Bone Structure and Regulation Quiz

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Questions and Answers

What is the main component of the mineralized organic matrix of bone?

Type 1 collagen fibers

Which biological function is NOT provided by bones?

Hormone regulation

What is the primary role of PTH (parathyroid hormone) in bone physiology?

Stimulate bone resorption to release calcium into the bloodstream

Which factor is primarily responsible for defective bone remodeling resulting in osteoporosis?

Hormonal changes in postmenopausal women Signup and view all the answers

What is the primary physiological function mediated by the ionized form of calcium (Ca$^{2+}$)?

Muscle contraction and nerve function Signup and view all the answers

How does acidosis affect free Ca$^{2+}$ levels in the body?

Decreases by promoting its binding to proteins Signup and view all the answers

What stimulates bone reabsorption and the reabsorption of Ca$^{2+}$ in the kidneys?

Parathyroid hormone (PTH) Signup and view all the answers

What does PTH stimulate the production of, which in turn promotes Ca$^{2+}$ absorption from the gut and mineralization of bone?

Active form of vitamin D Signup and view all the answers

What is osteoporosis characterized by?

Low bone mass, microarchitectural deterioration, and susceptibility to fracture Signup and view all the answers

What condition can vitamin D deficiency lead to in children?

Rickets Signup and view all the answers

What leads to the fusing of the epiphyseal plate in long bones?

Stopping of bone growth Signup and view all the answers

What continues throughout life despite the stopping of bone growth?

Bone turnover Signup and view all the answers

What is the overall effect of vitamin D in relation to Ca$^{2+}$ and phosphate into bone?

Increases the flux of Ca$^{2+}$ and phosphate into bone Signup and view all the answers

What can alter Ca$^{2+}$ availability and decrease bone mineralization?

Vitamin D deficiency Signup and view all the answers

What controls free Ca$^{2+}$ in the body by promoting its binding to proteins during alkalosis?

Alkalosis Signup and view all the answers

What hormone plays a crucial role in controlling plasma Ca$^{2+}$ levels and bone mineralization?

Parathyroid hormone (PTH) Signup and view all the answers

What is the main component of the microstructure of cortical bone?

Collagen concentric circles mineralized with hydroxyapatite Signup and view all the answers

What is the primary type of bone in the shaft of long bones?

Compact (cortical) bone Signup and view all the answers

At what age does the growth plate typically fuse with the metaphysis in long bones?

Around age 18 Signup and view all the answers

Which hormone is involved in controlling bone formation and mineralization?

Growth hormone and IGF-1 Signup and view all the answers

What is the primary function of osteoclasts in bone physiology?

Bone reabsorption by resorbing mineralized bone and creating resorption pits Signup and view all the answers

How often does bone turnover occur in the adult skeleton?

Every 10 years Signup and view all the answers

What is crucial for various physiological functions such as neurotransmitter release and muscle contraction?

Calcium movement across membranes Signup and view all the answers

In what form does calcium exist in body fluids?

Ionized (free), bound to protein, and bound to small anions Signup and view all the answers

What initiates mineralization and promotes bone formation?

Osteoblasts Signup and view all the answers

What is the primary type of bone in the epiphysis/metaphysis of long bones?

Trabecular (cancellous or spongy) bone Signup and view all the answers

What is responsible for adaptation to mechanical loading and fracture healing in bone remodeling?

Balance of mineralization through activation of osteoblasts and osteoclasts Signup and view all the answers

What is the primary type of bone in the adult skeleton?

Both compact (cortical) bone and trabecular (cancellous or spongy) bone Signup and view all the answers

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Study Notes

Bone Structure and Regulation

Bone is composed of two types: compact (cortical) bone, which is dense and makes up about 80% of human bone, and trabecular (cancellous or spongy) bone, which is spongy and has high porosity.
Long bones have a diaphysis (shaft) made of cortical bone and epiphysis/metaphysis made of trabecular bone.
Bone growth occurs at the growth plate until around age 18 when it fuses with the metaphysis.
Bone formation starts with cartilage modeling and then mineralization through ossification, controlled by growth hormone and IGF-1.
The microstructure of cortical bone consists of osteons, concentric circles of collagen around blood vessels, mineralized with hydroxyapatite.
Bone contains three main cell types: osteoblasts, osteoclasts, and osteocytes, each with specific functions in bone formation and remodeling.
Osteoblasts promote bone formation by laying down osteoid and initiating mineralization, while osteocytes transfer minerals and sense mechanical load.
Osteoclasts are responsible for bone reabsorption by resorbing mineralized bone and creating resorption pits.
Bone turnover in the adult skeleton occurs every 10 years with about 1 million basic multicellular units (BMUs) operating at any time.
Bone remodeling involves a balance of mineralization through activation of osteoblasts and osteoclasts, allowing adaptation to mechanical loading and fracture healing.
Calcium movement across membranes is crucial for various physiological functions such as neurotransmitter release, muscle contraction, and hormone secretion.
Calcium in body fluids exists in three forms: ionized (free), bound to protein, and bound to small anions, with different percentages in each form.