Cartilage and Bone | Human Anatomy | PPT

January 19, 2013 | By | Reply More

Cartilage and Bone | Human Anatomy | PPT

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Human Anatomy

Cartilage and Bone

Connective Tissue


General Osteology /Arthrology


Osteology: the study of bones

Bones: organs of the skeletal system

Skeletal System: bones and associated cartilages

Arthrology: the study of joints

Point of movement (fulcrum)

Endoskeleton: internal skeleton

endo- = inside

Versus exoskeleton

Skeletal System

Composed of dynamic living tissues

Osseous tissue, cartilage, fibrous CT, blood, nervous tissue.

Continually rebuilds and remodels itself

Changes over a lifetime

Interacts with all of the other organ systems.


bones of the skeleton



other connective tissues that stabilize or connect the bones.

Skeletal System


Supports our weight.

Interacts with muscles to produce movements.


Blood cell formation

Red bone marrow

Mineral storage



Cartilage Connective Tissue


Weaker than bone

More flexible than bone

Cells in an abundant matrix.

Cell Types


Chondrocytes in lacunae


3 Major Functions of Cartilage

Supporting soft tissues.

Providing a gliding surface at articulations (joints)

Providing a model for the formation of most of the bones in the body.


Types of Cartilage

Three types of cartilage:

Hyaline cartilage

Most abundant kind

Has a perichondrium (membrane)

Associated with synovial joints

Most bones first modeled in hyaline cartilage


Has collagen fibers

Intervertebral discs, pubic symphysis

Elastic cartilage

Has elastic fibers

Ear, respiratory tubing

Growth Patterns of Cartilage

Two main types:

Interstitial Growth

Appositional Growth.

Interstitial Growth.

Chondrocytes in lacuna undergoes mitosis.

Two chondrocytes in one lacuna

Will push apart, form separate lacuna


Growth Patterns of Cartilage

Appositional Growth.

Undifferentiated cells divide (mitosis)

One daughter cell remains a stem cell, one differentiates into a committed cell.

Committed cell further differentiates into chondroblast

Located at edge of cartilage

Both types common during growth

Later, mostly appositional

In adult, usually no growth unless for repair


Bones are organs

Bones are composed of all tissue types.

Their primary component is osseous connective tissue.

The matrix is sturdy and rigid due to calcification (also called mineralization).

Functions of Bone





Storage of minerals.

Energy Reserves (marrow)

Support and Protection

Bones provide structural support and serve as a framework for the entire body.

Bones protect many delicate tissues and organs from injury and trauma.



Muscles attach to the bones of the skeleton

contract and pull on bone

functions as a series of levers.




Blood cell production in red bone marrow

located in some spongy bone.

Red bone marrow contains stem cells

form all of the blood cell types.


Storage of Mineral and Energy Reserves

More than 90% of the body’s reserves of the minerals calcium and phosphate are stored and released by bone.

Calcium: needed for

muscle contraction

blood clotting

nerve impulse transmission.

Phosphate: needed for

ATP utilization

structure of nucleic acids (DNA, RNA)

Classification of Bone by Organization



Vertebral column












Classification of Bone by Shape





Surface features vary


Structure of Long Bone






Epiphyseal line

Articular cartilage

Medullary cavity

Structure of Long Bone

Endostium: lines marrow cavity, incomplete

Osteoprogenitor cells



Periostium: covers bone everywhere but articular surfaces

Two layers

Fibrous layer: outermost, dense irregular CT

Site of tendon attachment

Inner layer: next to compact bone

Osteoblasts present in young bone

Anchored to bone by perforating fibers (collagen)

Flat Bones of the Skull

Two layers of compact bone

Inner table

Outer table

Region of spongy bone sandwiched between them

Called the diploe

Both layers of compact bone are covered by periosteum


Four Types of Bone Cells

Osteoprogenitor cells

stem cells derived from mesenchyme which produce other stem cells and osteoblasts


produce new bone, and once osteoblasts become entrapped in the matrix they produce and secrete, they differentiate into osteocytes


mature bone cells

Osteoclasts: not derived form osteoprogenitors

Related to macrophages

Formed from multiple cells; are multinucleated

are involved in bone resorption



Located in Howship’s lacuna

Ruffled edge contacts bone

Secrete hydrochloric acid

Dissolves minerals



Secrete enzymes that dissolve matrix

Composition of Bone Matrix

Organic components: one third


Collagen fibers

Ground substance

Inorganic components: two thirds

Calcium phosphate

Hydroxyapatite crystals: calcium phosphate and calcium hydroxide

Types of Osseous Tissue


Dense, cortical


Cancellous, trabecular

Compact Bone Microanatomy

Osteon (Haversian) system: basic unit

Central (Haversian) canal

Concentric lamellae

Contain collagen fibers



Canaliculi: permit intercellular communication

Cylinder that runs with long axis of long bone

Compact Bone Microanatomy

Perforating canals (Volkmann canals)

Contain blood vessels, nerve

Run perpendicular to central canals, connect them

Circumferential lamellae

Internal to periostium

External circumferential lamellae

Internal to endosteum

Internal circumferential lamellae

Run the entire circumference

Interstitial lamellae

Remains of osteons

Spongy Bone Microanatomy

No osteons

In trabeculae:

Parallel lamellae

Osteocytes in lacunae



Osteogenesis: bone formation and development

Begins in the embryo: By the eighth through twelfth weeks:

the skeleton begins forming:

from mesenchyme

or from a hyaline cartilage model of bone.

