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129 Cards in this Set

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  • Back
What are the two main sections of the skeltal system?
Axial & appendicular.
What bones does the axial portion of the skeletal system contain?
The skull, the vertebral column & the rib cage.
What bones does the appendicular portion of the skeletal system contain?
The arms, legs, shoulders and hips.
What are the 5 shape categories for bones?
Long bones (i.e. humerus and femur), short bones (carpals and tarsals), flat bones (skull bones), irregular bones (vertebrae), and sesamoid bones (in tendon, for example: patella).
What two textures are bones made up of?
Compact bone (outside; support/protection) & spongy bone (inside; marrow).
What is an osteon?
The basic structure of bone tissue. They are concentric circles of bone cells surrounding a Central/Haversian canal.
What is an osteocyte?
A mature bone cell. Found in the concentric circles of the osteon.

Occupy lacunae at the junctions of of the lamellae.
What is in the Central/Haversian canal?
Blood vessels & nerve fibers.
What is the human skeleton initially made of?
Cartilages & fibrous membranes.
What is the perichondrium?
The dense irregular connective tissue that surrounds cartilage. Contains blood vessels that give nutrients to the cartilage (which lack it's own blood vessels).
What is skeletal cartilage made of?
A variety of cartilage tissue (mostly water).
What are the 3 types of cartilage?
Hyaline, elastic & fibrocartilage.
What do hyaline cartilages look like?
Frosted glass (when freshly exposed), with spherical chondrocytes.
Which is the most abundant skeletal cartiage?
What is the only fiber type in the extracellular matrix of hyaline cartilage?
Collagen fibers (not visible microscopically).
What are the 4 types of skeletal hyaline cartilages?
* Articular cartilages - covers end of bones at movable joins
* Costal cartilages - connect the ribs to the sternum
* Respiratory cartilages - form the skeleton of the larynx
* Nasal cartilages - support the external nose.
How is elastic cartilage different from hyaline cartilage?
They contain more stretchy elastic fibers so are more bendable.
What are the 2 locations of elastic cartilage in the body?
The external ear & the epiglottis.
What are the characteristics of fibrocartilage?
Highly compressible & great tensile strength. An intermediate between hyaline & elastic.

Consist of parallel rows of chondrocytes alternating w/ thick collagen fibers.
Where do you find fibrocartilages?
Sites that are subjected to heavy pressure & stretch.

Knee & discs between vertebrae.
What are the two ways cartilage can grow?
Appositional growth & interstitial growth.
What is appositional growth?

When cartilage forming cells in the perichondrium secrete new matrix against the external face of the existing cartilage tissue.
What is interstitial growth?

When lacunae-bound chondrocytes divide & secrete new matrix, expanding cartilage from within.
When does cartilage growth end?
During adolescence when skeleton stops growing.

Calcified cartilage is not bone.
What do the axial bones do?
Protect, supoprt or carry other body parts.
All limb bones are long bones except which?
Patella, wrist & ankle bones.
What is the shape of short bones?
Roughly cube shaped.
What are sesamoid bones?
A special type of short bone that are shaped like sesame seeds. They form in a tendon.
What type of bones are the sternum, scapulae, ribs, & skull bones?
Flat bones.
What type of bones are vertebrae & hip bones?
Irregular bones.
What is hematopoiesis?
Blood cell formation.
What are the 5 main functions of bones?
* Support
* Protection
* Movement
* Mineral storage
* Blood cell formation
What types of tissues are bones composed of?
* Bone (dominant)
* Nervous
* Cartilage
* Fibrous connective tissue
* Muscle
* Epithelial
What are the different types of bone markings?
Projections, depressions, openings.
What is another name for cancellous bone?
Spongy bone.
WHat is the medullary cavity?
The marrow cavity of the long bone. Surrounded by a thick collar of compact bone.
What are the main structural features of long bones?
* Diaphysis - axis
* Epiphyses - ends
* Membranes - periosteum
What is the periosteum?
The white double-layered membrane covering the bone (except joints).

Outer fibrous layer is dense irregular connective tissue. Inner osteogenic layer is made up of osteoblasts & osteoclasts.
What is an osteoblast?
Bone germinator
What is an osteoclast?
Bone breaker.
How is the periosteum secured to the bone?
By perforating (Sharpey's) fibers. They are tufts of collagen that extend from its fibrous layer into the bone matrix.
What is the endosteum?
The delicate connective tissue that covers the internal bone surfaces.
What is the structure of short, irregular & flat bones?
Periosteum-covered compact bone on the outside.
Endosteum-covered spongy bone on the inside.
NO shaft or epiphyses
Have marrow but no marrow cavity.
What is diploe?
What spongy bone is called in flat bones.
What is hematopoietic tissue?
Red marrow. Found in trabecular cavities of spongy bone in long bones. Found in diploe of flat bones.
WHere does blood cell production in adult long bones occur?
In the head of the femur & humerus.
What is another name for compact bone?
Lamellar bone.
What is a lamella?
A hollow tube of bone matrix, part of an osteon.
What are perforating or Volkmann's canals?
They lie at right angles to the axis of the bond and connect the blood and nerve supply of the periosteum to those in the central canals and the medullary cavity.
What are all internal bone cavities lined with?
What are canaliculi?
Hair-like canals that connect the lacunae to each other and to the central canal.

