ch 7 bones and cartilage ap lecture

What does the axial skeleton form and what are its functions?

It forms the central axis of the body and its primary functions are to support and protect the body.

What structures are included in the axial skeleton?

• Skull

• Vertebral column

• Ribs and sternum

• Hyoid bone

What does the appendicular skeleton form and what are its functions?

It forms the limbs and structures to attatch them your body. Main function is movement.

What structures are included in the appendicular skeleton?

• Pectoral girdle (clavicle and scapula)

• Upper limbs (humerus, radius, ulna, hand bones)

• Pelvic girdle (hip bones)

• Lower limbs (femur, tibia, fibula, foot bones)

Functions of bones

• support

• protection

• movement

• hematopoiesis: production of blood cells in red bone marrow

• mineral storage (calcium and phosphate)

• energy storage

Functions of cartilage

• Supports structures

• Cushions joints

Characteristics of Hyaline Cartilage

• Covers joints

• Supports the respiratory tract

• Forms growth joints

Characteristics of Fibro Cartilage

• Resist compression

• In intervertebral discs and knee menisci

Ligaments

• Connect bone to bone

• stabilize joints

Tendons

• Connect muscle to bone

• Muscle contraction moves bone

What are ligaments and tendond primarily composed of?

Dense Regular CT

What is the function of chondroblast?

Produces cartilage matrix

What is the function of chondrocyte

Mature cell that maintains cartilage

What is the function of lacuna?

Small space containing a chondrocyte

What is the function of perichondrium?

Connective tissue surrounding most cartilage

What is the function of extracellular matrix?

Material surrounding cartilage cells

What is the function of Glycosaminoglycans (GAGs)?

Help retain water and resist compression

What is the function of collagen fibers?

They provide strength

What is the function of elastic fibers?

They provide flexibility

Why does cartilage heal slowly?

Because they do not have not nerves or blood vessels.

What is the most abundant type of cartilage?

Hyaline cartilage

What cartilage has a smooth, glassy-looking matrix and provides support with some flexibility?

Hyaline Cartilage

Where is Hyaline Cartilage located?

• Costal cartilages connecting ribs to the sternum

• Larynx

• Trachea and bronchi

• Nose

• Articular surfaces of bones

Where is elastic cartilage located?

• External ear (pinna)

• Epiglottis

• Parts of the larynx

What structure is flexible and helps prevent food from entering the airway during swallowing?

epiglottis

Where is fibrocartilage located?

• Intervertebral discs

• Pubic symphysis

• Menisci of the knee

What does Interstitial Cartilage Growth mean?

It means the cartilage grows within.

What is the process of Interstitial Cartilage Growth?

Cartilage cells divide inside existing cartilage making cartilage expands internally.

What process lengthens the bone at the epiphysial plates?

Interstitial Cartilage Growth

What does Appositional Cartilage Growth mean?

It means cartilage grows by adding new material to its surface.

What is the process of Appositional Cartilage Growth?

cartilage increases in thickness and width through the addition of new layers on its external surface

What is the difference between of compact bone and spongy bone?

Compact bone is dense, strong, and solid-looking. It forms outer portion of bones.

Spongy bone is porous, lightweight, and arranged into a network of trabeculae.

What makes up approximately 80% of bone mass?

Compact Bone

What makes up approximately 20% of bone mass?

Spongy Bone

Compat Bones:

• Also called cortical bone.

• Contains osteons.

• Has canals that carry blood vessels and nerves.

Spongy Bone:

• Also called cancellous or trabecular bone.

• Located internally.

• Contains trabeculae, which are thin plates and rods of bone.

• Spaces between trabeculae often contain marrow.

