Chapter 6: In this chapter, we learned about the physiology of bones. By first exploring skeletal cartilages, and then understanding the functions of bones, developmental aspects of bones, bone classification, and repairing bones.

Background Info

Upstream Causes

Downstream Causes

Direct Cause

Indirect Cause

He was running and fell forward on his right arm

Trauma caused brake

Diet

Mostly eats junk food

Child does not consume enough calcium

Overall: Trauma caused the brake, bones were not as strong as they should be due to lack of calcium

Fracture Classification

Position of Bone

Completeness of Break

Whether skin is Penetrated

Open: skin penetrated

Closed: skin not penetrated

nondisplaced: ends retain normal position

displaced: ends are out of normal alignment

complete:broken all they way through bone

incomplete: not broken all the way through bone

Epiphyseal plate

Location: part of bone between diaphysis and epiphysis

Role: where new bone growth and remodeling takes place

Bone Growth

Ossification: process of bone tissue reformation

endochondral ossification: bone forms by replacing hyaline cartilage, form most of the skeleton

intramembranous ossification: bone develops fibrous membrane

Postnatal

  1. ossification centers are formed when mesenchymal cells cluster and become osteoblasts
  1. osteoid is secreted the calcified
  1. woven bone is formed when osteoid is laid down around blood vessels, resulting in trabeculae
  1. compact and spongy bone form, and red marrow appears

1.bone collar forms around diaphysis of cartilage model

  1. central cartilage in diaphysis calcifies and dies, then develops cavities
  1. periosteal bud invades cavitie, forming spongy bone
  1. diaphysis elongates, and medullary cavity froms
  1. epipyses ossify, hyaline cartilage remains in epipyses plates and articular cartialges

long bones grow length wise by interstitial growth

bones increase thickness through appositional growth

bones stop growing during adolescence

Bone remodeling

bone remodeling

bone resorption

bone deposit

function of osteoblasts

requires: vitamin D, vitamin C, calcium and phosphate

consists of both bone deposit and bone resorption

occurs at surfaces of periosteum and endosteum

packets of adjacent osteoblasts and osteoclasts coordinate remodeling process

occurs at different rates in different bones and even different parts of the same bones

function of osteoclasts

secrete lysosomal enzymes and protons that digest matrix

digested products are released into interstitial fluid and then into blood

once resorption is complete osteoclasts undergo apoptosis

Stages of bone healing

hematoma formation

torn blood vessels hemorrhage, forming mass of clotted blood called hematoma

fibocartilaginous callus formation

capillaries grow into hematoma

fibroblasts, cartilage, and osteogenic cells begin reconstruction of bone

this mass of repair tissue is called fibrocartilaginous callus

bony callus formation

within one week, new trabeculae appear in fibrocartilaginous callus

callus is converted to bony calls of spongy bone

bone remodeling

osteoclasts remove excess bony material

compact bone is laid down to reconstruct shaft walls

final structure resembles original structure because responds to same mechanical stressors

anatomy of long bone

diaphysis: shaft that forms long axis of bone

epipyses: ends of long bones that consist of compact bone externally and spongy bone internally

may be distal and proximal

epiphyseal line: between the diaphysis and epiphyses

compact bone: dense outer layer on every bone that appears smooth and solid

spongy bone: made up of honeycomb of small flat pieces called trabeculae

yellow and red bone marrow are in the open spaces of trabeculae

Fracture

upper arm: open due to skin penetration, compete, since it is through the skin, and is displaced since it is out of alignment

fragments of bone on the wound would be a comminuted break, since it was broken into peices

Overall

the boys diet had something to do with the fracture, bones are not mineralized and strong

elbow/upper arm is going to result in a cast and sling, stabilization is key to healing

He is young, he should heal just fine and have a faster recovery due to the fact that his bones are still growing