SECTION 1 Basic Sciences Flashcards
Describe the murmurs heard for Mitral stenosis ?
Opening snap that occurs early in diastole and a RUMBLING diastolic murmur
What is the stethoscope location for mitral stenosis murmur where they are best heard?
Best heard with the chest piece placed over the APEX
Describe the murmurs heard for Mitral Regurgitation?
The cardinal feature of mitral regurgitation is a blowing holosystolic murmur HEARD THROUGHOUT SYSTOLE
Where does mitral regurgitation murmur radiates to?
AXILLA
Murmur heard throughout systole
Mitral regurgitation murmur
2 murmur heard over the CARDIAC APEX
Mitral stenosis and mitra regurgitation
Describe the murmurs f the patient has aortic
Stenosis
Systolic murmur,
Best stethoscope location for AORTIC Stenosis
second right intercostal space (over the aortic arch)
Murmur that radiates to the neck?
AORTIC Stenosis
Murmur description for aortic regurgitation
Diastolic murmur
Best murmur heard over the Left sternal border?
Aortic Regurgitation
When the ventricle fills more during diastole, more blood is ejected during systole. Whose law is this?
Starling’s (or Frank-Starling’s) law of the heart.
Starling’s law of the heart relates ventricular filling during diastole to the
amount of blood ejected during systole.
Starling Law, the greater the ventricular filling during diastole , meaning the greater the _______, the
Preload; The greater the quantity of blood pumped into the aorta during systole.
What causes a change in blood pressure when changing the patient’s position?
Altered preload (altered venous return) is most responsible for a change in blood pressure when the patient is re-positioned.
What nerves carry the afferent and efferent signals of the Bainbridge reflex?
stretch receptors send Afferent signals to the medulla via the vagus nerve. The medulla then transmits Efferent signals via the sympathetic nerves to increase heart rate (by as much as 75%) and myocardial contractility.
What does the Bainbridge reflex help prevent?
The Bainbridge reflex helps prevent damming up of blood in veins, the atria, and the pulmonary circulation.
When does the Bainbridge reflex get activated?
When the great veins and right atrium are stretched by increased vascular volume
Describe the venous drainage of the lung. BAHIB
The venous drainage of the bronchi occurs through the bronchial, azygous, hemiazygos, and intercostal veins, which then drain into brachiocephalic veins of the neck and ultimately the superior vena cava.
The pulmonary circulation returns to the heart via
the pulmonary veins, which empty into the left atrium.
Describe the Valsalva maneuver.
Forced expiration with the glottis closed.
Valsava maneuver increase what kind of pressure?
All intrathoracic pressures including intrapleural and intrapulmonary pressures.
With valsava maneuver, intrapleural pressures changes from _______. What happens to CO and BP?
Negative to positive, so venous return to the RV decreases and CO and BP decrease
With valsava maneuver what causes an increase in HR?
The decrease in BP results in a reflex increase in HR.
The healthy adult lung receives each minute an alveolar ventilation (V) of about how many L?
4 L/min is the alveolar ventilation rate.
Normal pulmonary blood flow (Q) per min?
5L/min
What is the average resting ventilation:perfusion (V/Q) ratio?
0.8 (4/5 = 0.8)
A V/Q ration between zero and 1 indicates (0
Relative shunt
A V/Q ration greather than 1 indicates what?
Dead-spacing
Compared with the apex of the lung, the base exhibits GREATER or LESSER PERFUSION?
GREATER
Perfusion (blood flow) is best in which part of the lung?
Dependent
The base on the lung is dependent in what position?
In the upright (sitting or standing)
What is the total quantity of CO2 delivered to, and used by, the tissues each minute?
250 ml/min of 02 is normally delivered to, and used by, the tissues.
VO2 (oxygen consumption) is how much per min?
3-4 mlO2/kg/min
What are the three ways C02 is transported in the blood? What percent for each route of transport?
(l) physically dissolved in solution, 5% to 10%;
(2) as bicarbonate ion (HCO~ · ), 80% to 90%;
{3) protein bound (plasma proteins and hemoglobin)-these are called carbamino compounds, 5% to 10%.
The majority of CO2 is transported in blood in the form of
Bicarbonate 80-90%
A large number of diverse insults can trigger acute respiratory distress syndrome. List factors that can lead to
ARDS.
SHAFT BRUDDS CPM Shock Head injury Aspiration Fat or air embolus Trauma Burns Radiation of thorax UREMIA Drug Ingestion Drowning Sepsis Cardiopulmonary bypass Pancreatitis Massive Blood transfusion
What are the pulmonary consequences of prolonged 100% oxygen administration?
Loss of surfactant (due to prolonged exposure to oxygen radicals), leading to ARDS (adult respiratory distress syndrome).
What is responsible for creating the resting membrane potential?
The resting membrane potential of nerve and muscle is due primarily to the diffusion of potassium ions (K+) out of cells through potassium leak channels.
Give two reasons for up-regulation of adrenergic receptors.
(1) Sympathetic denervation, and (2) treatment with a sympathetic competitive antagonist (e.g., beta blockade) causes adrenergic receptors to up regulate)
Identify two forms of the enzyme, monoamine oxidase (MAO).
The two known forms of monoamine oxidase (MAO) are type A (MAO-A) and type B (MAO-B).
What substances are metabolized by MAO-A (SEND)
Serotonin
Epinephrine
Norepinephrine
Dopamine
What substances are metabolized by MAO-AB
Tyramine (cheese, red wine beer)
Phenylethylmaine
Dopamine
What substance is metabolized by both MAO-A and MAO-B?
Dopamine
Where is monoamine oxidase type A (MAO-A) found?
Monoamine oxidase type A (MAO-A) is an enzyme present in the central nervous system, adrenergic nerve endings, liver and gastrointestinal tract.
MAO-A was involved in metabolic degradation of SEND (Serotonin, epi, nore, dopamine) by
Oxidative deamination
What two tracts transmit impulses from the motor cortex to the spinal cord?
Pyramidal and extrapyramidal tracts.
Impulses from the motor cortex are carried directly to the spinal cord via the
pyramidal tract (aka CORTICOSPINAL TRACT)
Impulses are also carried through the basal
ganglia, cerebellum and brainstem nuclei to the spinal cord by
Extrapyramidal system
What are components of the extrapyramidal system?
basal ganglia, cerebellum and brainstem nuclei
Are the effects of sympathetic stimulation of a motor or sensory nature?
Motor (efferent)
Where do preganglionic PARAsympathetic nerves originate?
