A&P (Bone Development, Repair, and Disorder Notes)

ossification

the process by which bone forms

embryonic period, childhood, remodeling, repair

Bone formation occurs in four situations:

intramembranous, endochondral

bone formation follows one of two patterns: ____ or ____

skull, mandible

Flat bones of the _____ and _____ are formed via intramembranous ossification

soft spots

____ ____ that help the fetal skull pass through the birth canal later become ossified, forming the skull

endochondral ossification

the replacement of cartilage by bone

most bones

Which bones are formed via endochondral ossification?

6th Week

Cartilage formation and ossification occurs during the ______ of embryonic development

Step 1 of Intramembranous Ossification

Ossification centers appear in the fibrous connective tissue membrane

ossification center

cluster of mesenchymal cells that differentiate into osteoblasts

mesenchymal cells

stem cells that respond to injury or infection

Step 2 of Intramembranous Ossification

osteoid is secreted within the fibrous membrane and calcifies, osteoblasts continue to secrete osteoid, which calcifies in a few days

osteoid

unmineralized bone matrix

osteocytes

During Step 2 of intramembranous ossification, trapped osteoblasts become _______

Step 3 of Intramembranous Ossification

woven bone and periosteum form

woven bone

accumulating osteoid is laid down between embrnic blood vessels that result in a network of trabeculae called ________

periosteum

During step 3 of intramembranous ossification, vascularized mesenchyme condenses on the external face of the woven bone and becomes the ___________

Step 4 of Intramembranous Ossification

lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears

periosteal bone collar

During endochondral ossification, osteoblasts secrete osteoid against the hyaline cartilage diaphysis, encasing it in a collar of bone called the ___ ___ ___

Step 1 of Endochondral Ossification

During endochondral ossification, osteoblasts secrete osteoid against the hyaline cartilage diaphysis, encasing it in a collar of bone called the periosteal bone collar.

Step 2 of Endochondral Ossification

Calcified cartilage matrix is impermeable to nutrients, which causes it to deteriorate and develop cavities

Step 3 of Endochondral Ossification

Periosteal bud invades the internal cavities and spongy bone forms.

nutrient artery, nutrient vein, nerve fibers, red marrow elements, osteogenic cells, osteoclasts

What does the periosteal bud contain?

Step 4 of Endochondral Ossification

Osteoclasts open up medullary cavity, and secondary ossification centers appear

secondary ossification centers

this develops in the epiphyses of bone during endochondral ossification

25

By age __ nearly all bones are completely ossified and bones stop growign in plate

outer surface

bones grow in thickness at the ____ _____

thick, heavy

If too much new tissue is formed, the bones become abnormally ____ and ____

exceeds

In children and adolescents, bone formation ______ bone resorption

equals

In young adults, bone formation _____ bone resorption

dominates

During old age, rate of resorption _______

genetics

largest factor that determines how bone density changes overtime

bone mass, blood supply

Starting at age 40, ____ ____ and ____ ____ begin to decrease

males

skeletal mass in generally greater in _____

estrogen

the presence of ______ prevents bone resorption

fracture

break in a bone

comminuted fracture

a bone that is broken, splintered, or crushed into several pieces

Causes of Comminuted Fracture

Severe impacts, such as a car accident

greenstick fracture

incomplete break in a bone, one side of the shaft breaks while the other bends

greenstick fracture

fracture that is common in children, most often caused by a fall

compound fracture

bone sticks through the skin

Causes of Compound Fracture

severe impacts such as a car accident or falling

simple fracture

most common type of fracture

causes of simple fracture

exerting more force on a bone than what it can handle

spiral fracture

bone is broken at an angle

causes of spiral fracture

twisting motion in the bone when one part of the body is in motion while the other is planted

compression fracture

fracture that generally occurs in vertebrae as a result of osteoporosis

Step 1 of Bone Repair

bone breaks and a hematoma forms

Step 2 of Bone Repair

Fibrocartilage forms between the broken bones, called a callus

Step 3 of Bone Repair

Fibrocartilage is replaced with the bone. The combination of fibrocartilage and bone is called a bony callus

Step 4 of Bone Repair

osteoclasts remove and remodel the bone by removing any excess bone tissue, restoring its original structure

osteoporosis

bone reabsorption occurs faster than bone deposition. Bone beocme lighter and fracture easier. Common in elderly women.

causes of osteoporosis

decrease in estrogen/testosterone, improper amount of exercise, insufficient calcium consumption, insufficient Vitamin D.

Calcium, Vitamin D

Supplements to take to treat osteoporosis: ____ and ____

Paget's Disease

abnormal thickening and enlargement of bone caused by excessive and abnormal bone remodeling. Causes bones to be very brittle in areas.

Causes of Paget's Disease

unknown, possibly genetic factors

treatments of Paget's Disease

drug therapy to control bone remodeling rate, tylenol for pain

osteogenesis imperfecta

brittle bone disease

osteogenesis imperfecta

bones are very brittle and as a result can break from the slightest touch or movement

causes of osteogenesis imperfecta

genetic disorder in which body doesn't produce enough collagen (hardening protein)

treatment of osteogenesis imperfecta

possible surgeries to help with painful walking, environmental awareness

rickets

weak and brittle bones that fracture easily (more common in less developed countries)

rickets

preventable with a proper diet, common in young children

causes of rickets

lack of vitamin D

treatment of rickets

proper nutrient, vitamin D supplements

osteomalacia

rickets in adults, weak and brittle bones that fracture easily

causes of osteomalacia

lack of vitamin D

acromegaly

overgrown bones generally in face, hands, and feet

causes of acromegaly

benign tumor on the pituitary gland that causes abnormal amounts of growth hormone to be released

treatment of acromegaly

remove tumor

perthes' disease

femoral head flattens due to lack of blood supply, causing pain and inability to walk

causes of perthes' disease

unknown

treatments of perthes' disease

pain management, reshaping of the femoral head

fibrous dysplasia

excessive growth or swelling of bone due to abnormal cell development, causes bones to be brittle

causes of fibrous dysplasia

genetic mutation

treatment of fibrous dysplasia

surgery to alleviate troublesome or painful bone

osteomyelitis

bacterial infection in the bone, common in diabetics and those with HIV

causes of osteomyelitis

staph bacteria invading bone tissue

treatments of osteomyelitis

antibiotics, surgery to remove infected bone

leukemia

blood cancer, abnormal production of white blood cells that don't function properly

causes of leukemia

unknown

treatments of leukemia

chemotherapy, radiation, bone marrow transplant