Name: __KEY—THIS ONE NOT GRADED OR COLLECTED_________________________ Period: ____
Chapter 6: The Skeletal System
Functions of Bone and the Skeletal System- page 125
OBJ: Discuss the functions of bone and the skeletal system.
Basic functions of bone tissue and the skeletal system:
a. Support: _framework for the body, supports soft tissues, provides points of attachment for
most skeletal muscles_____________________________
b. Protection: _for internal organs; i.e. cranial bones protect brain, vertebrae protect spinal
cord, rib cage protects heart and lungs_______________
c. Assisting in movement: _skeletal muscles attach to bone-so when muscles contract they pull
on bone; bone + muscle produce movement___________
d. Mineral homeostasis: _bone tissue stores minerals; i.e. calcium and phosphorus; releases
them on demand when needed into blood stream to distribute to other body parts thus
maintaining homeostasis____________________________
e. Blood cell production:
i. Red bone marrow: _connective tissueproduces red blood cells, white blood cells, and
platelets_______________________________________
Consists of: _developing red blood cells, adipocytes, fibroblasts, and macrophages_____
Found where: _developing bones of fetus and in some adult bones i.e. pelvis, ribs,
sternum, vertebrae, skull, and ends of arm bones and thigh bones_____________
ii. Hemopoiesis: _process by which red blood cells, white blood cells, and platelets are
produced___________________________________________________________
f. Triglyceride storage:
i. Yellow bone marrow: _stores triglycerides in its adipose cells; potential energy reserve__
Consists of: _adipose cells and a few blood cells_____________________________
Found in: _mainly adults, newborn have red bone marrow involved in hemopoiesis which
changes to yellow as they age___________________________________________
I. Types of Bones: FYI Mr. Jones should be covering this with you- page 125
OBJ: Classify bones on the basis of their shape and location.
Four main types of bones of the body:
a. Long bones: have greater length and width, consists of a shaft and a variable number of
ends, usually somewhat curved for strength.
Examples: thigh (femur), leg (tibia and fibula), arm (humerus), forearm (ulna and
radius), and fingers and toes (phalanges)
b. Short bones: somewhat cube-shaped and nearly equal in length and width.
Examples: most wrist and ankle bones
c. Flat bones: generally thin, over considerable protection, have extensive surface areas
for muscle attachment.
Examples: cranial bones (protect the brain), sternum/breastbone and ribs (protect
organs in thorax), pelvis (protects digestive and reproductive organs),and scapulae
(shoulder blades)
d. Irregular bones: complex shapes
Examples: vertebrae of the backbone and some facial bones
II. Structure of Bones- pages 125- 129
OBJ: Describe the parts of a long bone.
Describe histological features of bone tissue.
A. Macroscopic Structure of Bone
Parts as they relate to a long bone with greater length than width
1. Diaphysis: _bone’s shaft or body—long, cylindrical, main portion of bone_____________
2. Epiphyses: _distal and proximal ends of bones__________________________________
3. Metaphyses: _regions in a mature bone where diaphysis joins epiphyses; in growing
bone each metaphyses includes an epiphyseal plate, layer of hyaline cartilage that
allows the diaphysis of bone to grow in length; when bone growth in length stops,
cartilage in epiphyseal plate replaced by bone and this bony structure is noe known as
the epiphyseal line________________________________________________________
4. Articular cartilage: _thin layer of hyaline cartilage covering part of the epiphysis where
bone forms a joint (articulation) with another bone; it reduces friction and absorbs
shock; lacks a perichondrium so repair of damage is limited________________________
5. Periosteum: _tough sheath of dense irregular connective tissue surrounding a bone’s
surface wherever it lacks articular cartilage; consists of bone-forming cells enabling bone
to grow in diameter or thickness; protects the bone, assists in fracture repair, helps
nourish bone tissue, serves as attachment point for ligaments and tendons___________
6. Medullary cavity: _marrow cavity; space within diaphysis containing yellow bone
marrow in adults__________________________________________________________
7. Endosteum: _thin membrane lining medullary cavity; contains single layer of boneforming cells_____________________________________________________________
B. Microscopic Structure of Bone
Composition of intracellular materials of the bone, or osseous tissue matrix
_25_% water
_25_% collagen fibers (protein)
_50_% crystallized mineral salts
Define calcification: _Mineral salts are deposited into a framework formed by collagen fibers
they crystallize and tissue hardens___________________________