Preganglionic parasympathetic nerves arise from nuclei of cranial nerves Ill, VII, IX and X in the brainstem and also from sacral segments (S2-S4) of the spinal cord
Owing to these origins, the parasympathetic system
is also known as the
craniosacral division.
Which autonomic nerves are cholinergic in nature?
Those fibers that release acetylcholine are cholinergic.
The cholinergic autonomic nerves are the the
- sympathetic and parasympathetic preganglionic neurons
- parasympathetic postganglionic neurons and the 3. sympathetic postganglionic neurons that
innervate sweat glands and piloerector muscles.
Sympathetic neurons release NE and EPI except two that release what?
Sympathetic postganglionic neurons that release SWEAT GLANDS and PILOERECTOR MUSCLES
Which three cranial nerves supply SENSORY innervation to the oropharynx? VGF
vagus (CN X), facial (CN VII), and glossopharyngeal (CN IX) nerves
Describe the anatomy and functions of the glossopharyngeal nerve (CN IX).
The glossopharyngeal nerve (GPN) supplies general and special (taste} sensory innervation to the posterior third of the tongue via the lingual branch (caution: not the lingual nerve, which is a terminal branch of the
mandibular division of CN V), the vallecula, the anterior surface of the
epiglottis, the posterior and lateral walls of the pharynx, and the tonsillar
pillars. Motor innervation from the glossopharyngeal nerve is to one of the
muscles of deglutition (swallowing).
Supply the posterior THIRD of the tongue
Glossopharyngeal nerve.
One of the muscles of deglutition (swallowing). [
Motor innervation from the glossopharyngeal nerve
The glossopharyngeal nerve (GPN) supplies general and special (taste} sensory innervation to the posterior third of the tongue via the
lingual branch
Innervates the vallecula
Glossopharyngeal nerve
Innervates the anterior surface of the epiglottis
Glossopharyngeal nerve
Innervates the posterior and lateral walls of the pharynx,
Glossopharyngeal nerve
Innervates the tonsillar pillars.
Glossopharyngeal nerve
What are the 3 division of Trigeminal nerve? OMaxMan
the ophthalmic, maxillary, and mandibula
Which nerve provides motor innervation to the muscles of mastication (chewing, “moves the mandible”)
masseter nerve
Which nerve give rise to the masseter nerve?
The anterior branch of the mandibular nerve (V3) gives rise to the masseter nerve
Provides sensory innervation to the lower teeth and gums (“feels the mouth inside and out”}.
The posterior branch of the mandibular nerve
The lingual nerve is a terminal branch of the
mandibular nerve:
General sensory innervation to the lingual mucous membranes,
The lingual nerve
Sensory innervation to the anterior two-thirds of the tongue
Lingual nerve (Mandibular nerve branch)
Sensory to the floor of the mouth
Lingual nerve (Mandibular nerve branch)
What is the chorda tympani nerve ?
A branch of the facial nerve, CN VII
What is the relationship between the chorda tympani nerve (branch ofCN VII) and the lingual nerve (Terminal branch of CN V3)
Chorda tympani joins lingual nerve, and courses with the lingual nerve to the anterior 2/3 of the tongue.
The chorda tympani supplies special sensory fibers to the
taste buds on the anterior two-thirds of the tongue.
What is the function of the Circle of Willis?
The Circle of Willis provides collateral blood flow to the brain if a major vessel carrying blood to the brain becomes obliterated.
What percent of the intracranial volume is occupied by brain?
80% brain matter and intracellular water
What percent of the intracranial volume is occupied by Blood?
12%
What percent of the intracranial volume is occupied by CSF?
8%
The composition of cerebrospinal fluid (CSF) differs from the composition of plasma LYTES?
7% more sodium
Higher magnesium
Higher Chloride
40% less Potassium
The composition of cerebrospinal fluid (CSF) differs from the composition of plasma GLUCOSE
30% less glucose
The composition of cerebrospinal fluid (CSF) differs from the composition of plasma HYDROGEN IONS
Higher H+ (lower pH);
How much cerebrospinal fluid is produced per day?
CSF production is about 500-750 mL/day
Cerebrospinal fluid production ranges from
15 mL/24 hours to 30 mL/24 hours,
What four factors determine how much of a substance will diffuse across the blood-brain barrier?
The movement of a given substance across the blood-brain barrier is governed simultaneously by its
size, charge, lipid solubility, and degree of protein binding in blood.
A substance generally must be_____and/or______ in order to cross the blood-brain barrier in substantial amounts.
very small or lipid soluble
What are the results of electrical stimulation to the reticular activating system (RAS)?
Stimulation of the reticular activating system (RAS) increases alertness..
Diffuse electrical stimulation of the RAS causes immediate and______cause a ________
marked activation of the cerebral cortex and will even cause a sleeping individual to awaken instantaneously
What is the typical time-frame for onset of autonomic hyperreflexia following spinal cord injury?
Autonomic hyperreflexia usually follows a period of spinal shock that typically lasts 1- 3 weeks. SO ONSET Is about after 3 weeks
How long does spinal shock last?
1-3 weeks
Onset of Hyperreflexia following SCI can be?
Few months to many years
What are four components for treatment for the syndrome of inappropriate antidiuretic hormone secretion?
RARA
- Remove the underlying cause(
3) Antagonize the effects of ADH on the renal tubule by giving demecolcine
(2) restrict water intake,
(4) administer hyperosmotic saline with or without diuretics.
Identify the gland that is both endocrine and exocrine.
Pancreas
What hormone does the pancreatic islet delta cells produce?
Somatostatin
What is the role of the hormone somatostatin?
Inhibits GI motilitiy and secretion including the production of HCL
The main physiologic function of glucagon .
increase serum glucose concentration by causing hepatic gluconeogenesis and glycogenolysis (breakdown of glycogen).
Plays a key role in glucose homeostasis
Glucagon
How does glucagon maintain homeostasis, 2 processes
Hepatic gluconeogeneis
Glycogenolysis
Antagonize effects of insulin
Glucagon
Effects of glucagon on gastric motility?
Inhibit gastric motility
Glucagon: Effects of gastric acid secretion?
Inhibit gastric secretion
Glucagon on bile secretion
Enhanced
Glucagon effects on tissue
Increased blood flow to tissues, especially kidneys
Glucagon effects on insulin
Increases insulin secretion
Glucagon and cardiac effects
inotropic and chronotropic
Glucagon and biliary effects?
relaxation of smooth muscle (biliary sphincter)
Identify the biochemical triad that defines diabetic ketoacidosis.
ketonemia, hyperglycemia, and acidemia.
