Bone Homesostasis Flashcards by Stacey Hansen

Calcium has this effect on blood coagulation

Promotes it

How well did you know this?

Not at all

Perfectly

3 organ systems involved in calcium balance

Bone, kidney, intestine

How well did you know this?

Not at all

Perfectly

3 hormones involved in calcium balance

PTH, Vitamin D, Calcitonin

How well did you know this?

Not at all

Perfectly

This is the primary mineral form in bone

Hydroxyapatite (Ca10(PO4)6(OH)2)

How well did you know this?

Not at all

Perfectly

Osteoid is the protein matrix of bone, and the majority of it is made up of this

Type I collagen oriented in a tight triple helical structure

How well did you know this?

Not at all

Perfectly

This provides site of nucleation of hydroxyapatite crystals with alignment along collagen fibers for tensile strength

Type 1 collagen oriented in tight triple helical structure in osteoid (bone matrix)

How well did you know this?

Not at all

Perfectly

Type 1 collagen oriented in a tight triple helical structure within osteoid provides site of nucleation of this, with alignment along collagen fibers for tensile strength

Hydroxyapatite crystals

How well did you know this?

Not at all

Perfectly

Cells the promote bone formation

Osteoblasts

How well did you know this?

Not at all

Perfectly

Cells that promote bone resoprtion

Osteoclasts

How well did you know this?

Not at all

Perfectly

Osteoblasts that localize to the bone during during mineralization and remain there

Osteocytes

How well did you know this?

Not at all

Perfectly

Cells that sense mechanical stress on bone and secrete factors to stimulate osteoblasts

Osteocytes

How well did you know this?

Not at all

Perfectly

Osteocytes are this type of cell that localize to the bone matrix during mineralization and remain there

Osteoblasts

How well did you know this?

Not at all

Perfectly

Flat quinescent cells with barrier function

Bone lining cells

How well did you know this?

Not at all

Perfectly

Mononuclear cells that seem to prepare areas for new bone deposition

“Reversal” cells

How well did you know this?

Not at all

Perfectly

Osteoprogenitor cells arise from this

Mesenchymal stem cells

How well did you know this?

Not at all

Perfectly

When these cells are stimulated by growth factors, daughter cells differentiate into osteoblasts

Osteoprogenitor cells

How well did you know this?

Not at all

Perfectly

When osteoprogenitor cells are stimulated by growth factors, daughter cells differentiate into these

Osteoblasts

How well did you know this?

Not at all

Perfectly

Osteoblasts are activated by this signaling

Wnt/beta-catenin

How well did you know this?

Not at all

Perfectly

The Wnt/beta-catenin signaling pathway governs this

Differentiation of osteoprogenitor cells into osteoblasts

How well did you know this?

Not at all

Perfectly

Cells that produce and deposit organic components to form matrix, and initiate the mineralization process

Osteoblasts

How well did you know this?

Not at all

Perfectly

Osteoblasts remaining on bone surface transforming to these

Bone lining cells

How well did you know this?

Not at all

Perfectly

Osteoblasts surrounded by new matrix differentiate to these

Osteocytes

How well did you know this?

Not at all

Perfectly

Osteocytes communicate via this

Canaliculi

How well did you know this?

Not at all

Perfectly

Regulators of bone remodeling that communicate via canaliculi

Osteocytes

How well did you know this?

Not at all

Perfectly

Osteocytes secrete this which decreases bone formation

Wnt inhibitor sclerostin

What is sclerostin?

Wnt inhibitor secreted by osteocytes that decreases bone formation

Cells that secrete Wnt inhibitor sclerostin that decreases bone formation

Osteocytes

Mechanical forces induce signaling of these cells, leading to expression of growth factors that stimulate osteoblasts and bone formation

Osteocytes

What effect does osteocyte death have on bone?

Triggers remodeling (apoptosis recruits osteoclasts, initiates resorption; lack of mechanical stimulation increases apoptosis, also aging and glucocorticoids)

What effect does mechanical force/stimulation have on bone?

