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Arab Board Surgery Part 1 study materials
Arab Board Surgery Part 1 study resources

Arab Board Surgery Part 1 practice questions

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Question 1Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The carotid sheath contains which of the following structures?

  1. Hypoglossal nerve
  2. Internal jugular vein Correct answer.
  3. Sympathetic trunk
  4. Recurrent laryngeal nerve

Explanation

The carotid sheath is a fascial tube containing the common and internal carotid arteries, the internal jugular vein, and the vagus nerve. The sympathetic trunk lies posterior to the sheath, outside it, and the hypoglossal and recurrent laryngeal nerves run in separate fascial planes.

Question 2Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The midpoint of the inguinal ligament is a surface landmark for which structure?

  1. Superficial inguinal ring
  2. Femoral nerve
  3. Femoral artery
  4. Deep inguinal ring Correct answer.

Explanation

The deep inguinal ring lies approximately 1.25 cm above the midpoint of the inguinal ligament, which spans the anterior superior iliac spine and the pubic tubercle. The mid-inguinal point, between the anterior superior iliac spine and the pubic symphysis, is the landmark for the femoral artery.

Question 3Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

From medial to lateral, what is the order of the contents of the femoral triangle?

  1. Femoral vein, femoral artery, femoral nerve Correct answer.
  2. Femoral vein, femoral nerve, femoral artery
  3. Femoral nerve, femoral artery, femoral vein
  4. Femoral artery, femoral vein, femoral nerve

Explanation

Within the femoral triangle, the structures are arranged from medial to lateral as vein, artery, and nerve, remembered as NAVEL. The femoral canal lies medial to the vein and contains fat and a lymph node.

Question 4Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The thyroid gland develops as an outgrowth from which structure?

  1. Third pharyngeal pouch
  2. Second pharyngeal arch
  3. Fourth pharyngeal pouch
  4. Foramen cecum at the base of the tongue Correct answer.

Explanation

The thyroid primordium arises from the floor of the pharynx at the foramen cecum and descends along the thyroglossal duct to its final position. The third and fourth pharyngeal pouches give rise to the parathyroid glands and thymus, not the thyroid follicular tissue.

Question 5Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The pectinate line of the anal canal marks the junction between which two embryological tissues?

  1. Hindgut endoderm and proctodeum ectoderm Correct answer.
  2. Foregut endoderm and hindgut endoderm
  3. Mesonephric duct and urogenital sinus
  4. Neural ectoderm and surface ectoderm

Explanation

The upper anal canal develops from the hindgut and is lined by endoderm, while the lower canal develops from the proctodeum and is lined by ectoderm. The pectinate line marks this junction and corresponds to differences in blood supply, lymphatic drainage, and innervation.

Question 6Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure passes through the aortic hiatus of the diaphragm?

  1. Inferior vena cava
  2. Oesophagus
  3. Thoracic duct Correct answer.
  4. Right phrenic nerve

Explanation

The aortic hiatus lies at the level of T12 and transmits the aorta, thoracic duct, and azygos vein. The oesophagus passes through the oesophageal hiatus at T10, and the inferior vena cava passes through the caval opening at T8.

Question 7Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Cantlie's line, which divides the liver into true right and left lobes, runs between which two landmarks?

  1. Gallbladder fossa and inferior vena cava Correct answer.
  2. Right and left hepatic veins
  3. Porta hepatis and round ligament
  4. Falciform ligament and ligamentum teres

Explanation

Cantlie's line extends from the gallbladder fossa to the inferior vena cava and represents the principal plane of the liver. This plane divides the liver into true right and left hemilivers, each with its own portal supply and biliary drainage.

Question 8Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which nerve passes through the quadrangular space of the shoulder accompanied by the posterior circumflex humeral artery?

