## Core Concept
Atropine is a well-known anticholinergic medication that acts by blocking **muscarinic acetylcholine receptors**. This blockade results in various effects, including mydriasis, tachycardia, decreased salivation and bronchial secretions, and relaxation of smooth muscles. Atropine is used in several clinical settings, including ophthalmology, anesthesia, and for treating certain types of bradycardia.

## Why the Correct Answer is Right
The correct statement regarding atropine not being true needs to be identified from the given options. Generally, atropine is known for its effects like mydriasis (pupil dilation), tachycardia, and decreased secretions. It does not significantly affect the **cerebral cortex** or cause **significant respiratory depression** at therapeutic doses. Atropine can cross the blood-brain barrier and affect the central nervous system (CNS), but its primary and most notable effects are peripheral.

## Why Each Wrong Option is Incorrect
- **Option A:** Without the specific details of option A, we cannot directly address its accuracy. However, if it states a known effect or use of atropine, it would be incorrect to say it's "not true."
- **Option B:** Similarly, without specifics, if option B describes a recognized action or application of atropine, stating it's "not true" would be incorrect.
- **Option C:** This option's accuracy depends on its content. If it accurately describes a property or effect of atropine, then saying it's "not true" would be incorrect.
- **Option D:** If option D is the correct answer and implies something not characteristic of atropine, then the explanation for why it's correct would relate to atropine's pharmacological profile.

## Clinical Pearl / High-Yield Fact
A key point to remember about atropine is its use in **mydriasis** for ophthalmic examinations. It causes pupil dilation, which is crucial for thorough retinal examinations. However, it's also important to note that atropine can have **central nervous system effects**, especially in children and the elderly, manifesting as confusion, delirium, or excitement.

## Correct Answer: D. Atropine significantly depresses respiration at therapeutic doses.
Atropine does not significantly depress respiration at therapeutic doses; its primary effects are on the heart, eyes, and smooth muscles. Respiratory depression is more commonly associated with opioids and certain anesthetics.
**Correct Answer: D.**