Anatomy and Physiology Chapter 6

BIOL251 Binghamton University

Chondr-

“cartilage”

Osteo-

“bone”

What are the functions of bones?

Support, protection, attachment point, storage, blood cell formation, and hormone production

How do bones support the body?

They hold up the body and cradles organs

How do bones protect the body?

They protect the central nervous system and visceral organs

How do bones attach to one another?

Skeletal muscle attaches to them via tendons

What is the purpose of tendons?

They are a cord-like band that attaches bones together with skeletal muscle tissue and allows them to move.

They are necessary for movement.

What is stored in bones?

Minerals, fat, and yellow marrow (in adults)

Hematopoiesis

Formation of blood cells in red bone marrow

(Blood cell formation in bones)

Osteocalcin

Regulates insulin release, glucose homeostasis, and energy expenditure/use

(Hormone production in bones)

What is the embryonic skeleton made of before the osseous skeleton forms?

Cartilage and connective tissue fibers

Characteristics of all cartilage types

Strong and resilient

Surrounded externally by perichondrium

Perichondrium

Fibrous connective tissue containing blood vessels for cartilage tissue that resists excessive outward expansion of cartilage

What are the three types of cartilage?

Hyaline cartilage

Elastic cartilage

Fibrocartilage

Hyaline cartilage

Most abundant cartilage type

Contains collagen fibers

Elastic cartilage

Cartilage type containing more elastic fibers

Fibrocartilage

Cartilage type containing rows of chondrocytes alternating with thick collagen bands (most of any type), making it very compressible and hard to do any damage to

What are the types of cartilage growth?

Appositional growth

Interstitial growth

Appositional growth

Laying down new cartilage on top of old cartilage, occurring at the surface of cartilage tissue causing it to increase in width/thickness

Interstitial growth

Cells divide and secrete matrix within pre-existing cartilage, occurring deeper in the cartilage tissue causing it to increase in length

Axial skeleton

Long axis of body

Which bones are located in the axial skeleton?

Skull, vertebral column, and ribs

Appendicular skeleton

Limbs (aka appendages) and the girdles

What bones are located in the appendicular skeleton?

Pectoral and pelvic girdles, arm and leg bones

What are the different shapes of bones?

Long bones, short bones, flat bones, irregular bones, and sesamoid bones

Long bones

Longer than they are wide

Short bones

cube-shaped

Sesamoid bones

bones that form in a tendon

ex: patella

Flat bones

thin, flat, curved

ex: ribs

Irregular bones

anything that does not fit in any of the other bone shape types

ex: vertebrae, os coxa

Compact bone

Outer layer of a bone that looks smooth and solid

Spongy bone

Inner layer of a bone that has open spaces with needle-like pieces of bone called trabeculae

Open space is filled with red or yellow marrow

Where is trabeculae mostly found?

Along lines of stress in spongy bone to help transmit pressure to resist mechanical stress and pushing to prevent bones from breaking easily

Structure of flat, irregular, and short bone

Thin plate of spongy bone covered by compact bone

No large cavities for bone marrow (all bone marrow found around trabeculae)

What features make up the structure of long bones?

Diaphysis

Epiphysis

Membranes

Vascularization and innervation

Diaphysis

bone shaft making up most of the length of the bones composed of compact bone “collar” with internal medullary cavity containing bone marrow

Epiphysis

Bone ends that form joints and are filled with spongy bone and covered with hyaline/articular cartilage. They are composed of compact bone externally and spongy bone internally.

What is the function of the epiphysis?

Location where one bone articulates with another bone at a joint and/or allows for attachment of ligaments and tendons

What membranes make up the structure of long bone?

Periosteum and endosteum

Periosteum in long bone

Double layered membrane covering external bone surface except at epiphysis

Well vascularized

Endosteum in long bone

Covers internal bone surfaces

How is the diaphysis vascularized?

The nutrient artery and nutrient vein

How is the epiphysis vascularized?

The epiphyseal artery and epiphyseal vein

How is long bone innervated?

Nerves travel with blood vessels

What are the types of hematopoietic tissue?

Red bone marrow

Produces blood cells

Hematopoietic tissue

Where is red bone marrow found in the skeleton of an infant?

Everywhere to support rapid growth and high blood cell production

Where is red bone marrow found in the skeleton of adults?

skull, ribs, hips, sternum, clavicle, scapula, vertebrae, heads of femur, and humerus

Yellow marrow

Is located in the medullary cavity of long bones in adults and contains more fat and less blood supply than red marrow

When is yellow marrow converted back to red marrow?

When a person is short on red blood cells (low on blood supply and/or oxygen)

Organic chemical composition of bone

Cells and osteoid

Inorganic chemical composition of bone

Mineral salts → mostly calcium phosphate salts packed around collagen fibers

How do mineral salts affect bone tissue?

Gives hardness and resistance to breakdown

What are the 4 primary cell types responsible for bone growth?

Osteoprogenitor (osteogenic) cells

Osteoblasts

Osteocytes

Osteoclasts

Osteoprogenitor (osteogenic) cells

Mitotically active cells that can remain as osteogenic cells or differentiate to form osteoblasts

What makes osteoprogenitor cells important throughout life?

These stems cells are foundational for making sure bone is continuously replenished

Osteoblasts

Bone-forming cells that secrete unmineralized extracellular matrix (osteoid) that forms bone tissue and secrete matrix until surrounded

Unmineralized

Organic bone tissue that has not yet had mineral crystals deposited into it

What happens to an osteoblast once it is surrounded by matrix?

It is converted to an osteocyte

Osteocytes

Mature bone cell that monitors and maintains the bone matrix

What do osteocytes respond to?

Mechanical stress on bone and chemical signals

Osteoclasts

Secrete collagenase to break down collagen in the bone matrix. They are bone-degrading cells that maintain, repair, and remodel bones and play an important role in blood calcium homeostasis.