Download THE SKELETAL SYSTEM

THE
SKELETAL
SYSTEM
I. BONE STRUCTURE & FUNCTION
A. FUNCTION
1. Support
2. Protection
3. Movement
4. Blood formation
5. Electrolyte Balance
6. Acid Base Balance
I. BONE STRUCTURE & FUNCTION
B. Structure
1. Shape
–
–
–
–
Long bones
Short bones
Flat bones
Irregular bones
Long bones
Short bones
Flat bones
Irregular
bones
Classify the
bone types
to the left
B. Structure
2. Parts of Bone
– Epiphyses
• Contains red
bone
marrow
• Spongy
bone and
compact
bone
B. Structure
2. Parts of Bone
– Diaphysis
• Shaft of
bone
• Contains
yellow bone
marrow
(stores fat)
• Spongy and
compact
bone
B. Structure
2. Parts of Bone
– Periosteum
– Epiphyseal
plate
 Allows for
growth in
bone
 Found only
in children
B. Structure
3. Mature Bone
Osseous
Tissue
3. Mature Bone
• Called
Lamellar
bone
•Two kinds
 Compact
 Spongy
(cancellous)
3. Mature Bone
• Spongy (cancellous)
• contains trabeculae
• contains spaces
3. Mature Bone
Compact
Bone
• Dense, few spaces
• Haversian canals
• Concentric Lamellae
I. BONE STRUCTURE & FUNCTION
C. Histology
Background minerals
1. Matrix
C. Histology
2. Bone cells
Osteoblasts
Osteocytes
Osteoclasts
Osteoclasts
Osteoblasts
Osteocytes
Name C, D & E
C = Osteoclast
D = Osteoblast
E = Osteocytes
D. Membranes
1. Periosteum:
a. The external
covering of bone
D. Membranes
2. endosteum:
a. Found on internal bone surface
b. covers trabeculae of spongy bone
c. in marrow cavities
II. BONE GROWTH & DEVELOPMENT
A. Two Patterns of Bone Formation
1. Intramembranous
bones
– originate
between
sheet-like
layers of
connective
tissues
II. BONE GROWTH & DEVELOPMENT
A. Two Patterns of Bone Formation
2. Endochondral
bones
– begin as masses
of hyaline
cartilage that
bone tissue later
replaces.
II. BONE GROWTH & DEVELOPMENT
B. Growth in Long Bones
1. grow by interstitial growth at
epiphyseal plates
a. rate of cartilage growth is
balanced by replacement with
bone
b. end of growth as cartilage
cells slow down division
II. BONE GROWTH & DEVELOPMENT
B. Growth in Long Bones
2. bones grow in width by
appositional growth
a. Osteoblasts in periosteum:
secretes bone matrix
b. Osteoclasts in endosteum:
removes bone matrix (a little
slower)
Appositional Growth
– New bone forms at ridges around
blood vessels
– Periosteum becomes endosteum
Appositional Growth
– New lamella formed
– More bone added forming osteon
II. BONE GROWTH & DEVELOPMENT
C. Hormones
1. growth hormone from pituitary:
stimulates growth in childhood
a. Gigantism: excessive growth
hormone
b. dwarfism: not enough growth
hormone or thyroid hormones
II. BONE GROWTH & DEVELOPMENT
C. Hormones
2. thyroid: regulates activity of
growth hormone
3. sex hormones: promote growth
spurt, induce epiphyseal plate
closure
estrogen: maintains bone
density
III. Bone Maintenance & Repair
A.Bone remodeling:
1. Life long process
2. Local areas of bone are destroyed
and rebuilt
3. Repairs microdamage caused by
normal wear and tear
B.Fractures
1. Simple
bone breaks
cleanly, does
not break
through skin
B.Fractures
2. Compound
broken ends
protrude
through the
skin, risk of
bone infection
B.Fractures
3. Greenstick
Does not
break
completely
Greenstick:
(children)
III. Remodeling and Repair
C. Repair
1. Hematoma forms
2. Spongy bone forms in area of
hematoma
C. Repair
3. Osteoblasts lay down new bone
matrix
4. Remodeling
III. Calcium Homeostasis
