Chapter 6: Osseous Tissue and Bone Structure

Report
Unit 2
Support & Movement
Fundamentals of
Anatomy & Physiology
Frederic H. Martini
PowerPoint® Lecture Slides prepared by
Professor Albia Dugger, Miami–Dade College, Miami, FL
Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 6:
Osseous Tissue
and Bone Structure
The Skeletal System

Skeletal system includes:




Bones of the skeleton
Cartilages
Ligaments
Connective tissues
What are the functions
of the skeletal system?
Functions of the
Skeletal System
1.
2.
3.
4.
5.
6.
Support
Storage of minerals (calcium)
Storage of lipids (yellow marrow)
Blood cell production (red marrow)
Protection
Leverage (force of motion)
How are bones classified?
Classification of Bones

Bone are identified by:



shape
internal tissues
bone markings
Bone Shapes
1.
2.
3.
4.
5.
6.
Long bones
Flat bones
Sutural bones
Irregular bones
Short bones
Sesamoid bones
Long Bones


Are long and thin
Are found in the:






Arms
Legs
Hands
Feet
Fingers
Toes
Long Bones
Femur
http://www.artemmedicalis.com/media/jpeg/femur.jpg
Figure 6–1a
Flat Bones


Are thin with parallel surfaces
Are found in the:




Skull
Sternum
Ribs
Scapula
Flat Bones
http://www.health.com/health/static/hw/med
ia/medical/hw/n1249.jpg
Figure 6–1b
Sutural Bones


Are small, irregular bones
Are found between the flat bones of the
skull
Sutural Bones
Figure 6–1c
Irregular Bones


Have complex shapes
Examples:


Spinal vertebrae
Pelvic bones
http://radiology.usc.edu/Presentations/S
addleProsthesis/pelvic%2520girdleb.jpg
Irregular Bones
Figure 6–1d
Short Bones


Are small and thick
Examples:

Bones found in the


Ankles (tarsals)
Wrists (carpals)
Short Bones
Tarsals
http://www.hpssandiego.com/KN043.jpg
Figure 6–1e
Sesamoid Bones


Are small and flat
Develop inside tendons near:



Joints of knees
Hands
Feet
Sesamoid Bones
Figure 6–1f
Bone Markings

Depressions or grooves:


Projections:



along bone surface
where tendons and ligaments attach
at articulations with other bones
Tunnels:

where blood and nerves enter bone
Bone Markings *
Table 6–1 (1 of 2)
Bone Markings
Table 6–1 (2 of 2)
Long Bones

The femur
Figure 6–2a
Long Bones

Diaphysis:


Epiphysis:



the shaft
wide part at each end
articulation with other bones
Metaphysis:

where diaphysis and epiphysis meet
The Diaphysis


Made up of a heavy wall of compact bone
(dense bone)
A central space called marrow cavity
The Epiphysis


Mostly spongy (cancellous) bone
Covered with compact bone (cortex)
Flat Bones

The parietal
bone of the
skull
Figure 6–2b
Flat Bones


Resembles a sandwich of spongy bone
Between 2 layers of compact bone
What are the types and
functions of bone cells?
Bone (Osseous) Tissue



Dense, supportive connective tissue
Contains specialized cells
Produces solid matrix of calcium salt
deposits around collagen fibers
Characteristics of Bone Tissue

Dense matrix, containing:


deposits of calcium salts
bone cells (osteocytes) within lacunae organized
around blood vessels
Characteristics of Bone Tissue

Canaliculi:


form pathways for blood vessels
exchange nutrients and wastes
Characteristics of Bone Tissue

Periosteum:


covers outer surfaces
of bones
consist of:


outer fibrous layer
inner cellular layer
http://www.nlm.nih.gov/medlineplus/ency/ima
ges/ency/fullsize/9734.jpg
Matrix Minerals

Two-thirds of the bone matrix is calcium
phosphate, Ca3(PO4)2:

reacts with calcium hydroxide, Ca(OH)2 to form
crystals of hydroxyapatite, Ca10(PO4)6(OH)2

which incorporates other calcium salts and ions
Ca3(PO4)2 + Ca(OH)2
Ca10(PO4)6(OH)2
Matrix Proteins

One-third of the bone matrix is protein
fibers (collagen)
Bone Cells

Make up only 2% of bone mass:




osteocytes
osteoblasts
osteoprogenitor cells
osteoclasts
Osteocytes

Mature bone cells
that maintain the
bone matrix
Figure 6–3 (1 of 4)
Osteocytes




Live in lacunae
Are between layers (lamellae) of matrix
Connect by cytoplasmic extensions through
canaliculi in lamellae
Do not divide
Osteocyte Functions


