http://www.youtube.com/watch?v=vya4wpS2fgk
You tube, My bones Song
Chapter 5: The Skeletal System
I: Bones: An Overview
A. There are 206 bones in the human body, which makes up about
20% of our body mass.
B. The parts of the skeletal system include:
1. Bones- internal framework that supports and anchors
all organs.
2. Joints- allow for flexibility and movement
3. Cartilages- provides additional support for structures
in the body.
4. Ligaments- connect bone to bone.
C. The skeletal system is subdivided into two groups: Axial
and Appendicular.
1. Axial Skeleton- includes the skull, vertebral column and
rib cage.
2. Appendicular Skeleton- includes bone of the upper and
lower limbs.
D: Functions of the Bones
1. Support- bones act as pillars to support the body
2. Protection- for soft body organs
3. Storage- for fat in the internal cavities (yellow marrow), also
bones store minerals such as calcium and phosphorous
4. Blood Cell Formation (Hematopoiesis) - blood cells are formed
in the red marrow of certain bones (Newborns contain only red
marrows. in adults about half of the marrow is red and located in ribs, breastbone, shoulder blades, collarbones, hip bones, skull, and
spine..
E: Two Types of Tissues
1. Compact bone- the external layer that is dense and
looks smooth and homogeneous
a. Contains the functioning units of bone called
osteons.
2. Spongy bone- the internal layer that is composed of
a honeycomb of needle like or flat pieces called
trabeculae.
a. The open spaces between trabeculae are
filled with red or yellow bone marrow
F: Chemical Composition of Bone- inorganic and organic
components
1. Inorganic- 65% of bone mass consists of
hydroxyapatites or mineral salts (largely calcium
phosphates)
a. Calcium salts account for the exceptional hardness of
bone and allows it to resist compression.
Foods high in calcium:
Foods high in phosphorous:
Foods that are high in phosphorus
include milk (234mg per 8 ounces),
milk products, poultry, fish, meat,
eggs, grains and legumes.
2. Organic- cells, osteoblasts (bone making cells), and osteoid.
a. Osteoid makes up 33% of bone matrix and includes
proteoglycans, glycoproteins and collagen fibers.
Major component of extracellular matrix
b. Organic components allow for bone flexibility and
great tensile strength to allow bone to resist stretch and
twisting motions.
G. Classification of bones according to shape
1. Long Bones
a. Typically longer than wide
b. Have a shaft with heads at both ends
c. Contain mostly compact bone
d. Examples: femur and humerus
2. Short Bones
a. Generally cube shaped
b. Contain mostly spongy bone
c. Examples: carpals and tarsals
d. Sesamoid bones are special type of short bones
that are embedded in a tendon. Ex. Patella
3. Flat Bones
a. Thin and flattened
b. Usually curved
c. Thin layers of compact bone around spongy bone
d. Example: skull, scapular, ribs. Sternum
4. Irregular Bones
a. Irregular shape that does not fit other bone
classifications
b. Example: vertebrae , sacrum, mandible
Mr. Bones Apart- pg. 5M
• Articulate Mr. Bones (cut out his bones and put him back
together. All bones should be connected.)
• Color his axial skeleton Red and his appendicular skeleton
Blue
• Label two: long bones, short bones, irregular, and flat bones
• Label the bones with their name.
• Write the functions of the skeletal system around Mr. Bones.
• Use the cards on pgs. 5I and J to write the meaning of the
bone name
• Answer questions on pg.5L
Question of the Week
• Why is it that once we sprain our ankle we are
more likely to sprain the same ankle again?
The ligaments in your ankle,
are laced with sensory
receptors. These are
responsible for telling the
brain where the ankle is in
space. When a sprain occurs,
some of these sensors are
permanently damaged; as a
result, your ankle can't
communicate as well with
your brain.
Rehab, when approached correctly, can
help you regain a kind of ankle virginity-that is, if you remain sprain-free for a year,
your risk returns to what it was before your
mishap.
II. Bone Structure
A. Gross Anatomy of a typical long bone
1. Diaphysis - the bone shaft that makes up
most of the bones length and is composed
of compact bone
a. The diaphysis is covered with a fibrous
connective tissue membrane called the
periosteum. Sharpey’s Fibers
(connective tissues) secure the
periosteum to long bone.
b. The diaphysis surrounds a central
medullary cavity or marrow cavity
(yellow marrow) primarily used for
storing adipose (fat) tissue. In infants
this area forms blood cells, and red
marrow is found here. In adults, the
red marrow is confined to
the cavities of spongy bone of flat
bones and the epiphyses of long bones
2. Epiphysis- the ends of long bones
a. Consists of a thin layer of
compact bone enclosing an area
filled with spongy bone
b. In adult bones, a thin line of bony
tissue spans the epiphysis and
separates it from the rest of the
bone in that area, this is called
the epiphyseal line. The
epiphyseal line is a remnant of
the epiphyseal plate (flat plate of
hyaline cartilage) you would see in
a young growing bone.