What are the diagnostic criteria for diabetic ketoacidosis?
ketonemia or significant ketonuria
blood glucose above 250 mg/dL or known diabetes mellitus; and
serum bicarbonate below 18 mmol/L or arterial pH< 7.3.
It is generally recommended to cancel nonurgent or elective surgery in the patient with diabetes mellitus if the serum glucose rises above what value?
Above 400 mg/dL
The clinical syndrome of diabetic ketoacidosis (DKA) includes
dehydration and hypovolemic shock from hyperglycemic osmotic diuresis
compensatory hyperventilation {Kussmaul pattern)
life· threatening electrolyte depletion (especially hypokalemia and hypophosphatemia)
AG gap with DKA
Greater than 10
Anion GAP formula is
Na+ - (Cl+HCO3)
The increase in hepatic arterial flow in response to a decrease in portal blood flow occurs for two reasons:
(l) to maintain hepatic oxygen supply, and (2) to maintain
total hepatic blood flow, which is essential for clearance of many compounds.
What is the “arterial buffer respons”?
Adjusting hepatic arterial flow in response to changes in portal blood flow
What are seven functions of the liver?
storage and filtration of blood,
(2) metabolic functions such as carbohydrate, fat, and protein metabolism
(3) secretion of bile
4) storage of vitamins
(5) blood coagulation
(6) storage of iron
(7) detoxification and excretion of drugs.
How does glomerular filtration rate (GFR) change if the efferent arteriole dilates relatively more than the afferent
arteriole?
Glomerular filtration rate will decrease if the efferent arteriole dilates more than the afferent.
How does GFR change If the efferent arteriole constricts relatively more than the afferent arteriole?
GFR will increase if the efferent arteriole constricts more
than the afferent.
How does GFR change if the afferent arteriole dilates relatively more than the efferent arteriole?
Glomerular filtration rate will increase if the afferent arteriole dilates more than the efferent
How does GFR change if the afferent arteriole Constricts relatively more than the efferent?
GFR will decrease if the afferent arteriole constricts more
than the efferent.
List and define three causes of perioperative
acute renal failure
Prerenal failure
Renal failure
Post renal failure
Cause of prerenal failure
Decreased renal blood flow
Cause of IntraRenal failure
Renal tubular damage secondary to decreased renal
blood flow, nephrotoxic drugs, or release of hemoglobin or myoglobin
Causes of Postrenal failure?
Obstruction of urine flow due to for example obstruction of the ureters or urethra
What is the best indicator of renal reserve?
The best indicator of renal reserve is the trend in serum creatinine values.
An important early step in hemostasis is
vasoconstriction of the damaged vessel.
An important early step in hemostasis is vasoconstriction? _______play a key role in this initial vasoconstriction by release of what substances?
Platelets; The vascular contraction is a result of autonomic nervous system reflexes and the release of thromboxane A2
The endothelium releases many procoagulant
factors following vascular injury: name two key procoagulants released by the endothelium.
Endothelial damage following vascular injury initiates release of many procoagulant factors including tissue factor (flII, TF) and factor VIII:vWF(von willebrand’s factor)
In addition to its role in early vasoconstriction, thromboxane A2 plays a key role in
activation and aggregation of platelets.
Once platelets adhere, they are activated by a complex series of steps including
release of ADP and thromboxane A2
Describe the actions ofTxA2 in activation and adhesion of platelets.
Adenosine diphosphate (ADP) and TxA2 are ligands for G protein coupled receptors (P2Yu and • TPa, respectively} that trigger signal transduction pathways, ultimately leading to expression ofGPIIb/IIIA receptors (fibrinogen receptors) on the platelet surface. TxA2 appears to amplify the signal and action of more potent platelet agonists, such as thrombin (Ila) and ADP
What may be given to treat the patient with a fibrinogen {factor I) deficiency?
Cryoprecipitate
Which two veins combine to form the hepatic portal vein?
The (hepatic) portal vein is formed by the union of the splenic vein and superior mesenteric vein posterior to the neck of the pancreas at the level of L2.
Usually drains into the splenic vein but occasionally
(10%) the Tip:
inferior mesenteric vein
inferior mesenteric vein joins the splenic and superior
mesenteric veins at their confluence at
portal vein.
Portal system: if a question asks for two vessels, the “best” answer, in our opinion, is
splenic and superior mesenteric veins.
If the immune system overreacts to an allergen, what occurs?
a hypersensitivity (allergic) reaction occurs.
Immune-mediated hypersensitivity reactions are classified
into
Four groups
Type I immune mediated reactions are
anaphylactic or immediate-type hypersensivity reactions.
Type II immune mediated reactions are
Cytotoxic reaction (antibody-dependent cell-mediated cytotoxicity)
Type III reactions are
immune complex reactions that produce tissue damage by deposition of the immune complexes.
Type IV reactions are
Delayed type hypersensitivity reactions from interactions of sensitized lymphocytes with specific antigens.
Describe type I allergic (hypersensitivity) reactions
In type I allergic reactions (immediate type, anaphylactic}, a specific antigen called an allergen interacts with specific IgE antibodies on tissue mast cells or circulating basophils to trigger mediator release
The key mediator of type I reactions is
histamine.
Examples of type I reactions are
allergic rhinitis, extrinsic asthma, and anaphylaxis
Describe type II hypersensitivity (allergic)reactions: include participating
cells and antibody(ies} and list common
examples of type II reactions
Type II cytotoxic reactions are mediated by lgM and lgG antibodies directed against antigens on the surface of foreign cells or extracellular tissue components.
The cell damage in type II reactions is produced by
(I) direct cell lysis after complete complement cascade
activation
(2) increased phagocytosis by macrophages
(3) killer T-cell lymphocytes producing antibody-dependent cell mediated cytotoxic effects.
Examples of type II reactions
ABO incompatible transfusion reactions drug-induced immune hemolytic anemia Hepain-induced thrombocytopenia Myasthenia gravis Goodpasture's syndrome.
Describe Type III allergic hypersensitivity reactions
Result from circulating soluble antigens and antibodies that bind to form insoluble complexes which then DEPOSIT in the microvasculature.
2 things that can lead to type III reactions?
Protracted infections
Autoimmune processes
3 diseases associated with type III reactions
SLE
RA
Glomerulonephrities
CLASSIC SERUM SICKNESS>
Describe type IV allergic (hypersensitivity) reactions: include participating
cells and antibody(ies) and list common
examples of type IV reactions.
Type IV delayed hypersensitivity reactions result from the interactions of sensitized lymphocytes with specific antigens.
