CT 2 A

Question 1

function of skeletal system:

Answer 1

1. Protection for critical organs (e.g. the ribs for the heart and lungs, the skull for the brain)
2. Mechanical support for locomotion; by supporting and providing attachments for muscles and joints for flexible movement.
3. Calcium and phosphate homeostasis: Bone is a tightly regulated reservoir of calcium for the entire body.
4. To house, protect, and regulate the stem cell precursors of blood cells (the hematopoietic system) (a function of bone).

Question 2

Like all connective tissues, bone and cartilage are composed of ______.

Answer 2

collagen-containing extracellular matrix secreted by cells of the connective tissue family

Question 3

connective tissues contain specialized cell types that lead to ______.

Answer 3

precise structural organizations and produce specialized ECMs

Question 4

In particular, the matrix of bone is _____.

Answer 4

mineralized or calcified, i.e. it contains crystals of calcium (Ca2+) and phosphate (PO4)

Question 5

Bone is a _____ tissue.

Answer 5

highly dynamic

It is associated with numerous blood vessels (vascularized) and is constantly turned over and remodeled even in adults.

Question 6

Bone maintains a population of precursor cells that are capable of ________.

Answer 6

cell division and differentiation into new bone cells

Question 7

This flexibility of precursor cells is required to _______.

Answer 7

adjust blood calcium and phosphate levels, to allow repair of damage, and allow changes in structure in response to various stimuli

Question 8

Cartilage is _____.

Answer 8

avascular in its matrix and is very limited in its ability for repair in adults

Question 9

cartilage is a template for ____.

Answer 9

conversion into bone

Question 10

In adults, cartilage retains the capacity to ___

Answer 10

convert into bone, which can cause problems as people age.

Question 11

Cartilage has two main functions:

Answer 11

(1) to provide a resilient but pliable support structure.

(2) to direct the formation and growth of bone.

Question 12

Where is cartilage in the fetus?

Answer 12

large segments of the skeleton are composed of cartilage.
This is replaced by bone, so that by adulthood only the articular surfaces of bones (where bones come together at joints) retain cartilage tissue.

Question 13

Cartilage is also found in specific places such as the:

Answer 13

tracheal rings, nasal passages, the external ear, intervertebral discs, ribs, skull sutures and where certain tendons attach to bones.

Question 14

Chondrocytes make ____.

Answer 14

cartilage matrix and tissue

Question 15

Chondrocytes arise initially from _____.

Answer 15

primitive mesenchymal cells during fetal development

Question 16

Once cartilage structures are formed, chondrocytes can also arise from ____

Answer 16

an external layer of connective tissue that surrounds the cartilage called the perichondrium

Question 17

undifferentiated mesenchymal cells or fibroblasts of the perichondrium generate new _____

Answer 17

chondrocytes during growth

Question 18

During cartilage growth, chondrocytes are _____

Answer 18

proliferative and secrete the components of the cartilage extracellular matrix (ECM).

Question 19

As chondrocytes secrete and surround themselves with matrix they become____

Answer 19

isolated from other cells, coming to reside in an isolated compartment called a lacuna.

Question 20

Proliferative chondrocytes are called ____

Answer 20

chondroblasts, but in essence they are the same cells engaged in the cell division cycle.

Question 21

After growth is completed chondrocytes _____

Answer 21

withdraw from the cell cycle, but retain the capacity to secrete cartilage matrix, albeit at lower rates.

Question 22

Chondrocytes secrete a ___

Answer 22

special extracellular matrix.

Question 23

three different kinds of cartilage that are distinguished by characteristics of matrix they contain:

Answer 23

1. hyaline cartilage
2. elastic cartilage
3. fibrocartilage

Question 24

Hyaline cartilage contains _____.

Answer 24

collagen that forms relatively thin fibrils that are generally arranged in an irregular three dimensional pattern

Question 25

The ground substance of hyaline cartilage is rich in _____

Answer 25

proteoglycans and the free glycosaminoglycan hyaluronic acid, which promotes hydration and flexibility

Question 26

This structural properties of hyaline cartilage ECM:

Answer 26

1. Allows metabolites to readily diffuse through the tissue.
2. Promotes resiliency to compression forces during joint movement.
3. Allows growth of chondrocytes and matrix from within the matrix.
4. During growth, it can calcify and attract cell that initiate bone formation.

Question 27

Elastic cartilage contains _____.

Answer 27

thin collagen fibrils and proteoglycans, but is distinguished by abundant elastic fibers and interconnecting sheets (lamellae) of elastic material

Question 28

Elastic cartilage is found in ______.

Answer 28

the external ear, in the epiglottis, and the larynx

Question 29

Elastic cartilage matrix is designed for ____

Answer 29

elasticity and flexibility, and, at least under normal circumstances, does not calcify

Question 30

Fibrocartilage contains ______.

Answer 30

large bundles of regularly arranged collagen that is very similar to dense regular connective tissue

Question 31

Fibrocartilage is found as a _____.

Answer 31

continuation of dense regular connective tissue where tendons attach to bones, and also in the intervertebral discs

Question 32

Fibrocartilage ECM is designed to ____

Answer 32

resist compression and sheer forces.

Question 33

Cartilage tissue ______.

Answer 33

avascular

Question 34

all of the nutrients and metabolites that are needed and produced by chondrocytes must _____

Answer 34

diffuse within the matrix to and from the perichondrium.

Question 35

What facilitates diffusion of nutrients and metabolites in cartilage?

Answer 35

diffusion is facilitated by the large amounts of hydrated glycosaminoglycans.