Lecture 9: Bone Cont. Flashcards Preview

First Semester: Microscopic Anatomy > Lecture 9: Bone Cont. > Flashcards

Flashcards in Lecture 9: Bone Cont. Deck (36):
1

Osteoblast shape

-Cuboidal to polygonal with basophilic cytoplasm
-Aggregate in a single layer

2

Osteocytes

Mature bone cells enclosed in the bone matrix within lacunae

3

Osteocytes maintain contact with adjacent osteocytes via

cytoplasmic branching processes (filopodia) that connect to each other via small tunnels or canaliculi

4

How do osteocytes transfer nutritional needs to the next cell?

gap junction

5

Are osteocytes capable of undergoing mitosis?

No, because they are mature cells

6

How do osteocytes maintain the homeostasis of Ca?

Synthesize and to a lesser extent absorb matrix

7

Osteoclasts

multinucleated cells closely related to macrophages

8

Osteoclast cytoplasm (baso or acido)

acidophilic

9

Osteoclasts - bone marrow origin (from moncytes), formed via

DNA replication without division of the cytoplasm

10

Where are osteocytes observed?

In indentations (bays) called Howship's lacunae, which are reabsorbed from bone surface

11

Osteoclasts induce

osteolysis to maintain Ca homeostasis and to remodel in response to growth or changing mechanical stress

12

When activated and in contact with a bony surface, osteoclasts

release acid and lysosomal enzymes to decalcify bone

13

Circumferential zone of osteoclast

Integrins tightly bind the matrix and surround a ruffled border of the cytoplasmic projections close to the matrix

14

(Osteoclast) The sealed space between the cell and the matrix is acidified by

A proton pump localized in the osteoclast membrane and receives hydrolytic enzymes secreted by the cell

15

Two ways of bone formation in fetal life

-Intramembrous ossification
-Endochondrial ossification

16

Intramembrous ossification

-Occurs within membranes of condensed primitive mesenchymal tissue
-Flat bones of the skull

17

Endochondrial ossification

-Bone develops from cartilaginous model (hyaline cartilage) that is subsequently replaced by osseous tissue at the ossification centers
-Occurs in the majority of bones of the skeleton.

18

Where does endochondrial ossification occur

Ossification centers of immature bones and in the growth plates (epiphyseal plates) of developing bones

19

Once growth plates are closed (mature animal),

no further longitudinal bone growth can occur

20

Two types of bone based on degree of maturity

Woven bone
Lamellar bone

21

Woven bone

-Immature bone present during fetal development and in the early stages of bone repair.
-Collagen fibers in woven bone are randomly arranged adopting a crisscross (woven pattern) microscopically

22

Lamellar bone

-Mature bone
-Collagen fibers are arranged in a parallel pattern
-Composed of successive concentric layers of bone (in laminar formation) around a central canal containing blood vessels and nerves

23

Osteons

functional unit of mature bone

24

5 factors that influence bone formation and resorption

-Parathyroid hormone (can increase recruitment and activity of osteoclasts)
-Vitamin D deficiency (May lead to bone disease)
-Hormones (Estrogen inhibits bone resorption)
-Mechanical constraints
-Genetic background

25

Synovium

The joint cavity between two movable ones

26

Bone surfaces of the synovium are covered by

articular cartilage

27

Synovial joints consists of

A joint capsule composed of fibrous portion and a well vascularized synovial membrane

28

The articular capsule inner part

-Called the synovial membrane
-Lines fibrous capsule of the joints
-A thin sheet of connective tissue, with abundant blood vessels and lymphatics

29

The surface facing the joint cavity is lined by epithelioid cells which

secrete hyaluronic acid and phagocytize debris

30

Synovial cells have epithelioid morphology but are

specialized connective tissue cells, not epithelial since they don't sit on a basement membrane or have intercellular junctions

31

Synovial fluid

-Hyaluronic acid and a dialysate of plasma from the blood vessels
-Viscous substance that lubricates the joints

32

Synovial membranes have variable _____ and may be arranged into ____ that project into the joint cavity

thickness
folds

33

Where can synovial fluid be found

Synovial joints such as stifle, elbow, hip joint, ect

34

Synovial fluid is secreted into joint cavity by

synovial cells

35

Normal synovial fluid is

clear, translucent, very viscous lubricant

36

Three functions of synovial fluid

Nutrition
Lubrication
Protection of articular surfaces