1/30/12A sagittal cut exposes the dorsal cavityEndocrine system and CNS bring the body back to homeostasis- the regulate the bodyPhysiology- function of the body partsFunction refers to the biochemical reactions occurring inside the cells of the bodyThe function of a part of the body depends on the structure of the partStructure: the makeup, cell type and tissue type.Structure defines function!The cellular make up/tissue make up of an organ dictates the function of that organ. Will see this theme over and overIn the human body there are 11 organ systemsHuman body exhibits structural complexityThe lowest level of structural complexity is the chemical level, where biochemical reactions result in the function of the body partsThe next level of structural complexity is the cellular level.Cells are the structural units of organismsCells are the smallest structures in which biomechanical reactions occurThe next level of structural complexity is the tissue level. Most cells in the body aggregate to form tissues. A tissue is composed of similar cells placed together to form sheet like structures with specific functions4 primary types of tissues:1) epithelial 2) connective3) muscle4) nervousthe next level of structural complexity is the organ system levelorgan system: consists of at least 2 organs that function in a complementary way to bring about a desired effect in the human body. 11 organ systems in a humanthe next level of structural complexity is the organismthe organism (human) exists when 11 organ systems work in unison to sustain he organism. Results in homeostasis, relatively constant environment maintained by the 11 organ systems, even though the external environment is changing.A homeostatic imbalance is one at least 1 organ system is not functioning properly. If not corrected by internal regulatory systems (endocrine and nervous) , it leads to a diseased state.A diseased state is referred to as a pathophysiology. Endocrine system: long time to kick in but long lastingNervous system: kicks in quickly but short livedThe first and the lowest level of structural complexity is the chemical levelThe basis of biochemical reactions in the human body; basis for all biochemical reactions is for atoms to achieve stability by having a complete outermost (valence) shell (orbit)The atomic nucleus is composed of 2 subatomic particles Neutrons and protonsIn the shells the subatomic particles called electrons orbit around the atomic nucleusEvery atom has an atomic number, refers specifically to the number of protons in the atomic nucleus in the atom. Because atoms have no charge, the atomic number also equals number of electrons. The number of protons must equal the number of electrons for the chargeto remain
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