Calcification is initiated by: _osteoblasts; bone-building cells______
Hardness of bone depends on _ crystallized inorganic mineral salts_________
Flexibility depends on _collagen fibers______________________________
Tensile strength is _provided by collagen fibers and other organic molecules that offer
resistance to being stretched or torn apart__
Four major types of cells in bone tissue are:
(1)_Ostegenic cells____________________
_unspecialized cells that produce other types of bone cells_________
(2)_Osteoblasts_______________________
_bone-building cells; do not undergo cell division; synthesize and secrete collagen fibers and
other organic components to build matrix of bone tissue. They become trapped in their
secretions and become osteocytes_
(3)_Osteocytes_______________________
_mature bone cells; main cells in bone tissue and maintain its daily metabolism, i.e. exchange of
nutrients and wastes with blood; do not undergo cell division____
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(4)_Osteoclasts________________________
_huge cells derived from fusion of up to 50 monocytes (type of white blood cells)-concentrated
in endosteum; release strong lysosomal enzymes and acids to digest proteins and mineral
components of bone matrix; this breakdown of bone matrix called resorption (part of normal
growth, development, maintenance, repair of bones______
Spaces between cells and matrix are for:
(a)_channels for blood vessels (supply bone with nutrients)__
(b)_storage for red blood marrow_________________________
Composition of skeleton: BASED ON SIZE AND DISTRIBUTION OF SPACES
_80___% compact bone
_20___% spongy bone
1. Compact Bone Tissue
Contains few spaces and arranged in repeating structural units called osteons or Haversian
systems; forms external layer of all bones; makes up bulk of diaphysis of long bone;
provides protection and support; resists stress produced by weight and movement
2. Spongy Bone Tissue
Makes up most of the bone tissue of short, flat, and irregularly shaped bones; forms most of
epiphyses of long bone and a narrow rim around the medullary cavity of the diaphysis of
long bones.
3. Chart summarizing differences and similarities between compact bone tissue and spongy
bone tissue:
Dense or Compact Bone
Mostly solid
Spongy or Cancellous Bone
Hardness
Bony structures with spaces
filled with bone marrow
Consists of
Osteocytes in lacunae
Osteocytes in lacunae
Location
Covers all bone surfaces; except Short, flat bones, inside ends of
where they could rub
long bones
Functional units
Osteons or haversian systems
Trabeculae filled with red bone
marrow
Stress tolerance
High end to end; low from side
Not on heavy stress areas, can
take stress from any directiondisperses it
4. What are trabeculae? little beams; irregular latticework of thin columns of bone; spaces
between filled with red bone marrow____
5. What is a bone scan? _diagnostic procedure that uses radioactive tracers injected intravenously;
x-ray like scan light or dark spots could be problem areas=> dark maybe cancerous, abnormal
heal spots from fracture, etc. light degenerative bone disease, fractures, bone
infections______________________________________________________________________
III. Bone Formation- pages 129- 134
OBJ: Explain the importance of bone formation during different phases of a person’s lifetime.
Describe the factors that affect bone growth during a person’s lifetime.
Where is the site of ossification? _loose fibrous connective tissue membranes and pieces of hyaline
cartilage, shaped like little bones in embryonic skeleton____
When does bone formation occur?
(1) Initial formation of bones in embryo and fetus
(2) Growth of bones during infancy, childhood, and adolescence until adult sizes are reached
(3) Remodeling of bone (replacement of old bone tissue by new bone tissue throughout life)
(4) Repair of fractures (breaks in bones) throughout life
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A. Initial Bone Formation in an Embryo and Fetus
What is the embryonic “skeleton” composed of? _ First composed of mesenchyme shaped liked
bones, sites/templates where ossification will occur__________________________________
When does ossification begin? _ Ossification begins during the sixth week of embryonic
development and follows one of two patterns______________________________________
What are the two methods of bone formation (ossification)?
(1)_Intramembranous ossification____________________________
Where? _ Bone forms directly in mesenchyme arranged in sheet-like layers resembling membranes;
directly on or within loose fibrous connective tissue membranes_________________
(2) _Endochondral ossification_________________________________
Where? _ Bone forms within hyaline cartilage that develops from mesenchyme____
1. Intramembranous Ossification
Simplest of two methods of ossification.
