1.
Genetic testing of a baby girl with facial and cardio vascular anomalies reveals a deletion on chromosome 22. This deletion, Di George Syndrome, results in migration defects of neural crest cells within the pharyngeal pouches. In this patient, the thymus and inferior parathyroid glands are absent. Which pharyngeal pouch is most likely affected?
Correct Answer
C. Third
Explanation
The third pharyngeal pouch is most likely affected in this patient. This is because Di George Syndrome, which is caused by a deletion on chromosome 22, is known to result in migration defects of neural crest cells within the pharyngeal pouches. In this patient, the absence of the thymus and inferior parathyroid glands suggests that the third pharyngeal pouch, which gives rise to these structures, is affected.
2.
Dr Martin
A 10 year old boy presents to the ER complaining of a sore throat, ear ache and high fever. On examination he is found to have severely swollen palatine tonsils. What nerve carries the sensory input for most of his symptoms?
Correct Answer
B. GlossopHaryngeal
Explanation
The glossopharyngeal nerve carries the sensory input for most of the boy's symptoms because it innervates the posterior third of the tongue, the tonsils, and the pharynx. This nerve is responsible for transmitting sensory information from these areas to the brain, which can cause symptoms such as a sore throat and earache. The other nerves listed do not innervate these specific areas and are therefore not likely to be responsible for the boy's symptoms.
3.
Annular pancreas is most commonly caused by which structure or tissue?
Correct Answer
E. Migration of the left portion of the ventral bud in the opposite direction to the right portion
Explanation
Annular pancreas is most commonly caused by the migration of the left portion of the ventral bud in the opposite direction to the right portion. This abnormal migration leads to the formation of a ring of pancreatic tissue that surrounds the duodenum, causing compression and obstruction of the duodenum. This can result in symptoms such as vomiting, abdominal pain, and intestinal obstruction.
4.
Which hormone is produced primarily in the paraventricular nucleus?
Correct Answer
D. Oxytocin
Explanation
Oxytocin is produced primarily in the paraventricular nucleus. Oxytocin is a hormone that plays a crucial role in childbirth, lactation, and social bonding. It is released during labor to stimulate uterine contractions and during breastfeeding to facilitate milk letdown. Oxytocin also promotes feelings of trust, empathy, and bonding between individuals. Its production in the paraventricular nucleus ensures its release into the bloodstream, where it can exert its various physiological and behavioral effects.
5.
Dr Kalliecharan
Which of the following statements is characteristic of the pituitary gland?
Correct Answer
B. BasopHils produce FSH and LH
6.
Which of the following statements is characteristic of the thyroid gland?
Correct Answer
C. Thyroid follicular cells respond to TSH
Explanation
Thyroid follicular cells respond to TSH (thyroid-stimulating hormone) is a characteristic of the thyroid gland. TSH is produced by the anterior pituitary gland and stimulates the thyroid follicular cells to produce and release thyroid hormones, such as T4 (thyroxine) and T3 (triiodothyronine). These hormones play a crucial role in regulating metabolism, growth, and development in the body. Therefore, the statement correctly describes the function of the thyroid follicular cells in response to TSH.
7.
Dr Barremkala
A 22-year-old woman presents to her physician with a neck swelling. She said the swelling started growing suddenly for past 1 week and it started to hurt and she can’t breathe. On Inspection physician identified it as a solitary swelling which moved up on deglutition. On palpation he found the swelling was firm in consistency and it was not attached to the skin. The following statements concerning this swelling would LEAST LIKELY suggest a diagnosis of the thyroid gland swelling?
Correct Answer
B. The swelling is located superficial to the sternothyroid muscle.
Explanation
The statement "The swelling is located superficial to the sternothyroid muscle" would least likely suggest a diagnosis of thyroid gland swelling because the thyroid gland is located deep to the sternothyroid muscle. The swelling being superficial to this muscle would suggest a different etiology for the neck swelling.
8.
Picture 1 shows a Lashley cup used for collecting saliva from the parotid gland. Picture 2 shows that the lasheley cup is placed over the opening of Stensen's duct to collect the saliva for performing saliva sample testing. Which of the following is the most ideal site for placing the cup?
Correct Answer
C. Opposite the second maxillary molar
Explanation
The most ideal site for placing the Lashley cup is opposite the second maxillary molar. This is because the parotid gland, which is responsible for producing saliva, is located in the cheek area opposite the second maxillary molar. Placing the cup at this site ensures that saliva from the parotid gland can be collected effectively for testing.
9.
