KAAP 309 EXAM 2 (Set 2)

function of osteoblasts

matrix synthesizing cell, responsible for bone growth

what hormones are important for maintaining bodies calcium levels

parathyroid, calcitrol, and calcitonin

osteoprogenitor cells

stem cells derived from mesenchyme

osteocyte

mature bone cell, monitors and maintains the mineralized bone matrix

osteoclasts function

bone resorption

intramembranous ossification forms what

Flat bones of the skull

Mandible

parts of clavicle

quick bones fully close/developed at birth

step one of intramembranous ossification

Mesenchymal cells cluster

around a vessel and become osteoblasts

They secrete osteoid and an ossification center (which controls the center for what to come) forms in fibrous CT

step two of intramembranous ossification

osteoblasts grow and continue to secrete osteoid, trapped osteoblasts now become osteocytes

step three of intramembranous ossification

osteoid continues to form around vessels, forming immature spongy bone

mesenchyme adheres to external surface-becomes periosteum (CT that surrounds bone)

step four of intramembranous ossification

immature spongy bone near periosteum remodeled and replaced with compact bone

central immature spongy bone matures

step one of endochondral ossification

mesenchymal cells specialize into osteoblasts

perichondrium becomes periosteum

osteoblasts secrete osteoid, creating bone collar

chondrocytes left within hypertrophy/become primary ossification center

step two of endochondral ossification

chondrocytes from primary ossification center ossify surrounding cartilage

chondrocytes (live in lacunae) die and matrix begins to dissolve (left with pockets)

cavities formed within model

remaining cartilage (ends) are healthy, growing rapidly to elongate the model

step three of endochondral ossification

cavities are invaded by periosteal bud

osteoclasts partially erode the cartilage matrix (eat up cartilage tissue to expand cavity)

osteoprogenitor cells become osteoblasts (spongey bone formation)

step four of endochondral ossification

osteoclasts break down the newly formed spongy bone and open the cavity (osteoblasts keep building)

the epiphyses stay as cartilage ends through birth (growing rapidly)

(depending on bone) after birth, secondary ossification centers develop at epiphyses (long bones=humerus, femur, have 3 centers)

step five of endochondral ossification

secondary ossification mimics that of priary, except spongy bone remains, no cavity is formed

space between diaphysis and epiphysis is epiphyseal plate (HYALINE CARTILAGE)

proliferation

"growth zone"

chondrocytes quickly dividing, want to elongate bone

older chondrocytes are then pushed to the hypertrophic

hypertrophic

made up of older chondrocytes

begin to expand

-lucunae erodes leaving empty spaces

continual process

Calcification

surrounding matrix notices no more lucunae for protection, calcifies, no more chondrocytes=DEATH

Ossification

*closest to diaphysis

bone marrow elements invade, osteoblasts and clasts eat up anything dead or leftover (like a race, chondrocytes from top bone marrow from bottom)

postnatal growth-width

- completed through appositional growth

- osteoblasts in periosteum secrete bone matrix to external bone surface

- osteoclasts on endosteal surface remove bone

post natal growth-length

proliferation, hypertrophic, calcification, ossification

mechanical stress determines:

where bone remodeling occurs, guide bone building to specific location

hormones determine:

if and when boned are remodeled

hormonal influences on growth

role of calcium in body (homeostasis for maintaining resting membrane potentials)

99% calcium stored in bone matrix

parathyroid hormone, calcitriol, and calcitonin (not sig in adults)

calcitonin

promotes mineralization and lowers blood Ca2+ concentration in children, usually little effect in adults; may prevent bone loss in pregnant and lactating women

Calcitriol (Vitamin D)

promotes intestinal absorption of Ca2+ and phosphate; reduces urinary excretion of both; promotes both resorption and mineralization; stimulates osteoclast activity

parathyroid hormone

indirectly activates osteoclasts, which resorb bone and raise blood ca2+ concentration; inhibits urinary Ca2+ excretion, promotes calcitriol synthesis

wolffs law

A bone grows or remodels in response to forces or demands placed upon it, how we get bone projections

non displaced fracture

bone ends retain their normal position

incomplete fracture

bone is not broken all the way through

closed fracture

broken bone with no open wound

displaced fracture

bone ends are out of normal alignment

complete fracture

bone is broken all the way through

open fracture

bone fracture that breaks through the skin

transverse fracture

occurs straight across the bone

oblique fracture

occurs at an angle across the bone

spiral fracture

a fracture in which the bone has been twisted apart

comminuated fracture

Broken into multiple pieces (most difficult to deal with)

avulsion fracture

fragment of bone chipped away from the main bone

impacted fracture

broken bone ends are forced into each other

fissure fracture

a crack extending from a surface into, but not through, a long bone

greenstick fracture

splinter

four stages for traumatic (acute) fracture healing:

hematoma formation

soft callus formation

hard callus formation

bone remodeling

hematoma formation

hematoma converted to granulation tissue by invasion of cells and blood capillaries (24-48 hrs)

soft callus formation

deposition of collagen and fibrocartilage converts granulation tissue to a soft callus (2 weeks-quick repair "bandaid")

hard callus formation

osteoblasts deposit a temporary bony collar around the fracture to unite the broken pieces while ossification occurs (cast like=protect while healing)

bone remodeling

small bone fragments are removed by osteoclasts, while osteoblasts deposit spongy bone and then convert it to compact bone (trying to reshape, work together to make bone look good)