  1. Musculocutaneous nerve
  2. Axillary nerve Correct answer.
  3. Suprascapular nerve
  4. Radial nerve

Explanation

The axillary nerve and posterior circumflex humeral artery pass together through the quadrangular space bounded by the teres major and minor, long head of triceps, and surgical neck of the humerus. The nerve supplies the deltoid and teres minor and provides sensation over the lateral shoulder.

Question 9Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

A 45-year-old man has a groin swelling. At surgery the hernia sac emerges through the deep inguinal ring, lateral to the inferior epigastric vessels. Which type of hernia is this?

  1. Femoral hernia
  2. Direct inguinal hernia
  3. Obturator hernia
  4. Indirect inguinal hernia Correct answer.

Explanation

An indirect inguinal hernia enters the deep ring lateral to the inferior epigastric vessels and travels within the spermatic cord. A direct hernia protrudes through Hesselbach's triangle medial to those vessels.

Question 10Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

During thyroidectomy, ligation of the superior thyroid artery very close to the upper pole risks injury to which nerve?

  1. Recurrent laryngeal nerve
  2. Hypoglossal nerve
  3. External branch of the superior laryngeal nerve Correct answer.
  4. Internal branch of the superior laryngeal nerve

Explanation

The external branch of the superior laryngeal nerve descends close to the superior thyroid vessels before supplying the cricothyroid muscle. Injury causes loss of high-pitched phonation and a lowered voice pitch, while the airway protective reflex remains intact.

Question 11Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Erb's palsy, producing a 'waiter's tip' deformity, results from injury to which part of the brachial plexus?

  1. Lower trunk (C8-T1)
  2. Upper trunk (C5-C6) Correct answer.
  3. Posterior cord
  4. Medial cord

Explanation

Erb's palsy follows injury to the upper trunk formed by C5 and C6, affecting the suprascapular, axillary, and musculocutaneous nerves. The arm hangs internally rotated with the forearm extended and the palm facing backward.

Question 12Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

A child aspirates a peanut. Which anatomical feature explains why the right main bronchus is more commonly affected?

  1. It is narrower and more horizontal
  2. It is wider, shorter, and more vertical Correct answer.
  3. It arises at a sharper angle from the trachea
  4. It is guarded by a stronger cough reflex

Explanation

The right main bronchus is wider, shorter, and more vertical than the left, so aspirated material tends to follow the straighter path into it. This anatomical difference also guides positioning when selecting a mainstem bronchus for intubation.

Question 13Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

In most people, which artery supplies the sinoatrial node?

  1. Right coronary artery Correct answer.
  2. Left anterior descending artery
  3. Left main coronary artery
  4. Left circumflex artery

Explanation

The sinoatrial node is supplied by the right coronary artery in approximately 60% of people, with the remainder supplied by the left circumflex. The right coronary artery also supplies the atrioventricular node in most individuals.

Question 14Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Above the arcuate line, which structures form the posterior layer of the rectus sheath?

  1. Parietal peritoneum only
  2. Posterior lamina of internal oblique and transversus abdominis Correct answer.
  3. External oblique aponeurosis
  4. Transversalis fascia alone

Explanation

Above the arcuate line, the posterior rectus sheath is formed by the posterior lamina of the internal oblique and the transversus abdominis aponeuroses, reinforced by transversalis fascia. Below the arcuate line all aponeurotic layers pass anterior to the rectus muscle, leaving only transversalis fascia and peritoneum posteriorly.

Question 15Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Hesselbach's triangle, a site for direct inguinal hernia, is bounded by which structures?

  1. Inguinal ligament inferiorly, rectus sheath laterally, inferior epigastric vessels medially
  2. Rectus sheath medially, inguinal ligament inferiorly, inferior epigastric vessels superolaterally Correct answer.
  3. Pubic tubercle medially, deep inguinal ring laterally, conjoint tendon superiorly
  4. Inguinal ligament superiorly, inferior epigastric vessels inferiorly, rectus sheath laterally

Explanation

Hesselbach's triangle is bounded medially by the lateral border of the rectus sheath, inferiorly by the inguinal ligament, and superolaterally by the inferior epigastric vessels. A direct inguinal hernia protrudes through this triangle medial to the inferior epigastric vessels.