Induces osteocyte signaling, leading to formation of growth factors that stimulate osteoblasts and bone formation Lack of mechanical stimulation increases osteocyte apoptosis, triggering remodeling

Osteoclasts originate from these

Myeloid precursors that arise from hematopoietic stem cells

Macrophage colony stimulating factor (M-CSF/CSF1), IL-2, and TNF regulate these cells

Osteoclasts

Osteoclasts are regulated by cytokines and growth factors, including these 3

Macrophage colony stimulating factor (M-CSF/CSF1), IL-2, and TNF

Cells that originate from myeloid precursors that arise from hematopoietic stem cells

Osteoclast

Mature multinucleated osteoclasts (a fusion of 6-12 precursors) survive about this long

2 weeks

Cells that promote bone resorption

Osteoclasts

Osteoclasts promote this

Bone resorption

Cells that bind tightly to bone surface via integrins attachment to vitronectin

Osteoclasts

Osteoclasts bind tightly to bone surface via this attachment

Integrins attachment to vitronectin

Osteoclasts bind tightly to bone surface via integrins attachment to this

Vitronectin

Cells that dissolve minerals by acid (uses proton pump system) and organic elements by proteases

Osteoclasts

Osteoclasts dissolve minerals by this

Acid (proton pump system)

Osteoclasts dissolve organic elements by this

Proteases

Cells that when mature, are multinucleated due to fusion of 6-12 precursors

Osteoclasts

Paracrine factor expressed by osteoblasts that induces osteoclast precursor differentiation

CSF1

CSF1 induces differentiation of this

Osteoclast precursors

Paracrine factor expressed by osteoblasts that promotes differentiation of preosteoclasts to osteoclasts

RANKL

RANKL promotes differentiation of this

Preosteoclasts to osteoclasts

Paracrine factor expressed by osteoblasts that inhibits differentiation of osteoclast precursors by competing with RANKL for receptor binding (a decoy)

Osteoprotegrin (OPG)

Osteoprotegerin (OPG) inhibits differentiation of this

Osteoclast precursors (competes with RANKL for receptor binding)

What effect does RANKL have on bone?

Promotes osteoclasts, which promote bone resorption

What effect does Osteoprotegerin (OPG) have on bone?

Inhibits differentiation of osteoclast precursors, preventing bone resorption

Cells that express CSF1, osteoprotegerin (OPG), and RANKL to control osteoclast differentiation

Osteoblasts

Osteoblasts express CSF1, osteoprotegerin (OPG) and RANKL to control differentiation of this cell type

Osteoclast

Osteoblasts secrete these 3 paracrine factors to control osteoclast differentiation

CSF1, osteoprotegerin (OPG), RANKL

Osteoclasts express this to induce osteoblast maturation

ephrinB4

Cells that express ephrinB4 to induce osteoblast maturation

Osteoclasts

Osteoclasts express ephrinB4 to induce maturation of this cell type

Osteoblast

What is ephrinB4?

Factor expressed by osteoclasts that induces osteoblast maturation

What effect do glucocorticoids have on bone?

Promote osteoblast cell death

PTH have this effect on calcium balance in the kidney

Promotes Ca reabsorption

PTH has this effect on phosphate balance in the kidney

Inhibits tubular phosphate reabsorption

Hormone that stimulates conversion of Vitamin D to 1,25-dihydroxyvitamin D (calcitriol) in the kidney

Parathyroid hormone

PTH in the kidney stimulates conversion of vitamin D to this

1,25-dihydroxyvitamin D (calcitriol)

Hormone that promotes calcium reabsorption in the kidney

PTH

Hormone that inhibits tubular phosphate reabsorption in the kidney

PTH

Hormone that stimulates conversion of Vitamin D to 1,25-dihydroxyvitamin D (calcitriol) in the kidney

PTH

Hormone that promotes bone homeostasis in the physiologic state

PTH

What effect does PTH have in bone in the physiologic state?

