How many bones are there?
206.
2 divisions of skeleton?
Axial and appendicular.
2 types of bone tissue?
Compact and spongy.
How much of the body mass is bone?
20%.
What are the components of the skeletal system?
Cartilage, bone, tendons, and ligaments.
Functions of the skeletal system?
Protection, support, movement, storage, and blood cell production.
Cartilage consists of?
Cells and extracellular matrix.
Does cartilage have arteries, veins, or lymphocytes?
No.
What are the types of cartilage?
Hyaline, elastic, and fibrocartilage.
Hyaline cartilage structure and location?
Most common but weakest. Chondrocytes, chonrotin sulfate, and some collagen. Embryonic skeleton, articular surfaces, respiratory passages, nasal septum, between ribs & sternum.
Elastic cartilage structure and location?
Chondrocytes, chondrotin sulfate, densely packed elastic fibers. Auricle, tip & lateral walls of nose, and epiglottis.
Fibrocartilage structure and location?
Chondrocytes, chondrotin sulfates, densely packed collagen fibers. Intervertebral disc, pubic symphysis, articular catrilage in knee.
Perichondrium structure and function?
Fibrous connective tissue. Support and protection surrounds cartilage.
Locations of perichondrium?
Hyaline cartilage and elastic cartilage.
Layers of perichondrium?
Outer: binds cartilage to adjacent tissues, provides support and protection. Inner: for growth & maintenance.
What is appositional growth?
Starts in perichondrium, mesenchymal cells become chondrogenic cells then chondroblasts which force cells apart and become chondrocytes.
What is interstitial growth?
Chondrocytes are enclosed in matrix and divide they start to move apart. Growth of cartilage from within.
Characteristics of osseous tissue?
Supportive CT, contains specialized cells, and solid extracellular matrix.
What is the osseous extracellular matrix composed of?
Osteoid (organic portion), ground substance (Ca salt), and water.
Types of bone cells?
Osteoprogenitor, osteoblasts, osteocytes, and osteoclasts.
What are osteoprogenitors?
Play role in initial bone growth and fracture repair.
What are osteoblasts?
Secrete osteoid causing bone growth.
What are osteocytes.
Mature cells, maintain homeostasis of Ca & PO4, found in Lacunae.
What are osteoclasts?
Breakdown bone.
Bone matrix is composed of?
Inorganic materials (65%) and osteoid (35%).
Compact bone is arranged into?
Osteons, which contain blood vessels and nerves and concentric lamellae.
Spongy bone is arranged into?
Trabeculae, latticework of thin plates of bone filled with red marrow, found in ends of long bones, and lightens bone.
Osteocytes communicate through?
Canaliculi that radiate outward and connect one cell to the next.
The different types of lamellae?
Concentric, interstitial, and circumferential.
Concentric lamellae is?
Layers of bone surrounding the central canal (makes up osteons).
Interstitial lamellae is?
Found between the osteons and represents older osteons partially removed during tissue remodeling.
Circumferential lamellae is?
Surrounds compact bone and directly produced from periosteum.
Spongy bone consists of?
Trabeculae, osteocytes in lacunae, canaliculi, and matrix.
What does periosteum do and absent from where?
Encloses bone. Site of attachemetn of muscles, tendons, and ligaments or surfaces covered by articular cartilage.
What are the layers of periosteum?
Outer: gives rose to collagen. Inner: for growth of new cells & maintenance.
What is the endosteum?
1 cell layer, covers surfaces of spongy bone & medullary cavity.
Cell types of the endosteum?
Osteogenic, osteoblasts, and osteoclasts.
Anatomy of a long bone?
Diaphysis(shaft), epiphysis(one end), metaphysis(growth plate), articular cartilage(over joint surfaces), and medullary cavity(marrow cavity).
Types of bone marrow?
Yellow and red marrow.
What is yellow marrow?
Areolar and adipose CT, in medullary cavity of long bones, and energy storage
What is red marrow?
Areolar and myeloid tissue, produces all types of blood cells, and located in spongy bone in adults.
Where are yellow and red marrow found in infants?
Yellow is not and red is in the medullary cavities.
The types of arteries of bone?
Periosteal, nutrient, metaphyseal & epiphyseal (all have corresponding veins).
What do periosteal arteries do?
Supply periosteum.
What do nutrient arteries do?
Enter through nutrient foramen and supplies compact bone of diaphysis & yellow marrow.
What do metaphyseal and epiphyseal arteries do?
Supply red marrow and bone tissue of epiphyses and metaphyses.
What is ossification?
Replacing CT with bone.
What is intramembranous?
Mesenchymal cells to spongy bone.
What is endochondral?
Hyaline cartilage to spongy bone
Where does bone growth occur?
At the epiphyseal plate.
When does growth stop?
When 2 ossification centers meet.
Cartilage depletes and epiphyseal plate narrows forming?
Epiphyseal line.
What are the 2 types of bone growth?
Appositional and elongation.
What is appositional growth?
Compact bone deposited beneath periostium, bone thickens, and bone remodeling occurs throughout life.
What causes bone remodeling?
Osteoclasts & osteoblasts.
What is bone remodeling?
Continual redistribution of bone matrix along lines of mechanical stress.
How much compact bone is remodeled per year?
4%
How much spongy bone is remodeled per year?
20%
What is remodeled every 4 months?
Distal femur.
Two types of fractures?
Closed (simple) and open (compound).
What is a closed or simple fracture?
Break that does not penetrate skin.
What is an open or compound fracture?
Broken bone penetrates through skin.
4 stages of bone repair?
Fracture hematoma, fibrocartilage callus, bony callus, and remodel tissue.
How long does a fracture hematoma take to form?
A few hours.
What is a fracture hematoma?
A mass of blood with swelling and inflammation.
What eliminate dead cells/broken matrix?
Phagocytes and osteoclasts.
What is a fibrocartilaginous callus ?
Consists of a mass bridging the broken ends of the bone.
What causes the fibrocartilaginous callus?
Fibroblasts in periosteum produce collagen and periosteum cells differentiate into chondrocytes. resulting in fibrocartilage.
How long does it take for a fibrocartilaginous callus to form?
About 3 weeks.
What causes a bony callus to form?
The fibrocartilaginous callus is converted to spongy bone trabuculae.
How long does a bony callus last?
3 to 4 months.
What is bone remodeling?
Remaining dead bone fragments are reabsored and compact bone replaces spongy bone.
Can you easily see where a bone was fractured when properly healed?
No.
How long can bone remodeling take?
weeks to months depending on severity of break.
Factors affecting growth, repair, & development.
Nutrition (vitamin D), sunlight, hormones, and physical stress.
What are the hormones that affect growth, repair, & development?
Parathyroid (PTH), calcitonin, growth hormone (GH), thyroid, and sex hormones.
What is osteoporosis?
Abnormal reduction of bone mass.
What causes osteoporosis?
Loss of estrogen at menopause, deficiency of minerals on youth, and imbalance in activity between osteoblasts & osteoclasts.
What is fibrodysplasia ossificans progressiva?
Fibrous tissue becomes ossified, genetic disorder, and injury results inappropriate bone formation.