Chapter 5 Skeletal System

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Chapter 5 Skeletal System
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Functions of Bone

• - How do bones contribute to homeostasis?
• -Protection
• -Support
• -Movement
• -Storage- store fat minerals
• -Blood cell formation- blood cells are formed
  within the marrow cavities of certain bones

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Anatomy of Bone
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Types of Bone
How many bones make up our skeleton?!? -206!
All bones fall under these two basic types

• Compact Bone
• -Dense
• -Smooth

• Spongy Bone
• -Composed of small pieces of bone
• -Lots of space

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Types of Bone
After a bone is classified as either compact or
spongy they are further classified according to
their shape -4 types of shape

• Long Bone

• Flat Bone
• -thin, flattened
• -usually curved
• -made up of layers of spongy bone squished
  between 2 compact bones

-longer then they are wide -mostly compact bone
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Types of Bone Contd

• Irregular Bone

• Short Bone

-bones that dont fit into the other categories
-cubed shaped -mostly spongy bone
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Classification of Bones

• - Take a few minutes to classify the bones of the
  skeleton

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Closer look at long bones

• -important structures of long bone in the
  picture your femur

-diaphysis -periosteum -epiphyses -articular
cartilage -epiphyseal line -epiphyseal
plate
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Closer look at long bones

• -important structures of long bone

-diaphysis AKA the shaft -makes up the bones
length -covered in protective fibrous connective
tissue called periosteum
epiphyses ends of long bone -covered by
protective cartilage, articular cartilage
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Closer look at long bones

• -important structures of long bone

-epiphyses 2 ends of the bone -proximal
epiphyses -remember what proximal means?
-closer to trunk/torso -distal epiphyses
-distal is the opposite, further away from the
trunk/torso
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Closer look at long bones

• -important structures of long bone

-epiphyseal line found in adult bones -remnant
of epiphyseal plate -which is seen in young
growing bones -cause growing of long bones
-end of puberty hormones stop growth of long
bones, the plate is replaced by bone leaving a
line to mark its location
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Microscopic look at long bones

• -important structures of compact bone that is
  only visible under a microscope

-riddled with passageways carrying nerves, blood
vessels provide living bone cells with
nutrients -osteocytes mature bone cells
-found in tiny cavities within the matrix
called lacunae -lacunae arranged in circles
called lamellae around central canals -each
complex contains a central canal matrix rings
are known as osteon or Haversian system
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-osteocytes mature bone cells -found in tiny
cavities lacunae -lacunae arranged in circles
called lamellae around central canals -each
complex contains a central canal rings are
called osteon or Haversian system
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Red Yellow Bone Marrow

• Yellow Marrow
• -middle cavity of a long bone shaft stores yellow
  marrow,
• AKA medullary cavity
• -made of adipose fat tissue
• Red Marrow
• -in infants middle cavity forms blood cells red
  marrow
• -in adults red marrow is confined to the cavities
  in spongy none
• - Found in flat bones (ribs, vertebrae, pelvic
  bones)

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Hyaline Cartilage

• Abundant cartilage fibers hidden by a rubbery
  matrix with glassy blue-white appearance

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Bone Growth and Formation

• Babies
• -Embryo hyaline cartilage
• -Infant cartilage replaced by bone
• Fibrous membranes connecting flat bones

• Adults
• -Almost entirely bone
• -Isolated cartilage remains (nose, ear, etc)
• Flat bones replace connective membranes

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Bone Growth and Formation

• -bones use cartilage as models during bone
  formation (ossification)
• -ossification happens in two steps
• 1.Hyaline cartilage model is superficially
  covered with bone matrix by osteoblasts
• 2.Hyaline cartilage is broken down, leaving
  behind an empty, medullary cavity.

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Ossification
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Ossification Contd

• After birth, only two regions of cartilage
  remain articular cartilages and epiphyseal plates

-articular cartilage covers ends of long bones
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• https//www.youtube.com/watch?vp-3PuLXp9Wg

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Bone Remodeling

• Bones change as the body grows. Why is this
  necessary?
• As the body changes in size and weight, our bones
  must compensate for the additional mass.
• Additionally, bones become thicker form
  projections where bulky muscles attach

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Bone Remodelingoccurs in response to two factors

• Blood Calcium Levels
• - Healthy balance must exist between Ca stored
  and excreted
• -Proper Ca is controlled by endocrine system
• Calcitonin- storing calcium
• Parahormone- release calcium into bloodstream

• Pull of gravity and muscles on the skeleton
• Determines where skeleton is remodeled

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Axial Appendicular Skeleton
Our skeleton is divided into two parts

• Axial Skeleton
• -divided into 3 parts
• -skull
• -vertebral column
• -bony thorax

• Appendicular Skeleton
• -composed of 126 bones of the limbs
• -pectoral pelvic gridle

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Axial Skeleton

• Skull, vertebral column, bony thorax

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Appendicular Skeleton

• Bones of the limbs and girdles

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Joints in our body

• Place where two bones come together

Classified by the amount of movement they allow
-immovable
-slightly movable
-freely movable
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Joints in our body

• 4 types of joints in our body

1. Hinge- only one single action is allowed
-similar to opening closing a door Ex
-our elbow fingers
2. Ball socket- rounded curved shape surface of
one bone fits into concave, cup shaped surface of
another bone
-allows for 360 degree movement Ex
-our hip shoulder bone
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Joints in our body

• 4 types of joints in our body

3. Pivot- movement occurs in a half circle,
rotation of one bone around another
Ex
-joint between the axis atlas of neck
4. Plane/gliding- surfaces are flat, only sliding
twisting movements are allowed without any
circular movement
Ex
-carpals in our wrist, tarsals in our ankle
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Healing a Bone

• Occurs in 4 Steps
• 1.Hematoma is formed
• 2.Break is splinted by fibrocartilage
• 3.Bony callus is formed
• 4.Bone remodeling occurs