To maintain protein and mineral content of
matrix
To help repair damaged bone
Osteoblasts

Immature bone cells
that secrete matrix
compounds
(osteogenesis)
Figure 6–3 (2 of 4)
Osteoid


Matrix produced by osteoblasts, but not yet
calcified to form bone
Osteoblasts surrounded by bone become
osteocytes
Osteoprogenitor Cells

Mesenchymal stem cells that divide to
produce osteoblasts
Figure 6–3 (3 of 4)
Osteoprogenitor Cells


Are located in the inner, cellular layer of
periosteum (endosteum)
Assist in fracture repair
Osteoclasts

Secrete acids and protein-digesting
enzymes
Figure 6–3 (4 of 4)
Osteoclasts



Giant, multinucleate cells
Dissolve bone matrix and release stored
minerals (osteolysis)
Are derived from stem cells that produce
macrophages
Homeostasis

Bone building (by osteocytes) and bone
recycling (by osteoclasts) must balance:


more breakdown than building, bones become
weak
exercise causes osteocytes to build bone
What is the difference between
compact bone and spongy bone?
Compact Bone
Figure 6–5
http://i27.photobucket.com/albums/c190/lovesthesunset/anatomy%20and%20physi
ology/bonecanaliculiandHaversiancanal.jpg
Osteon


The basic unit of mature compact bone
Osteocytes are arranged in concentric
lamellae

Around a central canal (Haversian canal)
containing blood vessels
Perforating Canals


Perpendicular to the central canal
Carry blood vessels into bone and marrow
Circumferential Lamellae


Lamellae wrapped around the long bone
Binds osteons together
Spongy Bone
Figure 6–6
Spongy Bone


Does not have osteons
The matrix forms an open network of
trabeculae

Trabeculae have no blood vessels
Red Marrow

The space between trabeculae is filled with
red bone marrow:



has blood vessels
forms red blood cells
supplies nutrients to osteocytes
Yellow Marrow

In some bones, spongy bone holds yellow
bone marrow:

is yellow because it stores fat
Weight–Bearing Bones

The femur transfers weight
from hip joint to knee joint:


causing tension on the lateral
side of the shaft
and compression on the medial
side
Figure 6–7
Periosteum and Endosteum

Compact bone is covered with membrane:


periosteum on the outside
endosteum on the inside
Periosteum
Figure 6–8a
Periosteum

Covers all bones:


except parts enclosed in joint capsules
It is made up of:


an outer, fibrous layer
and an inner, cellular layer
Perforating Fibers

Collagen fibers of the periosteum:

connect with:




collagen fibers in bone
fibers of joint capsules
attached tendons
ligaments
Functions of Periosteum
1.
2.
3.
Isolate bone from surrounding tissues
Provide a route for circulatory and
nervous supply
Participate in bone growth and repair
Endosteum
Figure 6–8b
Endosteum

An incomplete cellular layer:



lines the marrow cavity
covers trabeculae of spongy bone
lines central canals
Endosteum

Contains:




osteoblasts
osteoprogenitor cells
osteoclasts
Is active in bone growth and repair
What is the difference between
intramembranous ossification
and endochondral ossification?
Bone Development


Human bones grow until about age 25
Osteogenesis:


bone formation
Ossification:

the process of replacing other tissues with bone
Calcification


The process of depositing calcium salts
Occurs during bone ossification and in
other tissues
Ossification

The 2 main forms of ossification are:


intramembranous ossification
endochondral ossification
Intramembranous Ossification

Also called dermal ossification:



occurs in the dermis
produces dermal bones such as the mandible
and clavicle
There are 3 main steps in
intramembranous ossification
Intramembranous
Ossification: Step 1

Mesenchymal cells aggregate:



differentiate into osteoblasts
begin ossification at the ossification center
develop projections called spicules
Intramembranous Ossification:
Step 1
Figure 6–11 (Step 1)
Intramembranous
Ossification: Step 2

Blood vessels grow into the area:


to supply the osteoblasts
Spicules connect:

trapping the blood vessels inside bone
Intramembranous Ossification:
Step 2
Figure 6–11 (Step 2)
Intramembranous
Ossification: Step 3

Spongy bone develops and is remodeled
into:
osteons of compact bone
 periosteum
OR
 marrow cavities

