitive antagonist. Each receptor bound by the noncompetitive antagonist is no longer available to the agonist, thereby decreasing agonist efficacy, or the ability to produce an effect relative to a given number of drug-receptor complexes. In the Drug B graph the ED50 curve has undergone a parallel displacement to the right but no displacement downwards. This shift denotes a decrease in potency of the agonist but no change in its efficacy. Potency refers to the relative ability of a drug to produce a particular response at a given dose. It should be remembered that comparisons of potency are only useful if made at equieffective doses. In competitive antagonism, an optimal number of agonist-receptor complexes can be formed and a maximal response (100%) can still be achieved, but the dose necessary to elicit this level of response is higher as evidenced by the increased median effective dose. The pharmacologic blocking effect of the competitive antagonist can be reversed by increasing the dose of the agonist. This provides additional agonist drug to bind available receptors as the competitive antagonist "uncouples" from them. A classic example of this type of reversible pharmacologic antagonism is the competition for cholinergic receptors (N2-nicotinic) at motor end plates of neuromuscular junctions that occurs between acetylcholine acting as agonist and curarelike neuromuscular blockers acting as competitive antagonists.
B Increase the morphine until she is comfortable, even if she dies in the process Much literature has been published on the fact that terminal cancer patients are often inadequately treated when it comes to pain control. Many possible explanations have been proposed to explain this phenomenon. Some practitioners may fear they will be reprimanded by the Drug Enforcement Administration (DEA) for prescribing too many controlled substances. Some may believe that the patient really isn't in "that much" pain. Others fear that the side effects of the medication will cause further problems such as constipation, confusion, respiratory depression, or addiction (even in a patient that has days or weeks to live!) The literature emphasizes that narcotics can be dosed as high as it takes to achieve adequate pain control in terminally ill cancer patients. It is a common misconception that a practitioner will be criminally prosecuted when a terminal patient dies while receiving narcotics. If the patient in the aforementioned case inadvertently died while receiving high doses of morphine, it would not be considered murder or assisted suicide. The use of adequate pain medication for this patient is completely justified, especially in view of the patient's advanced directives, terminal diagnosis, and supportive family. An ethics consultation or risk management assessment would be an option if either the physician or the family were uncomfortable with the situation. Physician assisted suicide (the intentional administration of life-ending medication) is currently legal in Oregon, and other jurisdictions may legalize it or prohibit it in the future.
C Schizoaffective disorder Zelda's symptoms best describe the criteria for schizoaffective disorder. She presents with prominent schizophrenic and affective symptoms. As the name implies, schizoaffective disorder combines features of both disorders; a period where there is either a major depressive episode, a manic episode, or a mixed episode along with Criterion A symptoms for schizophrenia (i.e., delusions, hallucinations, etc.).
C Duodenum While villi, intestinal glands, and goblet cells might be found in the duodenum and ileum, submucosal glands, in combination with the former characteristics, could be found only in the duodenum. The submucosal glands, or Brunner's glands, secrete alkaline glycoproteins and bicarbonate ions to bring the pH of the intestinal contents to that optimal for action of the pancreatic enzymes. The esophagus does not possess villi on the cells of the stratified squamous epithelium. It may have mucosal glands, however. The colon does not have villi or submucosal glands, but does have extensive numbers of goblet cells.
A Blocking the release of acetylcholine at the synapse and thereby producing paralysis Botulinum toxin produced by Clostridium botulinum is a neurotoxin that blocks the release of acetylcholine at the synapset , producing paralysis. The genes for this toxin are encoded by a temperate bacteriophage. It is composed of 2 polypeptide subunits held together by disulfide bonds and one of the subunits binds to a receptor on the neuron.
