BIO 168 Midterm Exam Q&A
How are bones classified? - ANSWER-by location - axial (trunk) skeleton and
appendicular (limbs) skeleton and by shape - long bones, short (cube) bones, flat
bones, irregular complicated bones
Long bone diagram - ANSWER-
What are the four bone cells? - ANSWER-osteogenic, osteoblasts, osteocytes,
osteoclasts
Osteogenic cells - ANSWER-stem cells that differentiate into osteoblasts
Osteoblast cells - ANSWER-secrete the organic matrix of bone and osteocytes are
housed in lacunae, similar to chondrocyte cells
Osteocyte cells - ANSWER-mature bone cell (located in lacunae)
Osteoclast cells - ANSWER-break down bone matrix and resorb the minerals
Intramembranous ossification - ANSWER-membrane bone develops from fibrous
membrane, forms flat bones ex: clavicles and cranial bones
Endochondrial ossification - ANSWER-cartilage bone forms by replacing hyaline
cartilage, forms most of the rest of the skeleton
What are the stages of growth in a long bone? - ANSWER-fetal endochondrial
ossification - 1. bone collar forms around the diaphysis 2. cartilage calcifies in the
center of the diaphysis and then develops cavities 3. the periosteal bud invades the
internal cavities and spongy bone forms 4. the diaphysis elongates and a medullary
cavity forms, secondary ossification centers appear in the epiphyses 5. the
epiphyses ossify, when ossification is complete, hyaline cartilage remains only in the
epiphyseal plates and the articular cartilages
postnatal lengthening - proliferation zone, hypertrophic zone, calcification zone,
ossification zone
How is fetal development different from postnatal bone growth? - ANSWER-fetal
development - from hyaline cartilage (endochondrial ossification) or fibrous
membrane (intermembranous ossification); postnatal bone growth - interstitial growth
at epiphyseal plate cartilage and replacement with bone in long bones (mimics
endochondrial ossification) and all bones grow wider with appositional growth
What controls remodeling of bones? - ANSWER-hormonal mechanisms that
maintain calcium (PTH increases blood calcium, calcitonin decreases blood
calcium), Wolffs Law - bone grows/remodels in response to forces and demands
placed upon it, mechanical and gravitational forces
, How are fractures classified? - ANSWER-by position of bone after fracture
(nondisplaced/displaced), completeness of break (complete/incomplete), whether or
not the bone penetrates the skin (compound/simple), and where they are located,
external appearance, nature of the break
Communited fracture - ANSWER-bone is splintered into 3 or more pieces
Spiral fracture - ANSWER-a fracture in which the bone has been twisted apart
Depressed fracture - ANSWER-broken bone portion is pressed inward
Compression fracture - ANSWER-bone is crushed
Epiphyseal fracture - ANSWER-epiphysis separates from the diaphysis along the
epiphyseal plate
Greenstick fracture - ANSWER-one in which one bone is bent and other is broken
Describe the stages of fracture repair - ANSWER-1. a hematoma forms in which the
blood vessels in the bone and periosteum are torn and the blood clots forming the
hematoma 2. fibrocartilaginous callus forms and new blood vessels grow into the clot
and fibroblasts and chondroblasts invade which produce collagen fibers and
cartilaginous matrix respectively and forms a soft callus 3. bony callus forms when
the osteoblasts begin forming spongy bone (trabeculae) and the fibrocartilaginous
callus is replaced by immature bone forming a bony (hard callus) 4. bone remodeling
occurs in which the excess material on the diaphysis exterior and within the
medullary cavity is formed and compact bone is laid down to reconstruct the shaft
walls
Osteomalcia (adults)/Rickets (children) - ANSWER-softening of bones caused by
Vitamin D/calcium/phosphate deficiency
Osteoporosis - ANSWER-loss of bone mass due to lack of bone regeneration/bone
loss
Paget's disease - ANSWER-interference with the restoration of old bone material or
excessive bone formation and breakdown and high ratio of spongy to compact bone
and reduced mineralization
What are the functions of the skeletal system? - ANSWER-support, protection,
movement, storage (minerals, growth factors, triglyceride), blood cell formation
How is calcium in the blood regulated? - ANSWER-parathyroid hormone from
parathyroid stimulates calcium release from bone, calcitonin from thyroid stimulates
calcium reabsorption by bone
What is another name for joints? - ANSWER-articulations
How are joints structurally classified? - ANSWER-fibrous (adjoining bones by
collagen fibers), cartilaginous (adjoining bones by cartilage), synovial (adjoining
