Calcitonin is a 32 amino acid polypeptide that is primarily synthesised and released by the parafollicular cells (C-cells) of the thyroid gland in response to rising or high levels of plasma Ca2+ions. Its primary role is to reduce the plasma calcium concentration, therefore opposing the effects of parathyroid hormone.Secretion of calcitonin is stimulated by:- Increased plasma calcium concentration- Gastrin- Pentagastrin- The main actions of calcitonin are:- Inhibition of osteoclastic activity (decreasing calcium and phosphate resorption from bone)- Stimulation of osteoblastic activity- Decreases renal calcium reabsorption- Decreases renal phosphate reabsorption

Evidence-based medicine may be defined as the systematic, quantitative, preferentially experimental approach to obtaining and using medical information. Therefore, meta-analysis, a statistical procedure that integrates the results of several independent studies, plays a central role in evidence-based medicine.Meta-analysis is a quantitative, formal, epidemiological study design used to systematically assess previous research studies to derive conclusions about that body of research. Outcomes from a meta-analysis may include a more precise estimate of the effect of treatment or risk factor for disease, or other outcomes, than any individual study contributing to the pooled analysis.

Abductor pollicis longus is a muscle found in the posterior compartment of the forearm. It is one of the five deep extensors in the forearm, along with the supinator, extensor pollicis brevis, extensor pollicis longus and extensor indicis.Abductor pollicis longus is innervated by the posterior interosseous nerve (C7, C8), which is a continuation of the deep branch of the radial nerve. The radial nerve is a branch of the posterior cord of the brachial plexus.Blood supply to the abductor pollicis longus muscle comes from the interosseous branches of the ulnar artery.Acting alone or with abductor pollicis brevis, abductor pollicis longus pulls the thumb away from the palm. More specifically, it produces (mid-) extension and abduction of the thumb at the first metacarpophalangeal joint. This action is seen in activities such as bowling and shovelling.Working together with the long and short extensors of the thumb, the muscle also helps to fully extend the thumb at the metacarpophalangeal joint. This action is important for loosening the hand grip, for example, when letting go of objects previously being held. Abductor pollicis longus also helps to abduct the hand (radial deviation) at the radiocarpal joint.

Osmolality and osmolarity are measurements of the solute concentration of a solution. Although the two terms are often used interchangeably, there are differences in the definitions, how they are calculated and the units of measurement used.Osmolarity, expressed as mmol/L, is an estimation of the osmolar concentration of plasma. It is proportional to the number of particles per litre of solution.Measured Na+, K+, urea and glucose concentrations are used to calculate the value indirectly.It is unreliable in pseudohyponatremia and hyperproteinaemia.The equations used to calculate osmolarity are:Osmolarity = 2 (Na+) + 2 (K+) + Glucose + Urea (all in mmol/L)OROsmolarity = 2 (Na+) + Glucose + Urea (all in mmol/L)Doubling of sodium accounts for the negative ions associated with sodium, and the exclusion of potassium approximately allows for the incomplete dissociation of sodium chloride.

PO43-renal excretion is regulated several mechanisms. These include:-parathyroid hormone – increases excretion by inhibiting reabsorption in the proximal tubule-acidosis – increases excretion-glucocorticoids – increases excretion-calcitonin – increases excretion-activated vitamin D – decreases excretion by increasing reabsorption in the distal tubule

Following the action potential, Na+channels remain inactive for a time in a period known as the absolute refractory period where they cannot be opened by any amount of depolarisation. Following this there is a relative refractory period where the temporary hyperpolarisation (due to delayed closure of rectifier K+channels) makes the cell more difficult to depolarise and an action potential can be generated only in response to a larger than normal stimulus. The refractory period limits the frequency at which action potentials can be generated, and ensures that, once initiated, an action potential can travel only in one direction. An action potential is an all or nothing response so the amplitude of the action potential cannot be smaller.