Question 16Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure lies within the femoral canal, the most medial compartment of the femoral sheath?

  1. Femoral nerve
  2. Lymph node of Cloquet Correct answer.
  3. Great saphenous vein
  4. Femoral artery

Explanation

The femoral canal is the small medial compartment of the femoral sheath and contains fat and the lymph node of Cloquet. It is the route by which femoral hernias pass, and its rigid boundaries make strangulation more likely.

Question 17Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure lies immediately posterior to the prostate, separated from it by Denonvilliers' fascia?

  1. Pubic symphysis
  2. Urinary bladder
  3. Levator ani
  4. Rectum Correct answer.

Explanation

The rectum lies posterior to the prostate and is separated from it by Denonvilliers' fascia, also called the rectovesical septum. This plane is important during prostatectomy and in staging prostatic carcinoma.

Question 18Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

During hysterectomy, the ureter is at risk where it passes in relation to the uterine artery. What is the usual relationship?

  1. The ureter passes superior to the uterine artery
  2. The ureter passes anterior to the uterine artery
  3. The ureter passes lateral to the uterine artery
  4. The ureter passes inferior to the uterine artery Correct answer.

Explanation

The ureter passes inferior to the uterine artery near the lateral fornix of the vagina, a relationship remembered as 'water under the bridge'. This crossing is approximately 2 cm lateral to the cervix and is a key danger point during hysterectomy.

Question 19Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

During development, the midgut rotates around the superior mesenteric artery. What is the normal direction and amount of rotation?

  1. 270 degrees counterclockwise Correct answer.
  2. 270 degrees clockwise
  3. 90 degrees clockwise
  4. 180 degrees clockwise

Explanation

The midgut normally rotates 270 degrees counterclockwise around the superior mesenteric artery as it returns to the abdomen. This brings the cecum to the right lower quadrant and establishes the normal position of the duodenojejunal flexure.

Question 20Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The portal vein is usually formed by the union of which two veins?

  1. Inferior mesenteric vein and splenic vein
  2. Superior mesenteric vein and splenic vein Correct answer.
  3. Left and right gastric veins
  4. Hepatic veins and cystic vein

Explanation

The portal vein forms behind the neck of the pancreas from the superior mesenteric vein and the splenic vein. The inferior mesenteric vein usually joins the splenic vein before this confluence rather than forming the portal vein directly.

Question 21Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The inferior parathyroid glands and thymus develop from which pharyngeal pouch?

  1. Second pharyngeal pouch
  2. Sixth pharyngeal pouch
  3. Fourth pharyngeal pouch
  4. Third pharyngeal pouch Correct answer.

Explanation

The third pharyngeal pouch gives rise to the inferior parathyroid glands and the thymus. Because the thymus descends into the mediastinum, the inferior parathyroid glands can be found in ectopic lower positions.

Question 22Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The thoracic duct at the root of the neck usually drains into which structure?

  1. Superior vena cava directly
  2. Right venous angle
  3. Junction of the left internal jugular and left subclavian veins Correct answer.
  4. Azygos vein

Explanation

The thoracic duct ascends through the posterior mediastinum and neck and drains into the left venous angle, at the junction of the left internal jugular and left subclavian veins. This delivers chyle into the systemic venous circulation.

Question 23Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

A replaced right hepatic artery is most commonly a branch of which artery?

  1. Splenic artery
  2. Superior mesenteric artery Correct answer.
  3. Gastroduodenal artery
  4. Left gastric artery

Explanation

A replaced right hepatic artery usually arises from the superior mesenteric artery and passes posterior to the portal vein and pancreas. Recognition of this variant is important during pancreaticoduodenectomy and hepatic surgery to avoid arterial injury.

Question 24Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which nerve provides the primary direct somatic innervation to the levator ani muscle?