Delayed hypersensitivity reactions are mainly
mononuclear, manifest in
18 to 24 hours, peak at 40 to 80 hours, and disappear in 72 to 96 hours.
In Type IV hypersensitivity reaction what occurs?
Cytotoxic T cells are produced specifically to kill target cells that bear antigens identical with those that triggered the reaction.
Type IV examples of reations
tissue rejection Graft vs host reactions Contact dermatitis Tuberculin immunity Steven Johnsons syndrome
Another form of type IV hypersensitivity is
granulomatous hypersensitivity, in which chronic infection leads to the formation of granulomas in tissues.
Granulomatous diseases include
tuberculosis, sarcoidosis, and Crohn’s disease
What is anaphylaxis?
Anaphylaxis is a severe, generalized, life threatening immediate hypersensitivity reaction marked by interstitial edema-particularly laryngeal edema bronchospasm, and cardiovascular collapse
The most common type of immune-mediated anaphylaxis results when
-previous exposure to antigens in drugs or foods evokes production of antigen-specific lgE antibodies.
Subsequent exposure to the same or a chemically similar antigen results in antigen-antibody interactions that initiate marked degranulation of mast cells and basophil
Most common with anaphylaxis?
Urticaria and pruritus are common.
How does non-immune-mediated anaphylaxis (also known as anaphylactoid reaction) compare with anaphylaxis?
Non-immune-mediated anaphylaxis (also known as anaphylactoid reaction) is nearly identical to anaphylaxis; however, the triggering antigen directly stimulates mast cell and basophils- there is no IgE-mediated trigger.
Symptoms anaphylactoid vs anaphylaxis?
Symptoms of non-immune-mediated anaphylaxis are generally less severe than IgE-mediated anaphylaxis
What are the normal ranges for pH, PCO2 and bicarbonate in arterial blood?
pH - 7.35- 7.45; pC02 = 35 45 mm-Hg; bicarbonate - 22-27 mEq/L.
What is the normal HC0.1 /H1C0.1 ratio? What is the significance of this?
The normal HC03 /H2C03 ratio is 20: 1. When the HC03 :H2C03 ratio is 20:1, pH= 7.40. The pH increases when the ratio increases, and pH falls when the ratio decreases.
The pH increases when the HCO3:H2CO3 ratio
Increases
pH relationship to HCO3:H2CO3 ratio is
directly proportional
What is the anion gap?
The anion gap= major measured cations - major measured anions
What is the utility of measuring the anion gap?
The anion gap is used in the differential diagnosis of metabolic acidosis. Some metabolic acidoses are associated with a high anion gap (anion gap > 25
mEq/liter). Other metabolic acidoses are associated with a normal, or near normal, anion gap
Normal AG is
9-15
At what sodium level will the patient begin to exhibit signs and symptoms of hyponatremia?
A serum sodium concentration of 120 mEq appears to be borderline for development of severe reactions.
How is hyponatremia treated?
Treatment of hyponatremia is diuretics or infusion of hypertonic saline
Treatment of hyperkalemia can be divided into three categories, based upon mechanism of action: list these 3
categories.
l) physiologic antagonists and membrane stabilizers (calcium)
(2} agents that shift or drive potassium into cells (insulin, beta adrenergic agonists, sodium bicarbonate and hyperventilation
(3} agents or process that remove potassium from the body
Agents that shift or drive potassium into cells are
insulin, beta adrenergic agonists, sodium bicarbonate and hyperventilation
Treatments of hyperkalemia, state the onset {minutes) and duration of action (minutes or hours): calcium salts,
insulin-glucose infusion, sodium poly-
styrene sulfate (Kayexalate), and loop
diuretics.
l) calcium salts: onset in 1-3 minutes duration of action 30- 60 minutes;
Treatments of hyperkalemia, state the onset {minutes) and duration of action (minutes or hours):sodium bicarbonate,
onset of action : 5-10 minutes; a duration of action 1-2 hours;
Treatments of hyperkalemia, state the onset {minutes) and duration of action (minutes or hours): LOOP Diuretics
loop diuretics:Onset 15-30 minutes duration of action of 2-3 hours;
Treatments of hyperkalemia, state the onset {minutes) and duration of action (minutes or hours): Insulin glucose infusion
insulin-glucose infusion, onset of action is 30 minutes, followed by a duration of action of 4-6 hours; and
Treatments of hyperkalemia, state the onset {minutes) and duration of action (minutes or hours):Kayexalate
sodium polystyrene sulfate (Kayexalate), onset in 1 2 hours, duration of action 4-6 hours.
How does serum K• change with acute acidosis? Acute alkalosis? Explain.
Serum K+ increases in acidosis and decreases in alkalosis
Serum K changes with acute acidosis explain?
With acidosis, H+ diffuses into cells because of the increased extracellular H+ . As H+ enters cells, K+ leaves. This H+ - K+ exchange increases extracellular K+ concentration.
Serum K changes with acute alkalosis explain?
With alkalosis, W diffuses out of cells. As W leaves cells, K• enters. This H+-K+ exchange decreases extracellular K’ concentration.
List functions of magnesium.
Magnesium is an intracellular cation that functions as a cofactor in many enzyme pathways
Magnesium is important for the regulation of the
sodium-potassium pump, the regulation of the enzyme adenyl cyclase, and the regulation of slow calcium channels.
Magnesium antagonizes
calcium.
Magnesium controls the
threshold potential and serves as a membrane stabilizer
An important function of magnesium is the
regulation of the release of acetylcholine from nerve
terminals.
What are the manifestations of hypomagnesemia
when serum [Mg2] < 1.2- 1.6 mg/dL ( < 1.0-1.5 mEq/L,
0.5-0.75 mmol/L)?
When serum [Mg2•]
Tetany, seizures, and arrhythmias occur when serum magnesium falls below what level?
Tetany, seizures, and arrhythmias occur when serum magnesium concentrations are <1.2 mg/dL {
Where is the J-point in the ECG waveform?
The J-point is the point on the ECG when the QRS complex ends and the ST segment begins
How is the J-point used in ECG interpretation?
ST elevation or depression is measured by comparing
lead voltage at 60 or 80 milliseconds after the J-point to the isoelectric value, usually measured during the PR interval.
ST elevation or depression may also be measured at the
J-point.
Left bundle branch block (LBBB) is uniquely characterized by:
Broad Notched R wave in leads I, aVl, V5, V6
Deep S in the Right precoardial leads
Absent septal Q waves
LBBB and RBBB both characterized by a
HR <100 Regular rhytm Normal PRI QRS > 120ms ST segment and T waves in the opposite direction of the R wave.
