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Pathophys Semester 2 > Bone: Mace Slides 30-46 > Flashcards

Bone: Mace Slides 30-46 Flashcards

1
Q

Compact Bone Tissue:

-is composed of ______?

A
  • osteons (Haversian systems)
  • Concentric lamellae
  • External circumferential lamellae
  • internal circumferential lamellae
  • Interstitial lamellae
  • Canaliculi
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2
Q

Compact bone tissue:

Describe osteons

A
  • Small cylindrical structures
  • Basic functional and structural unit of mature compact bone
  • Oriented parallel to bone diaphysis
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3
Q

Osteons have a central canal and _______ canals

A

perforating canals (Volkmann canals)

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4
Q

Describe the central canal of osteons

A
  • Cylindrical channel
  • Lies at center of osteon and runs parallel to it
  • Houses blood vessels and nerves
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5
Q

Describe perforating canals (Volkmann Canals)

A
  • house blood vessels and nerves
  • run **perpendicular to the central canals
  • help connect multiple central canals within different osteons
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6
Q

Compact bone tissue:

-describe Concentric lamellae?

A

rings of matrix surround the central canal

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7
Q

Compact bone tissue:

-describe external circumferential lamellae

A

rings of matrix run immediately internal to bone periosteum

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8
Q

Compact bone tissue:

-describe internal circumferential lamellae

A

=rings of matrix run internal to the endosteum

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9
Q

Compact bone tissue:

-describe interstitial lamellae

A

=rings of matrix between osteons

if there are 2 osteons (the space b/w them is where interstitial lamellae is

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10
Q

Compact bone tissue:

-describe canaliculi= (list 4 functions)

A

-tiny interconnecting channels within bone connective tissue
extend from each lacuna, travel through lamellae
-connect to other lacunae and central canal
-house osteocyte projections permitting intercellular contact
-allow travel of nutrients, minerals, gases, and wastes between blood vessels and osteocytes

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11
Q

“eyelashes”=

A

canaliculi

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12
Q

Compact bone tissue: describe the cross section layout

A
  • central canal in the middle
  • around the central canal are the concentric lamellae
  • canaliculi inbweteen (around each lacuna (with osteocyte)
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13
Q

Compact bone cross section:

  • each osteon has a ?
  • central canals are connected via?
A
  • each osteon has a central canal

- perforating canals connect central canal to central canal

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14
Q

Compact bone (longitudinal section)

A
  • Central canals with osteons

- perforating calnals connecting central canals

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15
Q

Spongy bone tissue:

  • do they have osteons?
  • describe this tissue
A

-No osteon
-Lattice of rods and plates called trabeculae
The space between trabeculae is filled with bone marrow
-form a meshwork of crisscrossing bars that provide great resistance to stresses

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16
Q

Spongy bone tissue:

-trabeculae contains:

A

-parallel lamellae, canaliculi connect lacunae, no central canals, no perforating canals

17
Q

Describe a cross-section of spongy bone tissue

A
  • endosteum on outside (with osteoclasts), also osteoblasts aligned along trabeculae of new bone
  • canaliculi opening at the surface
  • parallel lamellae(surrounds trabeculae) (=next layer)
  • Osteocyte in lacuna
18
Q

Spongy bone:

-contains?

A
  • spicule
  • lacunas with osteocytes
  • Red bone marrow cavity
  • endosteum surrounds the red marrow cavity
19
Q

Bone remodeling= is a continual process of bone _____ and _____

A

bone deposition and resorption

20
Q

Describe bone remodeling

A
  • Occurs at periosteal and endosteal surfaces of a bone
  • Occurs at different rates
    e. g., distal part of femur replace every 4 to 6 months
    e. g., diaphysis of femur not completely replaced over a lifetime
21
Q

Bone remodeling: about ____% of the adult skeleton is replaced yearly

A

20%

  • -Dependent on the coordinated activities of osteoblasts, osteocytes, and osteoclasts
  • -The relative activity of these cells is influenced by mechanical stress and the hormones the bones receive
22
Q

