Exam 5: Lecture 68: Thyroid Hormone 2: AI Questions

Question 1

Negative feedback control of thyroid hormone secretion primarily occurs at the level of the:
A) Anterior pituitary
B) Hypothalamus
C) Thyroid gland
D) Adrenal gland

Answer 1

A

Question 2

Which enzyme converts T4 to the biologically active T3 in peripheral tissues?
A) 5’ deiodinase
B) Thyroid peroxidase
C) Na+/I- symporter
D) Pendrin

Answer 2

A

Question 3

Which of the following is NOT an effect of thyroid hormones on basal metabolic rate?
A) Increased oxygen consumption
B) Increased Na+/K+ ATPase activity
C) Decreased thermogenesis
D) Increased heat production

Answer 3

C

Question 4

In starvation, what happens to the conversion of T4 to T3?
A) It increases
B) It decreases
C) It remains unchanged
D) It shifts towards increased rT3 production

Answer 4

D

Question 5

Thyroid hormone receptors in target cells are primarily located in the:
A) Plasma membrane
B) Cytoplasm
C) Mitochondria
D) Nucleus

Answer 5

D

Question 6

Which of the following best describes the action of T3 at the cellular level?
A) Activates G-protein coupled receptors
B) Binds to nuclear receptors to alter gene transcription
C) Inhibits protein synthesis
D) Stimulates endocytosis of thyroid hormones

Answer 6

B

Question 7

In hyperthyroidism, you would expect the blood test results to show:
A) High T4, high TSH
B) High T4, low TSH
C) Low T4, high TSH
D) Low T4, low TSH

Answer 7

B

Question 8

Which of the following is a common clinical sign of hypothyroidism in dogs?
A) Hyperactivity and weight loss
B) Cold intolerance and weight gain
C) Increased appetite and increased heart rate
D) Muscle tremors and heat intolerance

Answer 8

B

Question 9

The major site of thyroid hormone degradation in the body is the:
A) Adrenal gland
B) Kidney
C) Liver
D) Brain

Answer 9

C

Question 10

T3 increases the expression of which receptor in the heart, enhancing its effects on heart rate?
A) Beta-1 adrenergic receptors
B) Alpha-1 adrenergic receptors
C) Muscarinic receptors
D) Dopamine receptors

Answer 10

A

Question 11

Which of the following factors would decrease circulating T3 levels?
A) Exercise
B) Cold exposure
C) Starvation
D) High carbohydrate intake

Answer 11

C

Question 12

In cats with hyperthyroidism, the most common underlying cause is:
A) Autoimmune destruction of the thyroid gland
B) Thyroid adenoma or adenocarcinoma
C) Iodine deficiency
D) Chronic renal disease

Answer 12

B

Question 13

Which of the following is a key role of thyroid hormones during fetal development?
A) Regulating blood pressure
B) Maturation of the central nervous system
C) Increasing skeletal muscle mass
D) Enhancing insulin sensitivity

Answer 13

B

Question 14

The primary effect of somatostatin on the hypothalamic-pituitary-thyroid axis is to:
A) Stimulate TSH release
B) Inhibit TSH release
C) Increase T3 production
D) Decrease TRH secretion

Answer 14

B

Question 15

A patient presenting with increased heart rate, heat intolerance, and weight loss likely has:
A) Hypothyroidism
B) Hyperthyroidism
C) Cushing’s disease
D) Addison’s disease

Answer 15

B

Question 16

The thyroid hormone that primarily functions as a prohormone is:
A) T3
B) rT3
C) T4
D) Calcitonin

Answer 16

C

Question 17

Which hormone exerts a tonic inhibitory effect on TSH secretion?
A) Insulin
B) Dopamine
C) Aldosterone
D) Glucagon

Answer 17

B

Question 18

A primary characteristic of congenital hypothyroidism (cretinism) is:
A) Excessive growth and development
B) Impaired brain development and growth retardation
C) Hyperactive reflexes
D) Increased metabolic rate

