Skeletal System Flashcards
Skeletal system includes?
bones, cartilage,
ligaments, connective tissues
Five Primary Functions of the Skeletal System
- Support
- Storage of Minerals (calcium) and Lipids (yellow
marrow) - Blood Cell Production (red marrow)
- Protection
- Leverage (force of motion)
Bones are classified by:
- Shape
- Internal tissue organization
Six Bone Shapes
- Sutural bones
- Irregular bones
- Short bones
- Flat bones
- Long bones
- Sesamoid bones
- Small, irregular bones
- Found between the flat
bones of the skull - Variable in number and
size
Sutural Bones
- Have complex shapes
- Examples: pelvic bones,
vertebrae, sphenoid, zygomatic bone
Irregular Bones
- Small and thick
- Examples: ankle and wrist
bones
Short Bones
- Thin with parallel surfaces
- Found in the skull,
sternum, ribs, and
scapulae
Flat Bones
- Long and thin
- Found in arms, legs, hands,
feet, fingers, and toes
Long Bones
- Small and flat
- Develop inside muscles or
tendons near joints of
knees, hands, and feet - Patella (kneecap)
Sesamoid Bones
give an example of long bone
Limbs
humerus, radius, ulna, phalanges, femur, tibia, ulna
give an example of short bones
wrist and ankle
carpals and tarsals
give an example of irregular bones
pelvic bones, sphenoid, zygomatic bone
give an example of flat bones
skull, ribs, parietal, frontal, sternum , scapulae
give an example of sesamoid bone
patella
Structure of a Long Bone
diaphysis
epiphysis
metaphysis
-The shaft (middle section)
- A heavy wall of compact bone
-A central space called medullary (marrow)
cavity
diaphysis
- Wide part at each end
- Articulation with other bones
- Mostly spongy (cancellous) bone
- Covered with compact bone (cortex)
Epiphysis
- Where diaphysis and epiphysis meet
Metaphysis
A central space of a long bone in a diaphysis
medullary (marrow)
cavity
Structure of a Flat Bone
- Resembles a sandwich of spongy bone between
two layers of compact bone - Spongy bone: Diploë
-Compact bone: Cortex - Spongy bone contains red
bone marrow in spaces
between bone meshwork
two layers of compact bone in flat bone
* Spongy bone: Diploë
* Compact bone: Cortex
- Spongy bone: Diploë
- Compact bone: Cortex
spongy bone=
diploe
compact bone
cortex
Spongy bone contains —— in spaces
between bone meshwork
red bone marrow
External surface of bones covered by
Periosteum
External surface of bones covered by Periosteum
* Except at ___________
the ends that are enclosed in joint capsule
bone is a ______tissue
connective
Bone is a connective tissue
which is made of
- Dense matrix
-2/3 Calcium salt
(Hydroxyapatite) - 1/3 Collagen
- Osteocytes
(mature bone cells)
within lacunae
dense matrix is made of
- 2/3 Calcium salt
(Hydroxyapatite) - 1/3 Collagen
Bone contains four types of cells which are
Osteocytes,
Osteoblasts,
Osteoprogenitor cells, Osteoclasts
Bone Cells make up only —% of bone mass
2%
are mature bone cell in lacunae that maintains the bone matrix
does BOTH
BREAKING & REBUILDING!!
Osteocytes
2 major functions of osteocytes
- To maintain surrounding protein matrix
- To help repair damaged bone
- Degrade surrounding bone matrix
- Rebuild matrix with new collagen, new hydroxyapatite
- Bone Turnover
-Immature bone cells that secrete organic compounds of matrix
-BABY CELLS
-only BUilds
osteoblasts
BBB
blast build baby cells
Matrix produced by osteoblasts is
osteoid
Organic components only (not yet calcified to form
bone)
osteoid
Osteoblasts become or mature into
osteocytes
- Stem cells that divide to produce osteoblasts
- Located in the inner cellular layer of periosteum and
the endosteum - Maintain osteoblast populations, assist in fracture
repair
Osteoprogenitor Cells
Osteoprogenitor Cells
* Stem cells that divide to produce
osteoblasts
Osteoprogenitor Cells is
Located in the inner cellular layer of ——— and
the ——–
- Located in the inner cellular layer of periosteum and
the endosteum
- Maintain osteoblast populations, assist in fracture
repair
-Packs CALCIUM AWAY INTO THE BONE
Osteoprogenitor Cells
-Giant, multinucleate cells
* Secrete acids and protein-digesting enzymes
* Dissolve bone matrix and release stored minerals
(osteolysis)
* Maintains blood concentrations of calcium & phosphate
* Derived from stem cells that produce macrophages
RELEASES CALCIUM!!
Osteoclasts
- Bone building (by osteoblasts) and bone recycling (by
osteoclasts) must balance
Homeostasis
More breakdown than building, bones become—–
* Immobility leads to reduction in bone mass
* More building than breakdown, bones —–
* Weight-bearing exercise causes osteoblasts to
build bone
weak
strengthen
The bone matrix acts
as a storage reservoir for Calcium
Serum Calcium Homeostasis
when Calcium is removed from the
bones
hypocalcemia
Stimulates the release of calcium
from bones
Parathyroid Hormone
when Calcium is packed into the bones
hypercalcemia
stimulates the deposition of calcium into bones
Calcitonin
the basic unit of The Structure of Compact Bone
Osteon
—–are Osteocytes arranged in concentric lamellae
around a central canal containing blood vessels
Osteon
- Perpendicular to the central canal
- Carry blood vessels into bone and marrow
Perforating canals