An audit assesses if a certain aspect of health care is attaining a recognized standard. This lets care providers and patients know where their service is doing well, and where there could be improvements. The aim is to achieve quality improvement and improve outcomes for patients.Audits are a quality improvement measure and one of the 7 pillars of clinical governance. It allows organizations to continually work toward improving quality of care by showing them where they are falling short, allows them to implement improvements, and reaudit or close the audit cycle to see if beneficial change has taken place.Clinical audits are a cycle with several steps:1. Identification of the problem2. Definition of criteria and setting of standards3. Observation of practice and collection of data4. Analysis of data and comparison of performance with the criteria and standards5. Implementation of change

CSF analysis typically shows: cloudy turbid appearanceraised WCC – predominantly neutrophilshigh proteinlow glucose (typically < 40% of serum glucose)Gram-negative diplococci seen under microscopy

Fenestrated capillaries, found in renal glomeruli, endocrine glands and intestinal villi, are more permeable than continuous capillaries with less tight junctions, and the endothelial cells are also punctured by pores which allow large amounts of fluids or metabolites to pass.

Antiarrhythmic drug amiodarone is used to treat both ventricular and atrial arrhythmias. It’s a class III antiarrhythmic that works by prolonging the repolarization phase of the cardiac action potential, where potassium permeability is normally high and calcium permeability is low.Dronedarone is sometimes used instead of amiodarone in certain situations. Although amiodarone is more effective than dronedarone, dronedarone has fewer side effects.Grapefruit juice inhibits the metabolism of amiodarone.The plasma half-life of amiodarone is very long, ranging from 2 weeks to 5 months. The half-life is about 2 months on average.Because amiodarone is excreted in breast milk, it should be avoided by breastfeeding mothers.

Calcium deficiency (low Ca2+ diet or hypocalcemia) activates 1-alpha-hydroxylase in the cells of the renal proximal tubule which catalyses the conversion of vitamin D to its active form, 1,25-dihydroxycholecalciferol. Increased parathyroid hormone (PTH) and hypophosphatemia also stimulate the enzyme. Chronic renal failure is associated with a constellation of bone diseases, including osteomalacia caused by failure of the diseased renal tissue to produce the active form of vitamin D.

Infection of the genital mucosa by Neisseria gonorrhoeae involves attachment to and invasion of epithelial cells. Initial adherence of gonococci to columnar epithelial cells is mediated by type IV pili assembled from pilin subunit PilE proteins and pilus tip-associated PilC proteins, it then invades the epithelial layer, triggering a local acute inflammatory response.

Bacterial infections are common in the following situations:Platelet transfusions are associated with a higher risk of bacterial infection (as platelets are stored at room temperature)Immersion in a water bath thawed previously frozen components.Components of red blood cells that have been stored for several weeksGram-positive and Gram-negative bacteria have both been linked to transfusion-transmitted bacterial infection, but Gram-negative bacteria are linked to a higher rate of morbidity and mortality.Yersinia enterocolitica is the most common bacterial organism linked to transfusion-transmitted bacterial infection. This organism can multiply at low temperatures while also utilising iron as a nutrient. As a result, it’s well-suited to proliferating in blood banks.The following are some of the most common clinical signs and symptoms of a bacterial infection transmitted through a blood transfusion. These symptoms usually appear shortly after the transfusion begins:Fever is very high.Rigours and chillsVomiting and nauseaTachycardiaHypotensionCollapse of the circulatory systemIf a bacterial infection from a transfusion is suspected, the transfusion should be stopped right away. Blood cultures and a Gram stain should be requested, as well as broad-spectrum antibiotics. In addition, the blood pack should be returned to the blood bank for an urgent culture and Gram-stain.

The ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching ventilation and perfusion. The ideal V/Q ratio is 1. In an average healthy male, the ventilation value is approximately 5 L/min and the perfusion value is approximately 5 L/min. Any mismatch between ventilation and perfusion will be evident in the V/Q ratio. If perfusion is normal but ventilation is reduced, the V/Q ratio will be less than 1, whereas if ventilation is normal but perfusion is reduced, the V/Q ratio will be greater than 1. If the alveoli were ventilated but not perfused at all, then the V/Q ratio would be infinity.

