BIO 201: Chapter 2.1 Osseous Tissue Histology and Physiology

four shapes of bones

long, short, flat, and irregular

compact bone

made up of multiple layers that are solid and dense

spongy bone

made up of deep loosely organized sponge

osteon

basic organizational and functional unit of osseous tissue

- present in both compact and spongy bones but much more in compact bone

- densely packed in compact bone

- scattered throughout the trabeculae (flat thin plates) and spicules (rods or spines) of spongy bone

layers of an osteon

- concentric lamellae: surrounds the central canal passageway

- interstitial lamellae: located in spaces between each osteon

- circumferential lamellar: runs parallel to the bone's surface, surrounding the circumference of the bone, is the most superficial lamellae

central canal

passageway that houses blood vessels and nerves

osteocytes

mature bone cells in between each lamellae in lacunae

lacunae

small gaps/pits/holes in the bone matrix that have an osteocyte inside

canaliculi

channels through the hard bone matrix that allow osteocytes to communicate with each other and the rest of the body

osteoblasts

immature bone forming/building cells that produce collagen fibers during bone formation

osteoclast

bone dissolving/crushing cells

long bones

cylindrical bones that are longer than they are wide

diaphysis

long central portion or shaft of a long bone that houses the medullary cavity

medullary cavity

contains yellow bone marrow and is lined by endosteum

endosteum

deep thin layer of epithelium that lines the medullary cavity, spongy bones, and canals within bone

epiphysis

complex end piece of long bones filled with red bone marrow

red bone marrow

tissue that produces blood cells

epiphyseal line

scar of where the diaphysis and epiphyses fuse together during development

periosteum

superficial thin layer of dense connective tissue that encases living bone tissue

articular cartilage

thin layer of hyaline cartilage that cushions the long bones where they meet at synovial joints and helps joints articulate

synovial fluid

fluid produced in the synovial joints that help joints articulate easily

nutrient foramina

holes that allow blood vessels and nerves to pierce and enter the bone

perforating fibers

part of the periosteum which penetrate into the bone matrix to help with its attachment to bone

true

true or false: flat bones lack a medullary cavity

Wolff's Law of Bone

bone grows stronger to better withstand the regular forces it encounters and the architecture of a bone is determined by the mechanical stresses placed on it

hormones that control and regulate the availability of free calcium in the bloodstream

parathyroid hormone (PTH), calcitriol, and calcitonin

parathyroid (PTH) hormone and calcitriol

encourage bone resorption

bone resorption

breakdown/dissolving of the matrix of osseous tissue and returning of minerals, like calcium, to the blood stream

parathyroid glands

release parathyroid hormone (PTH)

kidneys

secrete calcitriol

calcitonin

promotes bone deposition (mineralization) of the mineral components of bone, lowering blood calcium levels

parafollicular cells in thyroid gland

release calcitonin

high blood calcium levels can be lowered by

releasing calcitonin in the bloodstream

low blood calcium levels can be increased by

releasing PTH or calcitriol in the bloodstream