Forms what? _ Forms flat bones of skull and mandible (lower jawbone) _
Replaces what on infants? _ ‘soft spot’ on fetal skull _________________
What is the sequence of events at the center of ossification?
_(1) development of ossification center: mesenchymal cells cluster together and differentiate;
first into osteogenic cells then into osteoblast; osteoblasts secrete organic extracellular matrix
of bone until trapped/surrounded by it
_(2) calcification: secretion of extracellular matrix stops, cells now called osteocytes lie in
lacunae and extend their narrow cytoplasmic processes into canaliculi that radiate in all
directions. Within a few days calcium and other minerals salts are deposited and extracellular
matrix hardens or calcifies
_(3) formation of trabeculae: as bone extracellular matrix forms, develops into trabeculae that
fuse to one another to form spongy bone. Blood vessels grow in spaces between trabeculae
along surface of new bone. Connective tissue associated with blood vessels in trabeculae
differentiate into red bone marrow
_(4) development of periosteum: in conjunction with formation of trabeculae, mesenchyme
condenses at the periphery and develops into periosteum. Eventually a thin layer of compact
bone replaces surface layer of spongy bone replaced with compact bone; remains spongy in
center
2. Endochondral Ossification
Replacement of cartilage by bone; most bone is formed this way.
What is the sequence of events of endochondral ossification in long bones?
(1) _development of the cartilage model___________________________________
Explain: _mesenchymal cells crowd into shape of future bone develop into chondroblasts; these
secrete cartilage matrix consisting of hyaline cartilage; perichondrium membrane develops
around cartilage model_______
(2) _growth of the cartilage model_________________________________________
Explain: _chrondoblasts become chrondrocytes; cartilage model continues to grow; cells grow
some bursts release contents increasing pH of surrounding matrix; change in pH triggers
calcification; other cells die and lacunae form and slowly merge into cavities_______
(3) _development of the primary ossification center___________________________
Explain: _proceeds inward from external surface of bone; nutrient artery penetrates
perichondrium simulating osteogenic cells to differentiate into osteoblasts; perichondrium
starts to form bone now known as periosteum; periosteal capillaries grow into disintegrating
calcified cartilage; primary ossification center forms from capillaries now bone tissue will replace
most cartilage; osteoblasts deposit bone matrix forming spongy bone trabeculae then
osteoblasts break down trabeculae at bone ends leaving a cavity; medullary cavity fills with red
bone marrow___________________________________________
(4) _development of the medullary (marrow) cavity________
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Explain: as primary ossification center grows towards ends of the bone, osteoclasts break down
some of the newly formed spongy bone trabeculae, this activity leaves a cavity, the medullary
(marrow) cavity, in the diaphysis (shaft), most of diaphysis is replaced by compact bone
(5) _development of the secondary ossification centers________________________
Explain: _branches of epiphyseal artery enter epiphyses secondary ossification centers develop;
around time of birth; spongy bone remains in the interior of epiphyses no medullary cavities
formed; proceeds outward from center of epiphyses toward surface of bone________
(6) _formation of articular cartilage and the epiphyseal plate___________________
Explain: _hyaline cartilage covering epiphyses becomes articular cartilage; prior to adulthood
hyaline cartilage remains between diaphysis and epiphyses as epiphyseal plate = lengthwise
growth of bones; stops between ages 18-25 cartilage replaced by bone = epiphyseal line bone
length growth stops. Damage to epiphyseal plate may result with shorter bone in adulthood__
B. Bone Growth in Length and Thickness (long bones)
1. Growth in Length
Through the activity of the _epiphyseal plate_.
What divides in this plate? _young chondrocytes__
Explain how the bone increases in length.
_ As bone grows in length, new chondrocytes are formed on epiphyseal side of plate, old
chondrocytes on diaphyseal side are replaced by bone thus thickness of epiphyseal plate
remains constant but on the diaphyseal side it increases in length
At what age does your bone stop growing in length? _ Adolescence ends = formation of new cells
and extracellular matrix decreases and then stops between 18-25 years of age ____
What appears when bone stops growing in length? _ bone replaces all cartilage leaving bony
structure called epiphyseal line _____________________________________
2. Growth in Thickness
On surface, cells in the _periochondrium_ differentiate into _osteoblasts_,
lamella are added to e surface of the bone, new osteons of _compact bone tissue_.
