Question

question 82
0.25 pts
hormone that inhibits osteoclast activity in children.
calcitonin
thyroxine
oxytocin
parathyroid hormone
catecholamines
question 83
0.25 pts
which of the following areas has the highest concentration of cones?
the ora serrata retinae
the optic disc
the macula lutea
the fovea centralis
question 84
0.25 pts
receptors for hearing are located in the
semicircular canals.
cochlear duct.
tympanic membrane.
middle ear.

Explanation:

Question 82

To determine the hormone that inhibits osteoclast activity in children, we analyze each option:

• Calcitonin: Secreted by the thyroid gland, it inhibits osteoclast activity (bone resorption) and promotes calcium deposition in bones, especially relevant in children's bone development.
• Thyroxine: Involved in metabolism, not directly related to osteoclast inhibition.
• Oxytocin: Related to childbirth and lactation, not bone activity.
• Parathyroid hormone: Increases osteoclast activity (opposite of what's needed here).
• Catecholamines: Involved in stress response, not bone regulation.

So calcitonin is the correct hormone.

To find the area with the highest cone concentration:

• Ora serrata retinae: Peripheral retina, low cone density.
• Optic disc: Blind spot, no photoreceptors (cones or rods).
• Macula lutea: Contains cones but not the highest concentration.
• Fovea centralis: A small pit in the macula with the highest density of cones (responsible for sharp central vision).

Thus, the fovea centralis has the highest cone concentration.

To identify where hearing receptors are located:

• Semicircular canals: Involved in balance (vestibular system), not hearing.
• Cochlear duct: Contains the organ of Corti, which has hair cells (hearing receptors) that transduce sound vibrations.
• Tympanic membrane: Transmits sound to the middle ear, not the location of receptors.
• Middle ear: Contains ossicles (transmit sound), no hearing receptors.

So hearing receptors are in the cochlear duct.

Answer:

A. calcitonin

Question 83