Bone remodeling is dependent on 8 factors (list)

A
  • mechanical stress
  • growth hormone
  • thyroid hormone
  • calcitonin
  • parathyroid hormone
  • Sex hormones (estrogen and testosterone
  • Glucocorticoids
  • serotonin
23
Q

Bone remodeling:

  • mechanical stress results from?
  • mech. stress is detected by?
A
  • Results from muscle contraction and gravitational forces (e.g., weight bearing exercise)
  • Detected by osteocytes and communicated to osteoblasts which increase synthesis of osteoid, followed by deposition of mineral salts.
24
Q

Bone remodeling:

-growth hormone stimulates?

A

**Stimulates liver to produced another hormone, somatomedin, both stimulating growth of cartilage in epiphyseal plate,

25
Q

Bone remodeling:

-thyroid hormone stimulates?

A

metabolic rate of osteoblasts

26
Q

Bone remodeling:

-calcitonin stimulates?

A

calcium deposition in bone and inhibits osteoclast activity

27
Q

Bone remodeling:

  • Parathyroid hormone causes?
  • PTH is stimulated to be released by low ____
A
  • *cause bone loss (=bone resorption) by stimulating the osteoclast activity
  • low blood calcium levels
28
Q

Bone remodeling:

-Sex hormones (estrogen and testosterone) stimulate?

A

osteoblast activity, stimulate growth of epiphyseal plate

29
Q

Bone remodeling:

-Glucocorticoids cause?

A

Increase bone loss, impair growth at epiphyseal plate in children
(kids that are highly stressed can impair their growth)

30
Q

Bone remodeling:

-Serotonin inhibits?

A

Inhibits osteoprogenitor cells from differentiate into osteoblasts when there are chronically high levels

31
Q

Bone formation:

  • begins with?
  • Proceeds with
  • Requires?
A
  • Begins with secretion of osteoid
  • Proceeds with calcification, when hydroxyapatite crystals deposited–>calcium & phosphate ions precipitating out, forming crystals
  • Requires Vitamin D (active form=calcitriol) for enhancing calcium absorption from gGI tract
  • Requires vitamin C is needed for collagen formation
  • Requires calcium and phosphate for calcification
32
Q

Bone Resorption (describe)

A
  • Bone matrix destroyed by substances released from osteoclasts
  • Proteolytic enzymes released from lysosomes within osteoclasts
  • Calcium and phosphate dissolved by hydrochloric acid
  • May occur when blood calcium levels low
33
Q

Vitamin D production:

-steps

A

slide 42

34
Q

Ca 2+ Regulation (Vit D, PTH, negative feedback loop)

blood calcium regulation

A
  1. UV light hits cholesterol in skin capillaries and converts it to Cholecalciferol (Inactive, Vit D3)
  2. Vitamin D3 can also be taken in via the diet
  3. Cholecalciferol goes into blood
  4. At liver cholecalciferol is converted to calcidiol (inactive) and is released into the blood
  5. At the kidney calcidiol is transformed to calcitriol (active form of Vitamin D)
  6. Low blood Calcium stimulates the parathyroid gland to produce parathyroid hormone (PTH)
  7. PTH is released into the blood
  8. PTH amplifies the transformation of calcidiol to calcitriol at the Kidney.
  9. Effectors of PTH and Calcitriol are synergistically stimulated
    a. Bone – osteoclast activity is increased releasing Ca++ from bone matrix
    b. Kidney – urine loss of Ca++ is reduced thus conserving blood Calcium
  10. Calcitriol in the blood independently stimulates the small intestine to absorb more Ca++ into the blood from food.
  11. Ca++ from the bone, small intestine absorption & kidney conservation of Ca++ results in increased blood Ca++
  12. Increased blood Ca++ returns the Ca++ concentration to normal/homeostasis
  13. Normal blood Ca++ levels are sensed by receptors in the parathyroid gland (negative feedback mechanism) & PTH production/release is reduced.

Pathophys Semester 2 (12 decks)

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