C. Bone Remodeling
Define bone remodeling: _Ongoing replacement of old bone tissue by new bone tissue __
_Bone resorption_, removal of minerals and collagen fibers from bone by
osteoblasts.
-results in destruction of bone extracellular matrix
_Bone deposition_, addition of minerals and collagen fibers to bone by
osteoblasts.
- results in formation of bone extracellular matrix
What happens if too much mineral is deposited? _ surplus bone tissue may form thick bumps,
called spurs which can interfere with joint movement _
What happens if there is excessive loss of calcium or tissue? _ bone is weakened becomes overly
flexible and vulnerable to fracture_
D. Fractures
Define fracture: _any break in a bone_
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List and define the four different types of fractures below:
(1) partial: incomplete break across the bone; i.e. a crack
(2) complete: complete break across the bone; bone broken in two or more pieces
(3) closed (simple): fractured bone does not break through skin
(4) open (compound): broken ends of bone protrude through skin
E. Factors Affecting Bone Growth and Remodeling
Factors that control bone growth in the young, bone remodeling in adults, and the repair of
fractured bones:
(1) Minerals: _ Ca, P, Mg need adequate amounts of each __________________
(2) Vitamins: _A, C, D________________________________________________
(3) Hormones: _ hGH, IGFs (insulin-like growth factors; produced locally by bone and by the
liver when stimulated by hGH ), insulin, thyroid hormones, parathyroid hormones,
calcitonin ______________________________________________________
hGH: _ main hormone before puberty that stimulates bone growth; produced by
anterior lobe of pituitary gland _____________________________________
over secretion of hGH: _ produces giantism, person becomes taller and heavier than
normal _________________________________________________________
under secretion of hGH: _ produces dwarfism, short stature ______________
(4) Stress (weight bearing exercise):
Mineral crystals generate _ production of collagen fibers, bone mass _______
Osteoblasts are _bone-forming cells__________________________________
Heavily stressed bones are _ notably thicker; builds & retains bone mass ____
Unstressed bones become _ lose strength; loss of bone mass _____________
Example: leg in cast up to ~30% of bone mass
Examples of serious bone health risks: _ bedridden or paralyzed patients; people in
weightless environments ____________________________________
F. Bone’s Role in Calcium Homeostasis
Bone stores _99_% of the total amount of calcium in the body.
How does calcium become available to other tissues? _ when broken down during remodeling
(replacement of old bone with new bone)_______________________________
Effects of small changes in blood calcium levels:
a. Too high: _heart may stop___________________________________
b. Too low: _breathing may cease______________________________
Nerve cell functions depend on the right levels of _ Ca2+__.
Enzymes require _ Ca2+___, as a cofactor.
Blood clotting requires _ Ca2+___.
What is the function the bone in calcium homeostasis in blood calcium levels? _ to “buffer” the
blood calcium level, releasing Ca2+ to the blood when blood calcium levels falls and depositing
Ca2+ back in bone when blood level rises __________________________________________
What hormone regulates Ca2+? _parathyroid hormone (PTH)_________________________
Produced by? _parathyroid glands______________________________________________
What other hormone is involved in calcium homeostasis? _calcitonin (CT) _____________
Produced by? _thyroid gland_____________________________________
IV. Exercise and Bone Tissue – page 134
OBJ: Describe how exercise and mechanical stress affect bone.
Bone can alter its strength in response to _mechanical stress_ because it increases deposition of
_mineral salts__ and production of _collagen fibers_.
What happens in the absence of mechanical stress? _Without mechanical stress bone does not
remodel normally because resorption outpaces bone formation________
Comparison of Female and Male Skeletons- page 167
OBJ: Identify the principle structural differences between female and male skeletons.
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Male skeletal bones are generally larger/ smaller than female skeletal bones.