A Liver and gall bladder The photomicroscopic image depicts the histological appearance of two organs in close contact; the liver and gall bladder. Inspection of the epithelial lining of the gall bladder shows the presence of simple columnar cells. Underlying the epithelium is a loose connective tissue core, the lamina propria, thrown into irregular folds. A fairly prominent layer of smooth muscle is seen underlying the lamina propria, forming the muscularis layer of the gall bladder. Glisson's capsule is absent at the position where the liver and gall bladder are in contact, however, the characteristic hepatic plates with intervening sinusoids can be seen. The intervening area common to the liver and gall bladder is composed of connective tissue adventitia. Note that one of the folds of epithelium in the lumen of the gall bladder is pronounced and appears like a gland in the sectioned organ. Without careful inspection of the image, the liver may appear similar to the cells of the parenchyma within the pars distalis of the pituitary gland, but the pars intermedia may contain what appear as colloid-filled cysts or follicles lined by simple squamous or cuboidal epithelium, not present in this image. The seminal vesicle may show irregular folds of the lamina propria, similar to the gall bladder, but the epithelium is predominantly pseudostratified columnar lining the lumen. The prostate gland would show glands, whose lumen possibly contain concretions, lined by a variety of epithelia, usually pseudostratified columnar. Underlying the glands are a fibromuscular connective tissue. The gall bladder also may be confused with the uterine tube, since the uterine tube is lined with a simple columnar epithelium, and has folds of lamina propria. However, many of the epithelial cells of the uterine tube are ciliated. The ovary does not resemble the liver, since the parenchyma of the ovary contains ova in various stages of maturation interspersed throughout connective tissue.
B Stage 2 Sleep comprises approximately 1/3 of our lives and its function is far from being completely understood. Normally, sleep is an active (not passive) process where the brain activity fluctuates over about 45 cycles per night. Distinct sleep stages can be measured by EEG as patients pass through stages 1-4 (non-REM) and then enter REM sleep. Patients enter REM sleep (dream sleep) approximately every 90 minutes and the duration of this stage lengthens as the night progresses. The characteristic EEG pattern of the various sleep stages is listed below along with some physiological observations. Waking - alpha waves (8-12 cps) NREM Sleep - (Nonrapid eye movement) - low level of activity: lowered BP, heart rate, temperature, and respiratory rate. Good muscle tone and slow, drifting eye movements. Stage 1 - lightest sleep, a transition stage; low voltage, desynchronized waves. Stage 2 - sleep spindles, (13-15 cps) and high spikes (K complexes). Stage 3 - some delta waves (high voltage at 0.5-2.5 cps). Stage 4 - deepest sleep, mostly in first half of night; mostly delta waves. REM Sleep - active sleep characterized by rapid synchronous eye movement, twitching of facial and extremity muscles, penile erections, and variation in pulse, BP, and respiratory rate. Muscular paralysis is present. Depth is similar to stage 2. Dreaming can occur in several stages but is most common in REM sleep.
D Affect Affect is the visible expression of emotions. In this patient the affect is inappropriate to the content of his speech. Thought process denotes the connections between thoughts, and thought content is the actual thoughts themselves, which may be delusional or hallucinatory. Mood is emotion that is pervasive and long-lasting. Mood is best described in the patient's own words. Impulse control is a description of the patient's ability -or inability- to forego action in light of a particular feeling or urge.
B Reversibility of effect can be rapidly achieved Bioavailability (F) refers to the rate and extent to which a drug or a metabolite enters general circulation. From the bloodstream, the drug or metabolite is capable of reaching its site of action. Several variables affect bioavailability. For example, the formulation and pH of the drug can affect how rapidly the drug is absorbed through membranes. In addition, the route of administration influences bioavailability because bioavailability is determined by measuring either the amount of drug in circulation or the extent of the pharmacologic response produced by the drug. Either way, the route of administration plays a critical role. In theory, the intravenous (IV) and intra-arterial (IA) routes deliver 100% of the administered dose to the bloodstream (F = 1). Other parenteral routes such as the intramuscular (IM) or subcutaneous (SC) routes deliver somewhat less than 100% of the administered dose (F < 1) due to pharmacokinetic factors such as tissue binding and relatively slow tissue clearance by the lymphatic system. The inhalational route, due to the extensive surface area of the alveolar-capillary interface, can provide a relatively high bioavailability measurement, although not as great as that attained through direct introduction of drug into the bloodstream. The route yielding relatively low bioavailability—a distinct disadvantage—is the oral route. The low bioavailability of drug is due to the action of gastric enzymes, gastrointestinal motility, and extensive hepatic first-pass metabolism effects. First-pass effects refer to the rapid inactivation of a drug by hepatic enzymes (e.g. mixed function oxidases) and the rapid elimination of drug metabolites via the biliary route of excretion. Drug metabolism also occurs within the intestinal lumen, the intestinal mucosal cells, and the hepatic portal system, but the majority of first-pass effects are due to the action of hepatic enzymes. (Although inhalational drugs are not directly affected by hepatic first-pass effects, they are subject to lung first-pass effects, including metabolism and excretion.) Passage through general circulation or through the kidney does not contribute to first-pass effects in pharmacokinetics. Different routes of administration exhibit different advantages and disadvantages. The intravenous route delivers drug to the bloodstream nearly instantaneously as evidenced by the short time required to reach peak plasma concentration (Tmax) and maximal serum levels (Cmax). By contrast, the oral route requires a much longer time to reach Tmax and Cmax. The intravenous route provides precise control of dose via IV infusion and provides the means to deliver water-soluble drugs such as aminophylline in large volumes. A significant drawback to the rapid onset and distribution of drug through the IV route is the simple fact that the delivered dose is not retrievable should a dosage miscalculation or an unforeseen drug reaction occur. The enteral route, on the other hand, allows the retrieval of a portion of orally administered drug through induction of emesis or gastric lavage. In addition, orally administered drugs, because of their dosing convenience, are ideal for chronic outpatient use.