A 7 year old male is brought to his physician suffering from the early stages of precocious puberty. It is suspected that the primary problem is overproduction of testosterone and other androgens from a Leydig cell tumor in his right testicle. To confirm this, plasma levels of several other hypothalamic and pituitary hormones were assayed. If this diagnosis were correct, what would be the most likely set of findings for these assays?
Correct Answer
E. 5
Explanation
Explanation: For any of the hormones of the hypothalamus-pituitary-peripheral gland axis, the usual control mechanism is a combination of long-loop and short-loop negative feedbacks, resulting in homeostasis and a relatively stable level of peripheral gland hormones. In this patient, the hypothalamus and pituitary are not directly defective, but the uncontrolled production of testosterone from the gonadal tumor will cause complete inhibition of secretion of GnRH from the hypothalamus and both LH and FSH from the anterior pituitary gland. They would ALL be undetectable in the plasma of this boy, which is close to normal for a prepubertal normal child.
The picture below illustrates the process in this child:
10.
Dr Wright
A strain of mice were developed which had a reduced affinity for growth hormone (GH) at its receptors. What second messenger system’s activation would be directly reduced by the relatively more difficult binding of GH to its receptor?
Correct Answer
D. Janus kinase/STAT
Explanation
Explanation: Growth hormone receptors, like insulin receptors, bind as dimers and phosphorylate target proteins, including signal transduction of activators of transcription (STAT). They specifically activate Janus Kinase (JAK) then the STATs, and the mRNAs produced eventually result in new proteins that mediate the final cellular activities. It is also worth noting, as otherwise unmentioned in lecture, that prolactin also activates its target tissues using a JAK/STAT second messenger system, so it is used by two different pituitary hormones for different effects at their respective target tissues.
See Picture below for Prolactin’s JAK/STAT second messenger system, and proteins produced by same:
11.
A 26-year-old man reports to his physician that he is thirsty all the time and has been drinking a lot of water, which results in his having to urinate so frequently that it is disruptive to his daily activities. In addition, he has to get up frequently during the night to urinate. History reveals that the man sustained a head injury in a motorcycle accident one week earlier. Which of the following drugs is most likely to relieve his symptoms of thirst and diuresis?
Correct Answer
E. Desmopressin
Explanation
Desmopressin is the most likely drug to relieve the man's symptoms of thirst and diuresis. Desmopressin is a synthetic form of vasopressin, a hormone that regulates water balance in the body. The man's symptoms suggest that he may have developed diabetes insipidus as a result of his head injury. Diabetes insipidus is characterized by excessive thirst and urination due to a deficiency or resistance to vasopressin. Desmopressin acts as a replacement for the deficient vasopressin, reducing excessive thirst and urine production.
12.
Thyrotropin (thyroid-stimulating hormone) stimulates the secretion of thyroxine from the thyroid gland. It also feeds back to inhibit secretion of TRH (thyrotropin-releasing hormone) from the hypothalamus. Which of the following statements is true regarding the interaction of thyrotropin with its receptors?
Correct Answer
D. Thyrotropin is an agonist at thyrotropin receptors in both the thyroid gland and the hypothalamus.
Explanation
Thyrotropin is a hormone that stimulates the secretion of thyroxine from the thyroid gland. It also has a feedback mechanism where it inhibits the secretion of TRH from the hypothalamus. The correct answer states that thyrotropin is an agonist at thyrotropin receptors in both the thyroid gland and the hypothalamus. This means that when thyrotropin binds to its receptors in these two locations, it activates a response. This is consistent with the role of thyrotropin in stimulating the secretion of thyroxine from the thyroid gland and inhibiting the secretion of TRH from the hypothalamus.
13.
Drs. Thomas / Wright
Which of the following characteristics of a hormone administered as a drug is least likely to be accurately estimated or described based on knowledge of the chemical composition of the hormone?
Correct Answer
C. Potency
Explanation
Potency refers to the ability of a drug to produce a desired effect at a specific dose. It is determined by the drug's affinity for its target receptor and its ability to activate or inhibit the receptor. Knowledge of the chemical composition of a hormone may provide some insights into its potency, but it is not the sole determinant. Other factors such as receptor sensitivity, downstream signaling pathways, and interactions with other molecules in the body can also influence potency. Therefore, it is least likely to be accurately estimated or described based solely on knowledge of the hormone's chemical composition.
14.
A blood test reveals that a 20-year old non-obese male patient has high circulating glucose. You suggest a C-peptide test and it reveals that the values are very low compared with normal post-prandial (after meal) values. You make a diagnosis of Type I diabetes based on this low C-peptide value and other tests. Compared to a normal non-diabetic patient, what is your expectation for flux of glucose through the glycogen synthesis (glycogenesis) pathway after a meal in your patient’s muscle cells?
