Histology Questions Lecture 4

Front 1

What are the functional differences in skeletal tissues based on?

Back 1

The different nature and proportion of:
1) ground substance
2) fibrous elements
... in the ECM.

Front 2

The design of bone are what two things?

Back 2

1)Optimally provide maximum strength for the least weight.
2)Change in relation of how much stress is placed on the bone.

Front 3

What are both bone and cartilage derived from?

Back 3

Mesenchyme of the embryo.

Front 4

What are the functions/ uses of Cartilage?

Back 4

1) Protect soft tissues
2) Proved a sliding surface in joints
3) Help in Development and growth of long bones
4) Repair bone injury.

Front 5

How is cartilage different from bone in terms of nurishment?

Back 5

Cartilage has no nerves, blood suply, or lymphatic system.

Front 6

What is the main factor that gives cartilage it's characteristic?

Back 6

It's high water content.

Front 7

If cartilage is avascularized, then how do the cells get nourishment?

Back 7

Diffusion from the capillaries in the PERIOCONDRIUM or synovial fluid.

Front 8

What does the low Oxygen content of Cartilage tell us about cartilage

Back 8

It uses anaerobic glycolysis and has a low metabolism, thus it is slow at repairing an injury.

Front 9

What two types of cells are there in cartilage?

Back 9

CHONDROBLASTS - actively synthesize and deposit extracellular matrix components and fibers, however it is not yet trapped with in the matrix.
CHONDROCYTES - Mature cells of cartilage, which are completely surround by matrix.

Front 10

Where do CHONDROCYTES reside?

Back 10

In LACUNAE

Front 11

What is the capsular sheath that surrounds most cartilage and what is it made of?

Back 11

Perichondruim, which is made of dense connective tissues.

Front 12

What are the four principal components of the ECM in cartilage.

Back 12

1) Collagen (Type II)
2) Hyaluronic acid
3) Proteoglycans
4) glycoproteins

Front 13

What special ingredients are added to make fibrous and elastic cartilage?

Back 13

Elastin = E.C.
Collagen (type I) = F.C.

Front 14

What is the definition of tensile strength?

Back 14

The ability to distribute weight and resist breakage

Front 15

What is the composition of the ground substance between the fibers and cell bodies of cartilage and what properties does this give cartilage?

Back 15

Composition: Highly hydrated forms of Proteoglycans

Properties: Gives the Cartilage firmness and resiliency.

Front 16

What is a proteoglycan comprised of?

Back 16

Polypeptide chains glycosidically-linked with glucosaminoglycans.
Glucosaminoglycans are primarily condroitin sulfates and keratan sulfates. Individual proteoglycans attach to hyaluronic acid strands to make an aggregate.

Front 17

What are the three types of cartilage?

Back 17

1) Hyaline
2) Elastic
3) Fibrocartilage

Front 18

What are some facts about Hyaline Cartilage?

Back 18

1) It is the most widespread cartilage in the body
2) Most of bones were formed by replacing the hyaline model by endocondral bone formation.
3) In adults H.C. is found in the larynx, trachea, bronchi, ribs, and on articular surfaces of bone.

Front 19

How does Elastic cartilage differ from Hyaline and where can it be found?

Back 19

E.C. differs from H.C. because of its high concentration of elastin. This gives it flexibility and resiliency.
It can be found in the external ear, Eustachian tube, and the epiglottis.

Front 20

How does Fibrocartilage differ from the other types of cartilage and wher can it be found?

Back 20

Fibrocartilage differs due to the prominent bundles of collagen fibers(type I). This gives it great tensile strength.
It is found ins areas subject to high frictional forces, such as the intervertebral discs, pubic symphysis, and temporomandibular joint.

Front 21

How is bone distinguished from cartilage?

Back 21

1) Bone has the inorgainc calcium salts in its ground substance, which makes the matrix rigid. This makes the bone a reserve of Calcium.
2) Bone is vascularized, and contains nerves and a lymphatic system.
3) Bone is not as flexible as cartilage, however, the tensile strength is much greater.

Front 22

What are the three types of cells found in bone?

Back 22

Osteoblasts, Osteocytes, Osteoclasts

Front 23

Where are osteoblasts found and what do they produce?

Back 23

The can be found both internally and externally, since they arise from both the periosteum and endosteum. The Osteoblasts produce type I collagen.