  1. Branches of S3 and S4 Correct answer.
  2. Obturator nerve
  3. Pudendal nerve
  4. Inferior gluteal nerve

Explanation

The levator ani receives its main direct innervation from branches of S3 and S4, often called the levator ani nerve. The pudendal nerve supplies the external anal sphincter and perineal skin but is not the primary direct motor supply to levator ani.

Question 25Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

In the cubital fossa, which structure lies immediately medial to the biceps tendon?

  1. Radial nerve
  2. Median nerve
  3. Ulnar artery
  4. Brachial artery Correct answer.

Explanation

The contents of the cubital fossa from medial to lateral are the median nerve, brachial artery, biceps tendon, and radial nerve. The brachial artery therefore lies immediately medial to the biceps tendon and is a common site for arterial cannulation and pulse palpation.

Question 26Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure lies in the deltopectoral groove between the deltoid and pectoralis major muscles?

  1. Brachial artery
  2. Basilic vein
  3. Radial nerve
  4. Cephalic vein Correct answer.

Explanation

The cephalic vein ascends in the deltopectoral groove, which is bounded by the deltoid laterally and pectoralis major medially. It then pierces the clavipectoral fascia to drain into the axillary vein. This groove is a useful landmark for identifying the vein during pacemaker or port placement.

Question 27Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Through which foramen does the mandibular division of the trigeminal nerve leave the cranial cavity?

  1. Foramen ovale Correct answer.
  2. Jugular foramen
  3. Stylomastoid foramen
  4. Foramen rotundum

Explanation

The mandibular division (V3) of the trigeminal nerve exits through the foramen ovale in the greater wing of the sphenoid. The maxillary division (V2) passes through the foramen rotundum, and the ophthalmic division (V1) passes through the superior orbital fissure. The foramen ovale also transmits the accessory meningeal artery and the lesser petrosal nerve.

Question 28Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

After birth, the umbilical vein obliterates to become which structure?

  1. Falciform ligament
  2. Ligamentum teres hepatis Correct answer.
  3. Median umbilical ligament
  4. Medial umbilical ligament

Explanation

The intra-abdominal portion of the umbilical vein fibroses after birth to form the ligamentum teres hepatis, which runs in the free edge of the falciform ligament. The vessel may recanalize in portal hypertension and contribute to caput medusae. The median umbilical ligament is the remnant of the urachus, and the medial umbilical ligaments are remnants of the umbilical arteries.

Question 29Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

In a right-dominant coronary circulation, the posterior descending artery arises from which vessel?

  1. Left main coronary artery
  2. Left anterior descending artery
  3. Right coronary artery Correct answer.
  4. Left circumflex artery

Explanation

In approximately 85% to 90% of people the right coronary artery is dominant and gives rise to the posterior descending artery at the crux of the heart. This vessel supplies the inferior wall of the left ventricle and the inferior third of the interventricular septum. In left dominance, the posterior descending artery arises from the left circumflex artery.

Question 30Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

The marginal artery of Drummond provides collateral flow between which two arterial territories?

  1. Celiac trunk and superior mesenteric artery
  2. Inferior mesenteric artery and internal iliac artery
  3. Superior mesenteric artery and inferior mesenteric artery Correct answer.
  4. Celiac trunk and inferior mesenteric artery

Explanation

The marginal artery of Drummond runs within the mesentery along the colon and connects branches of the superior mesenteric artery with branches of the inferior mesenteric artery. It provides a collateral pathway between the midgut and hindgut territories. This collateral becomes clinically important when either main artery is occluded.

Question 31Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure separates the superficial perineal pouch from the deep perineal pouch?

  1. Perineal membrane Correct answer.
  2. Levator ani
  3. Ischiorectal fat
  4. Colles' fascia

Explanation

The perineal membrane, the tough triangular fascia between the ischial rami, separates the superficial perineal pouch from the deep perineal pouch. The superficial pouch contains the root of the penis or clitoris and the superficial perineal muscles. The deep pouch contains the external urethral sphincter, deep transverse perineal muscle, and internal pudendal vessels.