These models are replaced by hard bone

Continues during childhood and adolescence.

In the adult, ossification continues.


Intramembranous Ossification

Also called dermal ossification


the flat bones of the skull (cranial vault)

some of the facial bones (zygomatic bone, maxilla), the mandible (lower jaw)

the central part of the clavicle (collarbone).

It begins when mesenchyme becomes thickened and condensed with a dense supply of blood capillaries.

Intramembranous Ossification

1. Ossification centers form in thickened mesenchyme

Osteoprogenitors develop, become osteoblasts

2. Osteoid (bone matrix) calcifies

Trapped osteoblasts become osteocytes

Intramembranous Ossification

3. Woven bone (primary bone) forms, periostium forms (from mesenchyme)

4. Lamellar bone (secondary bone) replaces woven bone; compact and spongy bone form

Endochondral Ossification

Begins with a hyaline cartilage model

Produces most of the other bones of the skeleton

Long bone will be used as an example.

Endochondral Ossification


1. Cartilage model develops:

Chondroblasts become chondrocytes

Perichondrium develops

2. Cartilage calcification, bone collar develops in shaft

Chondrocytes hypertrophy, then die

Blood vessels grow toward cartilage

Osteoblasts under perichondrium form bone

3. Primary Ossification center forms:

Periosteal bud: osteoblasts and blood vessels

12th week: most have formed



Endochondral Ossification


3. Secondary Ossification centers:

In epiphysis

Some form post-natally

4. Cartilage replaced by bone

Except articular cartilage, epiphyseal plate

5. Epiphyseal plate ossifies:

Forms epiphyseal line

Between 10 and 25

Last… clavicle



Epiphyseal Plate Morphology

Hyaline cartilage

5 zones: from epiphysis to diaphysis

Zone of resting cartilage

Small chondrocytes in cartilage matrix

Looks like healthy cartilage

Secures epiphyseal plate to epiphysis

Zone of proliferating cartilage

Chondrocytes here are undergoing rapid mitosis

Stack up in columns


Epiphyseal Plate Morphology

Zone of hypertrophic cartilage

Chondrocytes stop dividing

Start hypertrophy

Absorb matrix

Zone of calcified cartilage

Few cells thick

Calcification of matrix

Kills the chondrocytes

Zone of ossification

Invasion by capillaries and osteoprogenitor cells

Bone Growth

Interstitial growth occurs in the epiphyseal plate as chondrocytes undergo mitosis

Growth in length

Appositional growth occurs within the periosteum.

Growth in diameter, thickness

Bone Remodeling

The continual deposition of new bone tissue and the removal (resorption) of old bone tissue.

helps maintain calcium and phosphate levels in body fluids, and can be stimulated by stress on a bone

occurs at both the periosteal and endosteal surfaces of a bone

Relative rates differ with age, bone

Blood Supply and Innervation

Bone is highly vascularized, especially in regions containing red bone marrow.

Kinds of blood vessels

Nutrient artery and the nutrient vein

supply the diaphysis of a long bone

Metaphyseal blood vessels

Diaphyseal face of epiphyseal plate

Periosteal blood vessels

Supply superficial osteons on diaphysis.



Effects of Hormones

Control and regulate growth patterns in bone by altering the rates of both osteoblast and osteoclast activity.

Growth hormone (Pituitary gland): affects bone growth by stimulating the formation of another hormone, somatomedin which is produced by the liver.

Somatomedin: directly stimulates growth of cartilage in the epiphyseal plate.


Effects of Hormones

Thyroid hormone (Thyroid gland): stimulates bone growth.

Growth hormone and thyroid hormone regulate and maintain normal activity at the epiphyseal plates until puberty.

Calcitonin (Thyroid gland): inhibits osteoclast activity.

Parathyroid Hormone (Parathyroid gland): increases blood calcium levels, stimulates osteoclast activity

Sex Hormones: gonads

Increase rate of bone formation

Production associated with puberty


Effects of Vitamins

Vitamin A: activates osteoblasts

Vitamin C: normal synthesis of collagen

Vitamin D: absorption and transport of calcium and phosphate


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