spongy bone
Proximal
compact bone
epiphysis
diaphysis
Endosteum
epiphyseal
line
yellow
marrow
Sharpey’s
Distal
epiphysis
fibers
hyaline
cartilage
periosteum
3. Bone Markings the bumps, holes, and ridges seen on bones and
reveal where muscles, ligaments, and tendons attach. There are two
categories of bone markings:
a. Projections or Processes grow out from the bone
surface, (see chart on pg.119)
Ex. Spinous process of vertebrae
b. Depressions or cavities - indentions in the bone, all
depressions begin with the letter F; ex. Foramen magnum of the
base of the skull
Microscopic Bone Anatomy
B. Microscopic Anatomy of Compact
Bone
1. Osteocytes - Mature bone cells
2. Osteons - units of bone (Haversian
System)
3. Haversian CANAL
a. opening in the center of an
osteon
b. Run lengthwise through the
bone carrying blood vessels
and nerves to all areas of the
bone
4. Perforating (Volkmann’s) canals
a. perpendicular to central canals
b. carries blood vessels and
nerves
http://www.youtube.com/watch?v=4qTiw8lyYbs&feature=related
5. Lacunae - tiny cavities
a. contain bone cells (osteocytes)
b. arranged in concentric rings
6. Lamellae - rings around the central canal
a. sites of lacunae
7. Canaliculi - tiny canals that radiate from
central canals to connect all bone cells
to the nutrient supply
Microslide of Bone Tissue
• Get a microslide viewer
to share with someone at
your lab station.
• Draw and label slide 4 of
bone tissue. Label this as
MICROSCOPIC bone
anatomy. This picture
should take up half of a
sheet of notebook paper.
Make sure it is neat and
labeled using the specific
names we discussed in
the notes today.
• Answer the following
questions on your paper
1. What are the chemicals found in our
cells that make them strong?
2. What are the fine dark lines
connecting each of the bone cells?
3. The dark area labeled B is used for
what purpose? Label the specific
name for this structure.
4. Explain what happens to the bones
of someone with osteoporosis.
5. What do you think would look
different about the bone tissue in a
patient with osteoporosis. Explain or
draw a picture (use words we have
learned today )
Choose a long bone in the body and complete one of
the choices below: 40 pts
_____ Write an advertisement (as if the bone is describing and selling itself and its
importance)
_____ Story from the bones perspective (The Bony Life of Henrietta Humerus, an
Autobiography)
_____ Facebook Profile Page (Ex. Freddy Femur)
_____ Create a flow chart/ Concept Map with pictures and diagrams
Regardless of which you choose YOUR FINAL PRODUCT MUST:
•Explain the structure and function of the following parts of the bone you choose:
•diaphysis, epiphysis, sharpey’s fibers, periosteum, cartilage, osteon, osteocytes,
osteoblasts, osteoclasts
•20pts. (1pt. For structure, one for function)
•What is your chemical composition and their functions (organic and inorganic)? 4pts.
•How do you fit into the entire skeleton? What bones do you articulate (come
together) with? 6 pts.
•What movements are allowed by this bone and the bones it articulates with? 5 pts.
•What muscles attach to your bone? 5 pts.
Microscopic Bone Anatomy
CHL-
III. Bone Formation and Growth
A. Bone formation is also
known as osteogenesis
(bone beginning)
ossification.
1. Formation of the skeleton
a. In embryos the
skeleton is composed
mainly hyaline cartilage
(fibrous membranes at skull
and clavicles)
b. Intramembranous
ossification process in
which the bones form to
replace fibrous membranes
of the skull and clavicles.
275 bones
12 weeks (6-9 inches
long)
Intramembranous
Ossification Fontanels (membranes)
become bone.
Fetus: 1st
2
months
Endochondral Ossification
= Cartilage to bone
2o ossification
center
cartilage
bone
calcified
cartilage
Just before
birth
epiphyseal line
epiphyseal
plate
Childhood
Adult
C. Endochondral ossification- process in which hyaline
cartilage is replaced by bone (includes all bones except skull and
clavicles)
i. The hyaline cartilage is covered in osteoblasts
(bone forming cells)
ii. The Fetus then has cartilage “bones” enclosed by bony
bones
iii. The enclosed hyaline cartilage is digested away, opening
up a medullary cavity within the newly formed bone.
