Carbohydrate, fat, and protein take different paths to acetyl CoA, but once there, the final pathways- the TCA cycle and electron transport chain- are shared. Instead of dismissing this figure as "too busy," take a few moments to appreciate the busyness of it all.
The digestion of carbohydrates yields glucose (and other momosaccharides): some is stored as glycogen, and some is broken down to pyruvate and acetal CoA to provide energy. The acetyl CoA can then enter the TCA cycle and electron transport chain to provide more energy. The digestion of fat yields glycerol and fatty acids; some are reassembled nd stored as fat, and others are broken down to acetyl CoA, which can enter the TCA cycle and electron transport chain to provide energy. The digestion of protein yields amino acids, most of which are used to build body protein or other nitrogen-containing compounds, but some amino acids may be broken down through the same pathways as glucose to provide energy. Other amino acids enter directly into the TCA cycle, and these, too, can be broken down to yield energy. In summary, although carbohydrate, fats and protein enter the TCA cycle by different routes, the final pathways are common to all energy-yielding nutrients.