1.
With an infection at the tip of the tongue, which lymph node is most likely to be initially
enlarged and tender?
Correct Answer
D. Sub-mental
Explanation
When there is an infection at the tip of the tongue, the lymph node that is most likely to be initially enlarged and tender is the sub-mental lymph node. The sub-mental lymph node is located beneath the chin, near the midline, and is responsible for draining the lymphatic fluid from the tongue. Therefore, when there is an infection at the tip of the tongue, the sub-mental lymph node will be the first to respond and become enlarged and tender.
2.
A 30-year old lady visited her dentist for the severe pain around the last lower molar
tooth. The dentist examined and decided to extract the last lower tooth. Two weeks after
the extraction, the lady complained of the loss of taste and general sensation over anterior
two-thirds of the tongue. Which of the following structures was most likely damaged during
the extraction?
Correct Answer
B. Lingual nerve
Explanation
The lingual nerve is most likely to be damaged during the extraction of the last lower molar tooth. The lingual nerve is responsible for providing sensory innervation to the anterior two-thirds of the tongue. Damage to this nerve can lead to loss of taste and general sensation in this area.
3.
After protraction of the mandible, it is retracted by which of the following muscles fibers?
Correct Answer
D. Posterior fibers of the temporalis
Explanation
After protraction of the mandible, the posterior fibers of the temporalis muscle are responsible for retracting the mandible. These fibers of the temporalis muscle are located towards the back of the muscle and when contracted, they pull the mandible back into its original position. The medial pterygoid muscle, anterior fibers of the temporalis muscle, middle fibers of the temporalis, and lateral pterygoid muscle are not involved in the retraction of the mandible.
4.
Picture 1 shows a Lashley cup used for collecting saliva from the parotid gland. Picture 2
shows that the Lashley cup is placed over the opening of Stensen's duct to collect the saliva
for saliva sample testing. Which of the following is the most ideal site for placing the cup?
Correct Answer
D. Opposite the second maxillary molar
Explanation
The second maxillary molar is the most ideal site for placing the cup because it is closest to the opening of Stensen's duct, which is the duct that carries saliva from the parotid gland. Placing the cup opposite the second maxillary molar ensures that it will be in the correct position to collect saliva from the parotid gland effectively.
5.
An 11-year-old boy who was hit in the chin by a baseball, is brought to the clinic with
complaints of a sore chin and an inability to taste ice-cream. Which of the following nerves
is most likely injured in this patient?
Correct Answer
A. Chorda tympani
Explanation
DON'T HAVE THE ANSWER TO THIS QUESTION...,,, NOT SURE IF "A" IS THE ANSWER
6.
A 20-yr-old girl visits her family physician complaining of difficulty swallowing. The
physician thinks that she has xerostomia, and starts examining the opening of the _____
gland in the oral vestibule.
Correct Answer
A. Right parotid
Explanation
DON'T HAVE THE ANSWER TO THIS QUESTION...,,, NOT SURE IF "A" IS THE ANSWER
7.
A patient presents with signs of hypothyroidism. To investigate the matter, you measure
the levels of T4 and TSH. If the patient suffers from iodine deficiency, you can expect the
following results:
Correct Answer
D. T4 reduced, TSH elevated
Explanation
If a patient suffers from iodine deficiency, it can lead to hypothyroidism. In hypothyroidism, the production of thyroid hormones, including T4, is decreased. As a compensatory mechanism, the pituitary gland releases more TSH (thyroid-stimulating hormone) to stimulate the thyroid gland to produce more hormones. Therefore, in the case of iodine deficiency, the levels of T4 would be reduced, indicating decreased thyroid hormone production, while the levels of TSH would be elevated, indicating increased stimulation of the thyroid gland.
8.
The above structure is
Correct Answer
D. A mineralocorticoid
Explanation
The given structure is most likely a mineralocorticoid because mineralocorticoids are a class of hormones that regulate the balance of minerals, particularly sodium and potassium, in the body. They are produced by the adrenal glands and help control blood pressure and fluid balance. Estrogens, androgens, glucocorticoids, and progesterone are other types of hormones with different functions and structures.
9.
An elderly patient who takes aspirin for chronic arthritis complains about frequent pain in
the stomach that can be relieved only by eating. One possible solution to the patient’s
problem is to
Correct Answer
E. Switch to a drug that has higher potency on COX-2 relative to COX-1
Explanation
Switching to a drug that has higher potency on COX-2 relative to COX-1 would be a possible solution for the patient's problem. COX-1 is responsible for producing prostaglandins that protect the stomach lining, while COX-2 is responsible for producing prostaglandins that cause pain and inflammation. By using a drug that specifically targets COX-2, the patient can potentially reduce stomach pain while still getting relief from arthritis symptoms.
10.
During the synthesis of steroid hormones, side chain cleavage reactions occur in two
biotransformations. These are:
Correct Answer
D. Cholesterol --> progestins and progestins --> androgens
11.
Thromboxane is formed in platelets, where it promotes platelet activation. The formation
of thromboxane can be suppressed by inhibitors of:
Correct Answer
E. COX-1
Explanation
COX-1 is the correct answer because it is an enzyme responsible for the production of thromboxane in platelets. Inhibitors of COX-1 can suppress the formation of thromboxane, thereby preventing platelet activation. The other options (21-hydroxylase, COX-2, 5-lipoxygenase, and desmolase) are not directly involved in the production of thromboxane.
