All of the following bind to intracellular receptors EXCEPT:

Correct Answer: D

Rationale: PTH binds to membrane G-protein-coupled receptors, while cortisol, aldosterone, 1,25-DHCC, and thyroxine act via intracellular nuclear receptors.

Correct Answer: C

Rationale: VIP, GIP, and glucagon do not stimulate gastrin; atropine doesn't inhibit it, amino acids do stimulate, secretin inhibits, and epinephrine can increase it.

Correct Answer: A

Rationale: The esophagus lacks BER, relying on peristalsis triggered by swallowing, unlike other GIT segments.

Correct Answer: C

Rationale: The actual structural unit that secretes insulin is the beta cell. Beta cells are found on the islets of Langerhans, which are in the pancreas.

Correct Answer: C

Rationale: The pancreas acts as an endocrine gland, secreting insulin directly into the bloodstream, and an exocrine gland, secreting digestive enzymes through ducts.