1. Honors Anatomy copy version
Skeletal System1
Honors Anatomy
copy version

2. Bone a combination of CT, epithelial & nervous tissues
18% of weight of human body
Skeletal System includes bones & cartilage
Part 1: Bone
Part 2: Axial Skeleton
Part 3: Appendicular Skeleton
Part 4: Joints

3. FUNCTIONS
SUPPORT
skeleton serves as structural framework by supporting soft tissues & providing attachments for tendons of muscle
2. PROTECTION
Protects most important soft tissue organs from injury

4. FUNCTIONS 3. MOVEMENT 4. MINERAL HOMEOSTASIS
Skeletal muscles attach to bones, when the muscle contract the bones move
4. MINERAL HOMEOSTASIS
Bone stores calcium, phosphorus which both help make bone strong
If body needs these minerals bone releases them

5. Parts of a long bone Diaphysis:
shaft or body; the long cylindrical portion of the bone
2. Epiphysis: distal & proximal ends of bone

6. Parts of a long bone 3. Metaphysis:
region between diaphysis & epiphysis
in growing bone includes metaphyseal plate (hyaline cart. that allows bone to lengthen
4. Articular Cartilage:
layer of hyaline cartilage covering part of epiphysis where bone forms a joint with articulating bone

7. metaphysis

8. Structure of Long Bones
7. ENDOSTEUM
thin membrane that lines marrow cavity
contains 1 layer of bone-forming cells and CT

9. Histology of bone
bone consists of widely separated cells surrounded by large amts extracellular matrix
*bone is hard due to crystallized inorganic mineral salts
*bone is flexible due to collagen

10. Types of Bone Cells OSTEOGENIC CELLS
Stem cells from mesenchyme (origin of all CT)
only bone cells to divide

11. Types of Bone Cells 2. OSTEOBLASTS bone-building cells
synthesize & secrete collagen fibers
initiate calcification

12. Types of Bone Cells 3. OSTEOCYTES mature bone cells main cells in bone
maintain exchange of nutrients & wastes with blood

13. Types of Bone Cells 4. OSTEOCLASTS
huge cells that form by merging of many (50)monocytes
in endosteum
ruffled border faces bone surface: releases lysosomal enzymes & acids that digest underlying bone (bone resorption): part of normal maintenance, growth, development, & repair of bone

14. Types of bone (2) Compact bone Spongy bone few open spaces
outer bone layer of all bones
Spongy bone
inside bones

15. COMPACT BONE strongest form of bone beneath periosteum of all bone
functions:
protection & support
resists stresses produced by weight & movement

16. Parts of Compact Bone OSTEON: aka Haversian Systems
repeating units thru out compact bone
each one has central canal with concentrically arranged lamellae (rings), lacunae (filled with 1 osteocyte)
aligned in same direction along lines of stress
space between osteon filled with interstial lamellae

17. Compact bone

18. Spongy Bone absence of osteons
made of lamellae arranged in irregular columns called trabeculae
makes up most of inside of short, flat, or irregular bones & epiphysis of long bones
lighter than compact bone
Function:
support & protect red bone marrow

19. Spongy bone

20. Bone growth longer: @ epiphyseal plate wider:
called appositional growth
periosteal osteoblasts on outer surface of bone
osteoclast remove compact bone inner border

21. Bone growth: longer

22. Bone growth: wider

23. Bone Remodeling
Most bones are formed b/4 birth but each one continually renews itself for rest of life
~5% of bone being any given time
bone remodeling is the ongoing replacement of old bone tissue by new bone tissue
Bone Resorption
Bone Deposition

24. Bone Resorption
removal of minerals & collagen fibers from bone by osteoclasts
results in destruction of bone extracellular matrix

25. Bone Deposition
addition minerals & collagen fibers to bone by osteoblasts

26. Factors Affecting Bone Growth & Remodeling
Minerals
Ca, P, F, Mg, Fe, Mn
Vitamins
C needed to make collagen fibers & for osteoblast  osteocyte
E & B12 needed for protein synthesis
Hormones
IGF’s in childhood (insulin-like growth factors)
estrogens & androgens important in puberty

27. Fracture & Repair of Bone
Fracture: any break in a bone
Fractures named by:
severity
shape or position of fracture line
person who 1st described it

28. Fracture Repair

29. Calcium Homeostasis
Bone is body’s main reservoir for calcium (stores 99% of total body Ca)
Normal blood level Ca mg/100mL
Calcium important for:
Muscle contraction
Nerve impulses
Blood clotting
Many enzymes require Ca as cofactor)

30. Control of Calcium 2 hormones control Ca in/out bone: Calcitonin
Decreases blood Ca levels by putting more Ca into bone
Parathyroid Hormone (PTH)
Increases blood Ca levels by taking Ca out of bone (increasing osteoclast resorption)

32. Homeostatic Imbalances in Bone
Osteoporosis
condition of porous bones (resorption > deposition)
causes: deficient Ca in diet
USA: > 1 million fractures (hip, wrist, vertebrae) & afflicts 30 million Americans
decreased stature, hunched back, bone pain

33. Homeostatic Imbalances in Bone
Osteoporosis
condition of porous bones (resorption > deposition)
causes: deficient Ca in diet
USA: > 1 million fractures (hip, wrist, vertebrae) & afflicts 30 million Americans
decreased stature, hunched back, bone pain