The taeniae coli are the three outer muscular bands of the cecum, ascending colon, transverse colon, and descending colon.

The taeniae coli converge at the base of the appendix in the cecum where they form a complete longitudinal layer. In the ascending and descending colon, the bands are located anteriorly, posteromedially, and posterolateral.

Lesser the potency of the drug, the higher the dose required to produce maximal receptor occupation. So, the least potent drug will have a log dose-response curve furthest to the right on X-axis.

Based on the option given, tramadol is the least potent drug and thus higher dose is required to produce maximal opioid receptor occupation.

Thus, Tramadol is the least potent opioid with a log dose-response curve furthest to the right on X-axis.

Note, Fentanyl is the most potent opioid with a log dose-response curve furthest to the left on the X-axis.

Second messengers relay signals to target molecules in the cytoplasm or nucleus when an agonist interacts with a receptor on the cell surface. They also amplify the strength of the signal. The most ubiquitous and abundant second messenger is calcium and it regulates multiple cellular functions in the body.

These include:
Muscle contraction (skeletal, smooth and cardiac)
Exocytosis (neurotransmitter release at synapses and insulin secretion)
Apoptosis
Cell adhesion to the extracellular matrix
Lymphocyte activation
Biochemical changes mediated by protein kinase C.

cAMP is either inhibited or stimulated by G proteins.

The receptors in the body that stimulate G proteins and increase cAMP include:

Beta (?1, ?2, and ?3)
Dopamine (D1 and D5)
Histamine (H2)
Glucagon
Vasopressin (V2).

The second messenger for the action of nitric oxide (NO) and atrial natriuretic peptide (ANP) is cGMP.

The second messengers for angiotensin and thyroid stimulating hormone are inositol triphosphate (IP3) and diacylglycerol (DAG).

Cardiac conduction

Phase 0 – Rapid depolarization. Opening of fast sodium channels with large influx of sodium

Phase 1 – Rapid partial depolarization. Opening of potassium channels and efflux of potassium ions. Sodium channels close and influx of sodium ions stop

Phase 2 – Plateau phase with large influx of calcium ions. Offsets action of potassium channels. The absolute refractory period

Phase 3 – Repolarization due to potassium efflux after calcium channels close. Relative refractory period

Phase 4 – Repolarization continues as sodium/potassium pump restores the ionic gradient by pumping out 3 sodium ions in exchange for 2 potassium ions coming into the cell. Relative refractory period

Severity of a reduction in restrictive defect (%FVC) or obstructive defect (%FEV1/FVC) predicted are classified as follows:

Mild 70-80%
Moderate 60-69%
Moderately severe 50-59%
Severe 35-49%
Very severe <35% This patient has a %FVC predicted of 60.4% and this corresponds to a moderate restrictive deficit. %FEV1/FVC ratio is 93.5%. FEV1/FVC ratio 80% < predicted and VC < 80% = mixed picture. FEV1/FVC ratio 80% < predicted and VC > 80% = obstructive picture.

FEV1/FVC ratio 80% > predicted and VC > 80% = normal picture.

FEV1/FVC ratio 80% > predicted and VC < 80% predicted= restrictive picture. The integrity of the alveolar-capillary barrier is measured by carbon monoxide transfer factor (TLCO) and carbon monoxide transfer coefficient (KCO). These values are seen to be reduced in emphysema, interstitial lung diseases and in pulmonary vascular pathology. However, the KCO (as % predicted) is high in extrapulmonary restriction (pleural, chest wall and respiratory neuromuscular disease), and in loss of lung units provided the structure of the lung remaining is normal. The KCO distinguishes extrapulmonary (high KCO) causes of ‘restriction’ from intrapulmonary causes (low KCO).

Osmolarity refers to the osmotic pressure generated by the dissolved solute molecules in 1 L of solvent. Measurements of osmolarity are temperature dependent because the volume of the solvent varies with temperature. The higher the osmolarity of a solution, the more it attracts water from an opposite compartment.

Osmolarity can be computed using the following formulas:

Osmolarity = Concentration x number of dissociable particles; OR
Plasma osmolarity (Posm) = 2([Na+]) + (glucose in mmol/L) + (BUN in mmol/L)

Posm = 2 (144) + 3.5 + 9.5 = 301 mOsm/L

Suppose there is electrical neutrality, the formula will double the cation activity to account for the anions.

Plasma osmolarity (Posm) = 2([Na+] + [K+]) + (glucose in mmol/L) + (BUN in mmol/L)

Posm = 2 (144 + 6) + 3.5 + 9.5 = 313 mOsm/L

The relationship between bacterial growth and time is a tear-away exponential. The mathematical relationship between y and x in this case is:

y = ex

Where: the power is x, and the base is e.

Euler’s number (e) is a mathematical constant that is the base for all logarithms occurring naturally. Its value is 2.718.

The statement X increasing with an increase in Y is proportional to Y refers to the change in y in terms of x when considering any exponential relationship.

This is not a build-up exponential, and that is mathematically stated as y = 1-e-kt.

The negative x axis being a horizontal asymptote and the y intercept being 0, 1 are examples of tearaway exponentials , but do not describe an exponential process.

Absolute risk reduction = (Control event rate) – (Experimental event rate)

Experimental event rate = 24 / 120 = 0.2

Control event rate = 60 / 240 = 0.25

Absolute risk reduction = 0.25 – 0.2 = 0.05 = 5% reduction

Systemic vascular resistance (SVR) is a derived value based on:

SVR = (MAP-CVP)/CO x 80

= (60 -10)/5 x 80 = 800 dynes.s.cm-5

A correction factor of 80 is needed in converting mmHg to dynes.s.cm-5
Normal values is between 700 -1600 dynes.s.cm-5

Pulmonary resistance (PVR) = (MPAP-PCWP)/CO x 80

= (10 – 5)/5 x 80 = 80 dynes.s.cm-5

To account for body size, cardiac index (CI) can be used instead of CO. CI = CO/body surface area (m2) or mL/minute/m2.
N/B: either MAP and CVP, or MPAP and PCWP are used in calculation to get dynes.s.cm-5

The hormone parathyroid hormone (PTH) and the receptor parathyroid hormone type 1 (PTH1-Rc) are important regulators of blood calcium homeostasis.

PTH can cause a rapid release of calcium from the matrix in bone, but it also affects long-term calcium metabolism by acting directly on bone-forming osteoblasts (by binding to PTH1-Rc) and indirectly on bone-resorbing osteoclasts.

PTH causes changes in the synthesis and/or activity of several proteins, including osteoclast-differentiating factor, also known as TRANCE or RANKL, when it acts on osteoblasts.

RANK receptors are found on the cell surfaces of osteoclast precursors. The osteoclasts are activated when RANKL binds to the RANK receptors. Osteoclasts lack PTH receptors, whereas osteoblasts do. Osteoclasts are activated indirectly when the RANK receptor binds to the RANKL secreted by osteoblasts, resulting in bone resorption. PTH1 receptors are found in osteoclasts, but they are few.

PTH activates G-protein coupled receptors in all target cells via adenylate cyclase.

The PTH2 receptor is most abundant in the nervous system and pancreas, but it is not a calcium metabolism regulator. It is abundant in the septum, midline thalamic nuclei, several hypothalamic nuclei, and the dorsal horn of the spinal cord, as well as the cerebral cortex and basal ganglia. Expression in pancreatic islet somatostatin cells is the most prominent on the periphery.

The distribution of the receptor is being used to test functional hypotheses. It may play a role in pain modulation and hypothalamic releasing-factor secretion control.

Gabapentin is an amino acid-like molecules that was originally synthesized as an analogue of GABA but is now known not to act through GABA mechanisms. It is used in the treatment of focal seizures and various nonepilepsy indications, such as neuropathic pain, restless legs syndrome, and anxiety disorders.

Despite its close structural resemblance to GABA, gabapentin does not act through effects on GABA receptors or any other mechanism related to GABA-mediated neurotransmission. Rather gabapentin binds avidly to ?2?, a protein that serves as an auxiliary subunit of voltage-gated calcium channels. Moreover, it binds to NMDA receptor to modulate its transmission.

Drugs cross the placenta by Simple, Ion channel and Facilitated diffusion; Exocytosis and Endocytosis, Osmosis, and Active transport (primary and secondary)

The following factors influence rate of diffusion across the placenta:

Protein binding
Degree of ionisation
Placental blood flow
Maternal and foetal blood pH
Materno-foetal concentration gradient.
Thickness of placental membrane
Molecular weight of drug <600 Daltons cross by diffusion
Lipid solubility (lipid soluble molecules readily diffuse across the placenta)

Rocuronium has a F/M ratios of 0.16, a 30% plasma protein binding, low lipid solubility, a low volume of distribution (0.25L/kg), and a high molecular weight (530Da).