A. Blood Ca2+ Level
1. Has a very narrow range
2. Ca2+ Required for
– For normal muscle contraction
– Nerve impulses
III. Calcium Homeostasis
A. Blood Ca2+ Level
3. Abnormal levels
– Hypocalcemia
causes marked jitteriness and
convulsive seizures
III. Calcium Homeostasis
A. Blood Ca2+ Level
3. Abnormal levels
– Hypercalcemia
the most common lifethreatening metabolic disorder
associated with cancer
III. Calcium Homeostasis
B. Bone’s Role
1. Major storage site for calcium
2. Calcium moves
– Into bone as osteoblasts build
new bone
– Out of bone as osteoclasts
break down bone
III. Calcium Homeostasis
C. Bone, Calcium and Hormones
1.Parathyroid Hormone –
Increases blood Ca2+ levels
2. Calcitonin
Decreases blood Ca2+ levels
III. Calcium Homeostasis
D. Homeostatic Imbalances
• Osteopenia
– Inadequate ossification
• Osteoporosis
– Bone absorption outpaces
deposition
– Fractures common
– More common in elderly women
D. Homeostatic Imbalances
• Rickets
– Lack of vitamin D or
calcium during
growth
– Bowed legs
– Deformed pelvis
Rickets
D. Homeostatic Imbalances
• Osteosarcoma
– Bone cancer
– Usually between ages 10-25
– Survival rate is about 50% with
amputation
D. Homeostatic Imbalances
• Bone spur
– Abnormal
projection at one
site of bone due to
overgrowth
– Common in aging
bones
IV. The Skeleton
There are 206 bone
IV. The Skeleton
A. Organization
1. Axial Skeleton
– Skull
– Vertebral Column
– Vertebrae
– Ribs
2. Appendicular Skeleton
– limbs
– girdles
B. Male vs. Female Skeleton - Pelvis
a. spines farther
apart in male
b. hole in ischium:
smaller and
triangular in
female
c. angle across
pubic
symphysis =
pubic arch: less d. distance between
than 90° and
ischia larger in
more sharply
female
angled in male
C.Bone Markings –
1. Kinds
1. Kinds
• Articulating
Surfaces
For
formation
of a joint
•Openings
• Depressions &
Enlargements
For muscle
attachment
To allow blood vessels or
nerves to pass through
C.Bone Markings –
2. Articulating surfaces
Head
A rounded projection
set off from the body
of a bone by a
constriction (the
neck) ex. head of
femur
C.Bone Markings –
2. Articulating
surfaces
Any large articulating
surface, may be concave or
convex
Condyle
C.Bone Markings –
2. Articulating
surfaces
A smooth, flat surface,
generally small
Facet
C.Bone Markings –
2. Articulating
surfaces
Fossa
A shallow depression
C.Bone Markings –
3. Enlargements & Processes
Process
generic term for bone projection
that serves as a point for
attachment of other structures
C.Bone Markings –
3. Enlargements
Epicondyle
projection or swelling to the side
of or above a condyle
C.Bone Markings –
3. Enlargements
a sharp, slender
projecting process
Spine
C.Bone Markings –
3. Enlargements
a small
rounded
projection
Tubercle
C.Bone Markings –
3. Enlargements
Turberosity
a large
rounded
roughened
projection
C.Bone Markings –
3. Enlargements
a large blunt
projection
Trochanter
C.Bone Markings –
3. Enlargements
a prominent
border or
ridge
Crest
C.Bone Markings –
A
major
3. Enlargements
branch or
division off
of the main
body of a
bone
Ramus
C.Bone Markings –
4. Openings
C.Bone Markings –
4. Openings
Meatus
Canal
like
opening
C.Bone Markings –
5. Depressions
Sulcus
A
shallow
groove
C.Bone Markings –
5. Depressions
Fovea
A very
shallow
groove
C.Bone Markings –
5. Depressions
Fissure
A deep
groove
That’s All Folks!