Biology: Discovering Life

action potential activity amino acids animals antibodies antigen arteries axon behavior bind birds blood cells bloodstream bone brain calcium called cancer capillaries cause cavity cell membrane cellular Chapter chemical cholesterol circulation circulatory system complex concentration contains contraction diffuse digestive system disease embryo endocrine enters environment enzymes female fibers Figure fluid function gas exchange gastrulation genes genetic germ layers glands glucose heart hemoglobin hormone human hypothalamus immune response immune system increase individual infection intestine ions kidney known layer levels liver lungs male mammals mesoderm metabolic molecules muscle cells nerve nervous system neural neurons neurulation normal nutrients organs ovum oxygen pituitary produce proteins pumped receptors release reproductive respiratory system Rossi salt sarcomere Senkarik sensory sexual skeletal skin smooth muscle sodium species sperm stimulates stomach sugar surface synapses T-cells temperature throughout the body thyroxine tion tissues tubule urine vertebrates virus viruses