Skeletal System
Chapter 6 & 7
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Skeletal System: Cartilage
Skeletal cartilage consists primarily of
water. (80%)
Cartilage contains no nerves or blood
vessels.
Chondroblasts =new cell growth cells
Chondrocytes = mature cells
Lacunae = groups of cavities that
contain the chondrocytes
Three types of cartilage
Hyaline Cartilage
Most abundant
Elastic cartilage
Maintains shape
while allowing
great flexibility
Fibrocartilage
Tensile strength
with the ability to
absorb
compressive
shock
Skeletal System
Organization of the skeletal
system
1. Axial skeleton =revolves
around the vertical axis
of the skeleton
2. Appendicular skeleton
=make up the limbs that
have been appended to
the axial skeleton
Skeleton
Consists of:
bones
Cartilage
Membranes that
Line the bones.
Types of Bones:
1.Long bones are longer
than they are wide.
2. Short bones are
cubelike, about as long
as they are wide.
3. Flat bones, such as ribs
and skull bones, are thin
or flattened.
4. Irregular bones, such as
vertebra, facial bones,
have specific shapes
unlike the other types of
bones.
Functions of bones
Support = bones provide a framework for the
attachment of muscles and other tissue
Protection= bones such as the skull and rib cage
protect internal organs from injury
Movement= bones enable body movements by
acting as levers and points of attachment for muscles.
Mineral storage. Bones serve as a reservoir for
calcium and phosphorus, essential minerals for various
cellular activities throughout the body.
Blood cell production= the production of blood
cells (hematopoietic) occurs in the red marrow found
within the cavities of certain bones.
Energy storage= lipids(fats) stored in adipose cells
of the yellow marrow serve as an energy reservoir
Bone
Bone is an organ that includes
1. Connective tissue(bone, blood, cartilage,
adipose, and fibrous connective tissue)
2. Nervous tissue
3. Muscle and epithelial tissues (within the
blood vessels)
Bone Structure: Gross Anatomy
Two types of bone tissue
Compact bone is the hard material that
makes up the shaft of long bones and the
outside surfaces of other bones.
Two types of bone tissue
Spongy bone consists of thin, irregularly
shaped plates called trabeculae, arranged in a
latticework network.
Long bone structure
Location of
Hematopoietic tissue
in bones
Red marrow located within
cavities of spongy bone of
long bones and in the diploe
of flat bones
Infants all areas of spongy
bone contain red blood cells
Adults in the head of the
femur and humerus, flat bone
of sternum, and irregular
bone of the pelvis
Epiphyseal
line
Microscopic Structure of Bone
Chemical Composition of Bone
Bone consists of organic and inorganic
components
Organic components include the cells
(osteoblasts, osteocytes, and osteoclasts)
and Osteoids
Inorganic components include
hydroxyapatites (mineral salts) largely
calcium phosphates
Organic bone cells
Osteoblasts - bone-forming cells
Osteocytes - mature bone cells
Osteoclasts - large cells that resorb or
break down bone matrix
Osteoid - unmineralized bone matrix
composed of proteoglycans,
glycoproteins, and collagen
Bone Markings
The external surface of bones are rarely
smooth and featureless.
These marking are named in many
different was.
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Bone Development
Osteogenesis and ossification are
synonyms indicating the process of
bone tissue formation
Occurs when?
Embryos = leads to formation of the
bony skeleton
Bone growth = until early adulthood to
increase in size (bones are capable of
growing in thickness throughout life.)
Ossification in adults serves mainly for
remodeling and repair of bones
Formation of the Bony Skeleton
Begins at week 8 of embryo development
1.Intramembranous ossification – bones
develops from a fibrous membrane
Formation of most flat bones of the skull and the
clavicles
2.Endochondral Ossification –bone
formation that occurs by replacing hyaline
cartilage
Begins in the second month of development
Uses hyaline cartilage “bones” as models for
bone construction
Requires breakdown of hyaline cartilage prior to
ossification
Postnatal Bone Growth
Bone Growth in length
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1. Epiphyseal plate or cartilage growth
plate
cartilage cells are produced by mitosis on
epiphyseal side of plate
cartilage cells are destroyed and replaced
by bone on diaphyseal side of plate
Between ages 18 to 25, epiphyseal plates
close.
cartilage cells stop dividing and bone
replaces the cartilage (epiphyseal line)
Growth in length stops at age 25
Growth in length of long bones
Hormonal Regulation of bone
growth during youth
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Initially promote adolescent growth spurts
Cause masculinization and feminization of
specific parts of the skeleton
Later induce epiphyseal plate closure,
ending longitudinal bone growth
Initially promote adolescent growth spurts
Cause masculinization and feminization of
specific parts of the skeleton
Later induce epiphyseal plate closure,
ending longitudinal bone growth
Bone Remodeling
In adult skeletons, bone remodeling is
balanced bone deposit and removal, bone
deposit occurs at a greater rate when
bone is injured, and bone resorption
allows minerals of degraded bone matrix
to move into the blood.
Control of Remodeling
The hormonal mechanism is mostly used
to maintain blood calcium homeostasis, and
balances activity of parathyroid hormone
and calcitonin.
Nutrition - Ca, P, Mg, vitamins, A, C and D.
In response to mechanical stress and
gravity, bone grows or remodels in ways
that allow it to withstand the stresses it
experiences
Calcium
The human body contains some 12001400 g of calcium
Over 99% of which is present as bone
minerals
Normal range is narrow= 9-11 mg per
100ml of blood by the hormonal control
loop
Calcium is absorbed from the intestine
under the control of vit. D metabolism
Daily req: birth to 10yrs = 400-800 mg
11 to 24 yrs = 1200-1500 mg
Wolff's law - a bone grows or remodels in response
to the forces or demands placed upon it
Comparing Skeletons
Adult= 206
Child = 275
Adult = Higher % of yellow marrow and
lower % of red marrow(sternum, pelvis,
femur)
Child = Higher % of red marrow and lower %
of yellow marrow
Adult = higher % of bone and lower % of
cartilage
Child = higher % of cartilage and lower % of
bone
Fractures
Stages in the healing of a bone
fracture
Homeostatic imbalances of Bone
1.
2.
3.
4.
5.
6.
7.
Osteomalacia
Rickets
Osteoporosis
Paget’s disease
achondroplasia
bony spur
ostealgia
8. osteitis
9. osteomyelitis
10. osteosarcoma
11. Pathologic
fracture
12. traction
Osteomalacia and Rickets
osteoporosis
Paget’s disease
achondroplasia
Bony spur
osteitis
osteomyelitis
osteosarcoma
Joints (articulations)= site where
two or more bones meet
Function to give the body mobility and
to hold bones together
Joints are the weakest parts of the
skeleton
Functional Classification:
Synarthroses= immovable joints
Amphiarthroses= movable joints
Diarthroses = freely moveable joints
Classifying joints based on
structure (PAGE 251)
Fibrous= Sutures
Cartilaginous
Synovial joint (page259-260)
Plane
Hinge
Pivot
Condyloid
Pivot
Saddle
Ball and socket
Diseases of the bone and/or skeletal sys.
5 conditions and/or diseases
Symptoms
Causes
Treatments
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