Histology - Bone And Cartilage

Question 1

General characteristics of cartilage

Answer 1

Extensive ECM with cells trapped within it, firm yet flexible, provides support, participates in bone growth, avascular

Question 2

Cartilage is usually surrounded by ________, which is fibrous connective tissue

Answer 2

Perichondrium

Question 3

The perichondrium has an outer fibrous layer composed of

Answer 3

Type I collagen and fibroblasts

Question 4

The inner layer of the perichondrium is comprised of

Answer 4

Type I collagen, fibroblasts, and osteoprogenitor cells

Question 5

______ manufacture the cartilage matrix, and are known as ______ when they become embedded within ______ in the matrix

Answer 5

Chondroblasts, chondrocytes, lacunae

Question 6

Features of hyaline cartilage

Answer 6

Chondroblast = immature cartilage fell on periphery

Chondrocyte = mature

Lacuna = occupied by chondrocyte

Capsule = basophilic matrix around lacuna

Isogenic cell nest = cluster of chondrocytes

Usually associated with perichondrium

Question 7

Composition of hyaline cartilage

Answer 7

70% water, type II collagen 40% of dry weight, GAGs, various proteins and glycoproteins

Question 8

Features of elastic cartilage

Answer 8

Contains type II collagen and elastic fibers

Appears fibrous and flexible

ALWAYS associated with perichondrium

Question 9

Where is elastic cartilage located?

Answer 9

External ear, external auditory canal, auditory tube, epiglottis

Question 10

Features of fibrocartilage

Answer 10

Isogenous aggregates often arranged in long rows

Type I and II collagen fibers in ECM

NEVER associated with perichondrium

Question 11

Where is fibrocartilage found?

Answer 11

Intervertebral disks, attachments of ligaments, pubic symphysis

Question 12

How to differentiate between types of cartilage

Answer 12

Hyaline appears glassy and regular

Elastic is much more fibrous, has a perichondrium

Fibrous never has perichondrium and cells are organized into rows

Question 13

Describe appositional growth of cartilage

Answer 13

Occurs at periphery, chondrogenic cells differentiate into chondroblasts and add to cartilage at periphery

Question 14

Define interstitial growth of cartilage

Answer 14

Adds to inner mass, only occurs during early stages of cartilage formation. No chondroblasts involved, pre-existing chondrocytes divide

Question 15

Functions of bone

Answer 15

Protection, support, Ca/phosphate reservoir, translates skeletal muscle force into movement

Question 16

Dense irregular connective tissue that covers bone

Answer 16

Periosteum

Question 17

Inner surface of bony tissue is lined by this thin vascular CT

Answer 17

Endosteum

Question 18

The periosteum and endosteum provide nutrition and continuous supply of ________

Answer 18

Osteoblasts

Question 19

Osteoblasts

Answer 19

Synthesize bone matrix

Question 20

Osteocytes

Answer 20

Maintain bone matrix

Question 21

Osteoblasts

Answer 21

Remodel bone

Question 22

Osteocytes are embedded in _____

Answer 22

Lacunae (Haversian canal)

Question 23

The bone matrix is arranged in concentric ______

Answer 23

Lamellae

Question 24

Osteocytes send cytoplasmic extensions through _______

Answer 24

Canaliculi

Question 25

Osteocytes communicate with each other via ____ ______ located in cytoplasmic processes

Answer 25

Gap junctions

Question 26

Spongy bone is composed of interconnected _______

Answer 26

Trabeculae

Question 27

Cavities between trabeculae are filled with _____ ______

Answer 27

Bone marrow

Question 28

Trabeculae contain _____ and are lined by a layer of osteoblasts in _______

Answer 28

Osteocytes, endosteum

Question 29

Spongy bone is always surrounded by _____ _______

Answer 29

Compact bone

Question 30

Cells within the inner surface of the _______ give rise to osteoblasts

Answer 30

Periosteum

Question 31

Fibers of periosteum that anchor to bone are called

Answer 31

Sharpey’s fibers

Question 32

Osteoblasts secrete ______ and ______

Answer 32

Type I collagen Proteoglycans and glycoproteins

Question 33

Newly formed bone matrix is called

Answer 33

Patel is

Question 34

Inorganic materials secreted by osteoblasts

Answer 34

Hydroxyapatite crystals, calcium, phosphorus, carbonate, magnesium, fluoride, sulfate

Question 35

What kind of crystals form during bone mineralization?

Answer 35

Hydroxyapatite

Question 36

Function of osteoclasts

Answer 36

Produce acidic micro environment that dissolved hydroxyapatite and digests collagen

Question 37

Osteoblasts occupy ______ at the edge of bone

Answer 37

Howship Lacuna or resorption bays

Question 38

Bone remodeling in adults

Answer 38

Osteoblasts bore a tunnel into bone matrix and are followed by osteoblasts depositing osteoid

Question 39

Intramembranous bone formation occurs in _____ and is the process by which _____ bones are formed

Answer 39

Fetus, flat

Question 40

In the presence of a vascular zone, mesenchyme cells condensed into ______ ______ ______, differentiate into ______, and begin secreting _______

Answer 40

Primary ossification centers, osteoblasts, osteoid

Question 41

During intramembranous bone formation, portions of the mesenchymal layer that do not undergo ossification become

Answer 41

The periosteum and endosteum

Question 42

Describe endochondral bone formation

Answer 42

1. Hyaline cartilage served as model 2. Initiates near middle of diaphysis 3. Chondrocytes hypertrophy, degenerate, and the lacunae become marrow cavities 4. Other ossification centers develop at epiphysis

Question 43

Describe appositional bone growth

Answer 43

Increases diameter of bone throughout childhood and puberty

Question 44

Endochondral bone growth continues until

Answer 44

Age 20

Question 45

Five zones of growing bone

Answer 45

1. Reserve 2. Proliferation 3. Hypertrophy 4. Calcified cartilage 5. Ossification

Question 46

Qualities of proliferation zone

Answer 46

High mitotic rate, cells look like stacks of coins

Question 47

Characteristics of zone of hypertrophy

Answer 47

Cells and lacunae enlarge

Question 48

Zone of calcification

Answer 48

Cartilage calcifies, cells die, blood vessels grow in from marrow cavity

Question 49

Zone of ossification

Answer 49

Calcifies cartilage is resorbed and replaced by bone

Question 50

PRH involvement in bone growth

Answer 50

Activated osteoclasts, maintains serum calcium, increases dissolution of bone and slowly induced proliferation of osteoclasts Hypocalcemja increases PTH secretion

Question 51

Calcitonin role in bone growth

Answer 51

Secreted by parafollicular cells in thyroid, opposes effect of PTH Reduces bone resorption and lowers blood calcium