BVB301 Lecture Notes - Lecture 12: Adipocyte, Dermal Bone, Blood Cell
Document Summary
The earliest vertebrates employed cartilage as the main skeletal component, and this is still seen in sharks and rays. Invertebrates: calcium carbonate: bone is approximately 25% collagen, 25% water, 50% crystallized mineral salts (hydroxyapatite, the use in bones of hydroxyapatite as opposed to calcium carbonate in many invertebrates may be adaptive. Vertebrates typically employ intense bursts of anaerobic activity: anaerobic metabolism produces lactic acid which lowers blood ph. Under acid conditions calcium carbonate dissolves: hydroxyapatite (mainly calcium phosphate) is less soluble than the calcite of many exoskeletons, so not as subject to dissolution by metabolic acids. This figure appears to be labelled by a vet. Vertebrate biologists and palaeontologists use different terminology in some cases. Incisive = premaxilla, maxillary = maxilla, temporal = squamosal. There are two main types of bones in our skeletons: Intramembranous (often called dermal) bones: these form within the dermis or tendons, and includes some skull bones, as well as the clavicle and patella.