Question 32Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Within the carotid sheath, which structure lies posterior and between the internal jugular vein and the internal carotid artery?

  1. Vagus nerve Correct answer.
  2. Sympathetic trunk
  3. Ansa cervicalis
  4. Hypoglossal nerve

Explanation

The vagus nerve lies posteriorly within the carotid sheath, in the groove between the internal jugular vein and the internal carotid artery. The sympathetic trunk lies posterior to the sheath on the prevertebral fascia, not within it. The hypoglossal nerve crosses the external and internal carotid arteries outside the sheath.

Question 33Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Muscles derived from the second pharyngeal arch are innervated by which nerve?

  1. Glossopharyngeal nerve
  2. Vagus nerve
  3. Facial nerve Correct answer.
  4. Trigeminal nerve

Explanation

The second pharyngeal arch gives rise to the muscles of facial expression, stapedius, stylohyoid, and the posterior belly of the digastric, all innervated by the facial nerve (CN VII). Each pharyngeal arch is supplied by its own cranial nerve. The first arch is supplied by the trigeminal nerve, the third by the glossopharyngeal nerve, and the fourth and sixth by the vagus and accessory nerves.

Question 34Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

Which structure crosses anterior to the third part of the duodenum?

  1. Inferior vena cava
  2. Portal vein
  3. Right renal artery
  4. Superior mesenteric artery Correct answer.

Explanation

The superior mesenteric artery arises from the aorta and passes anterior to the third part of the duodenum as it descends toward the mesentery. Compression of the duodenum between the artery and the aorta can produce superior mesenteric artery syndrome. The third part of the duodenum is retroperitoneal and crosses anterior to the inferior vena cava and aorta.

Question 35Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

In adults, the femoral head receives its main arterial supply from which artery?

  1. Obturator artery
  2. Lateral circumflex femoral artery
  3. Medial circumflex femoral artery Correct answer.
  4. Inferior gluteal artery

Explanation

The medial circumflex femoral artery gives rise to retinacular branches that ascend along the femoral neck and provide most of the blood supply to the adult femoral head. Disruption of these branches is a major risk in displaced femoral neck fractures. The lateral circumflex femoral artery contributes only a small amount, and the obturator artery is more important in children.

Question 36Anatomy and Embryology (including surgical anatomy of the neck, thorax, abdomen, pelvis, and limbs)

A thoracentesis is performed in the midaxillary line. To avoid the intercostal neurovascular bundle, the needle should be inserted in which relation to the rib?

  1. At the midpoint between adjacent ribs
  2. Just above the superior border of the rib below Correct answer.
  3. Just below the inferior border of the rib above
  4. Through the costal cartilage of the rib above

Explanation

The intercostal nerve, artery, and vein run in the costal groove along the inferior border of each rib. To avoid them, a needle should be inserted just above the superior border of the rib below, which is the safe part of the intercostal space. Insertion below a rib risks injury to the neurovascular bundle.

Question 37Physiology (systemic and organ-specific physiology relevant to surgical patients)

In a healthy 70 kg adult male, total body water represents approximately what proportion of body weight?

  1. 40%
  2. 50%
  3. 60% Correct answer.
  4. 80%

Explanation

Total body water averages about 60% of body weight (roughly 42 L in a 70 kg man), distributed as about two-thirds intracellular and one-third extracellular. Adipose tissue holds little water, so obese patients and women have a lower percentage despite similar absolute fluid needs.

Question 38Physiology (systemic and organ-specific physiology relevant to surgical patients)

Which hormone is the principal direct stimulus to parietal cell acid secretion after a protein-containing meal?

