tailieunhanh - Digital histology an interactive cd atlas with review text phần 3

Đánh bại trong một làn sóng giống như chức năng chuyển động để đẩy các vật chất dọc theo bề mặt của biểu mô (ví dụ, trong hệ thống hô hấp và ống dẫn trứng của hệ thống sinh sản nữ) Core cilium một được gọi là axoneme, trong đó chín cặp của các vi ống bao quanh một cặp trung tâm của các vi ống (9 + 2 sắp xếp). Axomene cilum mỗi bắt nguồn từ một cơ thể cơ bản mà | 5. Supporting Connective Tissues 45 Inorganic portion. Calcium and phosphate in the form of hydroxyapatite crystals are deposited along the collagen fibrils and form 50 of the dry weight of bone. This ossified matrix renders bone impermeable to diffusion of nutrients and requires that bone be well vascularized. Cells Osteoblasts Located on all exterior surfaces of bone as the innermost portion of the periosteum or in the endosteum lining all interior bony surfaces Inactive osteoblasts are flattened cells with heterochromatic nuclei. Active osteoblasts are stellate and contain organelles necessary for protein primarily collagen production. These cells synthesize high levels of alkaline phosphatase. Function to synthesize bone Secrete osteoid first In the presence of alkaline phosphatase osteoblasts facilitate the deposition of calcium phosphate thus mineralizing the osteoid. Osteocytes Are osteoblasts that have completely surrounded themselves by bony matrix and therefore must lie within rather than on bone tissue. These flattened inactive cells lie in lacunae spaces in the bone and extend long processes from the cell body. These processes lie in narrow tunnels called canaliculi and connect via gap junctions with adjacent osteocytes and or osteoblasts at the bone surface. Function to transport materials between blood and bone and to maintain surrounding matrix they do not divide or secrete matrix. Osteoclasts Are large cells with 15-20 or more nuclei and vacuolated frothy cytoplasm. A ruffled border the highly enfolded cell membrane facing the bone is the site of bone resorption. Are located on internal surfaces as part of the endosteum or on external surfaces as part of the osteogenic layer of the periosteum. Osteoclasts lie in depressions in the bone Howship s lacunae which form as osteoclasts resorb bone. Resorb bone via the acid phosphatase and proteolytic enzymes they secrete 46 Digital Histology Surface coverings Periosteum. Double layer of connective tissue .