Left bundle branch block (LBBB) is uniquely characterized by:
Prominent notched R waves with M patter (rabbite ears)
rsr’, rsR’, or rSR’ on the righst side leads, (aVR, V1)
Wide S on left side leads.
Which is more prevalent, RBBB or LBBB? Which is more ominous?
RBBB occurs in about 1 % of hospitalized patients and is much more common than left bundle branch
block (LBBB). LBBB, however, is more ominous LBBB does not occur in healthy individuals.
Right bundle branch block (RBBB) is common in
the general healthy population without clinical evidence of structural heart disease and has • no prognostic significance in this group
LBBB is often associated with
ischemic heart disease, hypertension, and valvular heart disease. LBBB obscures or simulates other ECG patterns.
In the presence of LBBB, the diagnosis of
LVH, acute ischemia, or myocardial infarction may be difficult or impossible
What is one concern with pulmonary artery catheter placement in a patient with left bundle branch block?
Insertion of a pulmonary artery catheter (PAC) may precipitate right bundle branch block, thus insertion of a PAC in a patient with left bundle branch block may precipitate complete heart block (third-degree block).
What is a dose-response curve?
A dose-response curve depicts the relationship between the dose of a drug administered (x- axis) and the resulting pharmacologic effect (y- axis).
Define volume of distribution (Vd)
Vd=’Q/C , where Vd is the volume of distribution, Q is the quantity of drug injected and CP is the plasma concentration of the drug that would be achieved if the drug distributed instantaneously within its volume of
distribution after its injection
Drugs that are absorbed from the gastrointestinal
tract must first pass through which organ before reaching the general circulation?
The drugs are delivered to the liver via the portal circulation. Drugs that are absorbed from the GI tract may be metabolized to some extent in the liver-this is the.first-pass effect
What are the vapor pressures of halothane?
244 mmHg
What is the vapor pressure of isoflurane?
240 mmHg
What is the vapor pressure of enflurane?
172 mmHg
What is the vapor pressure of desflurane?
669 mmHg
What is the vapor pressure of sevoflurane?
170 mmHg
List volatile agents according to their vapor pressure (lowest to highest vapor pressure). SEIHD
Sevo< enflurane
Which volatile agents most depress the baroreceptor reflex?
Halothane and sevoflurane most depress the baroreceptor reflex
Which volatile agentst least depress the baroreceptor ?
isojlurane and desflurane least depress the baroreceptor reflex (
NO Baroreceptor reflex means that there are
There are no increases in heart rate despite decreases in blood pressure with these agents
Baroreceptor reflex is working when
heart rate tends to increase reflexly with the decreases
in blood pressure produced by these agents
What are the minimum alveolar concentration (MAC) requirements for a full-term infant, compared to the adult?
The minimum alveolar concentration (MAC) value for a full-term infant is the same as for the adult.
At what age (months) is the minimum alveolar concentration (MAC) highest? Which agent is the exception to this rule?
By 6 months of age, the minimum alveolar concentration (MAC) is 50% greater compared to adult MAC. For example, the MAC of desflurane for a 6-month old is 9.9% compared to 5.8% for the adult. The exception to this rule is sevoflurane: the MAC of sevoflurane is greatest in the neonate (3.3%), compared to 2% for the adult.
Where and how are volatile anesthetics metabolized?
The modern inhaled anesthetics are primarily excreted via the lungs. The minimal amount of biotransformation 0.02% to 5%) of modern volatile anesthetics takes place in the liver by the cytochrome P450 enzyme system.
The cytochrome P450 enzymes are also known as
mixed-function oxidases.
The modern inhaled anesthetics are primarily excreted
via the lungs.
Amount of biotransformation of VA in the liver is
0.02% to 5%
What opioid receptor promotes respiratory depression?
Mu-2
Which opioid can block voltage-dependent sodium channels, in other words, which opioid has local anesthetic properties?
Meperidine
Which opioid has local anesthetic properties?
Meperidine
Meperidine is an agonists to
M and K receptors
Meperidine has well-known local anesthetic properties, particularly after
epidural administration.
What affect do opioids have on the blood C02 dissociation curve?
If respiratory depression occurs, Pa02 decreases, and the C02 curve shifts.
Except for remifentanil, how are opioids eliminated?
Except for remifentanil, opioids are eliminated by hepatic metabolism.
What are the implications for a patient with liver disease receiving an opioid?
In a patient with liver disease, the clearance of all opioids except remifentanil will be delayed (slowed) and significant accumulation can occur
Naltrexone is administered to treat what problems
Naltrexone is a long-acting opioid antagonists administered to treat alcohol addiction
Which intravenous agents will decrease intracranial pressure? BEBOP
Barbiturates Etomidate Benzodiazepines, Opioids Propofol.
Venous thrombosis and phlebitis are most likely after intravenous administration of what nonopioid anesthetics?
Why?
Diazepam, lorazepam and etomidate, because they are dissolved in the organic solvent, propylene glycol.
Name two nonopioid induction drugs that are associated with the excitatory phenomena during induction
Methohexital and etomidate
Which intravenous sedative-hypnotic inhibits platelet aggregation?
Propofol inhibits platelet aggregation that is induced by TxA2 and platelet-activating factor, although propofol does NOT alter tests of coagulation or platelet function
List the local anesthetics that are amides
Local anesthetics with an amide linkage are lidocaine, prilocaine, mepivacaine, bupivacaine, levobupivacaine, and ropivacaine
What antimicrobial preservatives are added to commercial preparations of local anesthetic solutions in multi-dose
vials?
Paraben derivatives such as methyl paraben, ethyl paraben, and propyl paraben.
Should preservative-containing solutions of local anesthetic be used for spinal, epidural, or intravenous regional anesthesia
No, because parabens are potentially cytotoxic (neurotoxic).
How do local anesthetics work?
Local anesthetics work by preventing voltage-gated fast Na• channels in nerve axons from opening. Local anesthetics bind to sodium channels inside
the neuron when they are in the Inactivated state.
Does conduction block by local anesthetics require the ionized form, unionized form, or both ionized and
unionized forms?
Both forms. The un-ionized form crosses the lipid bilayer to enter the neuron, and the ionized form binds to the gated sodium channel while in the inactivated state
Identify the part of the nerve cell that is affected by local anesthetics.
The nerve axon is the site of action of the local anesthetics. Only the axon has fast, voltage-gated sodium channels
What are the three states of the fast, voltage-gated sodium channel?
(1) Closed, (2) open, and (3) inactivated.
What is the primary determinant of local anesthetic potency?