Ipratropium bromide is an antimuscarinic drug used in the management of acute asthma and COPD. It can provide short-term relief in chronic asthma, but short-acting β2agonists act more quickly and are preferred.The BTS guidelines recommend that nebulised ipratropium bromide (0.5 mg 4-6 hourly) can be added to β2agonist treatment for patients with acute severe or life-threatening asthma or those with a poor initial response to β2 agonist therapy.The aerosol inhalation of ipratropium can be used for short-term relief in mild chronic obstructive pulmonary disease in patients who are not already using a long-acting antimuscarinic drug (e.g. tiotropium).Its maximum effect occurs 30-60 minutes after use; its duration of action is 3-6 hours, and bronchodilation can usually be maintained with treatment three times per day.The commonest side effect of ipratropium bromide is dry mouth. It can also trigger acute closed-angle glaucoma in susceptible patients. Tremor is commonly seen with β2agonists but not with antimuscarinics. Ipratropium bromide should be used with caution in: Men with prostatic hyperplasia and bladder-outflow obstruction (worsened urinary retention has been reported in elderly men), People with chronic kidney disease (CKD) stages 3 and above (because of the risk of drug toxicity), People with angle-closure glaucoma (nebulised mist of antimuscarinic drugs can precipitate or worsen acute angle-closure glaucoma)

Homeostasis is the property of a system in which variables are regulated so that internal conditions remain relatively constant and stable. Homeostasis is achieved by a negative feedback mechanism.Negative feedback occurs based upon a set point through receptors, comparators and effectors. The ‘set point’ is a NARROW range of values within which normal function occurs.The two body systems that regulate homeostasis are the Nervous system and the Endocrine system. The smooth muscle of the uterus becomes more active towards the end of pregnancy. This is a POSITIVE feedback.

The liver produces bile on a constant basis, which is then stored and concentrated in the gallbladder. In a 24-hour period, around 400 to 800 mL of bile is generated.Bile is involved in the following processes:Fats are broken down into fatty acids.Waste products are eliminated.Cholesterol homeostasis is the balance of cholesterol in the body.The enteric hormones cholecystokinin and secretin are primarily responsible for bile secretion. When chyme from an unprocessed meal enters the small intestine, they are released, and they play the following function in bile secretion and flow:Cholecystokinin promotes gallbladder and common bile duct contractions, allowing bile to reach the intestine.Secretin enhances the secretion of bicarbonate and water by biliary duct cells, increasing the amount of bile and its flow into the gut.Bile acids have a hydrophobic and hydrophilic area, making them amphipathic. Bile acids’ amphipathic nature allows them to perform the following crucial functions:Emulsification of lipid aggregates increases the surface area of fat and makes it easier for lipases to digest it.Lipid solubilization and transport: solubilizes lipids by creating micelles, which are lipid clumps that float in water.

In a triangular area between the vasa deferentia, the bladder and rectum are separated only by rectovesical fascia, commonly known as Denonvillier’s fascia.

Parasympathetic preganglionic neurones originate in the brainstem from which they run in cranial nerves III, VII, IX and X and also from the second and third sacral segments of the spinal cord. Parasympathetic preganglionic neurones release acetylcholine into the synapse, which acts on cholinergic nicotinic receptors on the postganglionic fibre. Parasympathetic peripheral ganglia are generally found close to or within their target, whereas sympathetic peripheral ganglia are located largely in two sympathetic chains on either side of the vertebral column (paravertebral ganglia), or in diffuse prevertebral ganglia of the visceral plexuses of the abdomen and pelvis. Parasympathetic postganglionic neurones release acetylcholine, which acts on cholinergic muscarinic receptors.

Because the middles of the shafts of the ribs are lower than either the anterior or posterior end, elevation of the ribs also moves the middles of the shafts laterally. This ‘bucket handle’ upwards and lateral movement increases the lateral dimensions of the thorax.