Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ANATOMY > Lecture 8: Microanatomy of Bone > Flashcards

Lecture 8: Microanatomy of Bone Flashcards

1
Q

what are the 3 parts of a long bone

A

epiphysis (E)
metaphysis (M)
diaphysis (D)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the function of bone

A
  • structural framework for support and protection of organs
  • levels for attached muscles
  • house and protect hematopoetic tissues & store fat
  • resevoir for minerals (Ca, P, Mg, K)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

compositon of the bone matrix

A

Organic component: type I collagen
Inorganic component: Calcium hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the cells of bone

A
  • osteoblast
  • osteocyte
  • osteoclast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the two layers of bone

A

Periosteum (lines external surface)
- fibrous periosteum
- inner cellular layer
Endosteum (lines central cavity)
- monolayer of osteogenic cells and osteoblasts

*both are vascularized CT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

layer of periosteum characterized by an outer layer of dense CT

A

fibrous periosteum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

layer of periosteum characterized by the presence of osteogenic cells

A

inner cellular layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

characteristics of the endosteum layer of bone

A

has cells similar to the periosteum but with loose CT

has a monolayer of osteogenic cells and osteoblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

type of bone that provides support to external surfaces of bones and makes up the shafts of long bones

A

compact (cortical bone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the 4 lamellar systems of compact bone ?

A
  1. outer circumferential lamellae
  2. inner circumferential lamellae
  3. osteons
  4. interstitial lamellae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

woven (immature) bone characteristics

A
  • initial bone formation; fracture repair
  • poorly organized type 1 collagen
  • relatively weak
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

lamellar (mature) bone characteristics

A
  • replaces woven bone
  • very strong, well organized
  • type I collagen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

when does lamellar (mature) bone replace immature woven bone?

A
  • during formation of primary bone (primary osteons)
  • during remodeling to form secondary bone (secondary osteons)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

bone type formed by interconnecting bony struts (trabeculae) that provide internal support to bone

A

Cancellous (trabecular, spongy) bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

characteristics of cancellous bone that makes it capable of calcium ion exchange b/w bone and blood

A

high surface area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what types of marrow (spaces) exist between the trabeculae of cancellous bone

A
  • red marrow : produces blood cells
  • yellow marrow : made of adipose tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what cell type is responsible for the formation of bone ECM

A

osteoblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are osteoprogenitor cells

A

stem cells near bony surfaces that differentiate into osteoblasts during periods of growth, remodeling, and fracture repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

cells responsible for the resorption of bone ECM

A

osteoclasts
— derived from monocyte-macrophage lineage located in the bone marrow

20
Q

cells responsible for the deposition of bone ECM (type I collagen, prosteoglycans, glycoproteins)

A

Osteoblasts

(when inactive, called bone-lining cells)

21
Q

what bone cell type lowers blood Ca levels

A

osteoclasts

22
Q

identifying characteristics of osteoblasts

A
  • found along surface of bone in sheet like arrangement
  • extensive rER and golgi
  • polarized organelles
    –> nucleus is away from region of secretory activity
  • communicate with each other via gap junctions
23
Q

what is an osteoid

A

the initial organic component synthesized by osteoblasts

*calcifies

24
Q

bone cell that forms gap junctions in response to mechanical stimuli by sending cell processes through channels in bone called canaliculi

A

osteocyte

25
Q

how is bone ECM formed

A

one lamellla at a time by osteoblasts

26
Q

what is the organic portion of bone ECM made of

A

mostly type I collagen fibers

27
Q

what is the inorganic (mineral) portion of bone made of

A

hydroxyapatite, calcium ions bound by multiadhesive glycoproteins (MGP)
bone specific alkaline phosphatase (BALP) aids in hydroxyapatite formation

28
Q

how do osteoclasts raise blood calicum levels

A

reabsorb bone, endocytose ECM byproducts, secrete them into blood

29
Q

characteristics of osteoclasts

A
  • large
  • multinucleated
  • ruffled border
  • clear zone
30
Q

what is the ruffled border of an osteoclast

A
  • portion of osteoclast that is in direct contact w/ bone
  • abundant lysosomes and mitochondria
31
Q

what is the clear zone of an osteoclast

area b/w black arrows

A
  • ring of cytoplasm around the resorptive compartment that immediately surrounds the ruffled border
  • lacks organelles (‘clear’)
  • actin ring inside clear zone helps seal off the subosteoclastic compartment
32
Q

what is the purpose of the actin ring found within the clear zone of osteoclasts

A
  • allows bone resportion to occur while preventing damage to surrounding tissue
  • by: sealing off subosteoclastic compartment
33
Q

how is the inorganic portion of bone ECM resorbed by osteoclasts

A
  • by pumping H+ into the resorptive cavity under the cell
34
Q

how is the organic portion of bone ECM resorbed by osteoclasts

A
  • gets degraded by lysosomal enzymes
35
Q

what happens to the byproducts of bone ECM resorption

A
  • they get endocytosed by osteoclast and secreted into the blood
36
Q

what hormones regulate the activity of resorbing osteoclasts and what is their effect

A
  • Parathyroid hormone (PTH)
    • stimulates osteoclasts to INCREASE bone resporbtion
  • Calcitonin
    • inhibits osteoclasts to DECREASE bone resorption
37
Q

what is the effect of calcitonin on blood Ca levels

A
  • decreases them by slowing resporption of bone ECM
  • calcitonin is secreted by thyroid gland
38
Q

what is the effect of PTH on blood Ca levels

A
  • PTH causes an increase in blood Ca levels by promoting ECM resorption
  • cause osteoblasts to produce osteoclast stimulating factor
39
Q

as the mesoderm develops, what affects the differentiation of mesenchymal cells into cartilage or bone

A

oxygen tension (O2 levels) in the tissue

40
Q

In a high O2 environment, what cell type do mesenchymal cells differentiate into

A
  • osteoprogenitor cells and osteoblasts that form bone
  • process is called: intramembranous ossification and requires vascularized mesenchyme to supply O2
41
Q

In a low O2 environment, what cell type do mesenchymal cells differentiate into

A
  • chondrogenic cells and chondrocytes that form hyaline cartilage
42
Q

explain the process of endochondral ossification

A
  • A low O2 environment causes mesenchymal cells to differentiate into chondrocytes that form hyaline cartilage
  • As blood vessels grow into the cartilage, forming ossification centers where chondrocytes exposed to high O2 start to act like bone cells by calcifying cartilage ECM.
  • Eventually, the cartilage ECM is replaced with bone.
  • process is called endochondral ossification. It begins in avascular mesenchyme and results in highly vascularized bone
43
Q

what are the steps of intramembranous ossification

A
  • mesenchymal cells near blood vessels become osteoblasts
  • osteoblasts form bone trabeculae
  • early sites of bone formation = ossification centers
  • overtime, trabeculae form bones w/ external compact bone and internal trabecular bone and marrow cavities
44
Q

growth plate

A
  • sheet of hyaline cartilage b/w epiphysis and diaphysis
  • responsible for longitdudinal growth
  • growth ends when growth plates become vascularized and are replaced w bone
45
Q

what are the 5 zones of a growth plate

A
  1. Zone of reserve - directs proliferation
  2. zone of proliferation - chondrocyte mitosis
  3. zone of hypertrophy - chondrocytes enlarge, bring in O2
  4. zone of calcification - chondrocytes calicify the ECM
  5. zone of ossification - cartilage is replaced w/ bone

ANATOMY (58 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions