Unit 1 natural science

The document discusses several key human body systems including the nervous system, senses, musculoskeletal system, and digestion. It explains that the nervous system allows humans to perceive and respond to internal and external stimuli through senses like sight, smell, taste, touch, and hearing. It also describes how the digestive system breaks down food for all cells to use for nutrition, while the musculoskeletal system facilitates movement through bones, joints, and muscles. Reproduction is mentioned as the creation of new organisms with similar characteristics to their parents through the union of male and female sex cells.