Anatomy and Physiology Exam 2

Functions of the skeletal system

1. Supports

2. Protects

3. Assists in movement

4. Mineral homeostasis

5. Blood cell production

6. Triglyceride storage (ybm)

Diaphysis

long shaft of the bone

Epiphysis

distal and proximal ends of the bone

Metaphyses

Regions in mature bone where diaphysis and epiphysis meet

Articular Cartilage

Thin layer of hyaline cartilage covering part of epiphysis in joints

Purpose of articular cartilage

Reduces friction and absorbs shock

Periosteum

sheet of tough, dense irregular connective tissue, surrounding the area of bone that is not covered with articular cartilage

Purpose of periosteum

Helps form attachment for ligament and tendons

Medullary cavity

marrow cavity found within diaphysis, adults contain fatty yellow bone marrow (either red or yellow bone marrow)

Endosteum

thin membrane that lines medullary cavity

Contact Bone

Outside layer of the bone

Spongy Bone

Central area in bone (allows to lighten weight)

Osteogenic cells

cells that are produced from mesenchyme, undergo cell division

Where are osteogenic cells found

inner portion of periosteum, endosteum, and canaliculi

Osteoblast

Non mature bone cell

Osteocyte

Mature bone cell

Osteoclasts

large cells derived from 50 monocytes(white blood cell)

break bone down and then rebuild it again

Purpose of osteoclasts

Ruffled border that releases lysosomal enzymes and acids that digest proteins and mineral components of bone

Mesenchymal Cells

Give rise to every cell that exsists

Order

Mesenchymal cells to Preosteoblast to Osteoblast to Osteocyte

Order 2

Hematopoietic stem cell to Monocyte/Macrophage to Preosteoclast to Osteaclast

Job of Macrophage

Engulf debris

Osteoporosis

breakdown of bone tissue, equilibrium is off so work of osteocyte declines but work of osteoclast stay the same

Bone Matrix formation

25% water

25% collagen fibers

50% crystallized mineral salts

Hydroxyapatite

Calcium phosphate combines with calcium hydroxide to form crystals of Hydroxyapatite

Volkmann's canal

Provides blood vessels, nerves, and lymphatic cells from periosteum to osteon

Haversian canal

These vessels and nerves run through each individual osteon through the canal

Concentric Lamellae

Surround the Haversian canal

Lacunae

Small spaces which contain osteocytes

Canaliculi

Radiating from the lacunae which contain extracellular fluids

All communication between neighboring lacunae

Interstitial Lamellae

Area between osteons containing fragments of older osteons

Circumferential Lamellae

Encircled bone beneath the periosteum or medullary cavity

Spongy Bone tissue

No osteons

Lighter then compact bone

Trabeculae

located in hips, ribs, ends of long bones

Trabeculae

Lamelae arranged in an irregular lattice of thin columns

lamellae contains osteocytes

supports and protects red bone marrow

Periosteal Arteries

Along with the arteries enter the diaphysis, supply outer part of compact bone

Nutrient artery

Found near center of diaphysis

Large hold called nutrient foramen

Metaphyseal arteries

Enter metaphyses of long bone with nutrient artery supply RBM and bone tissue

Epiphyseal arteries

Enter epiphyses of long bone and supply RBM and bone tissue

Nutrient veins

one of two accompany nutrient arteries

vein types

Periosteal veins, Epiphyseal veins, and metephyseal veins

Ossification

process of bone formation

when does bone formation begin

6th week of embryo, mesenchymal cells begin the process

endochondral ossification

Taking place in center arising in cartilage followed by secondary absorption and replacement

intramembranous ossification

Development of osseous tissue within mesenchymal tissue without prior cartilage formation

Development of ossification center

Chemical messages cause the mesenchymal cells to cluster and differentiate into osteoblasts. This is now the ossification center. The osteoblasts secrete an organic extracellular matrix that surrounds them.

Calcification

The matrix stops the cells (osteocytes) in a lacunae and extend their cytoplasmic processes into canaliculi that radiate in all directions. Within days calcium and mineral salts are deposited and the matrix calcifies and hardens.

Formation of trabeculae

As the matrix forms it develops into trabeculae that fuse together to form spongy bone tissue. Blood vessels grow in the spaces. Connective tissue associated with blood vessels in the trabeculae differentiates into red bone marrow.