Osteoporosis

osteoclasts outpacing osteoblasts

more absorption less building

risk: age, hormones, smoking, dec physical activity

osteomalacia

Bones are poorly mineralized

Osteoid is produced, but calcium salts not adequately deposited

Results in soft, weak bones

Pain upon bearing weight

child version is rickets

Paget's disease

A disease of unknown origin that is characterized by extensive breakdown of bone tissue followed by abnormal bone formation

high ratio of spongy bone

primary function of bones

support, protection, movement, storage, hematopoiesis, hormone production

how do bones provide support?

Provide a framework that supports the body (lower extremities=pillars, thoracic cage=walls, skull=enclosed room)

how does skeleton provide protection?

vital organs lie deep to bones

how does skeleton provide movement?

attachment for skeletal muscles, determined by joint types

how does skeleton provide storage?

triglyceride (fat)= yellow bone marrow

minerals=calcium and phosphate

Hematopoiesis

production of blood cells, occurs in red bone marrow

hormone production in bones

production of osteocalcin, regulates insulin secretion, glucose homeostasis, energy expenditure

what are the two classifications of the skeleton?

axial and appendicular

axial skeleton

core, protects center of body, includes skull, vertebrae, and ribs

appendicular skeleton

upper and lower limbs and girdles (scapula, clavicle, femur, pelvis)

what 5 ways are bones classified by shape?

long bone

irregular bone

short bone

flat bone

sesamoid

Where is hyaline cartilage found?

ends of bones, articular

Where is elastic cartilage located?

external ear, epiglottis

Where is fibrocartilage located?

intervertebral discs, pubic symphysis, discs of knee joint

perichondrium

Dense irregular connective tissue membrane covering cartilage, not directly adhered to bone, helps protect

appositional growth

cells in perichondrium secrete new matrix; adds layers from the outside (secretes new tissue in)

interstitial growth

cells within lacunae split and expand from inside (rapidly split giving off new lacunae)

describe spongy bone:

internal layer, filled with trabeculae (spindle like structure)

what is inside spongy bone?

red bone marrow

Describe compact bone

dense, smooth, external layer

long bone examples

humerus, ulna, radius, femur, tibia, fibula

where is long bone found?

extremities (aside from carpals and tarsals)

irregular bone examples

vertebrae and hip bones

flat bone examples

skull, ribs, sternum

short bone examples

wrist and ankle bones

Structure of short, irregular, and flat bones

outer and inner layer of compact bone, spongy bone in between

where is there minimal bone marrow?

short and irregular bones

structure of long bone

diaphysis and epiphysis

distal epiphysis

end of the bone located farthest away from the midline

in young adults, known as the growth plate*

Periosteum

on top, wrapping around

outer layer=dense irreg. CT

inner layer=bone cells

*high supply of nerves and blood vessels*

Endosteum

edges of spongy and compact bone

contains same cells as inner periosteum

covers trabeculae and canals

yellow bone marrow

fat, used for storage, only in adults

red bone marrow

hematopoiesis

everywhere in children, not as highly dense in adults (flat & irregular bones)

what is apart of the haversian system?

lamellae, lacunae, canaliculi, haversian canal, volkmans canal

lamellae

concentric rings of lacunae

resist torsional/tensile forces

lacunae

btwn rings of lamellae

spaces/home for osteocytes

canaliculi

connect lacunae to canals

what is inside canals?

veins, arteries, nerves

organic components of bone

cells

osteoid

inorganic components of bone

mineral salts

calcium

what is osteoid

ground substance and collagen fibers that support skeletal tissue

what do organic substances do for us?

resist tension and twisting forces

What do inorganic compounds contain?

resist compression forces

how does the vomer articulate

median aspect of nasal cavity (septum)

what are the four categories of bony markings?

Projections

surfaces

depressions

openings

why is change on the bone surface good?

allows for attachment of:

- Other bones

- Ligaments

- Muscles (tendons)

what is apart of Pectoral Girdle?

clavicle and scapula

What does the scapula articulate with?

Clavicle and Humerus

anterior of scapula is ______________

concave

posterior of scapula is ________________

convex