Which factor stimulates insulin secretion?

Correct Answer: C

Rationale: The correct answer is C: theophylline. Theophylline stimulates insulin secretion by increasing cAMP levels in pancreatic beta cells, leading to enhanced insulin release. Thiazide diuretics (A) can actually reduce insulin secretion. Phenytoin (B) and beta blockers (D) are known to inhibit insulin secretion. Therefore, theophylline is the only choice that directly stimulates insulin secretion.

Correct Answer: C

Rationale: The correct answer is C: Thyroid. The thyroid gland is located at the base of the throat, just inferior to the laryngeal prominence. It is responsible for producing hormones that regulate metabolism and growth. The pituitary gland (A) is located in the brain and controls other endocrine glands. The hypothalamus (B) is also in the brain and regulates hormone production. The pineal gland (D) is located in the brain and produces melatonin. Thyroid is correct due to its anatomical location and function in hormone regulation.

Correct Answer: C

Rationale: The correct answer is C: neural. In this scenario, the student experiences the fight or flight response, which is controlled by the sympathetic nervous system. The pupil dilation, increased heart rate, and rapid breathing are all physiological responses triggered by the activation of neural pathways in response to a perceived threat or stress. The other choices are incorrect because: A: Humoral stimuli involve changes in blood levels of certain substances triggering hormone release. B: Hormonal stimuli involve the release of hormones in response to other hormones. D: Positive feedback is a mechanism that amplifies a response, not directly related to the immediate physiological responses seen in this case.

Correct Answer: C

Rationale: The correct answer is C: Oesophagus. The oesophagus is the structure leading to the stomach that carries food from the mouth to the stomach through peristalsis. The pharynx (A) is the throat cavity, the epiglottis (B) is a flap that prevents food from entering the trachea during swallowing, and the larynx (D) is the voice box. Therefore, the oesophagus is the correct answer as it specifically functions to transport food to the stomach.

Correct Answer: D

Rationale: The correct answer is D. Hormones travel through the bloodstream while neurotransmitters travel across the synaptic cleft between neurons. Hormones are secreted by endocrine glands into the bloodstream to target distant tissues, while neurotransmitters are released by neurons into the synaptic cleft to transmit signals locally between neurons. Choice A is incorrect as hormones do not travel through the synaptic cleft, and neurotransmitters do not travel through the bloodstream. Choice B is incorrect as both hormones and neurotransmitters act on specific receptors. Choice C is incorrect as hormones do not use electrical impulses; instead, they travel through the bloodstream.