Lipid Solubility (thnk SLP)
In general, what structural characteristic of local anesthetic determines lipid solubility and, hence, potency
The total number of carbon atoms. “In general, lipid solubility (potency) is increased by increasing the total number of carbon atoms in the molecule
State three specific ways, in addition to adding carbon atoms, of increasing potency of a local anesthetic
Lipid solubility and potency are increased by adding:
a halide (chloride ion, bromide ion, etc) to the aromatic (benzene) ring;
(b) an ester linkage;
(c) a large alkyl group on the tertiary amide nitrogen.
What term defines the lowest concentration of local anesthetic that blocks impulse conduction along a given nerve fiber?
The Minimum Blocking Concentration (Cm) is the lowest concentration of a local anesthetic that blocks conduction
Which local anesthetic agent is the standard for comparison of potencies of local anesthetics?
Lidocaine.
The rapidity and extent of diffusion of a local anesthetic to its site of action depends primarily on what three factors?
(1) The pKa of the drug, (which determines the degree to which the drug is un-ionized), (2) the concentration injected, and (3) its lipid solubility.
How does succinykholine produce bradycardia?
Succinylcholine stimulates muscarinic receptors at the sino-atrial node.
Do patients with myasthenia gravis have increased or decreased sensitivity to nondepolarizing neuromuscular
blockers?
Patients with myasthenia gravis have greatly increased sensitivity to nondepolarizing agents
Do patients with myasthenia gravis have increased or decreased sensitivity To depolarizing neuromuscular
blockers?
These patients may be either very sensitive or resistant
to succinylcholine.
If possible, should muscle relaxants be avoided in the patient with myasthenia gravis?
If possible, muscle relaxants should be avoided in the
patient with myasthenia gravis
What type of muscle relaxant is preferred (short, intermediate or long-acting) if skeletal muscle paralysis in a patient being treated for myasthenia gravis is necessary?
Short or intermediate-acting (cisatracurium or mivacurium) muscle relaxants are preferred
Succinykholine is routinely administered before a paralyzing dose of a nondepolarizing agent. Does the succinylcholine antagonize or potentiate the nondepolarizing drug?
When administered after succinykholine, the potency of nondepolarizing muscle relaxants is enhanced. This is unexpected and may be related to unrecognized phase II blockade.
State the signs and symptoms of Beta receptor antagonist overdose. Which specific Beta receptor properties correlate with these signs and symptoms?
The manifestations of Beta receptor antagonist overdose depend on the characteristic of the drug, particularly its Beta-1 selectivity, intrinsic sympathomimetic activity, and membrane-stabilizing properties.
Are common signs of beta blocker toxicity.
Hypotension, bradycardia, prolonged AV conduction times and widened QRS complexes. Seizures and depression may occur, as well as hypoglycemia and bronchospasm.
Describe the treatment of Beta-adrenergic antagonist (beta blocker) overdose.
Overdose of Beta-blocking drugs may be treated with atropine, but isoproterenol, dobutamine, or GLUCAGON infusion (or some combination) may be required along with cardiac pacing to ensure an adequate rate of contraction.
The alpha-2 adrenergic receptor agonist, clonidine, acts where centrally to produce what therapeutic effect?
Stimulation of alpha-2A receptors of inhibitory neurons in the vasomotor center of the medulla in the brain stem inhibits sympathetic nervous system outflow. This action decreases blood pressure.
Alpha-2 adrenergic receptor agonists antagonize the sympathetic nervous system peripherally. How?
Alpha-2 receptors are found peripherally in the surface membrane of the norepinephrine-containing presynaptic nerve terminals of sympathetic postganglionic neurons. Stimulation of these receptors decreases the release of norepinephrine from the presynaptic nerve terminal. This decreased release of norepinephrine contributes modestly to the clonidine·induced decrease in blood pressure.
By what receptor and second messenger system does glucagon exert its positive inotropic and chronotropic effects?
Glucagon acts through its own G-protein coupled receptor (GPCR) and generation of cyclic adenosine monophosphate (cAMP). In other words, glucagon binds to glucagon receptors to promote the formation of cAMP.
The hemodynamic benefits of glucagon might be useful in what 5 situations?
The hemodynamic benefits of glucagon-positive inotropy and positive chronotropy may be beneficial in:
(I) low cardiac output syndrome following cardiopulmonary bypass;
(2) low cardiac output syndrome with myocardial infarction; (3) chronic congestive heart failure;
(4) anaphylactic shock with refractory hypotension; and,
(5) excessive Beta-adrenergic blockade
Define autacoid.
Autacoids (or autocoids) are biological factors that act like local hormones, that is they have a paracrine (neighboring) effect.
List examples of autacoids.
Notable human autacoids include eicosanoids, angiotensin, nitric oxide (NO), kinins, histamine, serotonin, and endothelins
Unlike hormones, autacoids are produced in
minute quantities and have local, evanescent (brief)
effects.
What are eicosanoids?
Eicosanoids (from the Greek eicosa “twenty”) are signaling molecules derived from omega-3 and omega-6 fatty acids including arachidonic acid.
Eicosanoids include
prostaglandins, thromboxanes, leukotrienes, and lipoxins.
Eicosanoids are not
stored but rather are produced on demand.
How are prostanoids related to eicosanoids?
Prostanoids are metabolic derivatives of arachidonic acid, therefore prostanoids are a category of eicosanoids.
Cyclooxygenase (COX) acts on_____To produce
arachidonic acid to produce PGH2.
Three types of prostanoids are then derived from
PGH2
prostaglandins, prostacyclins, and thromboxanes.
Arachidonic acid, an omega-6 fatty acid, is liberated from membrane phospholipids by the action of what enzyme?
Phospholipase A1 (PLA2). a calcium-dependent enzyme, acts upon membrane phospholipids to release arachidonic acid.
What is the rate-limiting step in eicosanoid synthesis?
The release of arachidonic acid from membrane phospholipids
Which prostanoid is implicated in the rebound prothrombotic state often seen following discontinuation of antiplatelet therapy?
An increased thromboxane A1 (TxA2) activity is seen during the rebound period following discontinuation of antiplatelet therapy
Name two prostanoids that are potent inhibitors of platelet aggregation and thus promote and maintain an antithrombotic state in vessels?
The vascular endothelium releases prostacyclin (PGI2) and PGD2, along with nitric oxide (NO) and other factors to maintain an anticoagulant state
Which prostanoid produces vascular smooth muscle contraction and is thus a potent vasoconstrictor?
Thromboxane A2 (TxA2) produces contraction of vascular smooth muscle and is a potent vasoconstrictor.