2. Cartilage remains in the bridge of the nose, parts of the ribs,
joints (articular cartilage), and epiphyseal plates.
http://wps.aw.com/bc_martini_eap_4/40/10466/2679495.cw/content/index.html
Chinese Binding of Feet
http://www.historyforkids.org/learn/china/clothing/
How do you think binding of the feet affected bone growth?
B. Bone growth- occurs at epiphyseal plates
1. Provides for longitudinal bone growth during childhood
2. Controlled by growth hormones and sex hormones
3. New Cartilage is continuously formed
4. Old cartilage becomes ossified
a. Cartilage is broken down and replaced by bone
• Differences in fetal skeleton vs. Adult
1. Abundance of cartilage vs. bone
2. Incomplete or lack of fusion between bones
3. Poor development based on lack of use
4. Large head size compare to the rest of body
( principle of cephalization)
5. Facial vs. Cranial parts of the skull
6. Frontal bone and the metopic suture
7. Fontanels
8. Pelvic bone
9. Spinal curvatures
On average, an adult
human has 206 bones
(according to Gray's
Anatomy, but the
number can vary
slightly from individual
to individual), but a
baby is born with
approximately 270 -275
bones.
5. Growing bones must also widen as they lengthen (called appositional
growth)
a. osteoblasts begin adding bone to the outside of the diaphysis
b. osteoclasts (bone destroying cells) in the endosteum remove
bone from the inside diaphysis wall
c. The work of osteoblasts and osteoclasts occur at almost the same
rate allowing the bone to expand and widen
Body Ratios and Proportions
(pg. 5U) and write a one page
summary including the
following:
Explain the changes to our skeletal
system throughout our lifetime
(osteogenesis to bone growth to
changes in old age). Include
data from your measurements to
determine if you are still growing
and how you used the data to
come to this conclusion.
Bone Anatomy Quiz
Osteoctyes
Canaliculi
Lacunae
Haversian Canal
Osteon (Haversian system)
1. The entire
structure pictured
(functioning unit
of bone) is called?
2. identify H
3. identify L
4. identify C
Epiphysis, diaphysis,
articular cartilage, spongy bone,
compact bone
5. Identify A
6. Identify B
7. C- what type of bone?
8. Identify D
Organic or Inorganic
Bone components?
9. Provides hardness
10. Allows for flexibility
and tensile strength
Structure
A
D.
C. Type of
Bone?
Structure
B
.
D
11. Growth in bones occurs at _________plates.
12.Function of red marrow?
13.Function of yellow marrow?
14.Which term does not belong?
Lamellae----- canaliculi-----circulation----osteoblasts
How much calcium is in that?
• http://www.fitsugar.com/How-Much-Calcium182622
Osteoblast
Osteocyte
Osteoclast
Builds new bone
Mature bone cell
Eats bone
IV. Bone Remodeling- the two processes
of bone deposits and removal
A. In an adult skeleton bone deposits
and bone removal are occurring all
the time (yes, bone is a dynamic,
active living tissue)
B. In a healthy adult the rate of bone
deposit and bone removal should
remain constant and equal
1. Bone deposits occur where bone
is injured or additional bone
strength is needed
a. Deposits are accomplished
through osteoblasts
b. Optimal bone deposits
require a diet rich in
proteins, vitamin C, A, and
B12, calcium, phosphorus,
and magnesium
20% of your skeleton is
replaced annually!!
Entire skeleton is
replaced every 7 to 10
years!
2. Bone Removal or resorption occurs when the blood levels of calcium become
too low.
a. Resorption is accomplished by osteoclasts
3. If bone removal (resorption) occurs faster than bone deposition takes place
homeostatic balance is lost. This results in porous, lightweight bones
that easily break. This condition is called osteoporosis. This occurs most
often in aged, postmenopausal women, but can occur in both sexes.
C. Bone remodeling is controlled by
hormones, diet and mechanical stress
1. Hormonal mechanism- involves the
parathyroid hormone (PTH) and
calcitonin in a negative feedback loop to
maintain homeostasis of blood calcium.
a. PTH is released when blood calcium levels are too low. It stimulates
osteoclasts to resorb (remove) bone releasing the calcium into the
blood.
b. When blood calcium levels rise calcitonin is secreted to encourage
calcium deposits into the bone.
2. Diet
a. Calcium is necessary for transmission of nerve impulses,
muscle contraction,blood coagulation, secretion by gland and nerve cells,
and cell division
i. Your daily recommend levels of calcium is
1200-1400 mg.
ii. Calcium is absorbed by the intestines under the control
of vitamin D metabolites
3. Mechanical Stress
a. This set of controls serves the needs of the skeleton itself- keeping
bones strong where stressors are present.
b. Wolff’s Law - holds that bones grow or remodel in response to the
forces or demands placed on it. Bone is laid down where
bone is
needed- for example large bony projections occur where heavy, active
muscles attach
Steps in Bone Remodeling
Quiescence means inactive, or dormant
Flashcard Warm-up March 8th
Bone Remodeling
#30
Three factors that affect bone remodeling are ____, _____ _____, and _____.