What other areas of male skeletal structures exhibit this same characteristic? _ The chief differences
between the male and female skeletons are the proportionately larger pelvis in the female and the
proportionately larger thorax, or rib case, in the male. These differences account for the wider
shoulders and narrower hips of the male; the longer waistline, lower buttocks, and wider hips of the
female. They also cause the female arms to flare out wider when they are swinging back and forth
and the femur, or thigh bone, to be a little more oblique. The hair and breasts, of course, distinguish
the female figure, but they are merely its most obvious characteristics. The female is different from
head to toe. The jaw is less developed. The neck is more slender. The hands are smaller and much
more delicate. The muscles of the arms are smaller and much less in evidence. The waistline is
higher. The great trochanter of the femur extends out farther; the buttocks are fuller, rounder, and
lower. The thighs are flatter and wider. The calf is much less developed. The ankles and wrists are
smaller. The feet are smaller and more arched. The muscles, in general, are less prominent, more
strap-like but those of the thighs and buttocks, which are proportionately larger and stronger in the
female. This extra strength is, like the larger pelvis, designed to carry the extra burden of the unborn
child___________________________________________________________________
V. Aging and the Skeletal System—pages 167-168
OBJ: Describe the effects of aging on the skeletal system.
 Birth to adolescence, more bone produced than lost through remodeling
 Young adults, rate of bone loss and production about equal
 As sex hormone levels decrease in middle age, decreases in bone mass occur; bone
destruction outpaces bone formation
 Women’s bones tend to be smaller so they lose bone mass earlier than men in old age
 Aging = brittle bones and loss of bone mass
 Brittle bones caused by decrease in protein synthesis rate and human growth hormones (less
collagen fibers = less bone strength and flexibility
 Loss of bone mass can lead to deformities: stiffness, loss of height, loss of teeth
Chapter 4: Tissues
I. Types of Tissue- page 79
OBJ: Name the basic type of tissue that is found in the skeletal system and state the characteristics of
it.
Which tissue discussed in this section relates to the skeletal system?
_ Connective; secondary muscular
Connective: -protects and supports the body and its organs, binds organs together, stores energy
reserves as fat, provides immunity
Muscular: -generates physical force to move body structures
What are cell junctions? _ Point of contract between plasma membranes of tissue cells
As each osteocyte lays matrix, it gets sealed into its own room and they reach out to the next
osteocyte and communicate by gap junctions (type of cell junctions) called lacunae even though
they are very isolated
II. Connective Tissue—pages 88- 96
OBJ: Discuss the general formation of connective tissue related to bone.
Describe the structure, location, and function of the various types of connective tissue related to
bone.
A. General Features of Connective Tissue—page 88
Connective tissue consists of:_cells and extracellular matrix__
Extracellular matrix consists of: _ materials between widely spaced cells composed of protein fibers
and ground substance ___________
What is ground substance? _ materials between cell ands and fibers________________________
What are fibers made of? _protein____________
What is the texture of the extracellular matrix of bone? _highly vascular__________________
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What does vascular mean? _have a rich blood supply__________________
Is cartilage vascular? _no___________________________________________
Are tendons vascular? _no_________________________________________
Do all types of connective tissue have nerves? If some do not, name them. _no, cartilage does not__
B. Connective Tissue Cells – pages 88- 89
Read through this section, what types of cells are found in bone tissue?
_ Plasma cells technically in blood/ Mast cells are found resident in tissues throughout the body,
particularly in association with structures such as blood vessels and nerves, and in proximity to surfaces
that interface the external environment. Mast cells are bone marrow-derived and particularly depend
upon stem cell factor for their survival/ adipocytes in brown bone marrow fat cells ________
C. Connective Tissue Extracellular Matrix—pages 89-90
Extracellular materials between cells vary dependent upon types of connective tissue.
1. Ground substance
Location: _ Between the cells and fibers______________________________________
Function: _ Supports cells, binds them together, provides medium through which substances are
exchanged between the blood and cells_____________________________________
What type of ground substance is found in bone tissue? _ Chondroitin sulfate ______
What is its function? _ Provides support and adhesiveness in bone connective tissues _____
2. Fibers
Function: _ Strengthen and support connective tissues _____________________________
Read through this section, what types of fibers are found in bone/skeletal muscle tissue?
_ Collagen fibers found in bones, cartilage, tendons, ligaments
What is/are the functions of this/these fibers in bone/skeletal muscle tissue?