Intramembranous Ossification:
Step 3
Figure 6–11 (Step 3)
Endochondral Ossification


Ossifies bones that originate as hyaline
cartilage
Most bones originate as hyaline cartilage
How does bone form and grow?
Endochondral Ossification

Growth and ossification of long bones
occurs in 6 steps
Endochondral
Ossification: Step 1

Chondrocytes in the center of
hyaline cartilage:



enlarge
form struts and calcify
die, leaving cavities in cartilage
Figure 6–9 (Step 1)
Endochondral
Ossification: Step 2


Blood vessels grow around the edges of
the cartilage
Cells in the perichondrium change to
osteoblasts:

producing a layer of superficial bone around the
shaft which will continue to grow and become
compact bone (appositional growth)
Endochondral
Ossification: Step 2
Figure 6–9 (Step 2)
Endochondral
Ossification: Step 3

Blood vessels enter the
cartilage:


bringing fibroblasts that
become osteoblasts
spongy bone develops at the
primary ossification center
Figure 6–9 (Step 3)
Endochondral
Ossification: Step 4

Remodeling creates a
marrow cavity:

bone replaces cartilage at
the metaphyses
Figure 6–9 (Step 4)
Endochondral
Ossification: Step 5

Capillaries and osteoblasts
enter the epiphyses:

creating secondary
ossification centers
Figure 6–9 (Step 5)
Endochondral
Ossification: Step 6

Epiphyses fill with spongy bone:


cartilage within the joint cavity is articulation
cartilage
cartilage at the metaphysis is epiphyseal
cartilage
Endochondral
Ossification: Step 6
Figure 6–9 (Step 6)
Endochondral
Ossification

Appositional growth:

compact bone thickens and
strengthens long bone with
layers of circumferential
lamellae
PLAY
Endochondral Ossification
Figure 6–9 (Step 2)
What are the characteristics of
adult bones?
Epiphyseal Lines
Figure 6–10
Epiphyseal Lines

When long bone stops growing after
puberty:


epiphyseal cartilage disappears
is visible on X-rays as an epiphyseal line
Mature Bones

As long bone matures:


osteoclasts enlarge marrow cavity
osteons form around blood vessels in compact
bone
Blood Supply of
Mature Bones

3 major sets of blood
vessels develop
Figure 6–12
Blood Vessels of Mature Bones

Nutrient artery and vein:



a single pair of large blood vessels
enter the diaphysis through the nutrient foramen
femur has more than 1 pair
Blood Vessels of Mature Bones

Metaphyseal vessels:

supply the epiphyseal cartilage

where bone growth occurs
Blood Vessels of Mature Bones

Periosteal vessels provide blood to:


superficial osteons
secondary ossification centers
Lymph and Nerves

The periosteum also contains:

networks of


lymphatic vessels
sensory nerves
How does the skeletal system
remodel and maintain
homeostasis, and what are the
effects of nutrition, hormones,
exercise, and aging on bone?
Remodeling

The adult skeleton:



maintains itself
replaces mineral reserves
Remodeling:


Recycles and renews bone matrix
involves osteocytes, osteoblasts, and osteoclasts
KEY CONCEPTS




Bone continually remodels, recycles, and
replaces
Turnover rate varies
If deposition is greater than removal, bones
get stronger
If removal is faster than replacement,
bones get weaker
Effects of Exercise on Bone


Mineral recycling allows bones to adapt to
stress
Heavily stressed bones become thicker and
stronger
Bone Degeneration


Bone degenerates quickly
Up to 1/3 of bone mass can be lost in a few
weeks of inactivity
KEY CONCEPTS


What you don’t use, you lose
Stresses applied to bones during physical
activity are essential to maintain bone
strength and mass
Effects of Hormones
and Nutrition on Bone

Normal bone growth and maintenance
requires nutritional and hormonal factors
Minerals

A dietary source of calcium and phosphate
salts:

plus small amounts of magnesium, fluoride, iron,
and manganese
Calcitriol

The hormone calcitriol:



is made in the kidneys
helps absorb calcium and phosphorus from
digestive tract
synthesis requires vitamin D3 (cholecalciferol)
Vitamins



Vitamin C is required for collagen
synthesis, and stimulates osteoblast
differentiation
Vitamin A stimulates osteoblast activity
Vitamins K and B12 help synthesize bone
proteins
Other Hormones



Growth hormone and thyroxine stimulate
bone growth
Estrogens and androgens stimulate
osteoblasts
Calcitonin and parathyroid hormone
regulate calcium and phosphate levels
Hormones for Bone Growth
and Maintenance
Table 6–2
The Skeleton as Calcium Reserve


