Lecture 5 - Bone Physiology Flashcards
Functions of the Skeletal System (5 points)
Support against gravity
Leverage for muscle action
Internal organ protection
Storage
Blood cell production
3 substances stores in Skeletal System
Calcium (for muscle contraction)
Phosphorus
Fat
6 types of bones
Flat
Long
Short
Irregular
Sutural
Sesamoid
3 Features of Long Bones
Diaphysis (shaft)
Epiphysis (ends)
Articular Cartilage
2 parts of Diaphysis
Compact Bone
Medullary Cavity
Function of Medullary Cavity
Stores yellow bone marrow
Function of Epiphysis
Forms joints
3 parts of Bone Tissue
Ground Substance
Protein
Bone Cells
Bone Ground Substance Features (2 points)
Two thirds of bone matrix
Contains minerals such as hydroxyapatite
Bone Protein Features (2 points)
One third of bone matrix
Mostly type I collagen fibres
3 types of Bone Cells
Osteoblasts
Osteocytes
Osteoclasts
Osteoblast Definition
Immature Bone Cell
Osteoblast Function
Secretes Matrix Proteins
Osteocytes Definition
Mature Bone Cell
Osteocytes Function
Maintains bone matrix
Detect forces in bone
Osteoclasts Definition
Multinucleate bone cell between medullary cavity and bone matrix
Osteoclasts Function
Secretes acids and enzymes to dissolve bone matrix
4 parts of compact bone
Osteon - Basic functional unit, surrounds central canal
Central Canal - Tunnel for blood vessels
Lamellae - Concentric Layers of Matrix
Lacunae - Contains osteocytes
3 parts of Trabecular Bone
Trabeculae
Red Marrow
Yellow Bone Marrow
Features of Trabeculae (3 points)
Contains Arches, rods and plates of bone
Branching network
Strong
Features of Red Marrow (3 points)
Between trabeculae
Forms red blood cells
Provides nutrients of osteocytes
Features of Yellow Bone Marrow (2 points)
Found in medullary cavity
Stores fat
Strength distribution in bone
Compact bone provides strength in long axis
Trabecular Bone provides strength in range of directions
Periosteum Definition
2 layer membrane outside bone
2 layers of Periosteum
Outer Fibrous Layer
Inner Cellular Layer
Endosteum Definition
Membrane lining bone
3 lines of Endosteum
Medullary Cavity
Central Canals
Trabeculae
Ossification Definition
Formation/Conversion of bone
3 types of bone formation/growth
Intramembraneous Ossification
Endochondral Ossification
Appositional Bone Growth
Intramembraneous Ossification Definition
Flat Bone Formation
Endochondral Ossification Definition
Formation from cartilage model
Appositional Bone Growth Definition
Bone Growth in width
4 steps of Intramembraneous Ossification
Mesenchymal Cells differentiate into osteoblasts
Ossification forms spicules of bone
Trabecular Bone formed
Remodeled into compact bone
Intramembraneous Ossification Example
Cranial Bones in Skull
5 steps of Endochondral Ossification
Chondrocytes within matrix enlarge then die
Osteoblasts cover the shaft in thin layer of bone
Blood vessels/Osteoblasts penetrate to form primary ossification centre
Primary ossification centre enlarges
Secondary ossification centre formed at epiphysis
Growth in Bone Length
Bone grows as cartilage from epiphyseal plate
2 steps in Appositional Bone Growth
Bone deposited by osteoblasts
Bone resorbed by osteoclasts
Requirements for normal bone growth
Calcium/Phosphate
Vitamin D
Growth Hormones
Forces applied to bone
Bone Remodeling Features
Continuous Breakdown/reforming of bone tissue
Adaptation of loading
Calcium homeostasis
2 Hormones used in Calcium homeostasis
PTH - bone resorption to release calcium
Calcitonin - bone formation to store calcium
4 steps of Fracture repair
Clot formation
Formation of external callus/internal callus
External callus replaced by bone, Internal callus unites broken ends
Initial swelling eventually remodeling
External Callus Definition
Cartilage
Internal Callus Definition
Spongy bone