Answer 18

B

Question 19

In hypothyroidism, protein metabolism is characterized by:
A) Increased protein synthesis
B) Increased protein degradation
C) Decreased protein synthesis and increased degradation
D) Normal protein turnover

Answer 19

C

Question 20

Which test is most commonly used to diagnose hypothyroidism in dogs?
A) Serum T4 measurement
B) Serum calcium measurement
C) Fasting glucose test
D) Liver enzyme test

Answer 20

A

Question 21

In the mechanism of thyroid hormone action, the hormone-receptor complex binds to:
A) Mitochondrial DNA
B) Membrane phospholipids
C) Thyroid response elements on nuclear DNA
D) Endoplasmic reticulum receptors

Answer 21

C

Question 22

Chronic iodine deficiency would most likely result in:
A) Hyperthyroidism
B) Goiter formation
C) Increased T3 production
D) Decreased TSH levels

Answer 22

B

Question 23

In a patient with primary hypothyroidism, you would expect the levels of TSH and T4 to be:
A) Low TSH, low T4
B) High TSH, low T4
C) Low TSH, high T4
D) High TSH, high T4

Answer 23

B

Question 24

Which of the following is a known effect of thyroid hormones on carbohydrate metabolism?
A) Decreased gluconeogenesis
B) Decreased glucose absorption from the gut
C) Increased insulin sensitivity
D) Increased glycogenolysis and gluconeogenesis

Answer 24

D

Question 25

The administration of exogenous T3 would most likely lead to:
A) Increased TSH secretion
B) Decreased TRH and TSH secretion
C) Enhanced production of thyroglobulin
D) Increased conversion of T4 to rT3

Answer 25

B

Question 26

Which of the following describes the effect of hyperthyroidism on bone metabolism?
A) Decreased osteoclast activity
B) Increased bone resorption and decreased bone density
C) Increased bone mineralization
D) Enhanced cartilage growth

Answer 26

B

Question 27

Which condition is characterized by an elevated TSH and elevated T4?
A) Primary hypothyroidism
B) Secondary hyperthyroidism (pituitary origin)
C) Tertiary hypothyroidism (hypothalamic origin)
D) Euthyroid sick syndrome

Answer 27

B

Question 28

The increased heart rate seen in hyperthyroid animals is primarily due to:
A) Enhanced vagal tone
B) Increased expression of β-1 adrenergic receptors
C) Direct stimulation of cardiac muscle by T4
D) Increased parasympathetic activity

Answer 28

B

Question 29

Which of the following is a common cause of acquired hypothyroidism in dogs?
A) Autoimmune thyroiditis
B) Iodine toxicity
C) Thyroid adenoma
D) Chronic kidney disease

Answer 29

A

Question 30

In hyperthyroid cats, the primary treatment involves:
A) Increasing iodine intake
B) Surgical removal of the adrenal glands
C) Administration of methimazole or radioactive iodine therapy
D) High-calorie diet to prevent weight loss

Answer 30

C

Question 31

Which of the following is NOT a typical sign of hypothyroidism in dogs?
A) Alopecia
B) Lethargy
C) Polyuria and polydipsia
D) Obesity

Answer 31

C

Question 32

The primary site of T3 degradation in the body is:
A) Brain
B) Liver
C) Thyroid gland
D) Spleen

Answer 32

B

Question 33

Which hormone directly inhibits TSH release from the anterior pituitary?
A) Cortisol
B) T3
C) Glucagon
D) Insulin

Answer 33

B

Question 34

In hypothyroid animals, the Na+/K+ ATPase activity is:
A) Increased due to high T4 levels
B) Unaffected by thyroid status
C) Decreased, leading to reduced basal metabolic rate
D) Increased, causing hyperthermia

Answer 34

C

Question 35

The clinical sign of “myxedema” in hypothyroid dogs is characterized by:
A) Puffy facial swelling and thickened skin
B) Muscle tremors and hyperactivity
C) Severe dehydration and sunken eyes
D) Increased heart rate and palpitations

Answer 35

A