Final answer:
The layers of hair most influenced by chemical texture services are the cortex and cuticle. The cortex determines hair texture and has to be altered during such services, while the cuticle must open up to allow chemicals to modify the cortex.
Step-by-step explanation:
The two layers of the hair most affected by chemical texture services are the cortex and cuticle. When providing such services in the field of hairstyling or chemical hair treatment, it's important to understand the structure of the hair. The cortex in hair, being the middle layer, consists of compressed, keratinized cells that give hair its texture; whether straight or curly. The cuticle, which is the outermost layer, consists of very hard, keratinized cells. It acts as the protective layer but is also affected by chemical services as they often aim to penetrate this layer to reach and alter the cortex. In the context of hair matrix, the cuticle and cortex originate from the basal cells, forming the hair bulb and shaft during hair growth. Chemical texture services modify the shape and structure of the cortex, changing the hair texture, while the cuticle must lift to allow such changes to take effect.