chapter 6: the skeletal system - warner pacific …classpages.warnerpacific.edu/bdupriest/bio...

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CHAPTER 6:

THE SKELETAL SYSTEM


SKELETAL CARTILAGE


Figure 6.1 The bones and cartilages of the human skeleton.

Axial skeleton

Appendicular skeleton

Hyaline cartilages

Elastic cartilages

Fibrocartilages

Cartilages

Bones of skeleton

Epiglottis Larynx

Trachea Cricoid cartilage Lung

Respiratory tube cartilages

in neck and thorax

Thyroid cartilage Cartilage in

external ear Cartilages in nose

Articular Cartilage of a joint

Costal

cartilage

Cartilage in

Intervertebral

disc

Pubic symphysis

Articular cartilage of a joint

Meniscus (padlike cartilage in knee joint)


GROWTH OF CARTILAGE


Intervertebral discs are made of which type

of cartilage?

1) Elastic cartilage

2) Fibrocartilage

3) Hyaline cartilage


BONE CLASSIFICATION


AXIAL VS. APPENDICULAR


Figure 6.1 The bones and cartilages of the human skeleton.

Axial skeleton

Appendicular skeleton

Hyaline cartilages

Elastic cartilages

Fibrocartilages

Cartilages

Bones of skeleton

Epiglottis Larynx

Trachea Cricoid cartilage Lung

Respiratory tube cartilages

in neck and thorax

Thyroid cartilage Cartilage in

external ear Cartilages in nose

Articular Cartilage of a joint

Costal

cartilage

Cartilage in

Intervertebral

disc

Pubic symphysis

Articular cartilage of a joint

Meniscus (padlike cartilage in knee joint)


Figure 6.2 Classification of bones on the basis of shape.

(a) Long bone

(humerus)

(b) Irregular bone

(vertebra), right

lateral view

(d) Short bone

(talus)

(c) Flat bone

(sternum)


FUNCTIONS OF BONES


True or false: Every bone has the same

primary functions.

1) True

2) False


BONE STRUCTURE

GROSS STRUCTURE


Proximal

epiphysis

(b)

(c) (a)

Yellow

bone marrow

Endosteum

Epiphyseal

line

Articular

cartilage

Periosteum

Spongy bone

Compact bone

Medullary

cavity (lined

by endosteum)

Compact bone

Compact bone

Periosteum

Perforating

(Sharpey’s)

fibers

Nutrient

arteries

Diaphysis

Distal

epiphysis

Figure 6.3 The structure of a long bone (humerus of arm).


Figure 6.5 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone.

Compact

bone

Trabeculae

Spongy bone

(diploë)


The connective tissue surrounding a bone

is called the…

1) Diaphysis

2) Endosteum

3) Epiphysium

4) Periosteum


True or false: Trabeculae are found in

compact bone.

1) True

2) False


BONE STRUCTURE

MICROSCOPIC ANATOMY


Figure 6.4 Comparison of different types of bone cells.

(a) Osteogenic cell (b) Osteoblast (c) Osteocyte

Stem cell Mature bone cell

that maintains the

bone matrix

Matrix-synthesizing

cell responsible

for bone growth

(d) Osteoclast

Bone-resorbing cell


Figure 6.6 A single osteon.

Structures

in the

central

canal

Artery with

capillaries

Vein

Nerve fiber

Lamellae

Collagen

fibers

run in

different

directions

Twisting

force


Figure 6.7 Microscopic anatomy of compact bone.

Endosteum lining bony canals

and covering trabeculae

Perforating

(Volkmann’s) canal

Perforating (Sharpey’s) fibers

Periosteal blood vessel Periosteum

Lacuna (with

osteocyte)

(a)

(b) (c)

Lacunae

Lamellae

Nerve

Vein

Artery

Canaliculi

Osteocyte

in a lacuna

Circumferential

lamellae

Osteon

(Haversian system)

Central

(Haversian) canal

Central

canal

Interstitial lamellae

Lamellae

Compact

bone

Spongy bone


The cells which build new bone are:

1) Osteoblasts

2) Osteogenic cells

3) Osteoclasts

4) Osteocytes


Osteocytes receive their nutrition from fluid in

the ________, which are connected to

the larger ___________.

1) Canaliculi / central canal

2) Lamellae / lacunae

3) Osteoblasts / lacunae


BONE STRUCTURE

CHEMICAL COMPOSITION OF BONE


Hydroxyapatite is part of the _______

component of bone.

1) Cellular

2) Organic

3) Inorganic


OSTEOGENESIS

INTRAMEMBRANOUS OSSIFICATION


Figure 6.8 Intramembranous ossification.

Mesenchymal cell

Collagen fiber

Ossification center

Osteoid

Osteoblast

Osteoid

Osteocyte

Newly calcified

bone matrix

Osteoblast

Mesenchyme condensing to form the periosteum

Blood vessel

Trabeculae of

woven bone

Fibrous periosteum

Osteoblast

Plate of compact bone

Diploë (spongy bone) cavities contain red marrow

1 2

3 4

Ossification centers appear in the fibrous

connective tissue membrane.

• Selected centrally located mesenchymal cells cluster

and differentiate into osteoblasts, forming an

ossification center.

