Skeletal System Flashcards
Periosteum
Membrane composed of dense irregular collagenous tissues
Forms a covering, rich with blood vessels & nerves
Surrounds outer surface of long bones
What bone structure is the periosteum associated with?
LONG BONE structure
Sharpeys ( aka perforating ) fibers
Made of collagen
Anchors periosteum firmly to underlying bone surface by penetrating deep into bone matrix
Diaphysis
Shaft of long bone
Each end is its epiphyses
Epiphysis
Covered with what?
Covered w/ a thin layer of hyaline cartilage (articular cartilage) found within joints (articulations) between bones
Marrow cavity?
Within diaphysis, it’s a hollow cavity
Contains either red or yellow bone marrow, depending on bone & age of individual
Compact bone
Hard, dense outer region that allows bone to resist linear compression & twisting forces among other stresses
(Linear compression is a vertical squash)
Spongy bone Aka ...? Found? Structure? Functions?
Aka cancellous bone
Found inside compact bone
Honeycomb-like frame work of bone struts
Allows long bones to resist forces from many directions
Provides a cavity for bone marrow
Endosteum
Thin membrane covering inner surfaces of bone
Contains different populations of bone cells involved in maintenance of bone homeostasis (building new cells -> skeleton every 10yrs)
Epiphyseal lines
Found separating both proximal and distal epiphyses from diaphysis
Remnants of epiphyseal plates (growth plates), a line of hyaline cartilage found in delegating bones of children
-replaced by bone by age 18-21
Short, flat, irregular, and sesamoid bones do not have what?
Do NOT have diaphyses, epiphyses, medullary cavities, epiphyseal lines, or epiphyseal plates
Characteristics of Flat, Irregular, Short, & Sesamoid bones
- Covered by periosteum, blood vessels, & nerves like long bone
- Internal structure composed of 2 outer layers of think compact bone with a middle layer of spongy bone, & it’s associated bone marrow
- some flat & irregular bones of skull contain hollow air-filled spaces called sinuses, which reduce bone weight
Sinuses
Hollow air-filled spaces that reduce bone weight
Is bone living or nonliving?
Bone is a living tissue
What are bones supplied with?
Well supplied w/ blood vessels & sensory nerve fibers
What bones does blood supply to?
Supplies to short, flat, irregular, and sesamoid bones
How are bones supplied with blood vessels and sensory nerve fibers?
Provided mostly by vessels in the periosteum that penetrate bone.
How is blood supply divided?
Long bones get 1/3 blood supply from periosteum; mostly supplies compact bone
Remaining 2/3 is supplied by nutrient arteries
-enter bone through small hole in diaphysis called nutrient foramen
-supply internal structures of bone
Osteoclasts
BREAK DOWN BONE
Responsible for bone resorption
Bone resorption
What do each parts do?
Released where after doing its job?
Process where cell secretes hydrogen ions & enzymes that break down bone matrix
- hydrogen ions dissolve inorganic matrix; enzymes break down organic matrix
- substances released into blood where reused or excreted from the body as waster products
Histology of compact bone
In cross section, resembles forest of tightly packed tress where each tree is a unit called an patron or a Haversian system
Rings of each tree are made up of thin layers of bone called lamellae
(Lamellae looks like a stacked cake)
What does the skeletal system include?
Bones, joints, and associated supporting tissues.
Composed of bone marrow, dense irregular & irregular collagenous connective tissue
Osteon structure components?
central canal, collagen fibers in lamellae, lacunae with osteocytes, lamellae, artery,vein, nerve, canaliculi
lamellae in osteons?
aka?
each osteon contains between 4 & 20 lamellae arranged in layered ring structures also known as concentric lamellae
function of lamellae in osteon?
lamellar arrangement is very stress resistant
collagen fibers in osteon?
collagen fibers of neighboring lamellae run in opposite directions
VERY STRONG
Central canal in osteon?
Central (Haversian) canal- endosteum-lined hole found in center of each osteon where blood vessels & nerves reside to supply bone
Lacunae in osteons?
connected to one another by a network of canals in matrix called canaliculi
contains osteocytes
2 types of bone marrow
red & yellow
red bone marrow
loose connective tissue that supports islands of blood-forming hematopoietic cells
facts of red bone marrow?
Age? Adult? Children?
amount DECREASES as a person ages
red marrow in adult is found only in pelvis, proximal femur, & humerus, vertebra, ribs, sternum, clavicles, scapulae, & some bones of the skull
Children need more red to assist in growth & development (adults dont need as much bc they are older & not growing)
Yellow bone marrow
composed of triglycerides, blood vessels, and adipocytes
Bone or osseous tissue
composed mostly of extracellular matrix w/ a small population of cells scattered throughout
What is the extracellular matrix of bone made of ?