B First node of Ranvier Pacinian corpuscles, which are touch receptors, have been studied in detail. Because of their relatively large size and accessibility in the mesentery of experimental animals, they can be isolated, studied with microelectrodes, and subjected to microdissection. Each capsule consists of the straight, unmyelinated ending of a sensory nerve fiber, 2 µm in diameter, surrounded by concentric lamellas of connective tissue that give the organ the appearance of a minute cocktail onion. The myelin sheath of the sensory nerve begins inside the corpuscle. The first node of Ranvier is also located inside, whereas the second is usually near the point at which the nerve fiber leaves the corpuscle. Deformation of the capsule causes a sudden change in the membrane potential by increasing its permeability and allowing positively charged sodium ions to leak to the interior of the fiber. This change in local potential causes a local circuit of current flow that spreads along the nerve fiber to its myelinated portion. At the first node of Ranvier the local current flow initiates action potentials in the nerve fiber.
C IgG1 Opsonization is an enhancement of phagocytosis through the binding to the surface of a pathogen. IgG antibodies, in particular IgG1 are very effective opsonins. Phagocytes express Fcg receptors on their surface. These receptors bind IgG antibodies, especially IgG1. Phagocytes also distinguish between free antibodies, to which they do not bind, and aggregated or multimeric antibodies on the surfaces of bacteria and viruses, to which they do bind.
B Interval shorter than T1/2 The T1/2 is the time required to reduce the blood level of a drug by one half, thus after one T1/2 only 50% of the drug remains. After two T1/2 intervals only 25% of the drug remains. If the dosage interval is more frequent than the T1/2 time, accumulation is guaranteed. The Kel is the elimination constant in concentration units eliminated per each time unit. This value cannot be used to assure accumulation since the starting blood level is not known. Four half-times will reduce the beginning blood concentration to about 6% of the starting concentration.
B Inhibition of acetylcholinesterase Of the above only the inhibition of acetylcholinesterase, the enzyme that breaks down acetylcholine into acetate and choline and effectively stops cholinergic signaling between two cells, would increase levels of acetylcholine in the synaptic cleft.
A Gunshot wounds Physicians in most jurisdictions are obligated to violate patient confidentiality when it is for the greater good or is required by law. The most common circumstances included are gunshot wounds, wounds secondary to crimes, communicable diseases, including venereal diseases and tuberculosis, child abuse, elder abuse, abuse of the mentally impaired, animal abuse, and driving impairment secondary to physical conditions. A notable exception to these rules is AIDS, despite the fact that it is a communicable disease, and that lack of notification of exposed individuals may result in more people contracting this disease. The reasons for this are social and political, and the devastating effect on the individual that would result from having his or her AIDS status become public knowledge are felt, at this time, to outweigh the rights of others to be protected from exposure. Obviously, this subject is quite controversial and not likely to be resolved in the near future. Other conditions that are generally not reported in violation of patient confidentially are intravenous drug abuse, spousal abuse, and psychosis.