Her symptoms are suggestive of trigeminal neuralgia which is a short, sudden, severe sharp unilateral pain in the facial region. The pain often follows the sensory distribution of the trigeminal nerve (CN V).

The trigeminal nerve gives rise to 3 sensory and 1 motor nuclei. Neuralgia can arise from any of the 3 sensory divisions.

The ophthalmic division gives rise to 3 further sensory branches, which are the frontal, lacrimal and nasociliary.

The frontal branch of the ophthalmic division of the trigeminal nerve is responsible for the innervation of the area in question.

The superior alveolar dental, zygomatic and sphenopalatine nerves are all branches arising from the maxillary division of the trigeminal nerve.

The mandibular division of the trigeminal nerve provides sensory and motor innervation. The sensory innervation is carried out by the auriculotemporal nerve which supplies the lower third of the face, while the motor fibres are responsible for controlling the muscles of mastication.

The somatic sensory branches of the vagus nerve are responsible for sensory innervation of the external acoustic meatus and tympanic membrane.

The incidence of a disease is the number of new cases of the disease in a population over a defined time period.

The prevalence of a disease is the number of cases of the disease in a population over a defined time period describes. It is NOT the number of new cases.

The number of new cases of a disease only, has no denominator (time period or population) from which to derive an incidence.

The number of new cases of a disease seeking medical treatment is the incidence of patients seeking medical treatment NOT the incidence of the disease in a population.

The death rate from a disease is the number of patients dying from the disease in a population.

Bucks fascia refers to the layer of loose connective tissue, nerves and blood vessels that encapsulates the penile erectile bodies, the corpa cavernosa and the anterior part of the urethra, including the entirety of the spongiose part of the urethra.

It runs with the external spermatic fascia and the penile suspensory ligament.

With respect to oxygen transport in cells, almost all oxygen is transported within erythrocytes. There is limited solubility and only 1% is carried as solution. Thus, the amount of oxygen transported depends upon haemoglobin concentration and its degree of saturation.

Haemoglobin is a globular protein composed of 4 subunits. Haem is made up of a protoporphyrin ring surrounding an iron atom in its ferrous state. The iron can form two additional bonds – one is with oxygen and the other with a polypeptide chain.
There are two alpha and two beta subunits to this polypeptide chain in an adult and together these form globin. Globin cannot bind oxygen but can bind to CO2 and hydrogen ions.
The beta chains are able to bind to 2,3 diphosphoglycerate. The oxygenation of haemoglobin is a reversible reaction. The molecular shape of haemoglobin is such that binding of one oxygen molecule facilitates the binding of subsequent molecules.

The oxygen dissociation curve (ODC) describes the relationship between the percentage of saturated haemoglobin and partial pressure of oxygen in the blood.
Of note, it is not affected by haemoglobin concentration.

Chronic anaemia causes 2, 3 DPG levels to increase, hence shifting the curve to the right

Haldane effect – Causes the ODC to shift to the left. For a given oxygen tension there is increased saturation of Hb with oxygen i.e. Decreased oxygen delivery to tissues.
This can be caused by:
-HbF, methaemoglobin, carboxyhaemoglobin
-low [H+] (alkali)
-low pCO2
-ow 2,3-DPG
-ow temperature

Bohr effect – causes the ODC to shifts to the right = for given oxygen tension there is reduced saturation of Hb with oxygen i.e. Enhanced oxygen delivery to tissues. This can be caused by:
– raised [H+] (acidic)
– raised pCO2
-raised 2,3-DPG
-raised temperature

A Wrights Respirometer measures the volume of air exhaled over the course of one minute of normal breathing

It is unidirectional and measures tidal volume and minute volume of gas flow in one direction. It is placed at the expiratory side (lower pressure than inspiratory side therefore lower chances of gas leaks)

Slits are arranged such that incoming gas will rotate the vane at a rate of 150 revolutions per litre of flowing gas

The Wright respirometer tends to over-read at high flow rates and under-read at low flows because of mechanical causes like friction and inertia and the accumulation of water vapour

The ideal flow for accurate readings is 2 L/min for the respirometer. The respirometer reads the tidal volume and minute volume with a ±5–10% accuracy within the range of 4–24 L/min.

