Chapter 7: Bone Tissue Flashcards
__ &__ are the most durable remains of a once living body?
bone & teeth
osteology
study of bone
What is the skeletal system composed of?
bone, cartilage, & ligaments
cartilage
precursor to bone
ligament
hold bones together at the joints
tendons
attach muscle to bone
What are the functions of the skeletal system? (6)
- support
- protection
- movement
- electrolyte balance
- acid/base balance
- blood formation
Flat bone
thin; protects soft organs
Long bone
longer than wide; acted upon muscles
Short bone (2)
- equal in length & width
- glide across one another in multiple directions
irregular bones
elaborate shapes that do not fit into any of the other categories
compact bone (2)
- outer shell of long bone
- makes up 3/4 of bone weight
diaphysis
shaft; cylinder compact bone to provide leverage
medullary cavity
space in the diaphysis of long bone that contains bone marrow
epiphyses
enlarged ends of long bone (strengthen attachment)
spongy bone (2)
- covered by durable compact bone
- makes up 1/4 of bone weight
articular cartilage (3)
- made up of hyaline cartilage
- covers the joint surfaces where one bone meets another
- allows for free movement of joints
nutrient foramina
minute holes in the bone surface that allows blood vessels to penetrate
periosteum
external sheath that covers the bone except where there is articular cartilage
what part of the periosteum is important to growth of bone & healing of fractures
inner osteogenic layer
endosteum
thin layer of reticular connective tissue lining marrow cavity
epiphyseal plate (3)
- area of hyaline cartilage that separates the marrow spaces of the epiphysis & diaphysis
- growth plate
- enables growth in length
Construction of flat bone (2)
- sandwich like structure: spongy bone in between compact bone (2)
- both surfaces of flat bone covered with periosteum
_____ is a type of joint
suture
diploe
spongy layer in cranium that absorbs shock
bone is connective tissue that consists of ___, ____, and _____
cells, fibers, and ground substance (made up of matrix)
What are the 4 types of bone cells?
osteogenic, osteoblast, osteocytes, & osteoclasts
osteogenic (osteroprogenitor) cells (3)
- stem cells found in endosteum, periosteum, & central canals
- undergoes mitosis
- arise from embryonic mesenchymal cells
What do osteogenic cells produce?
osteroblasts
osteoblast (3)
- nonmitotic
- lined up as single layer under endosteum & periosteum
- synthesize soft organic matter of matrix
What stimulates osteogenic cells to multiply more rapidly? What does this increase?
stress & fracture; osteocytes to rebuild bone
What is secreted by osteoblasts?What is it thought to be?
osteocalcin: thought to be structural protein of bone
What does osteocalcin stimulate?
stimulates insulin secretion of pancreas
osteocytes (2)
- former osteoblast that have become trapped in the matrix they have deposited
- contribute to homeostasis (phosphate & calcium ions //bone density)
lacunae
tiny cavities where osteocytes reside
canaliculi
channels that connect lacunae; are reached by cytoplasmic processes
osteoclasts (3)
- bone dissolving cells (mesenchymal) found on the bone surface
- different origin from rest of bone cells
- very large having 3-4 nuclei
Where does osteoclasts develop from?
same bone marrow stem cells that give rise to blood cells
ruffled borders
side facing bone surface that increases surface area of the plasma membrane
resorption bays
howships lacunae
pits on surface of bone where osteoclasts reside
remodeling
results from combined action of osteoclasts and osteoblast (balance of removing & building)
What 2 structural materials are bone made of?
ceramic(hydroxyapatite) & a polymer (collagen)
What allows the bone to support (hardness) the body weight? Gives bone some degree of flexibility?
ceramic (hydroxyapatite); protein
rickets
soft bones due to deficiency of calcium salts (too little hydroxyapatite)
bones are very “bendy”
hydroxyapatitie
mineral part in bone
Brittle bone disease
excessively brittle bone due to lack of protein, collagen
perforating canals
Volkmans canal
transverse or diagonal canals
what does spongy bone consist of? (3)
- spicules (silvers of bone)
- trabeculae (thin plates of bone)
- spaces filled with red bone marrow
Does spongy bone contain central canals of osteons?
very few
What is the purpose of trabeculae?
develop along bone’s line of stress
bone marrow
soft tissue occupying marrow cavities of long bones & small spaces of spongy bones
red marrow
contains hemopoietic tissue that produces blood cells
yellow marrow
fatty marrow that does not produce blood; can transform back to red marrow in the event of chronic anemia
ossification
the formation of bone
a ____ ____ remains a metabolically active organ
mature bone
osteoclast responsibility of ________; osteoblast responsibility of _______
resorption; formation
mineral deposition
crystallization process in which calcium phosphate & other ions are taken from blood plasma & deposited in bone tissue
____ produce collagen fibers that spiral the length of the osteon
osteoblasts
What helps harden the matrix?
