1) Coma is defined as a state of unresponsiveness where a patient cannot be aroused even with vigorous stimulation. It involves a lack of arousal and awareness.
2) The ascending reticular activating system and cerebral cortex are the two main anatomical components involved in consciousness. Damage or disturbances in these areas can result in altered mental states ranging from confusion to deep coma.
3) Causes of coma include structural injuries, lack of oxygen/substrates, toxicity from substances, and infections/inflammation of the central nervous system.