Bones store calcium and other minerals
Calcium is the most abundant mineral in
the body
Chemical Composition of Bone
Figure 6–13
Functions of Calcium

Calcium ions are vital to:



membranes
neurons
muscle cells (especially heart cells)
Calcium Regulation

Calcium ions in body fluids:


must be closely regulated
Homeostasis is maintained:


by calcitonin and parathyroid hormone
which control storage, absorption, and excretion
Calcitonin and Parathyroid
Hormone Control

Bones:


Digestive tract:


where calcium is stored
where calcium is absorbed
Kidneys:

where calcium is excreted
Parathyroid Hormone (PTH)
Figure 6–14a
Parathyroid Hormone (PTH)


Produced by parathyroid glands in neck
Increases calcium ion levels by:



stimulating osteoclasts
increasing intestinal absorption of calcium
decreases calcium excretion at kidneys
Calcitonin
Figure 6–14b
Calcitonin


Secreted by C cells (parafollicular cells) in
thyroid
Decreases calcium ion levels by:


inhibiting osteoclast activity
increasing calcium excretion at kidneys
KEY CONCEPTS (1 of 2)




Calcium and phosphate ions in blood are
lost in urine
Ions must be replaced to maintain
homeostasis
If not obtained from diet, ions are removed
from the skeleton, weakening bones
Exercise and nutrition keep bones strong
What are the types
of fractures, and
how do they heal?
Fractures

Fractures:



cracks or breaks in bones
caused by physical stress
Fractures are repaired in 4 steps
Fracture Repair:
Step 1
Figure 6–15 (Step 1)
Fracture Repair: Step 1

Bleeding:



produces a clot (fracture hematoma)
establishes a fibrous network
Bone cells in the area die
Fracture Repair:
Step 2
Figure 6–15 (Step 2)
Fracture Repair: Step 2

Cells of the endosteum and periosteum:


Divide and migrate into fracture zone
Calluses stabilize the break:


external callus of cartilage and bone surrounds
break
internal callus develops in marrow cavity
Fracture Repair:
Step 3
Figure 6–15 (Step 3)
Fracture Repair: Step 3

Osteoblasts:

replace central cartilage of external callus with
spongy bone
Fracture Repair:
Step 4
Figure 6–15 (Step 4)
Fracture Repair: Step 4

Osteoblasts and osteocytes remodel the
fracture for up to a year:

reducing bone calluses
PLAY
Steps in the Repair of a Fracture
Major Types of
Fractures
Pott’s Fracture
Figure 6–16 (1 of 9)
Comminuted
Fractures
Figure 6–16 (2 of 9)
Transverse
Fractures
Figure 6–16 (3 of 9)
Spiral Fractures
Figure 6–16 (4 of 9)
Displaced
Fractures
Figure 6–16 (5 of 9)
Colles’ Fracture
Figure 6–16 (6 of 9)
Greenstick
Fracture
Figure 6–16 (7 of 9)
Epiphyseal
Fractures
Figure 6–16 (8 of 9)
Compression
Fractures
Figure 6–16 (9 of 9)
What are the effects of aging on
the skeletal system?
Age and Bones



Bones become thinner and weaker with
age
Osteopenia begins between ages 30 and
40
Women lose 8% of bone mass per decade,
while men lose 3%
Effects of Bone Loss

The epiphyses, vertebrae, and jaws are
most affected, resulting in:



fragile limbs
reduction in height
tooth loss
Osteoporosis



Severe bone loss
Affects normal function
Over age 45, occurs in:


29% of women
18% of men
Hormones and Bone Loss


Estrogens and androgens help maintain
bone mass
Bone loss in women accelerates after
menopause
Cancer and Bone Loss

Cancerous tissues release osteoclastactivating factor that:


stimulates osteoclasts
produces severe osteoporosis
SUMMARY (1 of 5)



Bone shapes, markings, and structure
The matrix of osseous tissue
Types of bone cells
SUMMARY (2 of 5)



The structures of compact bone
The structures of spongy bone
The periosteum and endosteum
SUMMARY (3 of 5)



Ossification and calcification
Intramembranous ossification
Endochondrial ossification
SUMMARY (4 of 5)



Blood and nerve supplies
Bone minerals, recycling, and remodeling
The effects of exercise
SUMMARY (5 of 5)




Hormones and nutrition
Calcium storage
Fracture repair
The effects of aging

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