🦴 Bone Anatomy
In a long bone, this region contains mostly compact bone and surrounds the medullary cavity.
Diaphysis
This bone cell is responsible for breaking down bone tissue using acids and enzymes.
Osteoclast
This type of ossification builds bone from an internal fibrous membrane and forms cranial bones and clavicles.
Intramembranous ossification
These cells break down bone during the remodeling process.
Osteoclasts
This condition causes age- or inactivity-related loss of bone density and can progress to osteoporosis.
Osteopenia
A structure at the end of a long bone contains spongy bone with red marrow between its trabeculae.
Epiphysis
A cell secretes collagen and calcium-binding proteins, then becomes surrounded by calcium phosphate. What cell does it become?
Osteocyte
This type of ossification uses a cartilage model as the starting material for bone formation.
Endochondral ossification
According to Wolff’s Law, bones remodel in response to these demands placed on them.
Mechanical stress
A patient has soft bones caused by low bone calcium, often related to a deficiency of this vitamin.
Rickets
A bone has a hollow shaft filled with yellow marrow. Which internal structure are you looking at?
Medullary cavity
Removing this component would greatly reduce bone’s tensile strength, because it provides flexibility and forms sacrificial bonds.
Collagen
Bone length increases here because new chondrocytes form, enlarge, die, and their calcified matrix is replaced by bone.
Epiphyseal plate
Blood calcium drops below normal. Which hormone increases osteoclast activity to add calcium to the blood?
PTH
A condition described as having “bones with holes” causes decreased bone density and increased fracture risk.
Osteoporosis
If the central canal of an osteon contains blood vessels and nerves, which microscopic structure surrounds it?
Osteon
Bone is hard and durable because this inorganic component combines calcium and phosphate to form its mineral portion.
Hydroxyapatite
A bone is becoming wider rather than longer. Which type of growth is occurring?
Appositional growth
Blood calcium is high. Which hormone decreases osteoclast activity and ultimately lowers blood calcium?
Calcitonin
Vertebral compression and comminuted hip fractures are especially common injuries associated with this disorder.
Osteoporosis
An osteocyte cannot directly contact another osteocyte but still exchanges nutrients and wastes with it through tiny channels. What are these channels?
Canaliculi
A bone is hard but can resist being pulled apart without completely fracturing. Which two components are working together to provide these properties?
Collagen + hydroxyapatite
A long bone increases in length through cartilage growth, while its shaft increases in thickness. What two growth processes are responsible?
Interstitial + appositional growth
A bone experiences repeated compression from gravity and movement. According to Wolff’s Law, what process allows the bone to adapt to these demands?
Bone remodeling
A child develops soft, poorly mineralized bones after inadequate vitamin D. Which disorder best explains the condition?
Rickets