Ch.6 - Bone Flashcards
What is spongy (cancellous) bone?
Honeycomb of trabeculae filled w red bone marrow
What is compact (lamellar) bone?
Dense outer layer of bone
What is trabeculae?
In spongy bone, the arches of the structure
What minerals are stored in bone?
Calcium and phosphorus
Texture of spongy (cancellous) bone?
Honeycomb, w trabeculae full of red bone marrow
Texture of compact (lamellar) bone
Dense outer layer
Structure of long bone (3)
Epiphysis
Metaphysis
Diaphysis
What is yellow bone marrow?
Fat
What is the diaphysis of long bone made of?
Compact bone, surrounding medullary cavity
What is medullary cavity?
Inside of bone, hollow part of diaphysis
Bone membranes (2)
Periosteum and endosteum
Describe periosteum layers (2)
outer: where tendons + ligaments grab
Inner: allows creation of bone (osteoblasts + osteoclasts)
What makes up periosteum?
Irregular connective tissue proper
Components of periosteum
2 layers, nociceptors, blood, lymphatic vessels, Sharpey fibers
What are nociceptors
Nerve fibers signaling pain in periosteum
What are sharpey’s fibers?
Collagen fibers attach periosteum to actual bone
what does periosteum cover?
Everything but articular surfaces
What covers articular surfaces?
Hyaline cartilage
Where is epiphyses of long bone?
The top (proximal) and bottom (distal) ends
What membrane covers epiphyses?
Hyaline cartilage
Describe structure of epiphyses
Exterior is compact bone,
interior is spongy bone
Where is metaphyses of bone
Neck of bone and epiphyseal plate
What separates epiphyses from metaphyses?
Epiphyseal line (growth plate)
What does endosteum cover
Internal surfaces of bone (trabeculae)
what is structure of short, irregulars and flat bones?
Periosteum covered compact bone on outside of endosteum covered spongy bone
What’s normally inside irregular, flat, and short bones between the trabeculae?
Red bone marrow
Where is yellow bone marrow found?
Medullary cavity of adult bones
What’s in yellow bone marrow?
Adipose tissue and some red marrow cells
Where to find red marrow?
In spongy bone (skull, ribs, sternum, vertebrae, and most of pelvis, and proximal epiphysis of humerus and femur
What’s in red marrow?
Mostly red marrow cells (hematopoietic cells) in a reticular connective tissue proper
What is an osteoid
Unmineralized bone matrix secreted by osteoblasts
Makes bone less brittle
What are organic components of bone
Osteoblasts
Osteoclasts
Osteocytes
Osteoid
Inorganic component of bone
Mineral salts
Function of inorganic component of bone (mineral salts)
Bone hardness and ability to resist compression
What is an osteon? (Haversian system)
Compact ring around canal w BV + lymphatics
What are canaliculi?
Hairlike canals,
Gap junctions allowing cell-cell connections (little cracks in compact bone)
What’s lamella
Weight-bearing,
column-like tubes of bone matrix rich in collagen,
Components of cancellous bone
Osteoblasts Osteoblasts Osteocytes Canaliculi Lamellae
Formation of bony skeleton (2)
Intramembranous ossification
Endochondral ossification
Describe intramembranous ossification
Bone develops from fibrous membrane
Where would you see intramembranous ossification
Skull, mandible, and clavicles
Describe endochondral ossification
Bones forms from hyaline cartilage
Where would you see endochondral ossification
All bones of skeleton Below base of skull (except clavicles)
Functional zones in longitudinal bone growth (4)
Quiescent zone
Proliferating zone
Hypertrophic zone
Calcification zone
Describe quiescent zone
(resting), cartilage anchors growth plate to epiphysis
Describe proliferating zone
Cartilage cells are active,
Pushing epiphysis away from diaphysis (lengthening)
Describe Hypertrophic zone
Older cartilage cells dying,
Expanding of proliferating cells
Describe calcification zone
New bone formation
What is appositional bone growth
Bone increases in thickness in response to stress
What happens during appositional bone growth
2 layers of periosteum separate,
Periosteum becomes endosteum
What cells remodel bones
Osteoclasts break it down, osteoblasts rebuild
What cells do bone resorption
Osteoclasts, they secrete:
hydrochloric acid = concert calcium salts into soluble forms
Lysosomal enzymes = digest organic matrix
What is transcytosis
Osteoclasts release lysosome into interstitial fluid, then Ca+ into blood stream
What is Wolf’s Law
Bone remodels/grows in response to stress
Ways Ca2+ is necessary:
Transmit nerve impulses Muscle contraction Blood clotting Gland secretion Cell division
Describe Ca2+ homeostasis process of treating hypercalcemia
Thyroid release calcitonin,
Inhibits osteoclasts and inc osteoblasts
Describe Ca2+ homeostasis process of fixing hypocalcemia
Parathyroid releases parathyroid hormone,
Stimulates osteoclasts = breaking bone down and releasing stored calcium