Silent (S) is the most probable phenotype of the patient. In S phenotype, patients have significantly reduced levels of BChE, the lowest among the four phenotypes. Because of this, individuals with S phenotype are subjected to long periods of apnoea. In addition, their dibucaine number is very low.

Other BChE phenotypes are the following:

Usual (U)
Atypical (A)
Fluoride-resistant (F)

The starling forces operate to maintain a homeostatic flow across the pulmonary capillary bed.

The outward driving force comprises of the capillary hydrostatic pressure (13 mmHg), negative interstitial fluid pressure (zero to slightly negative), and interstitial colloid osmotic pressure (17 mmHg). The inward driving force is controlled by the plasma colloid osmotic pressure (25 mmHg).

This question is asking which structure would lie posterior to the rectus abdominis muscle and not the prosthetic mesh, as only peritoneum lies posterior to mesh during a total extraperitoneal (TEP) hernia repair.

The region of the repair lies below the arcuate line, meaning that the transversalis fascia and peritoneum lie posterior to the rectus abdominis.

The bucks fascia lies within the penis.

Decreased platelet concentrations with eclampsia were described as early as 1922 by Stancke. The platelet count is routinely measured in women with any form of gestational hypertension. The frequency and intensity of thrombocytopenia vary and are dependent on the severity and duration of the preeclampsia syndrome and the frequency with which platelet counts are performed.

Overt thrombocytopenia defined by a platelet count < 100,000/microliter - indicates severe disease. In general, the lower the platelet count, the higher the rates of maternal and fetal morbidity and mortality. In most cases, delivery is advisable because thrombocytopenia usually continues to worsen. After delivery, the platelet count may continue to decline for the first day or so. It then usually increases progressively to reach a normal level within 3-5 days. In some instances with HELLP syndrome, the platelet count continues to fall after delivery. If these do not reach a nadir until 48 to 72 hours, then preeclampsia syndrome may be incorrectly attributed to one of the thrombotic microangiopathies. The following are other severe features associated with preeclampsia: Proteinuria: >/= 300 mg/24 hours; or urine protein: creatinine ratio >/= 0.3; or dipstick 1+

Renal insufficiency: serum creatinine > 1.1 mg/dL or doubling of creatinine in the absence of other renal disease

Impaired liver function: two times elevated AST/ALT or unexplained right upper quadrant pain or epigastric pain unresponsive to medications

Pulmonary oedema

Cerebral or visual symptoms: headache, visual disturbances

Asthma is a lung condition that causes reversible narrowing and swelling of airway passages. It is classified by the frequency and severity of symptoms.

The following are symptoms of moderate asthma:

Symptoms include cough, wheezing, chest tightness, or difficulty breathing which occurs daily
Decreased activity levels due to flare-ups
Night-time symptoms 5 or more times a month
Lung function test FEV1 is 60-80% of predicted normal values
Peak flow has more than 30% variability

With moderate asthma attacks, the arterial pCO2 levels may decrease, but as severity increases, so does the pCO2, reaching normal levels, and then exceeding them in severe asthma attacks.

Airway obstruction increases the functional residual capacity.

Concentration of serum bicarbonate would not increase in moderate asthma, but it could possibly increase in life-threatening asthma via the same mechanism as what increases arterial PCO2.

FEV1 is a good measure of airway obstruction. and is reduced in acute asthma attacks.

In the case of a pneumothorax, a decrease in arterial PO2 is higher.

The superficial inguinal ring is an opening in the aponeurosis of the external oblique muscle, just above and lateral to the pubic crest.

The superficial ring resembles a triangle more than a ring with the base lying on the pubic crest and its apex pointing towards the anterior superior iliac spine. The sides of the triangle are crura of the opening in the external oblique aponeurosis. The lateral crura of the triangle is attached to the pubic tubercle. The medial crura of the triangle is attached to the pubic crest.

The external oblique aponeurosis forms the anterior wall of the inguinal canal and also the lateral edge of the superficial inguinal ring. The rectus abdominis lies posteromedially, and the transversalis posterior to this.

Dorsal column (ascending tract) – Proprioception, vibration, discriminative

Spinocerebellar (ascending tract) – Subconscious muscle position and tone

Corticospinal (descending tract) – Voluntary muscle

Rubrospinal (descending tract) – Flexor muscle tone

Vestibulospinal (descending tract) – Reflexes and muscle tone

Reticulospinal(descending tract) – Voluntary movements, head position.-

Autonomic – Descending tract.

