Musculoskeletal System Bones
Homeostasis
Bone Function
Bone Structure
Bone Growth
Homeostasis
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“steady state”
Need to maintain
balance between
intracellular and
extracellular fluid.
3 points:
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Each cell metabolizes
All cells contribute to the
body
Combined contributions
= stable ECF
Homeostasis
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3 players
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Sensory receptor: sense
change in environment;
ex) neurons
Integrator: processes
info; ex) brain
Effectors: carry out
response; ex) muscles
and glands
2 types of feedback:
Negative and Positive
Homeostasis
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Negative Feedback
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Reverses the altered condition
Ex) maintaining body temperature
Positive Feedback
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Intensify the
change from the
original condition
Ex) oxytocin in
giving birth
Bone Function
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5 major functions
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Movement
Support
Protection
Mineral Storage
Blood cell formation
Bone Structure
Made of both living
and non-living cells
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Living= osteocytes
Non-living =
mineralized matrix
of collagen,
protein, carbs, and
lacunae
Bone Structure
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1.
2 kinds of bone tissue:
Compact bone:
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2.
Outside of bones
Dense & solid
Made of collagen =
tensile strength
Made of osteons which
surround canals that
carry blood vessels and
nerves
Spongy Bone:
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Inside
Flattened struts
Can contain red marrow
which makes blood cells
Can contain yellow
marrow
Bone Structure
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Red bone marrow =
makes red blood cells,
platelets, and most
white blood cells
Yellow bone marrow =
consists mainly of fat
cells. Can be converted
back to red marrow.
Bone Growth
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Start with cartilage template
Growth continues at
epiphyses; triggered by GH
Remodeling= the process of
growing or breaking down
bone tissue
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Osteoblasts = deposit bone
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Calcitonin triggers uptake
and production
Osteoclasts = breakdown
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PTH triggers enzyme
production that breaks
down bone
Bone Growth
The skeletal
system helps
maintain Calcium
level homeostasis.
 http://bcs.whfree
man.com/thelifew
ire/content/chp42
/4202003.html
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Skeleton
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206 bones
Divided into:
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Axial Skeleton
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Appendicular Skeleton
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Hanging appendages
Ligaments
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Head to toe vertical axis
Connect bone to bone
Tendons
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Connect muscle to bone
Axial Skeleton
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Down the center of
the skeleton:
 Skull
 Vertebrae
 Ribs
 Sternum
Appendicular Skeleton
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The appendages of
the body.
Pectoral Girdle:
 Ex) shoulder
blade, arm bones,
and fingers
Pelvic Girdle
 Ex) pelvis, leg
bones, and toes
Joints
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Areas of contact/near
contact between bones.
3 types:
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Synovial
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Cartilaginous
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Have a cavity filled with
synovial fluid.
Most flexible joints
Ex) knee
Somewhat flexible
Ex) disk b/w vertebrae
Fibrous
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No cavity b/w bones
Not flexible
Ex) skull bones
Fibrous: A & B.
Cartilaginous C & D
Synovial E - J