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67 Cards in this Set

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How many named bones are there?
206
How many bones are you born with?
What happends to them?
Actually born with approximately 300 bones, but a number of these fuse during growth and development
What is the longest bone in the body?
Shortest bone in the body?
Longest= Femur (also strongest)
Shortest= Stapes(in the ear)
BONE
Characteristics of?
Is a type of tissue
Variety of shapes, sizes, functions
Made up of a variety of cell types
BONES: Classification of: By Group
2 Main Groups

Axial (Skull, Ribs, Vertebrae)

Appendicular (Extremeties & Pelvis)
OSTEOLOGY
The study of the formation of bone
BONE: Classification: By Shape
Name them all
Long Bones
Short Bones
Flat Bones
Irregular bones
LONG BONES
Longer than they are wide
Ex. humerus, femur, phalanges, radius, ulna, etc.
SHORT BONES
cube shaped bones of the wrist &
ankle
bones that form within tendons
(ex. patella)
FLAT BONES
thin, flattened, & a bit curved
(sternum, skull bones)
IRREGULAR BONES
bones with complicated shapes
(ex. vertebrae, hip bones)
FUNCTION OF BONES
Support (bones are primary support
involved in sitting, standing, etc)
Protection (ex. skull, thorax, vertebrae
Movement (ex. levers, joints)
Mineral Storage (resevoir for Ca, P)
Hematopoiesis ( formation of BC)
BONE STRUCTURE
Compact Bone
The external layer
Visible part of bone
What is the structural unit of compact bone?
Osteon
BONE STRUCTURE
OSTEON
description
function
Elongated cylinder oriented parallel
to long axis of the bone
Grouping of bony tubes (called
lamellae)
Serves as weight bearing pillars
BONE STRUCTURE
How are collagen fibers arranged in the lamellae?
What is the purpose of this?
Collagen fibers in alternating lamellae run in alternating directions

This allows for great resistance to torsional stress
BONE STRUCTURE
Haversian canal
what is it?
location
A canal filled with a blood vessel & a
nerve
Located in the osteon
BONE STRUCTURE
Volkmans Canal
what is it
location
which way does it run?
Canal that connects the blood supply
of the osteon to the fibrous covering
of bone called the periosteum.
Osteon
Runs left & right. perpendicular
BONE STRUCTURE
Osteocytes
what are they
where are they found
Mature bone cells
Lie on the edge of the lamellae (in
the osteon)
BONE STRUCTURE
CANALICULI
tiny canals through which Cell to cell connections occur