Inorganic & organic matrix
Inorganic matrix consists of?
consisting of minerals make up about 65% of bones total weight
HARD
Organic matrix consists of?
makes up remaining 35%, consists of collagen fibers & usual ECM components
FLEXIBLE
main different between organic & inorganic matrix
inorganic- harden bone
organic- flexible (bc collagen)
inorganic matrix
made up of? which ones? function?
mainly calcium salts
bone stores around 85% total calcium ions in body as well as large amount of phosphorus:
ions form crystalline structure that makes bone one of hardest substances in body
bicarbonate, potassium, magnesium, and sodium are also found in inorganic matrix
Organic matrix
aka? consists?
known as osteod; consists of protein fibers & bone-specific proteins
Collagen
location? definition? function?
in organic bone matrix, predominant protein fibers
forms cross-links w/ one another
helps bone resist torsion (twisting) & tensile (pulling or stretching) forces
Bones continually change as ______ bone is ________ for raw materials to ________________
older bone is broken down for raw materials to build new bone
3 types of bone cells
osteoblasts
osteoclasts
osteocytes
osteoblasts
active bone cells found in periosteum & endosteum
BUILD MATRIX WHEN WE NEED NEW BONE
Osteogenic cells
aka? description?
Stem cells for bone
Flattened cells that differentiate into osteoblasts when stimulated by specific chemical signals (type of stem cell)
Bone-building cells
perform bone deposition
osteoblasts
bone deposition
osteoblasts secrete organic matrix materials & assist in formation of inorganic matrix
Osteocytes
how are they made? definition?
mature bone cells
osteoblasts eventually surround themselves w/ bone matrix in lacuna, become osteocytes that are no longer actively synthesizing bone matrix
lacuna
small cavity
Spongy bone
function? description?
usually not weight-bearing like compact bone so is much less densely packed
provide protective structure for bone marrow tissue
trabeculae
location & description
struts or ribs of bone
covered w/ endosteum & usually not arranged into osteons, composed of concentric lamellae
IN SPONGY BONE
lacunae are found where?
in concentric lamellae, in trabeculae, in spongy bone
contain osteocytes
how does spongy bone obtain blood supply?
no central or perforating canals supplying blood to trabeculae; obtain blood supply from vessels in bone marrow
ossification is what?
bone formation
how many types of ossification are there? what are they?
2
intramembraneous ossification
endochondral ossification
intramembraneous ossification
bone forms directly from mesenchyme-> osteogenic cells-> osteoblasts
-begins about 6th embryonic week during fetal development
where does ossification occur?
embryo & fetus development
infancy, childhood, adolescence
bone remodeling/repair
what bones form from intramembraneous ossification
what happens if it’s incomplete
FLAT, broad bones
-skull, mandible, clavicle
incomplete intramembraneous ossification causes Fontanels (soft spots) in newborn skull
Endochondral ossification
what happens? what bones form? when are bones completely ossified?
bone forms within & replaces cartilage model
all bones below head except clavicle
most bones are completely ossified by age 7
Long bone growth
means? due to? what happens to diaphysis? when does growth stop?
longitudinal growth in length
- due to cell division of chondrocytes in epiphyseal plate
- diaphysis of bone increases in length
- by age 18-21 growth stops
Growth in width
means? what happens? how long can this go on?
appositional (width) growth
- osteoblasts btwn periosteum & bone surface make new bone
- forms new circumferential lamellae
- older deeper lamellae are removed or incorporated into osteons
- process can continue after longitudinal growth stops
Bone remodeling
defintion? includes? adult vs child?
continuous replacement of old bone tissue formation & loss
- bone deposition & resorption
- adult: formation & loss occur simultaneously
- childhood: deposition occurs faster than resorption
Bone resorption
removal of minerals & collagen fibers by OSTEOCLASTS
bone depostion
Addition of minerals & collagen fibers by OSTEOBLASTS
-About 5% of total bone mass is remodeled at any given time (skeleton every 10 yrs)
Factors affecting bone remodeling? (5)
Minerals Vitamins Hormones Activity Level Diet
Minerals that affect bone remodeling
magnesium, phosphorus, calcium in blood
need 1,000 to 1,500 mg Ca per day
Vitamins that affect bone remodeling
Vitamin A- stimulates osteoblasts
Vitamin C- helps synthesize collagen
Vitamin D- calcium absorption
Hormones that affect bone remodeling
Growth hormones- stimulates cartilage & bone growth
Parathyroid hormones- stimulate osteoblasts
Calcitonin- stimulates osteoclasts
Activity level affecting bone remodeling
weight bearing exercise (makes osteoblasts work ->build up bone!)
Fracture
any break in a bone
Simple Fracture
skin & tissue around fracture remain tack
Compound Fracture
Skin & tissues around fracture are damaged
Stress Fracture
Series of microscopic fissures in bone
w/o evidence of injury to other tissues
Types of fractures (5)
comminuted greenstick impacted spiral simple
comminuted fracture
splintered or crushed bone
greenstick fracture
partial fracture
impacted fracture
one end of fractured bone forcefully driven into interior of the other (jump off building)
spiral fracture
bone twists in opposite directions (football)
simple fracture
bone breaks totally w/o breaking the skin
Demineralization
loss of Ca & minerals from extracellular matrix bc of aging
- after age 30 females and after age 60 in males osteoblasts slow down
- about 30% of Ca in bones lost by age 70
what happens to bone when aging?
loss of bone mass & brittleness
Loss of bone mass
means?