Steps in the process are: (refer to your bone remodeling and briefly explain)
V. Bone Fractures
A. A break in the bone. There are two types:
1. Open (compound) fracture - the broken bone penetrates through the
skin
2.Closed (simple) fracture - the broken bone does not penetrate through
the skin
B. Bone fractures are treated by reduction
and immobilization
1. Realignment of the bone.
C. Common types - comminuted , compression, depression,
compacted, spiral and green stick - see book for pictures
I. F. Complete & Displaced
I. F. Incomplete/Greenstick
I. F. Comminuted
I. F. Spiral
hematoma
callus
bony callus
bone
remodeling
D. Repair of Bone Structures
1. After the fracture occurs, blood vessels rupture forming a blood filled swelling called a hematoma.
2. A fibrocartilage callus forms (made of various connective tissues)
and acts to splint the broken bone
3. A bony callus forms as osteoblasts replace the fibrocartilage
with bone.
4. The bony callus continues to be remodeled in response to
mechanical stress placed upon the bone.
I. E. Repair of Breaks
• 6-8 hr.: hematoma develops,
blood to site of break,
Leukocytes (WBC, fight
infection, swelling
I. E. Repair of Breaks

3 wks.: Fibrocartilage Callus
I. E. Repair of Breaks
• 3-4 mo.: Bony Callus –
Osteoblasts form spongy bone


Remodeling: Osteoblasts form
compact bone. Osteoclasts
reduce callus and reform
medullary cavity.
Some callus remains
IV. Developmental Aspects of the Skeleton
A. At birth, some fontanels are still present in the skull, Fontanels allow for
brain growth and ease birth passage. The growth of the cranium is related
to brain growth and the increase in size of the facial skeleton follows tooth
development and the respiratory passages.
B. The vertebral column is C-shaped at birth due to curvatures present in
the thoracic and lumbar vertebrae (similar to a four-legged animal). When
the baby begins to lift its head and walk the spine changes into its S-shaped
form.
C. During youth the skeleton changes not only in size but in body
proportions as well.
At birth the head and trunk are one and half times as long as the lower
limbs. The lower limbs then begin to grow much more rapidly than the
trunk. During puberty the female pelvis widens to prepare for childbearing.
Once the adult height is reached
the skeleton changes very little until late middle age.
D. As people age fractures and osteoporosis are the most common bone
problemsfor elderly. The bones must be physically stressed as we age
in order to remain healthy. In order to maintain healthy bones
through your adult years, a diet rich in calcium and Vitamin D are
important as well as weight bearing exercise to keep bones strong.
Bone Concept Map
• Match yellow vocabulary words with
definition
• Use these words to create a concept map (1
per group)
• You must include two pictures and all words
on yellow vocabulary cards
Bone Remodeling Wheel
• Complete 5H
• READ, yes I mean READ all of pg. 5G (highlight main ideas or
underline)
• Compare your NORMAL bone remodeling wheel with the
example of Abnormal remodeling (caused by osteoporosis,
menopause, anorexia, or hyperparthyroidism)
• Complete the Venn diagram on 5 I
• TURN IN YOUR PAPER BEFORE YOU LEAVE
Summarize the process of bone remodeling.
• What three factors affect bone remodeling?
• Use your completed pgs. 5H and I to explain
normal bone remodeling.
• What are the causes of abnormal remodeling.
• Explain how abnormal remodeling is different
from normal.
– TURN IN TODAY!!
biomedical engineer:
• A person who blends traditional engineering
techniques with the biological sciences and
medicine to improve the quality of human
health and life.
• Biomedical engineers design medical devices
and implants, artificial body parts, surgical and
diagnostic tools, and medical treatment
methods.
Bone Grafting Example
Graft material is removed from patient’s ilium (pelvis, hip) [left]
Bone graft fills a gap in a human spine [right]
Image source: US National Library of Medicine, National Institutes of Health, MedlinePlus,
(left) http://www.nlm.nih.gov/medlineplus/ency/imagepages/8745.htm and
(right) http://www.nlm.nih.gov/medlineplus/ency/presentations/100136_4.htm
External Fixation
Installing temporary
repair supports outside
of the skin to stabilize
and align bone while
the body heals.
Examples: screws in
bone, metal braces,
casts, slings.
Image source: US National Library of Medicine, National Institutes of Health, MedlinePlus,
http://www.nlm.nih.gov/medlineplus/ency/imagepages/18021.htm