Cartilage (Ch 6) Flashcards
1
Q
Structure of Cartilage
A
- avascular: no blood supply (get blood from diffusion)
- cell type: chondrocytes (cartilage cell) in lacunae
2
Q
Functions of cartilage
A
- support soft tissue
- model for formations of bone
- gliding surface at articulations (joints)
- ->cartilage is NOT a soft bone
3
Q
Types of cartilage
A
- Hyaline
- Elastic
- Fibrocartilage
4
Q
Hyaline cartilage
A
- most common
- support, but can be somewhat manipulated
- has fibrils: tiny (almost invisible) collagen fibers
- glossy/smooth looking
- ->found at ends of long bones, respiratory structures, and in fetal skeletons
5
Q
Elastic cartilage
A
- similar to hyaline, but LOTS of elastic fibers
- VERY resilient and flexible - tolerates repeated bending
- -> found in pinna (outer ear) and epiglottis
6
Q
Fibrocartilage
A
- little ground substance and matrix has thick/dense collagen fibers
- resists strong compression (shock/strong pressure)
- -> found in intervertebral discs, knee joint, public symphysis
7
Q
What are the types of cartilage growth?
A
- Interstitial Growth
2. Appositional Growth
8
Q
Interstitial Growth
A
- chondrocytes within existing cartilage divide and secrete new matrix to LENGTHEN the skeleton
- mostly in utero
9
Q
Appositional Growth
A
- chondroblasts in perichondrium make new cartilage tissue by secreting new matrix on the perichondrium (outside edge)
- on the outside –> widens the cartilage
10
Q
What is the skeletal system?
A
- internal, muscles attach to and pull against it
- bones connect via joints
- considered organs because they contain different tissue types
- Axial vs. Appendicular
11
Q
What makes up the axial skeleton?
A
skull, vertebral column, sternum, ribs
12
Q
What makes up the appendicular skeleton?
A
pectoral/pelvic girdles, bones of upper and lower limbs
13
Q
Functions of the skeletal system
A
- support
- protection
- movement
- hemopoiesis (blood cell production)
- energy/mineral reserves (good source of calcium)
14
Q
What is bone tissue?
A
- denser than cartilage
- resists compression/tension = strong
- well vascularized = heal/remodel easily
- cells: osteocytes, osteoblasts, osteoclasts
- ->constantly built up/broken down (growth, strengthening, remodeling, healing, maintenance)
15
Q
What is the extracellular matrix?
A
organic: fibers (lots of collagen), ground substance
inorganic: 65% mineral salts (calcium phosphate)
16
Q
Epiphysis
A
ends of long bone (proximal and distal)
17
Q
Diaphysis
A
middle portion of bone
18
Q
Compact bone
A
aka Cortical
- more superficial
- smooth, dense, strong, rigid
- osteon is structural unit
19
Q
Spongy bone
A
aka Trabecular
- more deep
- better at shock absorption
20
Q
Periosteum
A
- most external surface, white tissue –> helps ligaments and tendons attach to the bones
- well supplied with nerves/blood vessels
- attached to underlying bone by collagen fibers
(ex. shin splints = tears in periosteum)
21
Q
Endosteum
A
where osteoblasts and osteoclasts hide out, line medullary cavity
22
Q
Medullary Cavity
A
aka bone marrow
fills diaphysis, includes RBCs
23
Q
Nutrient Arteries
A
fed bone
24
Q
Articular Cartilage
A
on ends of long bone
25
Osteons
- made up of concentric tubes called lamellae
- oriented parallel to long axis/main compression stresses
- Haversian (central) canal runs through core of each osteon and provides blood supply/nutrients/nerves
26
Flat, Irregular, and Short Bones
- compact bone with periosteum on outside
- spongy bone with endosteum inside
- marrow, but no marrow cavity
27
What is osteogenesis?
process of bone development
| -begins in embryonic period --> continues thru life
28
What is the skeleton made of before week 8?
hyaline cartilage/mesenchyme
29
What the skeleton made of after week 8?
bone tissue begins to replace most cartilage
30
What are the types of bone ossification?
1. Intramembranous Ossification
| 2. Endochondrial Ossification
31
Intramembranous Ossification
* between the two membranes
1. mesenchymal cells congregate in CT membrane
2. become osteoblasts and region is called "ossification center" (osteoid)
3. osteoblasts --> osteocytes and new bon tissue is formed
4. embryonic blood vessels grow through the region, forming "woven" bone tissue (trabeculae)
- -> forms flat bones (ex. skull, clavicle)
32
Endochondrial Ossification
* most bones grow this way
1. skeleton begins as hyaline cartilage model
2. from primary center of ossification in diaphysis, bones begin to replace cartilage cells
3. secondary centers of ossification form in epiphysis
4. skeleton continues to grow via diffusion of cartilage cells (and bones) until maturity
- ->when two centers meet = growth stops
33
Achondroplasia
mutation in gene on chromosome 4 inhibits cartilage proliferation in epiphyseal plates --> close too early
- truck and head = normal size, limbs = short
- autosomal dominant, most common form of dwarfism
34
Osteoporosis
- imbalance in normal building/degradation cycle
- mostly in post-menopausal women who don't absorb as much calcium --> osteoclasts break bone down to release calcium from blood to bloodstream (bone = mineral reserve)
35
Osteoarthritis
-articular cartilage is thin and doesn't have a good blood supply so it heals poorly --> bones rub creating bone spurs, PAIN! (periosteum is innervated)
36
Bone Healing
- requires both osteoblasts and osteoclasts
| - osteoblasts tend to overgrow at the site and form bony callus, then osteoblasts smooth it out (strengthen bone)
37
What are the steps to bone healing?
1. Broken blood vessels = hematoma (blood clot) --> inflammation response
2. New blood vessels grow, osteoblasts form a fibrocartilaginous (soft) callus
3. Trabecular (part of spongy bone) appear and join together the pieces of broken bone and new bone forms
4. Bony callus is formed, osteoclasts smooth away excess tissue (replaces fibrocartilaginous callus)