  1. Somatostatin
  2. Secretin
  3. Cholecystokinin
  4. Gastrin Correct answer.

Explanation

Gastrin released from antral G cells in response to amino acids and vagal activity binds CCK-2 receptors on parietal cells and also triggers histamine release from enterochromaffin-like cells, amplifying acid output. Acetylcholine and histamine act synergistically with gastrin on the proton pump.

Question 39Physiology (systemic and organ-specific physiology relevant to surgical patients)

What is the principal digestive action of bile salts in the small intestine?

  1. Hydrolysis of triglycerides into fatty acids and monoglycerides
  2. Emulsification of dietary fat into micelles Correct answer.
  3. Neutralization of gastric acid entering the duodenum
  4. Activation of pancreatic amylase

Explanation

Bile salts are amphipathic molecules that emulsify large fat droplets and form micelles, greatly increasing the surface area available for pancreatic lipase and enabling absorption of fat-soluble vitamins. Bicarbonate, not bile salts, is responsible for neutralizing chyme.

Question 40Physiology (systemic and organ-specific physiology relevant to surgical patients)

What is the main acute effect of insulin on the distribution of potassium in the body?

  1. No measurable effect on potassium distribution
  2. Increased renal potassium excretion
  3. Promotion of potassium entry into cells Correct answer.
  4. Potassium efflux from cells into plasma

Explanation

Insulin activates membrane Na+/K+-ATPase and shifts potassium from the extracellular space into skeletal muscle and other cells. This is why insulin with glucose is used to treat hyperkalaemia, and why potassium must be monitored when insulin is given.

Question 41Physiology (systemic and organ-specific physiology relevant to surgical patients)

Within physiological limits, an increase in ventricular end-diastolic volume raises stroke volume because of which change?

  1. Reduced myocardial oxygen demand
  2. Reflex sympathetic activation and faster heart rate
  3. Greater myofilament calcium sensitivity Correct answer.
  4. Peripheral vasodilation and reduced afterload

Explanation

Stretching cardiac myocytes to a longer sarcomere length increases their sensitivity to calcium and brings actin and myosin into a more favourable overlap, generating greater force (the Frank-Starling relationship). This allows the heart to eject the extra volume it receives without a change in heart rate.

Question 42Physiology (systemic and organ-specific physiology relevant to surgical patients)

Fibroblast proliferation, angiogenesis and new collagen deposition are characteristic of which phase of wound healing?

  1. Remodelling
  2. Haemostasis
  3. Inflammatory
  4. Proliferative Correct answer.

Explanation

The proliferative phase, lasting from about day 3 to 3 weeks, is dominated by angiogenesis, fibroblast migration and deposition of type III collagen along with granulation tissue formation. It follows the inflammatory phase and precedes the remodelling phase, where collagen matures and cross-links.

Question 43Physiology (systemic and organ-specific physiology relevant to surgical patients)

Which function is performed by the spleen in the adult?

  1. Storage of vitamin B12
  2. Production of intrinsic factor
  3. Production of bile by hepatocytes
  4. Removal of aged erythrocytes from blood Correct answer.

Explanation

The spleen filters blood through the red pulp, where macrophages remove senescent or damaged red cells and recycle iron, and the white pulp mounts immune responses to encapsulated organisms. This filtration function explains the anaemia and thrombocytopenia of hypersplenism.

Question 44Physiology (systemic and organ-specific physiology relevant to surgical patients)

Renin release from juxtaglomerular cells is most strongly stimulated by which condition?

  1. Reduced renal perfusion pressure Correct answer.
  2. Increased sodium delivery to the macula densa
  3. Volume expansion with higher renal perfusion pressure
  4. Elevated plasma angiotensin II concentration

Explanation

Juxtaglomerular cells are stretch-sensitive baroreceptors; a fall in afferent arteriolar pressure reduces wall stretch and triggers renin release, supported by beta-1 sympathetic input. Reduced distal sodium delivery to the macula densa provides a second stimulus, while angiotensin II feeds back negatively.