Front 24

What are osteocytes and where can they be found?

Back 24

Osteocytes are osteoblasts trapped in by matrix. Osteocytes can be found within small canals called CANALICULI.

Front 25

What are osteoclasts and what are their function?

Back 25

osteoclasts are multinucleated cells which come from the fusion of bone marrow-derived precursors. They remodel the bone through reabsortion of both the mineral and organic components of bone.

Front 26

What is the outer surface of bone made up of?

Back 26

Fibroblast-like cells called the periosteum.

Front 27

What is the meaning of osteoprogenitor cell?

Back 27

A cell that can differentiate into osteoblasts.

Front 28

What are the inner surfaces of bone lined with and how thick is it normally?

Back 28

Endosteum and it is about one cell thick.

Front 29

What is the ratio of inorganic salts and organic matrix in bone?

Back 29

~65-70% Inorganic salts
~30-35% Organic Matrix.

Front 30

What is the makeup of the organic matrix of bone?

Back 30

1) ~90% type I collagen
2) Proteoglycans
3) Specific and non-specific bone proteins (other than collagen).

Front 31

What are examples of specific bone proteins found in the organic matrix?

Back 31

1) bone sialoproteins
2) ostenecin
3) osteocalcin.

Front 32

What is the primary make up of the inorganic component of bone?

Back 32

Hydroxyapatite

Front 33

What is primary bone and what are its other names?

Back 33

It is the first bone formed in the fetus and also the bone formed in repairing an broken bone. It is also known as woven bone or immature bone.

Front 34

What characteristics are there primary bone and where can it be found in an adult?

Back 34

1)Primary bone is temporary and arranged in irregular arrays of collagen fibers. It contains a lower ratio of inorganic to organic tissues than normal bone.
2) It can be found in tooth sockets and some tendon insertions.

Front 35

What are some differences in the structure of compact/dense bone and spongy/cancellous bone?

Back 35

Compact Bone has a defined concentric pattern of different layers called lamellae which cellter round a blood supply.

Front 36

What type of canals are there in compact bone?

Back 36

1) Volkmann's canals which run horizontally to the bone structure and
2) Haversian canals which run vertically.
Both canals interconnect with each other to for a maze like structure.

Front 37

What run through the Haversian and Volkmann canals?

Back 37

Blood supply, nerves and lymphatics.

Front 38

Where is the circumferential lamellae and what makes it?

Back 38

It is on the outer layer of the compact bone and it is made by osteoblasts from the periosteum.

Front 39

What are Haversian Systems? (AKA Osteons)

Back 39

They are the function unit of bone made up of ~5-20 concentric circles of lamellae. They are continually remodeled and the lamellae that are left behind make up the interstitial lamellae

Front 40

What are the two ways that bone can grow?

Back 40

1) Intramembranous Ossifcation
2) Endochondral Ossification

Front 41

What are the facts of Intramembranous Ossification?

Back 41

1) Mostly in the bones of the skull and face
2) Osteoblasts lay down bone until they are surrounded by the matrix
3) If it occurs at the out ends of the bone it is called appositional growth and this is the process responsible for makeing long bones grow.

Front 42

What are the six steps in Endrochondral Ossification?

Back 42

1) A Hyaline model is formed
2) The shaft is surrounded by intramembraneous bone and starts to calcify the cartilage
3)The diaphysis is innervated by blood vessals and mesenchymal cells which become osteoprogenitor cells, which become osteoblasts.
4) The cartilage is reabsorbed by osteoclasts, while the calcified matrix is being secreted by osteoblasts
5) A secondary ossification center starts in the epiphyses, creating a epiphyseal plate
6) The epiphyseal plate slowly disappears as growth finishes of the long bones.

Front 43

A bone can grow both in length as well as in width, which is responsible for what?

Back 43

Width = intramembranous/apposition
Length = Endochondrial

Front 44

What are the five layers of the epiphyseal plate?

Back 44

1) Resting Zone - Cartilage cells, no Mitosis
2) Proliferative Zone - Cartilage cells are proliferating
3) Hypertrophic Cartilage zone - cells are hypertrophing
4) Calcified cartilage zone - matrix is becoming calcified
5) Ossification zone - the Ca matrix is remodeled and bone is layed down.