TxA2 has local effects at the
systemic vasculature, coronary vasculature, and renal vasculature (decreased RBF and decreased GFR).
List two prostanoids that cause bronchodilation. List three prostanoids that cause bronchoconstriction.
PGEi and PGh are bronchodilators, whereas PGF2a • PGD2, and TxA2 cause bronchoconstriction
How are leukotrienes related to eicosanoids?
Leukotrienes are metabolic derivatives of arachidonic acid, therefore leukot rienes (LT) are a category of eicosanoids.
Lipoxygenase (LOX) acts on _____To produce what?
arachidonic acid to produce the Leukotriene family.
Leukotrienes that increase smooth muscle contraction,
microvascular permeability, and airway mucus secretion.[
LTC4 , LTD4, LTE4 and LTB 4
What action do leukotrienes (LT) have on the lungs?
Leukotrienes evoke inflammatory responses in the lungs including intense bronchoconstriction and increased pulmonary vascular permeability.
Leukotrienes also promote
eosinophil degranulation and attract neutrophils, both key players in the inflammatory response.
What is another name for the mixture of leukotrienes C4, D4 and E4?
The mixture ofleukotrienes C4, D4, and E4 is the classic slow-reacting substance of anaphylaxis (SRS-A).
Which herbal supplement is a potent inhibitor of thromboxane synthetase and thus has synergistic effects with other antiplatelet agents?
Ginger is a potent inhibitor of thromboxane synthetase and thus increasesbleeding time and morbidity
Which herbal supplement is a potent inhibitor of thromboxane synthetase and thus has synergistic effects with other antiplatelet agents?
Ginger is a potent inhibitor of thromboxane synthetase and thus increases bleeding time and morbidity
Which dopamine antagonists is the only FDA-approved agent for treatment of Diabetic GASTROPARESIS
Metoclopramide is the only drug approved by the FDA for diabetic gastroparesis
How does metoclopramide work?
Via cholinergic stimulation , acts as a gastrointestinal prokinetic drugs that increases LES tone and stimulated motility of the upper GI tract.
List 7 common adverse effects of metoclopramide?
TRES-GIA
- Treatable hypotension and tachycardia
- Restlessness
- EPS
- Sedation
- Galatorrhea
- Inhibition of plasma cholinesterase
- Abdominal cramping
4 contraindications to administration of metoclopramide (PRIM)
Parkinson’s disease
Restless leg syndrome
Intestinal obstruction ,(Because metoclopramide prokinetic effect)
Movement disorders related to dopamine inhibition or depletion
For what conditions are alpha-glucosidase inhibitors administered?
The medical treatment of insulin resistance and hyperglycemia in metabolic syndrome, type 2 diabetes, and obesity is usually achieved with oral hypoglycemic drugs including a-glucosidase inhibitors,
sulfonylureas, meglitinides, D-phenylalanine derivatives, diguanides, and thiazolidinediones
How do alpha-glucosidase inhibitors work?
a-Glucosidase inhibitors (acarbose, miglitol) decrease postprandial carbohydrate digestion and absorption at the intestinal brush border. By reducing absorption of starch, dextrose, and disaccharides, a-glucosidase inhibitors blunt the rise of postprandial glucose.
Medications that blunt the rise of postprandial glucose?
Alpha glucosidase inhibitors
What medications are classified as alpha glucosidase inhibitors?
Acarbose
Miglitol
List the most common side effects of alpha-glucosidase inhibitors (FAD)
Flatulence
Abdominal cramping,
Diarrhea are side effects that frequently
result from undigested carbohydrates that reach bacteria in the lower colon.
Medications for diabetes, Safe and nontoxix With the exception of occasional increases in liver transaminases,
alpha-glucosidase inhibitors
What type of metabolic disturbance may furosemide (Lasix) promote?
Furosemide (Lasix) causes increased delivery of Na+ to the distal tubules and collecting ducts which increases K+ and H+ secretion, leading to HYPOKALEMIA and METABOLIC ALKALOSIS
What type of metabolic disturbance may Acetazolamide (Diamox) promote?
Acetazolamide {Diamox) may promotes excretion of an alkaline urine and a resulting HYPERCHLOREMIC METABOLIC ACIDOSIS
What diuretics is an inhibitor of carbonic anhydrase?
Acetazolamide
Where does carbonic anhydrase act?
Proximal tubule
Where does acetazolamide act?
Proximal tubule
Osmotic diuretics medications are (3)
{mannitol, glycerin, isosorbide)
Where do osmotic diuretic medication work
Loop of Henle (If you see proximal tubule may be right as well)
What are loop diuretics (34) BET Fu
Bumetanide
Ethacrynic acid
Furosemide
Torsemide
Loops diuretics act by
Inhibition of Na+-K-2Cl- symport acting at the thick ascending limb (TAL) of the Loop of Henle.
Loop diuretics work where
TAL of LOOP of HENLE
What are the thiazide and thiazide like diuretics name a few?
HCTZ, chlorothiazide, Methylclothizide, -zide, -azone, -one)
How do the thiazide diuretics work?
Inhibition of Na+-Cl- symport at the distal tubules
What are 2 of the potassium-sparing diuretics?
Triamterene
Amiloride
How does potassium sparing diuretics work?
Inhibit renal sodium channels in the LATE DISTAL TUBULE and COLLECTING TUBULE
Where does potassium sparing diuretics work
LATE DISTAL TUBULE
COLLECTING TUBULE
What are the medications classified as ANTAGONISTS of mineralcorticoid receptors?
Spironolactone
Eplerenone
Where do Antagonists of mineralcorticoid receptors work?
Late Distal tubule
collecting ducts
A human recombinant BNP is what medications?
Nesiritide
Where does nesiritide, a human recombinant BNP work?
at the inner medullary collecting duct
Mnemonic to remember where medications class work COL TKA
Carbonic anhydrase inhibitors Osmotic diuresis Loop diuretics Thiazides K+ Sparing Aldosterone Antagonists.
Bleomycin is toxic to what body organ?
Bleomycin, an antibiotic/chemotherapeutic, is toxic to the pulmonary system.
Why does bleomycin accumulate in the pulmonary system?
Bleomycin is concentrated preferentially in the lung because the enzyme that inactivates bleomycin {hydrolase) is relatively deficient in lung tissue
In what two ways does bleomycin damage the lung?
l) Bleomycin initially produces pulmonary capillary endothelial damage, progressing to alveolar epithelial injury with necrosis of type I and proliferation of type II alveolar cells. Interstitial fibrosis develops and may progress to involve the entire lung. (2) Pulmonary injury also occurs because of the production of reactive oxygen metabolites.