Promotes bone homeostasis

Hormone that stimulates bone resorption by osteoclasts during pathologic state

PTH

What effect does PTH have on bone in a pathologic state?

Stimulates bone resorption by osteoclasts

In the pathologic state, PTH inhibits synthesis of this by osteoblasts

Collagen

Hormone that stimulates calcium absorption by inducing expression of key proteins (calcium channels) and may also enhance diffusion by increasing overall permeability in the small intestine

Vitamin D

Hormone that stimulates phosphate absorption by increasing transporter protein levels in the small intestine

Vitamin D

What effect does Vitamin D have on phosphate balance in the small intestine?

Stimulates phosphate absorption by increasing transporter protein levels

Hormone that acts synergistically with parathyroid hormone to enhance calcium reabsorption in the kidney

Vitamin D

Vitamin D acts synergistically with this hormone to enhance calcium reabsorption in the kidney

PTH

What effect does Vitamin D have on calcium balance in the kidney?

Acts synergistically with parathyroid hormone to enhance calcium reabsorption

Hormone that directly mobilizes calcium out of bone

Vitamin D

Hormone that inhibits resorption activity when it binds to osteoclasts receptor to induce retraction

Calcitonin

What effect does calcitonin have on bone?

Binding inhibits resorptive activity of osteoclasts

In the kidney, this hormone promotes diuresis and excretion of phosphate, sodium and calcium in urine

Calcitonin

Does calcitonin secretion increase when calcium is high or low?

High to inhibit osteoclast bone resorption and activate osteoblast bone formation

Does PTH secretion increase when calcium is high or low?

Low to enhance Ca reabsorption in the kidney, stimulate conversion of vit D to calcitriol, and inhibit tubular reabsorption of P

Testosterone and estradiol have this effect on bone

Promote bone deposition favors balance of bone formation over resorption

These enhance bone resorption by altering gene expression and cell survival

Glucocorticoids promote death of osteoblasts and osteocytes

What effect do glucocorticoids have on bone?

Enhance bone resorption

Pyrophosphate analogs that chelate calcium, have strong affinity for bone and inhibit bone resorption

Bisphophonates

Bisphophonates are analogs of this

Pyrophosphate

Bisphophonates chelate this

Calcium

Bisphophonates have this effect on bone

Inhibit bone resorption

Which are more potent: nitrogenous bisphophonates or non-nitrogenous?

Nitrogenous

Heartburn and esophageal irritation are adverse effects of these

Bisphophonates

Very potent bisphophonate that may induce hypocalcemia and reduced renal function

Zoledronate

Zoledronate is this type of drug

Bisphophonate

Alendronate is this type of drug

Bisphophonates

Zoledronate is a Bisphophonate that may induce this

Hypocalcemia and reduced renal function

2 common adverse effects of Bisphophonates

Heartburn Esophageal irritation

Monoclonal antibody targeting sclerostin

Romosozumab

Romosozumab targets this

Sclerostin

Anabolic drug with black box warning of increased risk of cardiovascular events

Romosozumab

Romosozumab have this black box warning

Increased risk of cardiovascular events

Anabolic drug that is a terminal fragment of PTH

Teriparatide

Anabolic drug that needs intermittent administration

Teriparatide

Anabolic drug with a black box warning of increased risk of osteosarcoma

Teriparatide

Teriparatide has a black box warning of this

Increased risk of osteosarcoma

Bisphophonate alternative that inhibits osteoclast formation by depleting RANKL, and can lead to bone gain

Denosumab

Bisphophonate alternative with a black box of severe hypocalcemia in patients with advanced kidney disease

Denosumab

Denosumab inhibits formation of these cells by depleting RANKL

Osteoclasts

Denosumab inhibits formation of these cells

Osteoclasts

Denosumab inhibits formation of osteoclasts by depleting this

RANKL

Denosumab has a black box of this in patients with advanced kidney disease

Severe hypocalcemia

What are SERMs?

Selective estrogen receptor modulators Used as a Bisphophonate alternative Ex: Raloxifene

Bone Homesostasis Flashcards

(113 cards)