Bone matrix (osteoid) is secreted within the

fibrous membrane and calcifies.

• Osteoblasts begin to secrete osteoid, which is calcified

within a few days.

• Trapped osteoblasts become osteocytes.

Woven bone and periosteum form.

• Accumulating osteoid is laid down between embryonic

blood vessels in a random manner. The result is a network

(instead of lamellae) of trabeculae called woven bone.

• Vascularized mesenchyme condenses on the external face

of the woven bone and becomes the periosteum.

Lamellar bone replaces woven bone, just deep to

the periosteum. Red marrow appears.

• Trabeculae just deep to the periosteum thicken, and are later

replaced with mature lamellar bone, forming compact bone

plates.

• Spongy bone (diploë), consisting of distinct trabeculae, per-

sists internally and its vascular tissue becomes red marrow.


OSTEOGENESIS

ENDOCHONDRIAL OSSIFICATION


Figure 6.9 Endochondral ossification in a long bone.

1 2 3 4 5 Bone collar

forms around

hyaline cartilage

model.

Cartilage in the

center of the

diaphysis calcifies

and then develops

cavities.

The periosteal

bud invades the

internal cavities

and spongy bone

begins to form.

The diaphysis elongates

and a medullary cavity

forms as ossification

continues. Secondary

ossification centers appear

in the epiphyses in

preparation for stage 5.

The epiphyses

ossify. When

completed, hyaline

cartilage remains only

in the epiphyseal

plates and articular

cartilages.

Hyaline

cartilage

Area of

deteriorating

cartilage matrix

Epiphyseal

blood vessel

Spongy

bone

formation

Epiphyseal

plate cartilage

Secondary

ossification

center

Blood vessel of

periosteal

bud

Medullary

cavity

Articular

cartilage

Childhood to

adolescence

Birth Week 9 Month 3

Spongy

bone

Bone collar

Primary ossification center


The starting point for endochondrial

ossification is called the…

1) Medullary cavity

2) Periosteal bud

3) Primary ossification center

4) Bone collar


POSTNATAL BONE GROWTH

AND REMODELING


Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate.

Calcified cartilage

spicule

Osseous tissue

(bone) covering

cartilage spicules

Resting zone

Osteoblast depositing

bone matrix

Proliferation zone

Cartilage cells undergo

mitosis.

Hypertrophic zone

Older cartilage cells

enlarge.

Ossification zone

New bone formation is

occurring.

Calcification zone

Matrix becomes calcified;

cartilage cells die; matrix

begins deteriorating.

1

2

3

4


Figure 6.11 Long bone growth and remodeling during youth.

Bone growth Bone remodeling

Articular cartilage

Epiphyseal plate

Cartilage grows here.

Cartilage is replaced by bone here.

Cartilage grows here.

Bone is resorbed here.

Bone is resorbed here.

Bone is added by appositional growth here. Cartilage

is replaced by bone here.


Growth of bone length is due largely to

increasing numbers of cells in

the _______ zone…

1) calcification

2) hypertrophic

3) ossification

4) proliferation


CONTROL OF BONE REMODELING


Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels.

Osteoclasts

degrade bone

matrix and

release Ca2+

into blood.

Parathyroid

glands

Thyroid

gland

Parathyroid

glands release

parathyroid

hormone (PTH).

Stimulus

Falling blood

Ca2+

levels

PTH

Calcium homeostasis of blood: 9–11 mg/100 ml

BALANCE BALANCE


Figure 6.13 Bone anatomy and bending stress.

Load here (body weight)

Head of

femur

Compression

here

Point of no stress

Tension

here


Which of the following does NOT control

bone growth or remodeling?

1) Growth hormone

2) Mechanical force

3) Parathyroid hormone

4) Thyroid hormone

5) Calcitonin


FRACTURES


Table 6.2 Common Types of Fractures (1 of 3)


The type of fracture which commonly occurs in

porous bones subjected to a fall is a…

1) Comminuted fracture

2) Compression fracture

3) Spiral fracture

4) Epiphyseal fracture

5) Depression fracture

6) Greenstick fracture


BONE REPAIR


Figure 6.15 Stages in the healing of a bone fracture.

Hematoma External callus

Bony callus of spongy bone

Healed fracture

New blood vessels

Spongy bone trabecula

Internal callus (fibrous tissue and cartilage)

1 A hematoma forms. 2 Fibrocartilaginous

callus forms.

3 Bony callus forms. 4 Bone

remodeling

occurs.


True or false: if a bone breaks, it bleeds.

1) True

2) False


HOMEOSTATIC IMBALANCES


Figure 6.16 The contrasting architecture of normal versus osteporotic bone.


The disease which causes children to have

soft, malformed bones due to vitamin D or

calcium deficiency is…

1) Rickets

2) Osteomalacia

3) Osteporosis

4) Paget’s Disease


FETAL SKELETAL DEVELOPMENT


Figure 6.17 Fetal primary ossification centers at 12 weeks.

Parietal bone

Radius

Ulna

Humerus

Femur

Occipital bone

Clavicle

Scapula

Ribs

Vertebra

Ilium

Tibia

Frontal bone

of skull Mandible

chapter 6: the skeletal system - warner pacific …classpages.warnerpacific.edu/bdupriest/bio...

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