How are bones classified? - ANSWER-by location - axial (trunk) skeleton and
appendicular (limbs) skeleton and by shape - long bones, short (cube) bones, flat
bones, irregular complicated bones
Long bone diagram - ANSWER-
What are the four bone cells? - ANSWER-osteogenic, osteoblasts, osteocytes,
osteoclasts
Osteogenic cells - ANSWER-stem cells that differentiate into osteoblasts
Osteoblast cells - ANSWER-secrete the organic matrix of bone and osteocytes are
housed in lacunae, similar to chondrocyte cells
Osteocyte cells - ANSWER-mature bone cell (located in lacunae)
Osteoclast cells - ANSWER-break down bone matrix and resorb the minerals
Intramembranous ossification - ANSWER-membrane bone develops from fibrous
membrane, forms flat bones ex: clavicles and cranial bones
Endochondrial ossification - ANSWER-cartilage bone forms by replacing hyaline
cartilage, forms most of the rest of the skeleton
What are the stages of growth in a long bone? - ANSWER-fetal endochondrial
ossification - 1. bone collar forms around the diaphysis 2. cartilage calcifies in the
center of the diaphysis and then develops cavities 3. the periosteal bud invades the
internal cavities and spongy bone forms 4. the diaphysis elongates and a medullary
cavity forms, secondary ossification centers appear in the epiphyses 5. the
epiphyses ossify, when ossification is complete, hyaline cartilage remains only in the
epiphyseal plates and the articular cartilages
postnatal lengthening - proliferation zone, hypertrophic zone, calcification zone,
ossification zone
How is fetal development different from postnatal bone growth? - ANSWER-fetal
development - from hyaline cartilage (endochondrial ossification) or fibrous
membrane (intermembranous ossification); postnatal bone growth - interstitial growth
at epiphyseal plate cartilage and replacement with bone in long bones (mimics
endochondrial ossification) and all bones grow wider with appositional growth
What controls remodeling of bones? - ANSWER-hormonal mechanisms that
maintain calcium (PTH increases blood calcium, calcitonin decreases blood
calcium), Wolffs Law - bone grows/remodels in response to forces and demands
placed upon it, mechanical and gravitational forces
, How are fractures classified? - ANSWER-by position of bone after fracture
(nondisplaced/displaced), completeness of break (complete/incomplete), whether or
not the bone penetrates the skin (compound/simple), and where they are located,
external appearance, nature of the break
Communited fracture - ANSWER-bone is splintered into 3 or more pieces
Spiral fracture - ANSWER-a fracture in which the bone has been twisted apart
Depressed fracture - ANSWER-broken bone portion is pressed inward
Compression fracture - ANSWER-bone is crushed
Epiphyseal fracture - ANSWER-epiphysis separates from the diaphysis along the
epiphyseal plate
Greenstick fracture - ANSWER-one in which one bone is bent and other is broken
Describe the stages of fracture repair - ANSWER-1. a hematoma forms in which the
blood vessels in the bone and periosteum are torn and the blood clots forming the
hematoma 2. fibrocartilaginous callus forms and new blood vessels grow into the clot
and fibroblasts and chondroblasts invade which produce collagen fibers and
cartilaginous matrix respectively and forms a soft callus 3. bony callus forms when
the osteoblasts begin forming spongy bone (trabeculae) and the fibrocartilaginous
callus is replaced by immature bone forming a bony (hard callus) 4. bone remodeling
occurs in which the excess material on the diaphysis exterior and within the
medullary cavity is formed and compact bone is laid down to reconstruct the shaft
walls
Osteomalcia (adults)/Rickets (children) - ANSWER-softening of bones caused by
Vitamin D/calcium/phosphate deficiency
Osteoporosis - ANSWER-loss of bone mass due to lack of bone regeneration/bone
loss
Paget's disease - ANSWER-interference with the restoration of old bone material or
excessive bone formation and breakdown and high ratio of spongy to compact bone
and reduced mineralization
What are the functions of the skeletal system? - ANSWER-support, protection,
movement, storage (minerals, growth factors, triglyceride), blood cell formation
How is calcium in the blood regulated? - ANSWER-parathyroid hormone from
parathyroid stimulates calcium release from bone, calcitonin from thyroid stimulates
calcium reabsorption by bone
What is another name for joints? - ANSWER-articulations
How are joints structurally classified? - ANSWER-fibrous (adjoining bones by
collagen fibers), cartilaginous (adjoining bones by cartilage), synovial (adjoining
