Post on 18-Dec-2015
The Skeletal System
1. framework
A. Components
B. Functions
2. protection
3. storage
4. blood cell formation
C. Changes with age
The Skeletal System
C. Types of bone
1. Short, long, flat, irregular
2. Long bone structure
a. diaphysis
b. epiphysis
c. medullary cavity
d. compact bone
e. spongy bone
f. periosteum
g. endosteum
The Skeletal System
D. Compact bone structure
1. Bone cells
a. osteogenitor cells
b. osteoblasts
c. osteocytes
d. osteoclasts
osteoprogenitor osteoblast osteocyte osteoclast
The Skeletal System
D. Compact bone structure
2. Haversian system (osteon)
a. central canal
b. lamellae
c. lacunae
d. canaliculi
lamella
lacuna Haversian canal
osteon
Volkmann’s canal
The Skeletal System
D. Compact bone structure
3. Bone matrix
a. ground substance (25%)
b. collagen (25%)
c. mineral salts (50%) = hydroxyapatite primarily
d. functions
The Skeletal System
E. Bone formation
1. Endochondral ossification
2. Intramembranous ossication
F. Bone resorption
G. Bone remodeling
1. Resist mechanical stress
2. Remove worn/heavily deposited bone
3. Participate in calcium homeostasis
The Skeletal System
G. Bone remodeling – parathyroid hormone (PTH)
CONTROLLED CONDITIONNormocalcemia
(blood calcium = 9.5-10.5mg%)A stress or stimulus causes a decrease in
blood calcium
RECEPTORChief cells of parathythyroid glands
recognize hypocalcemia(blood calcium <9.5 mg%
CONTROL CENTER
Chief cells secrete PTH
EFFECTORS
Increased osteoclast activityDecreased osteoblast activity
Increased urine phosphate outputDecreased urine calcium output
RETURN TO HOMEOSTASISIncreased bone breakdown results in increased calcium release to blood –
Return to normocalcemia
negative feedback
The Skeletal System
G. Bone remodeling – calcitonin (CT)
CONTROLLED CONDITIONNormocalcemia
(blood calcium = 9.5-10.5mg%)A stress or stimulus causes a increase in
blood calcium
RECEPTORParafollicular cells of thyroid gland
recognize hypercalcemia(blood calcium >10.5 mg%
CONTROL CENTER
Parafollicular cells secrete CT
EFFECTORS
Decreased osteoclast activityIncreased osteoblast activity
Increased urine calcium output
RETURN TO HOMEOSTASISIncreased bone formation results in
increased calcium deposition in bone --Return to normocalcemia
negative feedback
The Skeletal System
H. Cartilage
1. chondrocytes
2. matrix type determines function
a. hyaline c. elasticb. fibrocartilage
3. avascular and aneural
The Skeletal System
I. Synovial joints
1. Components
a. articulating bones
b. articular (joint) capsule
c. articular cartilage
d. synovial membrane
e. synovial fluid
f. ligaments
2. Movements allowed
J. Other joint types
medullary cavity
compact bone
spongy bone
fibrous capsule
synovial membrane
periosteum
synovial membrane
joint cavity
articular cartilage
tendon sheath
tendon
The Skeletal System
K. Age-related changes
1. Loss of calcium from bone matrix
2. Collagen fiber replacement slows with age
3. Results in ration change, leading to brittle bones
4. Articular cartilages wear thin and aren’t replaced
5. Fibrocartilage changes result in disc problems
The Skeletal System
L. Age-related dysfunctions
1. Bursitis
a. What is a bursa?
b. Where are they found?
c. What causes bursitis?
d. How is it treated?
The Skeletal System
L. Age-related dysfunctions
2. Arthritis
a. To what does the term ‘arthritis’ refer?
b. What parts of a synovial joint are involved?
c. What is the response of the joint?
d. Three main types
i. osteoarthritis
ii. rheumatoid arthritis
iii. gouty arthritis
The Skeletal System
L. Age-related dysfunctions
2. Arthritis
d. Three main types
i. osteoarthritis (degenerative joint disease)
1) 90% of people >40 years old have it
2) articular cartilages degenerate
3) bony spurs develop
4) most common locations
5) possible causes
The Skeletal System
L. Age-related dysfunctions
2. Arthritis
d. Three main types
ii. rheumatoid arthritis
1) not necessarily old age disease
2) bilateral effects
3) initial insult is inflammation of synovial membrane
4) scarring occurs with growth of a pannus
5) causes
6) what can be done
The Skeletal System
L. Age-related dysfunctions
2. Arthritis
d. Three main types
iii. gouty osteoarthritis
1) excessive blood uric acid sodium urate crystal precipitation
2) inflammatory response usually begins in great toe
3) tends to be chronic
4) can lead to tophus formation
5) causes
6) what can be done
The Skeletal System
L. Age-related dysfunctions
3. Osteoporosis
a. Bone remodeling gone bad?
b. Women vs. men
c. Vertebrae most affected
d. Suspected factors
i. calcium
ii. vitamin D
iii. estrogen
iv. lack of exercise
normal osteoporotic
normal osteoporotic
The Skeletal System
L. Age-related dysfunctions
3. Osteoporosis
e. treatments
i. estrogen replacement therapy
ii. calcitonin therapy
iii. exercise
4. Tumors of bone
end
The Skeletal System
M. Take home messages
1. Healthy bone is in balance between formation (osteogenesis) and resorption (osteolysis)
2. Synovial joints allow free movement
3. Bursitis and arthritis are inflammatory problems that limit movement
4. Osteoporosis is a direct result of decreased sex steroids that affects us all