7/28 Quiz

Which of the following best describes the effect of elevated blood calcium levels on the nervous system?

• Increased excitability of neurons due to enhanced sodium influx

• Decreased neuronal excitability due to increased threshold for action potential

• Increased neurotransmitter release at synapses

• Seizures and muscle spasms due to spontaneous nerve firing

Which of the following cell types has receptors for parathyroid hormone (PTH)?

• Osteoblasts

• Osteoclasts

• Chondrocytes

• Skeletal muscle cells

Which of the following would most likely increase 24-alpha-hydroxylase activity in the kidney?

• Elevated parathyroid hormone

• Low levels of calcitriol

• Elevated levels of active vitamin D

• Low calcium levels

How does vitamin D3 (calcitriol) promote calcium absorption in the small intestine?

• By increasing expression of calcium-binding proteins like calbindin

• By activating osteoclasts directly

• By blocking sodium channels

• By stimulating parathyroid hormone secretion

How does PTH affect phosphate handling by the kidneys?

• Increases phosphate reabsorption

• Decreases phosphate excretion

• Increases phosphate excretion

• No effect on phosphate

What is the primary cause of rickets in children?

• Vitamin D deficiency

• Excessive calcium intake

• Hyperparathyroidism

• Overactive osteoblast activity

What effect does calcitonin have on the kidneys?

• Increases calcium reabsorption

• Increases phosphate reabsorption

• Promotes calcium and phosphate excretion

• Stimulates vitamin D activation

Which of the following is a classic laboratory finding in primary hyperparathyroidism?

• Low PTH, high calcium

• High PTH, low calcium

• Normal calcium and phosphate with high PTH

• High PTH, high calcium, low phosphate

Why is the liver especially affected by hormones released from the pancreatic islets?

• It has receives blood directly from the pancreas via the portal vein

• It produces insulin and glucagon itself

• It filters hormones from the bloodstream before other organs

• It is the primary site of hormone degradation

How does glucagon affect the carnitine shuttle in the liver?

• It inhibits the carnitine shuttle, reducing fatty acid transport into mitochondria

• It activates the carnitine shuttle, increasing fatty acid transport into mitochondria for β-oxidation

• It promotes glucose transport into mitochondria

• It decreases carnitine synthesis