encrusted fibers with minerals (hydroxyapatite) via osteoblasts
___ &___ ion concentration must reach a critical value called ___ ____ for crystal formation to occur
calcium & phosphate; solubility product
Who allows for salts to precipitate in the bone marrow? how do they do this?
osteoblast; by neutralizing inhibitors
What is the suppose of inhibitors in tissues?
to prevent calcification
mineral resorption
- the process of dissolving bone & releasing minerals into the blood
- performed by osteoclasts at the ruffled border
What type of pumps secrete hydrogen into spaces between osteoclast & bone space? What follows?
hydrogen pumps; chloride ions by electrical attraction
What dissolves bone mineral during mineral resorption?
hydrochloric acid
What enzyme digests the collagen during mineral resorption?
acid phosphatase
Other components of phosphate? (4)
DNA & RNA
ATP
phospholipids
pH buffer
Other components of calcium? (3)
neuron communication
muscle contraction
blood clotting
What 3 hormones regulate calcium homeostasis?
calcitriol
calcitonin
parathyroid hormone
Calcitriol
a form of vitamin D produced by the sequential action of the skin, liver, and kidney
Explain how calcitriol processed?
- epidermal keratinocytes use UV radiation to convert 7-dehydrocholesterol to previtamin D (skin)
- Liver adds hydroxyl group-> calcidiol
- Kidney adds another hydroxyl group-> calcitriol
What can not be absorbed with calcitriol?
calcium or phosphate
Which hormone raises blood calcium concentration?
calcitriol
Functions of calcitriol? (3)
- increase Ca absorption by small intestine
- increase Ca resorption from the skeleton
- promote kidney reaborption of Ca ions (so less lost in urine)
What is necessary for bone deposition?
adequate calcium and phosphate
Calcitonin
secreted by C cells (clear cells) of theTHYROID GLAND when Ca concentration rises too high
How does calcitonin lower blood calcium concentrations?
- osteoclast inhibition
- osteoblast stimulation
Parathyroid hormone (2)
- secreted by parathyroid gland (beside thyroid gland)
- released with low calcium blood levels
What are the 2 types of ossification?
intramembranous ossification
endochondral ossification
Bone can grow in 2 directions?
length & width
epiphyseal plate
a region of transition from cartilage to bone
interstitial growth
bones increase in length
appositional growth
bones increase in width
what does disturbance of calcium homeostasis disrupt?
other organ systems
which crystals attract more calcium & phosphate from solution during mineral deposition?
first few crystals
abnormal calcification
ectopic ossification
calcified mass in soft organs (calculus)
braces
dissolving bone ahead of tooth performed by osteoclast (highest pressure) & depositing bone more slowly by osteoblast behind tooth
rickets vs. osteomalacia
basically the same disorder that describes the abnormal softness of bone due to lack of hydroxyapatite, but referred to as rickets in children
which hormones are used to raise calcium levels? lower?
raise: calcitriol & parathyroid hormone
lower: calcitonin
Is phosphate levels tightly regulated like calcium? how is it?
NO: Calcitriol ->absorption by small intestines
PTH ->lowers phosphate by urinary excretion
stress fracture
break caused by abnormal trauma to a bone
pathological fracture
break in a bone weakened by some other disease
What structural characteristics are fractures classified? (3)
- direction of fracture line
- break in the skin
- multiple pieces
nondisplaced fracture
fracture where bone partially or fully breaks in one part, but is still aligned (clean break)
displaced fracture
fracture where bone breaks into 2 pieces, but is no longer aligned
comminuted fracture
A fracture in which a bone is broken, splintered, or crushed into a number of pieces
greenstick fracture
when a bone bends and cracks, instead of breaking completely into separate pieces. (bowed)
when you break a bone what happens first?
hematoma (leakage of blood)
Steps for bone replacement after it is broken?
- hematoma
- soft callus formation
- hard callus formation via osteroblast
- bone remodeling (small fragments removed via osteoclasts)
Closed reduction vs. open reduction
treatment for fracture
closed: manipulation into normal position without surgery
open: involves surgical exposure (plates, screws)
cast
used to stabilize & immobilize movement
osteoporosis
severe loss of bone density; leads to widows hump
traction
used to treat femur fractures in children
achondroplastic dwarfism (2)
- spontaneous mutation produces dominant alleles
- normal torso, short limbs
pituary dwarfism (2)
- lack of growth hormone
- normal proportions with short stature