In lungs, Bleomycin generates
superoxide anions which damage tissue and also attract and activate neutrophils and macrophages. Neutrophils and macrophages cause tissue damage when activated.
Pulmonary toxicity occurs in what percentage of the patient’s treated with bleomycin?
4. Cisplatin is
Pulmonary toxicity occurs in 10-25% of patients on bleomycin. The toxicity ranges from a decrease in pulmonary function to severe pulmonary fibrosis.
WIth BLEOMYCIN, Do pulmonary function tests demonstrate normal function, restrictive disease, or obstructive disease?
Pulmonary function tests demonstrate restrictive pulmonary disease
What happens to pulmonary diffusing capacity with BLEOMYCIN?
decreased pulmonary diffusing capacity
Cisplatin is toxic to what organ?
Kidney
How does kidney function change during cisplatin therapy?
Cisplatin causes a progressive fall in glomerular filtration rate (GFR) and development of acute tubular necrosis beginning 3 to 5 days after administration.
There is_______ and ________ with cisplatin therapy
Increase BUN and Creatinine
2 issues with cisplastin aside from INcrease BUN and cr
Proteinuria
Hyperuricemia
There is a magnesium-wasting defect in up to 50% of patients. Renal impairment may progress to acute renal
failure requiring hemodialysis.
Antiemetic agents typically block one (or more) of six receptors-list these six receptors. HiMuDoGSeN
(2) histamine receptors
(3) muscarinic Ach Receptors
((l) dopamine receptors (D2)
(5) GABA A receptors;
(4) serotonin receptors (S-HT3); and,
(6) NKl (neurokinin-l) receptors.
Antiemetics and receptors: Dopamine receptors
metodopramide, droperidol, haloperidol, alizapride, perphenazine, and prochlorperazine
Which dopamine receptor do antiemetic mostly work on
D2
Antiemetic Medication that work on Histamine receptors (H1) receptors
dimenhydrinate, diphenhydramine, cyclizine, and promethazine. Muscarinic ACh receptors: hyoscine.
Antiemetic Medications that work on Serotonin receptors (5-HT3) :” -setron”
ondansetron, dolasetron, granisetron, tropisetron,
ramosetron, and palonosetron.
Antiemetic medication work on Neurokinin-1 receptors NK
Aprepitant
The antiemetic mechanism of action of dexamethasone is
unknown
List 8 treatments for hypercalcemia.
(l) volume expansion with normal saline (4-6 Lin first 24 hours)
(2} loop diuretics (enhances renal excretion of calcium)
(3) bisphosphonates (zoledronic acid, pamidronate, etidronate) to inhibit bone resorption of calcium
(4} mithramycin
(5) calcitonin
(6)Glucocorticoids
(7) phosphates, and
(8) rarely, plicamycin
What is the Bronsted-Lowry theory?
The Bronsted-Lowry theory is a theory pertaining to acids and bases wherein the acid is a proton (hydrogen ion) donor and the base is a proton (hydrogen ion) acceptor
What is the pH of a liter of water?
pH= 7, at 24 degrees C.
What is an acid? Why is a substance called a weak acid?
An acid is a hydrogen ion, or proton, donor. A weak acid is one that does not ionize 100% in solution. Strong acids, such as hydrochloric acid, are 100% ionized in solution
Why is carbonic acid considered a weak acid?
Carbonic acid ionizes only 0.2% in physiologic solution. An acid that does not dissociate 100% to its ionized form is a weak acid.
What agents used in anesthesia are weak acids?
Barbiturates and propofol
What agents used in anesthesia are weak bases?
Weak bases include: all local anesthetics; all opioids (fentanyl, alfentanil, morphine, etc); benzodiazepines (diazepam, midazolam, etc); etomidate;nand ketamine.
What are optical isomers? Give two examples.
Optical isomers are mirror images. L-glucose and d-glucose are examples of optical isomers. L-ketamine and d-ketamine are also optical isomers.
What is the name for two optical isomers mixed together in a solution?
A solution with two optical isomers is a racemic solution
Le Chatelier’s principle, derived from the law of mass action is when
When the concentration of a reactant increases, the reaction is driven toward the production of products. Conversely, when the concentration of reactant decreases,
the reaction is driven toward the production of more reactants and less products.
Le Chatelier’s principle, derived from what law?
law of mass action
What effect does hypothermia have on gas solubility?
As a liquid is cooled, more gas dissolves in the liquid, therefore hypothermia will cause an increase in gas solubility.
Define the inverse square law.
Isaac Newton demonstrated that the strength of emanating energy is inversely proportional to the square of its distance from the source, the inverse square law.
Newton’s original description was for the force of gravity and we now know the inverse square law applies to
pressure energy (sound), light, electricity, and radiation
Occupational exposure to radiation comes primarily from X-rays scattered by the patient and the surrounding
equipment, rather than directly from the X-ray generator itself. State 4 methods to minimize exposure to scattered
radiation.
1) Limit the Duration of exposure.
(2) Increase the Distance from source (the inverse square law)
(3) Use protective shielding such as lead-lined garments or protective shields-Deflect the radiation.
(4) Use a Dosimeter to monitor exposure
Since X-rays obey the inverse square law, the best protection from scattered radiation is physical separation. What is the minimum safe distance from the
X-ray source?
Since X-rays obey the inverse square law, the minimum recommended distance from an X-ray source is 6 feet.
X-rays obey what law?
inverse square law,
The greatest intensity of an X-ray is
directly in front of the beam generator.
Standing at least 6 feet away and behind or to the side of the beam direction
lessens exposure
What is the annual dose limit for occupational exposure to radiation?
In the United States, the National Council on Radiation Protection and Measurements (NCRP) recommends a limit for occupational exposure to radiation of 50 mSv (5 rem) in any 1 year.
The lifetime dose limit for radiation exposure is
The lifetime limit for occupation exposure to radiation is 10 mSv (1 rem) multiplied by the individual’s age
What is Dalton’s law?
Dalton’s law of partial pressures states that the total pressure (TP) of a group of gases is equal to the sum of their individual partial pressures. • Mathematically, Ptotal = P1 + P2 + P3.
The formation of metanephrine is the result of:
catechol-O-methyltransferase metabolism of epinephrine
Catechol-O-methyltransferase (COMT) metabolizes epinephrine to and norepinephrine to normetanephrine
metanephrine
Subsequently, monamine oxidase (MAO) further metabolizes metanephrine and normetanephrine to
vanillymandelic acid (VMA).
Catechol-O-methyltransferase (COMT) metabolizes norepinephine to
normetanephrine
