Part 2: Introduction to skeletal tissue Flashcards
3 functions of cartilage
-supports soft tissue
-shock absorbing surface at articulations (joint)
-model for majority of bone formation
4 properties of cartilage
-resists compression
-firm yet flexible
-avascular
-covered by connective tissue sheath
cartilage is able to resist compression because of ___
high amount of ground substance
only CT without blood vessels is ____
cartilage (need to be associated with other CT)
avascular nature of cartilage restricts ____ & ___
thickness & capability to heal
cartilage coved by which CT sheath (name & type)
perichondrium (dense irregular CT)
cartilage type without CT sheath (2)
-fibrocartilage & articular cartilage
formation of cartilage cells process
mesenchymal cells -> chondroblasts -> chondrocytes
mesenchymal cells are the origin of ___
all CT
mesenchymal cells are the ___ of cartilage
stem cells
chondroblasts secrete ___
matrix (ECM)
chondrocytes are the ___ of cartilage
body guards
chondrocytes maintain ____
the matrix (ECM)
If chondrocytes die. then _____
cartilage becomes bone
types of cartilage is based on ___ & ____ of ECM
composition & structure
3 types of cartilage
-hyaline
-elastic
-fibrocartilage
most common type of cartilage
hyaline
hyaline cartilage provides ___, ____, & ____
- flexibility, support & resilience
hyaline cartilage is found in ____(4)
-growth plates
-respiratory cartilage
-nasal cartilage
-articular cartilage
elastic cartilage provides ____ to maintain ____ while ____
-more elasticity
-shape of structure
-allowing flexibility
elastic cartilage is found in ___ (2)
-epiglottis
-external ear
fibrocartilage is _____
highly compressed with great tensile strength
fibrocartilage is found in ___ (4)
knee. intervertebral discs, pubic symphysis, temporomandibular joint (TMJ)
4 functions of bone tissue
-support & protect soft tissues
-support general body shape
-muscle/tendon attachments
-dynamic mineral storage
red and yellow marrow are both ___
connective tissue
red marrow is CT in ___ where ____ occurs
-medullary cavity
-blood formation
yellow marrows is CT in ___ where ____ is stored
-medullary cavity
-adipose tissue
bone is able to resist compressive stress due to ____
calcium phosphate (minerals- very strong but inflexible)
bone is able to resist stretching, bending & twisting stress due to ___
collagen fibers (tough & flexible)
bone is composed of inorganic + organic components:
-calcium phosphate
-collagen fibers
bone cells are ___ in mineralized matrix
embedded
bone is covered by which type of CT?
dense irregular CT
bone is alive via ___
high vascularization
dense irregular CT outside bone is called ____
periosteum
dense irregular CT within bone is called ____
endosteum
bone remodels under ___
influence of forces
bone is anisotropic which means it has ____
different strength depending on its orientation
epiphysis
ends of bone
diaphysis
middle or shaft of the bone
spongy (cancellous/trabecular) bone
open network; shape + direction depends on external forces
metaphysis
where the epiphysis + diaphysis meet
spongy/trabecular bone found @
metaphysis
compact (cortical) bone
dense & solid (lamellae-circles); thickness + density depends on external forces
periosteum + endosteum are ____ CT and contain ___ & ____
-highly vascularized
-stem cells and sensory nerves
appositional growth, which is ___, can occur at ___ & ____
-growth that increases in diameter
-periosteum
-endosteum
Mesenchymal cells are ____ of bone
stem (osteogenic) cells
Osteoblasts secrete ____
matrix
matrix of bone is ___
osteoid = collagen
osteocytes maintain _____
matrix (lacunae/canaliculi)
osteoclasts (monocytes) reabsorb ____
matrix
functional unit of bone is ____
osteons
osteons are oriented ___ to line of stress
parallel
osteons formed by ____
osteocytes organizing in concentric layers around central canal with blood vessels and nerves
two types of bone development
-intramembranous ossification
-endochondral ossification
intramembranous ossification occurs in ____
flat bone like crania, face
in intramembranous ossification, osteoblasts differentiate ____
directly form mesenchymal tissue (mesenchyme -> bone)
endochondral ossification occurs in ___
long bones (ed. limbs,ribs, vertebrae)
in endochondral ossification, bone replaces ___
a hyaline cartilage template
Intramembranous growth process
1) chemical message tells mesenchymal cells to crowd together
2) differentiate osteogenic cells -> osteoblasts.