Question 45Physiology (systemic and organ-specific physiology relevant to surgical patients)

At the arterial end of a capillary, capillary hydrostatic pressure is 30 mm Hg, interstitial hydrostatic pressure is 0 mm Hg, plasma oncotic pressure is 25 mm Hg and interstitial oncotic pressure is 2 mm Hg. What is the net filtration pressure?

  1. 3 mm Hg
  2. 7 mm Hg Correct answer.
  3. 12 mm Hg
  4. 5 mm Hg

Explanation

Net filtration pressure equals capillary hydrostatic pressure minus interstitial hydrostatic pressure minus plasma oncotic pressure plus interstitial oncotic pressure: 30 - 0 - 25 + 2 = 7 mm Hg outward. This small positive balance drives fluid into the interstitium, where lymphatics return it to the circulation.

Question 46Physiology (systemic and organ-specific physiology relevant to surgical patients)

Which hormone is the principal stimulus for bicarbonate-rich fluid secretion by the pancreatic ductal cells?

  1. Secretin Correct answer.
  2. Gastrin
  3. Motilin
  4. Cholecystokinin

Explanation

Duodenal acidification releases secretin from S cells, which acts on pancreatic ductal cells to increase cyclic AMP and drive bicarbonate secretion, neutralising chyme. Cholecystokinin instead acts mainly on acinar cells to stimulate enzyme-rich secretion.

Question 47Physiology (systemic and organ-specific physiology relevant to surgical patients)

In normal bilirubin metabolism, unconjugated bilirubin is carried in plasma bound chiefly to which protein?

  1. Haptoglobin
  2. Transferrin
  3. Prealbumin
  4. Albumin Correct answer.

Explanation

Unconjugated bilirubin is poorly water-soluble and circulates tightly bound to albumin, which prevents renal excretion and limits tissue deposition. Once taken up by hepatocytes it is conjugated with glucuronic acid, becoming water-soluble and excretable in bile.

Question 48Physiology (systemic and organ-specific physiology relevant to surgical patients)

Why does aldosterone act as a mineralocorticoid on principal cells despite much higher circulating cortisol concentrations?

  1. Higher plasma concentration of aldosterone than cortisol
  2. Aldosterone binding to glucocorticoid receptors
  3. Absence of cortisol receptors in principal cells
  4. Cortisol inactivation by 11-beta-HSD2 in principal cells Correct answer.

Explanation

Principal cells express the enzyme 11-beta-hydroxysteroid dehydrogenase type 2, which converts cortisol to cortisone and prevents it from occupying the mineralocorticoid receptor. Aldosterone escapes this inactivation and therefore selectively drives sodium reabsorption and potassium secretion.

Question 49Physiology (systemic and organ-specific physiology relevant to surgical patients)

What is the immediate physiological response to a fall in ionized plasma calcium?

  1. Increased calcitonin secretion from the thyroid
  2. Increased urinary calcium excretion
  3. Increased PTH secretion with renal calcium reabsorption Correct answer.
  4. Reduced renal phosphate reabsorption

Explanation

A fall in ionized calcium is sensed by the parathyroid calcium-sensing receptor, which increases PTH release. PTH then raises calcium by increasing renal tubular reabsorption, stimulating bone resorption and activating 1-alpha-hydroxylase to generate calcitriol.

Question 50Physiology (systemic and organ-specific physiology relevant to surgical patients)

A patient has serum sodium 136 mEq/L, chloride 100 mEq/L and bicarbonate 12 mEq/L. What is the serum anion gap?

  1. 36 mEq/L
  2. 12 mEq/L
  3. 48 mEq/L
  4. 24 mEq/L Correct answer.

Explanation

The anion gap is sodium minus the sum of chloride and bicarbonate: 136 - (100 + 12) = 24 mEq/L, well above the normal range of roughly 8 to 12 mEq/L. A raised gap with a low bicarbonate indicates a high-anion-gap metabolic acidosis such as ketosis, lactic acidosis or renal failure.