SAP2b: Relate structure and function in skeletal system Anatomy November 6th Warm Up: Brief definition of these terms: pg 134: axial skeleton, appendicular skeleton, compact bone, spongy bone, Classwork: Introduction to skeletal system; color sheet bone structure Closing: discussion of bone types

The Skeletal System Chapter 6

System Functions: Support (bones, cartilage, ligaments) Protection (ribs & skull) Movement (muscle to bone by tendons) Storage Calcium & Phosphorus in bone Adipose in Yellow Bone Marrow Blood Cell Production in Red Bone Marrow

Made of Connective Tissue with different substances in their Matrix:

Bone – collagen, calcium, phosphate Cartilage – collagen & proteoglycans Tendons – collagen (tough & ropelike) Ligaments – collagen

Types of tissues Collagen – common fibrous protein found in our bodies – makes up about 25% or more of the protein we have Proteoglycans – carbohydrate and amino acid chains bound together

Bone Types:

Long Bones – longer than wide ex. Ulna & Femur Short Bones – long as they are wide ex. Carpals & Tarsals Flat Bones – thin & flat ex. Scapula, ribs & skull bones Irregular Bones – shape doesn’t fit other types ex. Vertebrae & Facial Bones

Bone Structure/Contents:

Diaphysis – central shaft Epiphysis – ends Articular Cartilage – covers the Epiphyses

Medullary Cavity – spaces within the Diaphyses that contains Marrow Red Marrow – forms blood cells Yellow Marrow – adipose storage

Periosteum – dense connective tissue covering bone contains blood vessels & nerves

Endosteum – thinner connective tissue lining the Medullary Cavity

Osteoblasts – bone forming cells (they originate from the periosteum or from the bone marrow) Osteoclasts – bone removing cells Osteocytes – mature bone cells

Osteoclasts Osteoblasts Osteocytes

Lamellae – thin sheets of bone matrix Lacunae – spaces in bone where osteocytes are located Trabecular is synonymous with Cancellous or Spongy bone.

2 Major Types of Bone Based on their Density:

1.) Compact Bone – mostly solid (dense) cells 2.) Cancellous or Spongy Bone - A Lacy network of bone with small marrow filled spaces

Bone Formation/Growth

Ossification – Bone Formation By Osteoblasts A matrix of collagen and proteoglycans is laid down by the osteoblasts Osteocytes form (this starts during fetal development & ends around 18-24 yr of age)

Bone Growth in Length Composed of cartilage Epiphyseal Plate also called the Growth Plate Composed of cartilage Found between the epiphysis & diaphysis Growth occurs from this point. When growth stops, the plate cartilage is replaced by bone and it is then called the Epiphyseal Line.

Bone Growth in Width New bone lamellae (sheets of bone cells) are deposited onto existing bone Osteoblasts are deposited onto new bone on top of the periosteum, which increases the width.

Bone Remodeling Allows for bone to restructure and reshape itself to help to maintain bone strength Existing bone removed by osteoclasts & deposition of new bone using osteoblasts

Incomplete & Closed Fracture Complete & Closed Fracture Bone Fractures Incomplete & Closed Fracture Complete & Closed Fracture

Bone Fractures Open Complete Fracture

Repair of Bone Fractures Bones contain Nerves and Blood Vessels

What occurs in a broken bone… damages blood vessels within bleeding occurs & a clot forms a fibrous network of connective tissue forms at the break – holding bone together cartilage is added this zone of tissue repair is called the Callus

Cancellous Bone is slowly remodeled to from Compact Bone Continued…. Osteoblasts invade the Callus & forms cancellous bone – taking 4-6 weeks for completion Cancellous Bone is slowly remodeled to from Compact Bone Total healing time requires several months for normal bone strength to return

Bleeding & clotting occurs Fibrous Connective Tissue & Cartilage is formed. Compact bone eventually replaces cancellous bone. Cancellous Bone forms.