3) osteoblasts secreting ECM (osteoid) forms an ossification center (multiple formed)
4) Osteoid calcifies over time with minerals.
5) Osteoblasts become trapped osteocytes in lacunae (project cytoplasmic processes via canaliculi)
6) Developing bone (calcified matrix) forms trabeculae (spongy bone) & blood vessels supply the new bone -> trapped blood vessels become red marrow
7) Mesenchymal cells around outside of bone condense to form periosteum
8) Thin layer of cortical bone is deposited over the trabeculae
Endochondral growth (pre-natal)
1) Mesenchymal cells -> chondroblasts -> secrete matrix to create hyaline cartilage model -> chondrocytes
2) Mesenchymal cells condense to form outer covering (perichondrium)
3) Hypertrophic (large) chondrocytes secrete an attractant for blood vessels then die
4) Invading blood vessels stimulate cells differentiate into osteoblasts (perichondrium) & osteoclasts (blood)
5) Cells will make & remodel bone -> primary ossification centre (just one)
6) At the same time osteoblasts differentiate in the perichondrium (now called the periosteum) & create a bony collar
Endochondral growth (post-natal)
1) At birth -> diaphysis mostly ossified, but the epiphyses (ends) are still cartilage
2) After birth, secondary ossification centres appear in the epiphyses (same process as seen for the primary ossification centre)
3) Secondary ossification centres expand to ossify most of the epiphysis
4) The epiphyseal cartilage plate (metaphysis) remains between epiphysis & diaphysis
5) Epiphyseal (growth) plate -> most of the
lengthening (interstitial) growth of the bone occurs through proliferation of chondrocytes & replacement by bone
ossification of growth plate means what?
no more growth in length (but can still change shape)
Bone is remodelled throughout life, but will not grow in length after ______
growth plates close
Inactivity & age does what?
decreases cellular bone activity
Bones can grow appositionally in response to ______
stimuli (muscular activity) or bone damage
Interstitial growth is ____
growth in length
Appositional growth is ___
change in diameter (overall shape of bone)
Bone remodeling and repair process
- Fracture hematoma: rupture of blood -> hemorrhage
- Fibrocartilaginous callus (soft): invasion of macrophages + collagen + cartilage - no structural rigidity
- Bony (hard) callus: healthy blood vessels are produced, bringing in osteogenic cells -> osteoblasts
- Bone remodeling: remodeling of the repaired portion, Osteoclast activity increases to remove dead/damaged cells, spongy bone => cortical bone
Joints (articulations) are places of contact between
___ (3)
- Bone & bone
- Bone & cartilage
- Bone & tooth
motion at joint goes from ____ (ex. ____) to ____ (ex. ___)`
no movement at all
sutures
extensive movement
shoulder
structure of joint determines its ____ & _____
mobility
stability
↑ mobility of joint = ____ stability of joint
↓
Joints can be classified in two ways: ______
1) The connective tissue that binds the bones together & the potential space between them
2) Functionality
Fibrous joints (def + examples)
Bones held together by (fibrous) connective tissue;
cranial sutures
interosseous membrane- between radius & ulna, between two bones - “syndesmosis”
gomphosis - in teeth
Cartilaginous joints (def. )
where bones are joined by cartilage
Two types of Cartilaginous joints
1) Primary or synchondrosis
2) Secondary or symphysis
Primary or _____: (def. + example + movement + found in ___)
synchondrosis
temporary cartilaginous union between bones
cartilage of growth plate
no movement
people who are growing
Secondary or _____: (def + example + movement + function)
symphysis
permanent cartilaginous (fibrocartilage) union between bones
intervertebral discs; public symphysis
very little movement
compression; resistance
Synovial joints:
fluid-filled cavity that separates cartilage covered joint surfaces
In synovial joints, bones are united by ____ containing _____. This membrane will help to ______
capsule
synovial fluid
absorb shock & provides nutrients to the articulation
Most common joints of body is ______ because it allows _____
synovial joints
motion
A hinge joint is ___ whereas a ball-and-socket joint is ____.
-unaxial
-multiaxial
The _______of a synovial joint dictates its
_____
shape of the articular surfaces
range of movement