more bone is lost than made
increase in osteoclast activity
demineralization
Brittleness
decreased rate in protein synthesis & production of collagen fibers
Skeletal diseases (9)
Paget's disease Osteoporosis Osteophytes (Bone Spurs) Hallux Valgus (Bunions) Rickets Scurvy Scoliosis Lordosis Kyphosis
Paget’s Disease
abnormal bone remodeling process
most common in adults
heredity
Symptoms: pain bone deformity, arthritis
Osteoporosis
Deterioration of cartilage & bone
Caused by aging & genetics
Bones become brittle & break easily (FRAGILE)
Symptoms: joint swelling, muscle weakness, limited movement (why older ppl break hip)
Osteophytes (bone spurs)
bony projections develop along edges of bone - near joints
caused by osteoartritis/osteoporosis
Symptoms: pain or loss of motion in joints, inflammation
Hallux valgus (Bunions)
Enlargement of bone at joint of base of big toe
caused by narrow toe shoes
Symptoms: swelling, displacement of big toe
Rickets
Softening/weakening of bones due to lack of vitamin D
Symptoms: Bowed legs, curved spine, fragile bones
(like in Africa, under developed countries)
Scurvy
Abnormalities in bone development, epiphyseal disease, lifting of periosteum
lack vitamin C
Symptoms: Loose teeth, bleeding gums, degeneration of cartilage
(like pirate teeth)
Scoliosis
Curvature of spine from side to side
‘S’ shape
Symptoms: lean to 1 side, uneven shoulder or waist height
Lordosis
Curvature of spine from front to back
“sway back”
Symptoms: sway back, pain in lumbar region
Kyphosis
Curvature of upper spine
‘Dowers Hump’
Symptoms: leaning forward, hump back
Functions of the skeletal system? (6)
Protection Mineral storage & acid-base homeostasis Blood cell formation Fat storage Movement Support
Protection
skeleton protects underlying vital organs such as the brain
Mineral storage and acid-base homeostasis
bone stores minerals such as Ca and phosphorus which are necessary for electrolyte & acid-base balance
store house for Ca P and MG salts (P & Mg for pH balance)
Blood cell formation
red bone marrow is the site of blood cell formation (hematopoiesis)
Fat storage
yellow bone marrow stores triglycerides fat cells (adipocytes) used for fuel by cell (ATP)
Movement
muscles produce body movement via their attachment to bones
MUSCLE CONTRACT->BONES MOVE (MUSCLES MAKE BONES MOVE)
Support
the skeleton supports the weight of the body
provides structural framework (HARD BONES)
Long bone
definition & examples
bone is longer than it is wide, named for overall shape
ex. Femur, Tibia, Humerus
short bone
definition & examples
bone is about as long as it is wide, roughly cubed shape
ex. wrist or carpal & ankles or tarsals
Flat bone
definition & examples
bone is broad, flat, and thin
ex. ribs,pelvic, sternum (breastbone) MOST BONES IN SKULL
irregular bone
definition & examples
bone’s shape does not fit into other classes, irregular shape
ex. vertebra and certain skull bones
sesamoid bone
definition & examples
round, flat bone found within tendon
- specialized bones located within tendons, usually small, flat & oval-shaped
ex. kneecap, within tendons
how are the bones classified ?
by shape, into 5 classes
difference between long & short bone
long- named for overall shape
short- roughly cubed shape
Intramembraneous ossification means what?
within (intra) 2 layers (membraneous)
process of intramembraneous ossification
1) osteoblasts develop in the primary ossification center
2) osteoblasts secrete organic matrix which calcifies
3) early spongy bone is formed
4) early compact bone is formed
endochondral ossification means what?
inside (endo) replacing cartilage (chondral)
process of endochondral ossification
1) chondroblasts in the perichondrium differentiate into osteoblasts
2a) Osteoblasts build bone collar on bone;s external surface as bone begins to ossify from the outside
2b) Simultaneously, internal cartilage begins to cacify & chondrocytes die
3 )In primary oss, center, osteoblasts replace calcified cartilage w/ early spongy bone; secondary oss. centers & medullary cavity develop
4) As medullay cavity enlarges, remaining cartilage is replaced by bone; epiphyses finish ossifying
process of fracture repair
1) Hematoma fills gap btwn bone fragments (Hematoma formation (blood clot) -6-8 hrs after fracture)
2) Fibroblasts & chondroblasts infiltrate hematoma, & soft callus forms (fibrocartilaginous callus form cartilage& fibers to form soft callus, about 3 wks to form)
3) Osteoblasts build bone (bony callus, forms hard callus lasts 3-4 months to make callus)
4) Bone callus is remodeled & primary bone is replaced w/ secondary bone (remodeling, restores new bone structure) (takes about 1 yr, area stronger than any other bc its new!)
functions of osteoblasts & osteocytyes
1) osteogenic cells differentiate into osteoblasts
2) osteoblasts deposit bone until they are trapped & become osteocytes
3) osteocytes maintain the bone extracellular matrix
mono-nucleic vs multi
osteocytes and osteoblasts- 1 nuclei
osteoclasts, large ruffled w/ multi nuclei
