The skeletal system Flashcards

1
Q

The yellow (fatty) marrow is found in the _____________ of the bone:

A

Diaphysis

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2
Q

Spongy bone is mostly found in the…

A

Epiphysis and metaphysis

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3
Q

What is the functional unit of COMPACT bone called?

A

An osteon

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4
Q

Osteocytes are arranged in concentric layers called:

A

Lamellae

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5
Q

What is the extracellular fluid called that holds an osteocyte in place?

A

Lacuna

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6
Q

What are the interconnected channels called that connect the lacuna, and what do they feed into?

A

Canaliculi feed into Haversian Canal

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7
Q

Volkmann’s canals run (perpendicular/parallel) to bone

A

Perpendicular

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8
Q

Osteogenic (osteoprogenitor) cells are in the endosteum and periosteum of growing/injured bone. What do they do?

A

Either differentiate into osteoblasts OR osteocytes

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9
Q

Osteocytes are mature bone cells that do what?

A

Transfer bone minerals from the interior to the growth surface

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10
Q

Osteoblasts are modified fibroblasts that:

A

Synthesize and secrete organic matrix and help calcify is. They CAN become osteocytes too!

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11
Q

Osteoclasts are derived from:

A

monocytes

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12
Q

What do osteoclasts do?

A

resorption of bone which releases CA+

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13
Q

The organic matrix of bone (secreted by osteoblasts) is called “Osteoid” and is made up of:

A
  • Type 1 collagen
  • Proteoglycans
  • Glycoproteins
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14
Q

Inorganic mineral salts (mostly calcium phosphate) are part of extracellular fluid in bone and are brought in by:

A

osteocytes

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15
Q

A fetal skeleton is made up of _______________ with no minerals

A

Hyaline cartilage

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16
Q

The formation of the primary ossification center indicates:

A

Chondrocytes begin to hypertrophy and start secreting alkaline phosphatase

17
Q

A “periosteal bud” invades the central cavity to do what?

A

Vascularize the tissue

18
Q

The formation of the secondary ossification center indicates:

A

Osteoclasts are further breaking down the cavity to develop it more

19
Q

What is RANKL?

A

a protein expressed by osteoblasts that in fact has to do with the formation, function, and survival of osteoclasts!

20
Q

What is OPG (osteoprotegerin)?

A

Secreted by osteoblasts, inhibitor of RANKL

21
Q

What does estrogen do to RANKL?

A

It limits production of it by osteoblasts

22
Q

Where is calcitonin made?

A

Parafollicular cells in thyroid gland

23
Q

Kidneys and GI system are also involved in _____ homeostasis:

A

Calcium

24
Q

Low calcium levels stimulates secretion of what hormone and why?

A

Parathyroid hormone, because it tells osteoblasts to tell osteoclasts to increase breakdown and release of CA+

25
Q

Parathyroid hormone does what to the kidneys?

A

Stimulates the CA+ reabsorption by kidneys and decreases phosphate reabsorption

26
Q

What does calcitonin do?

A

Inhibits release of calcium from bone when CA+ levels are high

27
Q

Post-menopausal women have lower levels of estrogen, what happens with RANKL then?

A

Levels of RANKL are not limited, so more is produced and more osteoclasts break away bone

28
Q

Vitamin D (steroid hormone) is hydroxylated where?

A

In the liver and the kidneys!

29
Q

Causes of Hypocalcemia:

A
  • Hypoparathyroidism
  • Vitamin D deficiency
  • Chronic Kidney Disease
  • renal failure
30
Q

Causes of Hypercalcemia:

A
  • Hyperparathyroidism
  • cancer
  • renal failure
31
Q

What can happen as a result of Hypocalcemia?

A
  • seizures
  • tingling in hands/feet and around mouth because of excitability
  • bronchospasm
  • brittle nails/hair
  • Chvostek’s sign: (tapping over facial nerve causes twitch)
  • Trousseau’s sign: (BP cuff induces carpopdeal spasm)
32
Q

What is hypocalcemia?

A

Increase in neuronal excitability

hypocalcemic tetany

33
Q

What can happen as a result of hypercalcemia?

A
  • depressed neuronal excitability (coma/confusion)
  • decreased reflexes, constipation, lack of appetite
  • precipitation of calcium phosphate in blood and tissues
  • bradycardia
  • polyuria/polydyspia