Development of periosteum

At the periphery of bone the mesenchyme condenses to form the periosteum. After a while a thin layer of compact bone develops on the surface layers of spongy bone.

what directs growth

Osteoblasts

Articular cartilage

Articulation - meeting with joint

Hyaline cartilage

helps bones move smoothly past eachother in joints

endochondral ossification order

Mesenchymal - chondroblast - chondrocyte - osteoblast - osteocyte

Development of cartilage model

Mesenchymal Cells start to come together and develop into chondroblasts

Chondroblasts secrete an extracellular matrix that produces a model with hyaline cartilage

Perichondrium develops around cartilage model

Growth of Cartilage model

Chondroblasts become imbedded in matrix

Grows by length by mitosis and further secretion - interstitial growth

Growth in perichondrium results in thickness growth

Calcifying cartilage die the lacunae form and merge into smaller cavities

Development of primary ossification center

Nutrient artery penetrates perichondrium - androgenesis

Provide

Osteogenic cells turn into osteoblasts

Perichondrium starts to form

Osteoblasts deposit matrix forming spongy bone

Development of marrow cavity

Osteoclasts break down spongy bone

Diaphysis is replaced by compact bone

Development of secondary ossification center

Episheal artery enters epiphysis

Spongy bone remains in center and no marrow develops

Formation of articular cartilage and epiphyseal plate

Hyaline cartilage covers the epiphysis becomes articular cartilage

Hyaline cartilage remains between diaphysis and epiphysis

Zone of resting cartilage

layer nearest to epiphysis, cells don't function, the anchor to epiphyseal plate

Zone of proliferating cartilage

large chondrocytes stacked like coins

Zone of hypertrophic cartilage

large maturing chondrocytes arranged in columns

zone of calcified cartilage

few cells thick consisting of dead chondrocytes, becomes "new diaphysis"

when get you not get any taller

after the epiphyseal plate fuses

Appositional growth

growth in thickness

steps of appositional growth

1. At surface of bone cells in periosteum differentiate into osteoblasts, secrete collagen + matrix, osteoblasts develop into osteocytes

2. Ridges fold and fuse forming a tunnel to enclose blood vessels

3. Osteoblasts in endosteum form concentric lamellae, eventually produces osteon

4. Osteon is forming new circumferential lamellae increasing thickness of bone

3 types of bone changes

Bone remodeling

Bone aging

Bone disease

Remodeling

involves resorption by osteoclasts and replacement by osteoblasts

Purpose of bone remodeling

1. Regulate calcium homeostasis

2. Repair micro damage

3. Shape skeleton during growth

4. Mature bone is removed and new bone tissue is formed

Bone aging

Different hormone concentration

wear and tear

Bone disease

Osteoporosis

Osteogenesis imperfecta

Osteoporosis

medication declines osteoclasts

Osteogenesis imperfecta

Genetic abnormality

collagen fiber problem

Bone Break

callus forms between bone ends

Callus becomes ossified

Compact bone replaces woven bone

4 steps of bone break repair

1. hematoma formation

2. fibrocartilaginous callus formation

3. bony callus formation

4. bone remodeling

Closed Fracture

broken bone with no open skin wound; also called simple fracture

open fracture

compound fracture; broken bone with an open wound

complete fracture

break goes completely through the bone, separating it in two

displaced fracture

a gap forms where the bone breaks

partial fractures

the break doesnt go all the way through the bone

stress fracture

the bone gets a crack in it

avulsion fracture

a tendon or ligament pulls part of bone off

what do ligaments do

Connect bone to bone

what do tendons do

Connect muscle to bone

comminuted fracture

bone shatters into several different pieces

compression fracture

the bone gets crushed or flattened

impacted fracture

bones get driven together

oblique fracture

the break goes diagonally across the bone

spiral fracture

the fracture spirals around the bone

transverse fracture

the break goes in a straight line across the bone

greenstick fracture

the break is not all the way through

linear fracture

does not crack the bone

synathroses

immovable joints (skull sutures)

amiphiarthroses

slightly movable joints (vertebrae)

Diarthrosis

fully moveable (appendicular)

fibrous joints

bones joined by fibrous tissue - little to no movement (skull)

cartilaginous joints

articulating bone ends are connected by a pad of cartilage - slightly moveable (intervertebral discs)

synovial joints

joint contains synovial fluid - freely moving (shoulder)

plane joint

gliding movements

hinge joint

movement in one plane

pivot joint

rotational movement in one plane