Opioid receptors are a large family of seven transmembrane domain receptors. They are of four types:

1) Delta opioid receptor

2) Mu opioid receptor

3) Kappa opioid receptor

4) Orphan receptor-like 1

They contain about 372-400 amino acids and thus their molecular weight is different.

Opioid receptor activation reduces the intracellular cAMP formation and opens K+ channels (mainly through µ and δ receptors) or suppresses voltage-gated N-type Ca2+ channels (mainly κ receptor). These actions result in neuronal hyperpolarization and reduced availability of intracellular Ca2+ which results in decreased neurotransmitter release by cerebral, spinal, and myenteric neurons (e.g. glutamate from primary nociceptive afferents).

However, other mechanisms and second messengers may also be involved, particularly in the long-term

The derived unit of energy, work or amount of heat is joule (J). It is defined as the amount of energy expended if a force of one newton (N) is applied through a distance of one metre (N·m)

J = 1 kg·m/s2·m = 1 kg·m2/s2 or 1 kg·m2·s-2

Kinetic energy (KE) = ½ MV2

An object with a mass of 1500 kg moving at 30 m/s correlates to 675 kJ:

KE = ½ (1500) × (30)2 = 750 × 900 = 675 kJ

Total energy released when 1 kg fat is metabolised to CO2 and water is 37 MJ. 1 g fat produces 37 kJ/g, therefore 1 kg fat produces 37,000 × 1000 = 37 MJ.

Raising the temperature of 1 kg water from 0°C to 100°C correlates to 420 kJ. The amount of energy needed to change the temperature of 1 kg of the substance by 1°C is the specific heat capacity. We have 1 kg water therefore:

4,200 J × 100 = 420,000 J = 420 kJ

In order to calculate the energy involved in raising a 100 kg mass to a height of 1 km against gravity, we need to calculate the potential energy (PE) of the mass:

PE = mass × height attained × acceleration due to gravity
PE = 100 kg × 1000 m × 10 m/s2 = 1 MJ

The heat generated when a direct current of 10 amps flows through a heating element for 10 seconds when the potential difference across the element is 1000 volts can be calculated by applying Joule’s law of heating:

Work done (WD) = V (potential difference) × I (current) × t (time)
WD = 10 × 10 × 1000 = 100 kJ

This sudden change in pulse rate is due to the oculocardiac reflex. It is a >20% reduction in pulse rate as a result of placing pressure directly on the eyeball. The reflex arc has an afferent and efferent arm:

The afferent (sensory) arm: The trigeminal nerve (CN V)

The efferent arm: The vagus nerve (CN X)

The most appropriate action is to ask the surgeon to stop retraction of the extraocular muscles, Assess for hypoxia, and give 100% oxygen if indicated.

Atropine of glycopyrrolate can be administered to counteract the reflex, and also prevent any further vagal reflexes.

Administration of fentanyl may increase patient’s risk of bradycardia and sinus arrest in this case.

Adrenaline is not indicated here as other treatment options will provide sufficient relief from arrhythmia.

Bilirubin is the tetrapyrrole and a catabolic product of heme. 70-90% of bilirubin is end product of haemoglobin degradation in the liver.

Bilirubin circulates in the blood in 2 forms; unconjugated and conjugated bilirubin.

Unconjugated bilirubin is insoluble in water. It travels through the bloodstream to the liver, where it changes from insoluble into a soluble form (i.e.; unconjugated into conjugated form).

This conjugated bilirubin travels from the liver into the small intestine and the gut bacteria convert bilirubin into urobilinogen and then into urobilin (not urobilin to urobilinogen). A very small amount passes into the kidneys and is excreted in urine.

Sensory innervation of the larynx is controlled by branches of the vagus nerve.

The internal and external bifurcations of the superior laryngeal nerve is responsible for sensory innervation of the aspect of the larynx superior to the vocal cords, while the recurrent laryngeal nerve is responsible for sensory innervation of the intrinsic musculature of the larynx except for the cricothyroid muscle.

Number needed to treat (NNT) is a time specific epidemiological measure that indicates how many patients would be require for an intervention to prevent one additional bad outcome. A perfect NNT would be 1, where everyone improves with treatment, thus the higher the NNT, the less effective the treatment.

Thus if you treat 1000 patients then you will expect to have 50 fewer strokes.