Correct Answer
A. Low insulin will result in lower rates of glycogen production
Explanation
In Type I diabetes, the pancreas does not produce enough insulin, resulting in low insulin levels. Insulin is responsible for promoting glycogen synthesis (glycogenesis) in muscle cells. Therefore, in this patient with low insulin levels, the flux of glucose through the glycogen synthesis pathway after a meal would be expected to be lower compared to a normal non-diabetic patient. This is because low insulin levels will result in lower rates of glycogen production.
15.
Dr Meisenberg
Angiotensin converting enzyme plays a role in blood pressure regulation. What is one of its immediate actions?
Correct Answer
B. Inactivates bradykinin
Explanation
Angiotensin converting enzyme (ACE) inactivates bradykinin. Bradykinin is a peptide that causes blood vessels to dilate, leading to a decrease in blood pressure. ACE breaks down bradykinin, preventing its vasodilatory effects and ultimately contributing to an increase in blood pressure.
16.
A laboratory advertises a new test for one of the neurophysins that is claimed to work better than hormone assays. For what diagnostic problem can a test for a neurophysin be useful?
Correct Answer
B. Distinction between nepHrogenic and non-nepHrogenic diabetes insipidus
Explanation
A test for neurophysin can be useful in distinguishing between nephrogenic and non-nephrogenic diabetes insipidus. Neurophysin is a carrier protein that transports the hormone vasopressin, also known as antidiuretic hormone (ADH). In nephrogenic diabetes insipidus, the kidneys are unable to respond to ADH, leading to excessive urination and thirst. Non-nephrogenic diabetes insipidus, on the other hand, is caused by a deficiency or lack of ADH production in the hypothalamus or pituitary gland. By testing for neurophysin, the laboratory can determine the presence or absence of this carrier protein, helping to differentiate between the two types of diabetes insipidus.
17.
A routine laboratory test for cardiovascular risk factors in a normal 60-year-old man shows that his levels of both T3 and T4 are only about 20% of normal. TSH is in the normal range, and the thyroid gland is of normal size without palpable masses. There are no clinical signs of abnormal thyroid function. Which of the following proteins is most likely deficient in this patient?
Correct Answer
C. Thyroxin-binding globulin in the blood
Explanation
In this patient, the levels of both T3 and T4 are only about 20% of normal, but TSH is in the normal range and there are no clinical signs of abnormal thyroid function. This suggests that there is a problem with the transport or binding of T3 and T4 rather than a problem with the production or release of these hormones. Thyroxin-binding globulin (TBG) is a protein that binds to T3 and T4 in the blood, allowing them to be transported to target tissues. Therefore, a deficiency in TBG would result in decreased levels of T3 and T4 in the blood, explaining the laboratory findings in this patient.
18.
A 72-year-old male patient with average blood pressure readings of 210/120 is found to have renal artery stenosis caused by atherosclerotic plaques. This patient will probably have
Correct Answer
C. Elevated renin in the blood
Explanation
The correct answer is "Elevated renin in the blood." Renal artery stenosis leads to reduced blood flow to the kidneys, causing a decrease in perfusion pressure. This triggers the release of renin from the juxtaglomerular cells in the kidneys. Renin then converts angiotensinogen into angiotensin I, initiating the renin-angiotensin-aldosterone system. This system leads to vasoconstriction and increased sodium and water reabsorption, ultimately increasing blood pressure. Therefore, in this patient with renal artery stenosis, elevated renin levels would be expected.
19.
Dr Grogan
A patient in your care has a 5 year history of Type II diabetes. In controlling the condition, the patient admits to fasting as a means of controlling weight gain (the patient is obese). After one recent day-long fast the patient experienced fatigue and light-headedness after taking the drug metformin – which works in part by suppressing the liver’s gluconeogenesis pathway enzymes. Given your extensive knowledge of hepatic metabolism– what advice should be given to the patient about future behavior?
Correct Answer
A. Don’t do the double whammy of diet and drug again, they both reduce blood glucose
Explanation
The correct answer advises the patient to avoid combining fasting with the drug metformin because both can reduce blood glucose levels. This is important because metformin works by suppressing the liver's gluconeogenesis pathway enzymes, which can further lower blood glucose levels when combined with fasting. Therefore, it is recommended that the patient does not repeat the combination of fasting and taking metformin to prevent fatigue and light-headedness.