Long Bones

• longer than wide

• femur and humerus

Short Bones

• Cube Shaped

• tarsals and carpals

Flat bones

• thin and flat

• sternum, ribs, and scapula

Irregular Bones

• complex shapes

• vertebrae and hip bones

Seasamoid Bones

• sesame seed shaped

• patella

Bone markings commonly serve as

• Muscle or ligament attachment sites

• Joint surfaces

• Passageways for nerves and blood vessels

Tuberosity

Large, rough projection

Tubercule

Small, rounded projection

Trochanter

Large projection found on the femur

Crest

Prominent ridge

Line

Low, narrow ridge

Spine

Sharp projection

General term for a projection

Process

Head

Rounded articular end

Condyle

Rounded joint surface

Facet

Small, flat articular surface

Foramen

Opening through a bone

Fissure

Narrow slit

Meatus/Canal

Tube-like passage

Sinus

Air-filled cavity

Fossa

Shallow depression

Groove/Sulcus

Furrow

Ramus

Branch or extension of a bone

Neck

Narrow region connecting a head to the rest of a bone

Structure of a Flat Bone

• like a sandwhich: compact bone, spongy bone (diploe when cranial), compact bone

Diaphysis of a long bone

• the shaft

• surround the medullary cavity aka yellow bone marrow

Epiphyses of a long bone

• the end of the bone\

• Compact bone outside spongy bone isnide

Articular cartilage of long bone

hyaline cartilage covers surfaces of the end

cartilage region for lengthening bone growth

eiphysial plate of a long bone

epiphysial line

the bone left when the plate closes

Metaphysis region of long bone

between the end and the shaft is where the growth plate is located aka transition region

Periosteum

• Covers the outer surface of bone, except at articular cartilage

• 2 layers

Outer fibrous layer

Dense irregular CT that attatchs tendons and ligaments

What contains cells involved in bone growth and remodeling?

Inner osteogenic layer

Endosteum

cellular membrane lining internal bone surfaces

Compact bone recieves blood through:

• Central (Haversian) canals

• Perforating (Volkmann's) canals

Red bone marrow

• Responsible for hematopoiesis.

• Produces blood cells.

• Found in spaces associated with spongy bone.

Yellow Bone marrow

• Rich in adipose tissue.

• Stores energy as fat.

• Common in the medullary cavity of adult long bones.

Stages in bone cell development

Osteoprogenitor cell → Osteoblast → Osetocyte

Osteoprogenitor cell

comes from mesenchymal cells and becomes an osteoblast

Osteoblast

secretes ostoid and becomes osteocytes if trapped when matrix calcifies

Osetocyte

• mature bone cell

• senses mechanical stress

Osteoclasts

• breaks down bones

• has multple nuclei

• located at bone surfaces

• removes mineralized bone and releases calcium into the blood

Where are osteocytes found?

• within the bone matrix in lucunae

• Trabeculae of spongy bone

• Lamellae of compact bone

Osteoid

• organic compound

• provides Flexibility, Tensile strength, Resistance to stretching and twisting

Hydroxyapatite

• inorganic compound

• provides hardness, mineral strenght, and resistance to compression

The process of bone resorption:

Osteoclasts attach to the bone surface and release acid which disssolves the mineral componenets, breakind down the matrix and Ca and P are released into the blood.

What happens to the bone if there is no hydroxyapatite?

Bone becomes flexible and cen bend

What happens to the bone if there is no collagen?

Bone becomes brittle and breaks easily

WHat is the structural unit of a compact bone?

an osteon

What is ossification?

The process of forming bone tissue.

Intramembranous ossification

• process of direct bone formation within mesenchymal tissue without a cartilage intermediate

• essential for fetal development

• primary bone healing

Endochondral ossification

process where bone tissue replaces hyaline cartilage to form the long bones

Zone of resting cartilage

Chondrocytes are inactive and cartilage anchors the plate to the epiphysis

Zone of proliferation

Chondrocytes divide and form columns

Zone of hypertrophic cartilage

Chondrocytes enlarge and stop dividing

Zone of calcified cartilage

Cartilage matrix calcifies and chondrocytes die

Zone of ossification

Blood vessels and osteoblasts enter; bone is deposited

Zones of the Epiphyseal Plate in order

Resting → Proliferation → Hypertrophy → Calcification → Ossification

Parathyroid hormone (PTH)

Increases blood calcium

Calcitonin

Can lower blood calcium by inhibiting osteoclast activity

Growth hormone

Stimulates growth partly through IGF-1

Thyroid hormones (T3, T4)

Support normal skeletal growth and development

Estrogens

Help maintain bone density and regulate bone turnover