Allows for cel to cell communication & transport of nutrients & waste
SPONGY BONE
What does it contain?
Where does it accumulate?
What is its function?
Contains bony struts called
traneculae (only few cells thick)
Occur in areas of stress points
Built to provide structural stability (similar to the idea of an arch)
CHEMICAL COMPOSITION OF BONE
Is bone made of organic or inorganic constituents?
Contains both organic & inorganic
constituents
ORGANIC CONSTITUENTS OF BONE
What is it comprised of?
What does osteoid do?
What does collagen do?
Comprised of osteoid (glycoproteins,
proteoglycans & collagen fibers-main component) &
several types of bone cells
Osteoid contributes to flexibility & strength of bone
Collagen forms sacrificial bonds that help to dissipate energy
INORGANIC CONSTITUENTS OF BONE
describe it
what is it comprised of
what may it also contain?
Tightly packed crystals of mineral salts called hydroxyapatite
Comprised mostly of calcium phos
phate
May also contain Mg, Na, K, Carbona
te, & heavy metals
INORGANIC CONSTITUENTS OF BONE
Mechanism of deposition?
Function?
Polymerization (can connect with
each other to form long chains) of
collagen
Allows for calcium salt precipitation,
& formation of HAP crystals
SKELETAL TISSUE CELLS: OSTEOBLASTS
Where is it derived from?
Function?
What does it contain?
Where is it located
Derived from the mesenchyme
Function: secretes components of
osteoid, contains important matrix
proteins, mineralizes osteoid.
Contains proteins: osteocalcin,
osteopontin (binds calcium,
promotes mineralization)
Organic portion of bone
SKELETAL TISSUE CELLS: OSTEOCLASTS
what are they?
what are they similar to?
function?
what does it contain?
Multinucleate cells, derived from
bone marrow.
Similar to macrophages
F: bone resorption (combine to bone
using integrins to hold on to bone)
Contains intracytoplasmic acidifying
vesicles that demineralize bone
What happends to the bone when there is too much resorption?
Weakened, brittle bone
SKELETAL TISSUE CELLS: OSTEOCYTES
Derived from?
Contains?
Function?
What does strain do?
Derived from "trapped" osteoblasts
(only until signaled back into osteo
blasts)
Contains: Sensory cells that form a
network of communication with the
bone
F: May act as mechanosensory cells
F: Conveys info relating to the
microenvironment of the neighborin
bone
Strain may initiate signaling of
osteoblasts/osteoclasts
BONE MARROW
How many types of bone marrow are there?
What are they called?
2 Types
Red
Yellow
YELLOW MARROW
What is it?
What is its function?
Mostly adipose tissue
Used as an energy reserve
RED MARROW
Contains?
Contains pluripotential stem cells from which all circulating blood cells are derived
STEM CELLS
Undifferentiated cells that can be signalled to make necessities
STEM CELLS DIFFERENTIATION: PROERYTHROBLASTS
what are they?
where do they develop?
what do they develop into?
how many generations?
what does it regulate?
Newly forming immature RBCs
Develop in the bone marrow into erythrocytes
Several generations, each successive step gains more Hgb
Regulation: erythropoietin
ERYTHROCYTES
Anucleate
Short living because of no nucleus so they must constantly reproduce
ERYTHROPOIETIN
what is it
what does it do
what does it secrete?
hormone
promotes formation of proethryroblas
ts
secreted by kidneys when 02 levels
are low
MEGAKARYOCYTES
what is it?
what is it regulated by?
Huge cell type that gets fragmented
into smaller cells called platelets
Regulated by thrombopoietin &
interleukins
PLATELETS
what are they?
what is a special feature of them?
Fragments of a cell, not cells of their
own
Anucleate
Biochemically active
PHAGOCYTIC CELLS
what does it produce?
What does it regulate?
Produce a wide variety of WBCs
Regulates granulocyte Stimulating
Factor (secreted by other cells)
WHITE BLOOD CELLS
what is their primary role?
Example?
Predominately involved in immunity
(ex. anitbodies)
LYMPHATIC CELLS
what are they?
B & T Cell pathways
B CELLS
what are they
what do they do?
Immunoglobulin secreting
Signals T cells to come & kill the
antigen
T CELLS
what are they?
where do they travel?
what is so special about these cells
Killer Cells
Travel through thymus glands
They are the only cells that can
recognize the difference between
good cells & antigens.
HORMONE CONTROL
Name 3 ways hormones are
controlled in bone
Bone Growth
Bone Remodeling
Calcium Homeostasis
BONE GROWTH
what is it stimulated by?
What are the steps of bone growth?
Stimulated by Growth Hormone (GH)
1. Secreted by Anterior Pituitary
2. GH binds to liver
3. GH secretes insulin growth factor
(IGF-1)
4. IGF-1 binds to cartilage & stimul
ates movement of chondroblasts
from G1 to S phase.
CALCIUM HOMEOSTASIS
Maintained by the parathyroid horm
one
PARATHYROID HORMONE
what is it secreted by?
what does it increase/decrease?
secreted by parathyroid gland
increases calcium reabsorption from
bone
decreases renal calcium excretion
PARATHYROID GLAND
where is it located?
what does it contain?
what does it secrete?
Located near thyroid gland but can
be ectopic (in chest)
Contains calcium receptors that
signal to either make more or less
calcium
Secretes parathyroid hormone
CALCITONIN
secreted by?
what does it reduce/decrease?
Secreted by parafollicular cells of the
thyroid
Reduces calcium levels in the blood
decreases osteoclast activity
decreases formation of new osteocl
asts
BONE HEALTH
Name the molecules that contribute
to bone health
Vitamin A
Vitamin D
Vitamin C
Alkaline Phosphate
VITAMIN A
why is this important for bone health
Important in the balance of mineral
deposition & resorption as well as
cell growth
VITAMIN D
what does it do?
Acts as a steroid in the intestine to
increase the production of a
transporter protein which increases
calcium absorption
VITAMIN C
what does it do?
what is a unique characteristic about it?
where is it located?
involved in collagen synthesis
water soluble
Makes up organic portion of bone
ALKALINE PHOSPHATE (ALP)
Secreted by?
what is it?
what does it do?
Secreted by osteoblasts, kidneys, &
other organs
It is an enzyme that is essential for
collagen mineralization
ALP splits phosphorous compounds
which can combine with calcium to
form Hydroxyapatite (HAP)
OSTEOGENESIS
what does it mean?
how many types are there?
what are the types?
bone formation & growth
2 types
intramembranous & endochondral
INTRAMEMBRANOUS
what is it?
bone formation from fibrous tissue
ENDOCHONDRAL
what is it?
bone fromation from hyaline cartilage
ENDOCHONDRAL OSSIFICATION
when does it begin?
how does it know where to form bone?
what does it require?
-begins in the second month of development
-uses hyaline cartilage "bones" as models for bone construction
-requires breakdown of hyaline cartilage prior to ossification
STAGES OF INTRAMEMBRANOUS
OSSIFICATION
explain the 4 stages
1. An ossification center appears in the fibrous connective tissue membrane
2.bone matrix is secreted w/in fibrous tissue
3.Woven bone & periosteum form
4.Bone collar of compact bone forms & red marrow appears
WHAT IS AN OSSIFICATION CENTER?
place where bones form
STAGES OF ENDOCHONDRAL OSSIFICATION
explain the 5 stages
1. Formation of bone collar
2. Cavitation of the hyaline cartilage
3.Invasion of internal cavities by
periosteal bud & spongy bone formtn
4.Formation of medullary cavity, appearance of secondary ossification centers in epiphyses
5. Ossification of epiphyses, with hyaline cartilage remaining only in the epiphyseal plates.
POSTNATAL BONE GROWTH
name 3 things that happen in terms of growth in the length of long bones
Growth in length of long bones
*cartilage on side of epiphyseal plate closest to epiphysis is relatively inactive
*cartilage abutting shaft of bone organizes into pattern that allows fast, efficient growth
*cells of epiphyseal plate proximal to resting cartilage form 3 functionally different zones: growth, transformation, & osteogenic
FUNCTIONAL ZONES IN LONG BONE GROWTH
Growth Bone
Cartilage cells undergo mitosis,
pushing epiphysis away from diaphysis
FUNCTIONAL ZONES IN LONG BONE GROWTH
Transformation Zone
older cells enlarge, matrix becomes calcified, cartilage cells die, matrix begins to deteriorate
FUNCTIONAL ZONES IN LONG BONE GROWTH
Osteogenic Zone
new bone formation occurs
LONG BONE GROWTH
what happends here?
cartilage continulally grows and is replaced by bone
REMODELING
what happends to bone here?
bone is resorbed & added by appositional growth