1. Support

2. Protection

3. Movement

4. Mineral Homeostasis

(ca 2+ and phosphorus)

5. Hemopoisis

6. Triglyceride Storage

Types of Bone

1. Long

2. Short

3. Flat

4. Irregular

5. Seasmoid

Bone that forms in a tendon

Ex. Patella

Fuctions of periosteum

1. Protect and nourish bone tissue

2. Attachment for tendons & ligaments

3. Contains bone- building cells

Marrow Cavity of Long Bone

(Medullary Cavity)

thin membrane lining marrow cavity

Contains bone-building cells

Unspecialized cells developed from mesenchyme (tissue that all CT developes from)

Only bone cells that are able to divide

Found along innner periosteum and endosteum

Cells that make and secrete the EM of bone tissue

** Bone-building Cells**

As they get trapped in their own secretions, they become osteocytes

Found beneath periosteum of ALL bones

Makes up diaphysis of long bones

1. Does not contain osteons

2. Made up of columns of bone called Trabecular with spaces between- filled with red bone marrow

3. Makes up bulk of bone tissue of short, flat and irruglar bones

4. Forms epipysis of long bones

** sites of hemopoiesis in adults are hip bones, sternum, ribs & epiphysis**

2 methods of Ossificaiton

1. Intramembraneous Ossification

2. Endochondral Ossificaiton

(both involve replacing cartilage with bone)

Flat skull bones and mandible

A. Cells cluster together and differentiate into osteoblasts

B. osteoblasts create spongy bone throughout to make a contineous sheet of bone

C. Red bone marrow fills spaces between trabeculae.

D. Eventually a thin layer of compatct bone replaces spongy bone at periphery only; spongy bone remains in the center

Endochondral Ossification

2 Parts

Bone forms within hyaline cartilage model (Developed from mesenchyme)

1. Primary Ossification- occurs before birth and in diaphysis only.

a. Nutrient artery pierces cartilage model

b. osteoblasts make up spongy bone throughout diaphysis

c. Osteoclasts break down some newly formed bone to create marrow cavity

d. Replace remaining spongy bone with compatct bone

2. Secondary Ossification- occurs around birth and in epipthesis only.

a. Nutrient artery pierces epipthesis

b. Osteoblasts make spongy bone throughout BUT leave a ring of cartilage which becomes articular cartilage and growth plate

1. Movement of body

2.stabilize postition

3. store and move substances within body

4. prodcuce heat

1. epimysium

2. perimysium

3. endomysium

outer most layer

surrounds entire muscle

each muscle fiber is in close contact with one or more capallaries

each musle fiber also very near axon terminal

network of tiny tubules

stores ca2+ for contraction

extend entire length of fiber

(paper towel roll and pipe cleaner)

composed of thick and thin protein filaments

protein filaments arranged in specific compartments

Smallest part that can contract

middle of filaments

seperates by Z discs

composed of myosin

just hang out in middle of thin filaments

Mysoin structure

1. troponin

2.tropomyosin

Actin molecule

shortening of all sarcomeres of a msucle fiber at the same time

Done by thin filaments sliding past thick (toward center of sarcomere)

Muscle must be stimulated by an Ap carried by a MOTOR NEURON

SAME AS CH 9

Synaptic vesicles, NT, Etc

ACH

always excitatory

Steps of excitation

(stimulation)

1. Impulse travels down axon

2. Ca2+ goes into synaptic end bulb

3. ACH released into synaptic cleft

4. ACH binds to receptors

5. Na+ channels open = na+ enters muscle fibers

6. muscle AP generated

7. AP travels down sarcolemma and down T tubules

8. SR- release ca2+ into sarcoplasm

9. ca2+ binds troponin and opens the myosin binding sites

1. myosin head splits ATP and becomes energized

2. crossnridge is formed-myosin heads attach to the actin on the thin filaments

3. powerstroke- all of the myosin heads swivel and rotate to center pulling thin filaments with it

4.ATP binds myosin head and detaches cross bridge

**cyle will continue as long as enough ca2+ and ATP in sarcoplasm

**myosin can be attached to ATP or to actin, but not to both

1. When muscle AP stops, it closes ca2+ channels in SR

2. ca2+ rapidly "put back" into SR

- as ca2+ levels drop in sarcoplasm, tropomyosin moves back over binding sites

thickness

marrow cavity

1. hormones

-prepuberty

-after puberty

2. adequate minerals (ca2+)

3. vitamins A, C & D

4. weight bearing exercises

99% of calcium is stored in bones

becomes available when bone is broken down

bone acts as "buffer" for calcium

main regulator of calcium levels

1. stimulus is decreased blood calcium

2. PTH released by parathyroid glands

3. PTH-

a. increases number and activity of osteoclast

b. decrease calcium loss through urine

c. increase absorbtion in GI tract

1. presence or abscence of synovial cavity

2. type of CT holding bones together

no synovial cavity

fibrous CT

no synovial cavity

cartilage

presence of synovial cavity

dense irregular CT

Synarthosis- immovable

Amphiarthrosis- slightly movable

Diarthrosis- freely movable

hyaline cartilage present

example: epiphyseal plate and between ribs and sternum

fibrocartilage

ex/; pubic symphysis and intervetebral discs