12.
For a “classical” radioimmunoassay of insulin, you need
Correct Answer
B. Radioactive insulin in the test tube
Explanation
In a "classical" radioimmunoassay of insulin, radioactive insulin in the test tube is needed. This is because radioimmunoassay involves the use of a radiolabeled antigen (insulin in this case) to measure the presence and quantity of specific antibodies in a sample. By adding radioactive insulin to the test tube, it allows for the binding of the insulin to the insulin receptor, which can then be detected and measured. This radioactive insulin serves as a tracer to determine the concentration of insulin in the sample.
13.
The antihypertensive drug captopril acts as an inhibitor of angiotensin converting
enzyme. In addition to reducing the formation of angiotensin II, captopril will also reduce
the level of circulating
Correct Answer
D. Aldosterone
Explanation
Captopril acts as an inhibitor of angiotensin converting enzyme, which is responsible for the conversion of angiotensin I to angiotensin II. Angiotensin II stimulates the release of aldosterone from the adrenal glands, which promotes the reabsorption of sodium and water in the kidneys. By inhibiting the formation of angiotensin II, captopril will also reduce the release of aldosterone, thereby decreasing the level of circulating aldosterone.
14.
The nurse notices that a newborn girl has an unusually enlarged clitoris, and asks you
whether this might be a disorder of sexual development. You notice that in addition to the
large clitoris the labia are partially fused. Some tests are done. The hospital lab reports
normal values for serum sodium, potassium and ACTH. An ultrasound scan shows normalsized
adrenal glands. A buccal smear is sex chromatin negative (no Barr body). If this child
has an enzyme deficiency, the missing enzyme is most likely
Correct Answer
E. 5α-reductase
Explanation
The correct answer is 5α-reductase. This is because the newborn girl has an enlarged clitoris and partially fused labia, which suggests a disorder of sexual development. The normal values for serum sodium, potassium, and ACTH, as well as normal-sized adrenal glands, indicate that the adrenal glands are functioning properly. The negative sex chromatin in the buccal smear suggests that the child does not have a chromosomal abnormality. 5α-reductase is the enzyme responsible for converting testosterone into dihydrotestosterone (DHT), which is necessary for the development of male external genitalia. Therefore, a deficiency in 5α-reductase would explain the abnormal genital development in this newborn girl.
15.
After several attacks of autoimmune thyroiditis, Mrs. O. has developed signs of
hypothyroidism. Her hormone measurements will most likely show:
Correct Answer
D. Low T4, high TSH
Explanation
In autoimmune thyroiditis, the immune system mistakenly attacks the thyroid gland, leading to inflammation and damage. This can result in decreased production of thyroid hormones, leading to hypothyroidism. In hypothyroidism, the levels of thyroid hormones, such as T4, are low. However, the pituitary gland senses the low levels of thyroid hormones and releases more thyroid-stimulating hormone (TSH) in an attempt to stimulate the thyroid gland to produce more hormones. Therefore, in Mrs. O.'s case, her hormone measurements will most likely show low T4 levels and high TSH levels.
16.
The hydroxylation reactions of steroid hormones in the endocrine glands require
cytochrome P450, NADpH and
Correct Answer
D. Molecular oxygen
Explanation
The hydroxylation reactions of steroid hormones in the endocrine glands require molecular oxygen. Oxygen is needed for the hydroxylation process to occur, which involves adding a hydroxyl group (-OH) to the steroid molecule. This reaction is catalyzed by enzymes called cytochrome P450, which use molecular oxygen as a co-substrate. Without oxygen, the hydroxylation reactions cannot take place, leading to a deficiency in the production of steroid hormones.
17.
Insulin is synthesized from a larger precursor protein. The following events occur during
insulin synthesis: (1) Formation of disulfide bonds; (2) Secretion by exocytosis; (3)
Removal of the signal sequence; (4) Removal of the C-peptide. In which sequence are these
events most likely to occur?
Correct Answer
C. 3 --> 1 --> 4 --> 2
Explanation
During insulin synthesis, the first event is the removal of the signal sequence, which is followed by the formation of disulfide bonds. After that, the C-peptide is removed, and finally, insulin is secreted by exocytosis. Therefore, the most likely sequence of events is 3 --> 1 --> 4 --> 2.
18.
Selective COX-2 inhibitors have been developed, but they should be used with caution
because they can increase the risk of
Correct Answer
D. Acute myocardial infarction
Explanation
Selective COX-2 inhibitors are a type of medication that specifically targets the COX-2 enzyme, which is involved in inflammation. While these medications can be effective in reducing inflammation, they have been associated with an increased risk of acute myocardial infarction, also known as a heart attack. This is why they should be used with caution, as the potential benefit of reducing inflammation must be weighed against the potential risk of heart attack.
19.
Low doses of aspirin are used to reduce the risk of acute myocardial infarction. Which
enzyme is targeted when aspirin is used for this purpose?
Correct Answer
C. COX-1
Explanation
Aspirin targets the enzyme COX-1 when used to reduce the risk of acute myocardial infarction. COX-1 is an enzyme involved in the production of thromboxane A2, which promotes platelet aggregation and vasoconstriction. By inhibiting COX-1, aspirin reduces the formation of thromboxane A2, leading to decreased platelet aggregation and a lower risk of blood clot formation that can cause a heart attack.