_resist pulling forces, but flexible, provide strength
D. Classification of Connective Tissues—pages 91-96
1. Loose Connective Tissue
a. areolar connective tissue---not applicable to bones
b. adipose tissue---yellow bone marrow, padding around joints
function: _ serves as energy reserve; support __________________
c. reticular connective tissue---red bone marrow (gives rise to RBCs)
function: _filters and removes worn-out blood cells; forms a scaffolding for bone marrow
2. Dense Connective Tissue
a. dense regular connective tissue---forms tendons (attach muscle to bone), most ligaments
(attach bone to bone), and aponeuroses (sheet-like tendons attach muscle to muscle or muscle
to bone)
function: _ provides strong attachment between structures, allows them to resist pulling tension)
b. dense irregular connective tissue---periosteum of bone, periosteum of cartilage, joint capsules
function: _ provides tensile (pulling) strength___________________
c. elastic connective tissue---not applicable to bones
*****NOTE: FOUND IN SOME LIGAMENTS
BETWEEN VERTEBRAE
3. Cartilage
Consists of: _ dense network of collagen fibers and elastic fibers embedded in a rubbery
component of ground substance (chrondroitin sulfate)__________________________
Strength is due to: _collagen fibers__________________________________________
Resilience due to: _ chrondroitin sulfate _____________________________________
Cells called _chondrocytes__ which are found in _lacunae__
What are lacunae? _ spaces in the bone matrix where osteocytes lie ____________
What surrounds the surface of cartilage? _ membrane of dense irregular connective tissue
called perichondrium ___
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How is cartilage different from other types of connective tissue? _ has no blood vessels or
nerves, except in perichondrium ___
What are the three types of cartilage?
(1)_ hyaline cartilage_ (most common; weakest)
Consists of: _resilient gel as its ground substance; appears in body as bluish-white shiny
substance__________
Properties: _compressible, flexible, insensitive____
Locations: ribs to sternum; supporting larynx, trachea, and bronchia; bone ends at synovial
joints; part of large septum
(2) _fibrocartilage____ (strongest)
Consists of: _chondrocytes scattered among bundles of collagen fibers_____
Lacks: _perichondrium________
Properties: _strength and rigidity____
Location: _discs between vertebrae, pads of knee joints_______
(3) _elastic cartilage____
Consists of: _chondrocytes within threadlike network of elastic fibers_______
Properties: _strength and elasticity; maintains shape of certain structures; i.e. external ear__
Locations: auricle of external ear; epiglottis and part of larynx; auditory canal
4. Bone Tissue
List the types of bone tissue: SHOULD READ COMPOSED OF…
a. _bone or osseous tissue____________
b. _periosteum_____________________
c. _red and yellow bone marrow______
d. _endosteum_____________________
Main component of compact bone: _ Osteon of Haversian system _______
Main component of spongy bone: _Trabeculae_______________________
Main functions of bone tissue:
(1) _ Supports soft tissue
(2) Protects delicate structures
(3) Works with skeletal muscles to generate movement
(4) Stores calcium and phosphorus
(5) Stores red bone marrow
(6) Storage site for triglycerides
5. Liquid Connective Tissue---NOT APPLICABLE TO BONE TISSUE
III. Membranes—pages 96-98
OBJ: Define synovial membrane.
Describe the classification of membrane that relates to bones.
Define synovial membrane: _ (flat sheets of pliable tissue) line the cavities of some joints
A. Mucous Membrane---NOT APPLICABLE TO BONE
B. Serous Membrane---NOT APPLICABLE TO BONE
C. Synovial Membrane
Location: _ joints areas of bone
Types of tissue: _composed of areolar connective tissue and adipose tissue with collagen fibers
Function: secretes synovial fluid from its synoviocytes that lubricates ends of bones as they move at
the joints, nourishes cartilage, removes microbes and debris from joint cavity___
IV. Muscular Tissue---page 98
OBJ: Describe the function of muscular tissue.
Contrast the locations of the three types of muscular tissue and identify the type associated
with bone.
Read through this section, what type of muscular tissue is found in bone? Skeletal ______
V. Tissue Repairing: Restoring Homeostasis—pages 98-99
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OBJ: Describe the role of tissue repair in restoring homeostasis.
_Tissue repair_ is the process that replaces worn-out, damaged, or dead cells.
Bone connective tissue has a continuous capacity for renewal because it has an _ample blood
supply_.
Cartilage does not have a continuous capacity for renewal because of _a poor blood supply_.
Muscular tissue _relatively poor capacity for renewal of lost cells_ .
VI. Aging and Tissues---page 100
OBJ: Describe the effects of aging on tissues.
 The younger a body is, the quicker tissues repair themselves because of a better nutritional
state and a better blood supply.
 Bone is mostly affected by the changes in the number of and quality of collagen fibers that
are responsible for the strength of tendons.
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