Nokea
How do hormones from the thyroid and parathyroid regulate the calcium concentration of the blood?
- A. Calcitonin lowers blood calcium; parathyroid hormone raises blood calcium.
- B. Parathyroid hormone lowers blood calcium; calcitonin raises blood calcium.
- C. Thyroxine and triiodothyronine together regulate calcium levels, as needs dictate.
- D. Both parathroid hormone and the three thyroid hormones function to regulate blood calcium levels.
Correct Answer: A
Rationale: Step 1: Calcitonin is secreted by the thyroid gland and lowers blood calcium levels by promoting calcium deposition in bones.
Step 2: Parathyroid hormone (PTH) is secreted by the parathyroid gland and raises blood calcium levels by stimulating bone resorption and increasing calcium reabsorption in the kidneys.
Step 3: Since Calcitonin lowers blood calcium and PTH raises blood calcium, choice A is correct.
Summary: Choices B, C, and D are incorrect as they provide inaccurate information about the roles of calcitonin, PTH, thyroxine, and triiodothyronine in regulating blood calcium levels.
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Which disease can be caused by a lack of vitamin C?
- A. AIDS
- B. coronary heart disease
- C. rickets
- D. scurvy
Correct Answer: D
Rationale: The correct answer is D: scurvy. Scurvy is caused by a deficiency of vitamin C, leading to symptoms such as fatigue, bleeding gums, and skin discoloration. Vitamin C is essential for collagen synthesis, and its deficiency impairs collagen formation.
A: AIDS is caused by the human immunodeficiency virus (HIV), not by a lack of vitamin C.
B: Coronary heart disease is primarily related to factors such as high cholesterol, high blood pressure, and smoking, not vitamin C deficiency.
C: Rickets is caused by a deficiency of vitamin D, leading to soft and weak bones, not by a lack of vitamin C.
Mrs. Klein, aged 35 years, has just been diagnosed as diabetic. She is being put on a 1200 calorie diabetic diet with 50% of the calories to be from carbohydrates, 20% from protein, and 30% from fat. In instructing her about her diet, which of the following would be the best breakfast to suggest?
- A. Three waffles with butter, dietetic syrup, coffee
- B. One boiled egg, corn flakes with one glass milk, coffee, glass of orange juice
- C. A cheese omelet (4 oz cheddar, three eggs), one slice toast, one glass milk
- D. Two buttered English muffins, glass of grapefruit juice, coffee
Correct Answer: C
Rationale: A cheese omelet with protein and appropriate carbohydrate content fits the macronutrient distribution for a diabetic diet.
Organophosphate insecticides and nerve gases exert their lethal effects by:
- A. Blocking alpha and β-adrenergic receptors
- B. Blocking all muscarinic receptors on target cells
- C. Blocking nicotinic receptors in the brain
- D. Inhibiting acetylcholine metabolism
Correct Answer: D
Rationale: The correct answer is D because organophosphate insecticides and nerve gases inhibit acetylcholine metabolism by irreversibly binding to acetylcholinesterase enzyme, leading to accumulation of acetylcholine at synapses. This results in overstimulation of cholinergic receptors, causing symptoms of cholinergic toxicity.
Choice A is incorrect because alpha and beta-adrenergic receptors are not the targets of organophosphates. Choice B is incorrect because organophosphates do not block all muscarinic receptors. Choice C is incorrect because organophosphates do not specifically target nicotinic receptors in the brain.
The islets of Langerhans:
- A. are cells found in the adenohypophysis.
- B. secrete insulin and glucagon.
- C. secrete steroids.
- D. secrete releasing hormones.
Correct Answer: B
Rationale: Step 1: Islets of Langerhans are clusters of cells in the pancreas.
Step 2: These cells secrete insulin to lower blood sugar levels and glucagon to raise blood sugar levels.
Step 3: Therefore, choice B is correct as it accurately describes the function of the islets of Langerhans.
Summary: Choices A, C, and D are incorrect as islets of Langerhans are not found in the adenohypophysis, do not secrete steroids, and do not secrete releasing hormones.
Which gland is responsible for the production of adrenaline?
- A. Adrenal
- B. Parathyroid
- C. Gonadal
- D. Pancreas
Correct Answer: A
Rationale: The correct answer is A: Adrenal. The adrenal gland is responsible for producing adrenaline, also known as epinephrine, which is a hormone released in response to stress or danger. Adrenaline helps the body prepare for fight or flight responses by increasing heart rate, dilating airways, and boosting energy. The other choices, Parathyroid, Gonadal, and Pancreas, are not responsible for producing adrenaline. Parathyroid glands regulate calcium levels, gonadal glands produce sex hormones, and the pancreas produces insulin and digestive enzymes. Therefore, the adrenal gland is the correct answer for the production of adrenaline.