Bone TissueBone Tissue
A. Physiology: functions of boneA. Physiology: functions of bone
B. Anatomy: structure of boneB. Anatomy: structure of bone
C. Histology of boneC. Histology of bone
D. Bone homeostasisD. Bone homeostasis
1. Remodeling1. Remodeling
2. Bone's role in calcium 2. Bone's role in calcium homeostasis homeostasis
Physiology: Functions of BonePhysiology: Functions of Bone
1. support1. support
2. protection2. protection
3. movement3. movement
4. mineral homeostasis4. mineral homeostasis
5. blood cell production (hematopoiesis)5. blood cell production (hematopoiesis)
6. energy storage6. energy storage
Shapes of BonesShapes of Bones
1. long1. long
2. short2. short
3. flat3. flat
4. irregular4. irregular
Types of BoneTypes of Bone
1. compact (dense)1. compact (dense)
2. spongy 2. spongy (cancellous)(cancellous)
Long Bone AnatomyLong Bone Anatomy
1. diaphysis1. diaphysis2. epiphysis2. epiphysis3. metaphysis3. metaphysis4. epiphyseal plate4. epiphyseal plate
(Read bone dvp. pg. 220-227)(Read bone dvp. pg. 220-227)5. articular cartilage5. articular cartilage6. articular surfaces6. articular surfaces7. periosteum7. periosteum
a. fibrousa. fibrous b. osteogenicb. osteogenic
8. medullary cavity8. medullary cavity9. endosteum9. endosteum
Bone Cell TypesBone Cell Types1. osteoprogenitor cells1. osteoprogenitor cells
2. osteoblasts -- (osteogenesis)2. osteoblasts -- (osteogenesis)
3. osteocytes– (strain sensors)3. osteocytes– (strain sensors)
4. osteoclasts -- (bone resorption/osteolysis)4. osteoclasts -- (bone resorption/osteolysis)
Bone MatrixBone Matrix
1. ground substance (25%)1. ground substance (25%)
2. collagen (25%)2. collagen (25%)
3. mineral salts (50%)3. mineral salts (50%)
-- tricalcium phosphate (hydroxyapatite)-- tricalcium phosphate (hydroxyapatite)
-- ossification-- ossification
Bone HistologyBone Histology
1. Haversian system1. Haversian system
(osteon)(osteon)
2. Haversian canal2. Haversian canal
3. lacuna3. lacuna
4. lamella4. lamella
5. canaliculus5. canaliculus
Bone and Calcium HomeostasisBone and Calcium Homeostasis
1. remodeling1. remodeling
2. serves to:2. serves to:
a. resist mechanical stressa. resist mechanical stress
b. remove worn boneb. remove worn bone
c. store calciumc. store calcium
(1) parathyroid hormone and vitamin D(1) parathyroid hormone and vitamin D
(2) calcitonin(2) calcitonin
> 10.5 mg/dL
< 9.5mg/dL
Less kidney reabsorption(more calcium excretion)
(osteogenesis)
(osteolysis)
(Intestinal absorption too)
CALCITONIN and BLOOD CALCIUM REGULATION
CONTROLLED CONDITION
RECEPTOR
RETURN TO HOMEOSTASIS
EFFECTORS
CONTROL CENTER
Normocalcemia(blood calcium = 9.5-10.5mg%)
A stress or stimulus causes an increase in blood calcium
Parafollicular cells of thyroid gland recognize hypercalcemia
(blood calcium >10.5 mg%
Parafollicular cells secrete calcitonin
Reduced osteoclast activity
Increased osteoblast activity
Increased bone formation results in increased calcium deposition in bone –
Return to normocalcemia
negative feedback
PTH and BLOOD CALCIUM REGULATION
CONTROLLED CONDITION
RECEPTOR
RETURN TO HOMEOSTASIS
EFFECTORS
CONTROL CENTER
Normocalcemia(blood calcium = 9.5-10.5mg%)
A stress or stimulus causes a decrease in blood calcium
Chief cells of parathythyroid glands recognize hypocalcemia
(blood calcium <9.5 mg%
Chief cells secrete PTH
Increased osteoclast activity
Decreased osteoblast activity
Increased urine phosphate output
Decreased urine calcium output
Increased bone breakdown results in increased calcium release to blood –
Return to normocalcemia
negative feedback
end
Bone Growth, Stress and Bone Growth, Stress and OsteoporosisOsteoporosis