Correct Answer: C

Rationale: The correct order of airflow in the lungs starts with air entering through the trachea, moving into the bronchi, then proceeding to the bronchioles, and finally reaching the alveoli where gas exchange occurs. Therefore, the correct sequence is Trachea, Bronchi, Bronchioles, Alveoli, making choice C the accurate representation of the airflow in the lungs. Choices A, B, and D are incorrect because they do not follow the anatomical path of airflow in the lungs as air moves from the trachea to the bronchi, then bronchioles, and finally the alveoli for gas exchange.

Correct Answer: C

Rationale: The correct answer is C: Hypothalamus. The hypothalamus is a significant structure of the limbic system responsible for regulating various functions such as emotions, autonomic functions, and hormone production. It plays a crucial role in maintaining homeostasis and orchestrating responses to stress and emotional stimuli. Choices A, B, and D are incorrect. The brainstem, although a vital part of the brain, is not a major structure of the limbic system. The spinal cord is not part of the limbic system; it is primarily involved in transmitting sensory and motor information between the brain and the rest of the body. The cerebral cortex is responsible for higher cognitive functions but is not a major structure within the limbic system.

Correct Answer: A

Rationale: The correct answer is A: Amygdala. The amygdala is a key brain structure involved in the processing of emotions, including anxiety. Medications for anxiety disorders often target the amygdala to help regulate emotional responses and control anxiety attacks. The amygdala plays a crucial role in the brain's fear circuit and is essential for the appropriate response to stress and threat perception. Choices B, C, and D are incorrect because the parietal lobe is primarily involved in sensory processing and spatial reasoning, the hypothalamus regulates basic functions like hunger, thirst, and body temperature, and sensory neurons transmit signals from sensory receptors to the central nervous system, none of which are directly related to the regulation of anxiety attacks.

Correct Answer: A

Rationale: The cell is indeed the most basic unit of life, forming the foundation of all living organisms. Cells are the building blocks of all living things, containing organelles that perform specific functions. While oxygen is essential for life, it is not a structural unit. Similarly, pigment is a component found within cells but is not the fundamental unit of structure. Therefore, the correct answer is 'A: Cell.'

Correct Answer: C

Rationale: The correct answer is C: Paracrine. Somatostatin acts in a paracrine manner by inhibiting the release of insulin from nearby cells within the pancreas. Paracrine signaling involves the secretion of signals that act on neighboring cells, as seen in this scenario where somatostatin affects nearby pancreatic cells without entering the bloodstream or affecting distant cells. Autocrine signaling involves cells responding to substances they themselves release, which is not the case here. Neuromodulators are chemicals that modulate the activity of neurons, not directly related to this scenario. Pheromones are chemicals released into the environment to communicate with individuals of the same species, not relevant to the signaling within the pancreas.