Permit nutrients & wastes to be relayed from one osteocyte to the next.
What are interstitial lamellae?
Incomplete lamellae that lie between intact osteons.
What are circumferential lamellae?
Located just deep to the periosteum and just superficial to the endosteum.

Resist twisting of the long bone.
Are the trabeculae in spongy bone haphazard?
No, they are aligned precisely along lines of stress & help the bone resists stress.
How do nutrients reach the osteocytes of spongy bone?
They diffuse through the canaliculi from cappilaties in the endosteum.
What is the intracellular matrix of bone tissue made up of?
Organic (osteoid) & inorganic portions (hydroxyapatite).
What is hydroxyapatite made of?
Calcium phosphate mineral salts.
What is osteoid made of?
Secretions of osteoblasts: protein, carbs, collagen.
What is osteogenesis/ossification?

What are the two forms?
Bone growth & development.

Intramembraneous ossification
Endochondral ossification
What is another name for the epiphyseal plate?
The growth plate.
What controls bone growth?
At first, it is controlled by growth hormone & thyroid hormones. At puberty, estrogen & testosterone take over.
What are sacrifical bonds?
Bonds in or between collagen molecules that break easily on impact, dissipating energy to prevent fractures.

Healthy bone is half as strong as steel in resisting compression, and fully as strong in resisting tension.
What purpose does ossification serve in adults?
Bone remodeling.
When does bone tissue begin to replace fibrous membranes & hyaline cartilage in an embryo?
Week 8
What is a membrane bone?
What a bone is called when it develops from a fibrous membrane.
What is a cartilage/endochondral bone?
What a bone is called when it develops by replacing hyaline cartilage.
Which bones are the result of intramembranous ossification?
Crial bones & the clavicles (all flat bones).
Which bones are the result of endochondral ossification?
All bones below the base of the skull (except clavicles).
How is secondary ossification different from primary ossification?
It occurs in one or both epiphyses, and it retains the spongy bone in the interior. No medullary cavity forms.
Most bones stop growing during adolescence. Which continue to grow throughout life?
Nose & the lower jaw.
When does bone growth end?
At end of adolescence, as the epiphysis & diaphysis fuse.
Can a bone still grow in adulthood?
Yes, it can grow by appositional growth if stressed by lots of muscle activity or excessive body weight.
What are osteoblasts supported by?
Vitamins A, C & D, calcium, phosphorus, magneseum & maganese.
What are the two things that control deposition & reabsorption of bone?
Mechanical stress remodeling.

Parathyroid hormone & calcitonin.
What does parathyroid stimulate?
What does calcitonin stimulate?

Hormones are released in response to bone calcium levels?
False, they are released in response to BLOOD calcium levels.
How much of our bone mass to we recycle each week?
How often is spongy bone replaced?

compact bone?
3-4 years.

10 years.
What is the most common disorder of bone homeostasis?
Bone breakage.
What is bone remodeling?
The coupled processes of bone deposit & resorption occuring at the surface of the periosteum & endosteum.

Bone remodeling occurs uniformly.
WHat is a bone deposit?
It occurs wherever a bone is injured or added bone strenght is required.
What does the ruffled border of the osteoclast secrete?
LYsosomal enzymes (digest the organic matrix)
Hydrochloric acid (converts calcium salts into a soluble form)
What is ionic calcium used for in the body?
Tranmission of nerve impulses
Muscle contraction
Blood coagulation
Secretion by glands & nerve cells
Cell division

It has been suggested that electrical signals direct remodeling.
What are the 4 ways a bone fracture can be classified?
1. Position of bone ends
2. Completeness of break
3. Orientation of the break relative to the long axis.
4. Whether the bone ends penetrate the skin.
What is a nondisplaced fracture?
The bone ends retain their normal position.
What is an incomplete fracture?
Whent he bone is not broken through.
What is a transverse fracture?

When it's perpendicular to the long axis.

When a bone breaks parallel to the long axis.
What is an open/compound fracture?
When the bone penetrates the skin.
What is open reduction?

Closed reduction?
When the bone ends are secured together surgically with pins or wires.

When the bone ends are coaxed into position by physicians hands.
What are the 4 stages of simple fracture repair?
1. Hematoma formation
2. Fibrocartilaginous callus formation
3. Bony callus formation
4. Bone remodeling
What is fibrocartilaginous callus?
The entire mass of repair tissue.
What underlies every disease of the skeleton?
Imbalances between bone deposit & bone resorption.
What is osteomalacia?

A disorder when the bones are inadequately mineralized.

The same thing in kids. More serious.
What are osteomalacia & rickets caused by?
Insufficient calcium or Vitamin D deficiency.
What is Paget's disease?
Excessive bone deposit & resorption. The bone has an abnormally high ration of spongy bone to compact bone.
How many bones are in the human skeleton?
What are bones of the adult skeleton composed of?
Two types of osseaous tissue: Compact bone & spongy bone.
What is a trabeculae?
The small bars that spongy bone is composed of. They are interspersed with lots of open space.
What are long bones composed primarily of?
Compact bone.
What are short bones composed primarily of?
Spongy bone.
Are flat bones all level?
No, some of them are curved (ex - skull)
What type of bones are the patellas?
What types of bones are not included in the bone count of 206?
Sesamoid (except patella) & Wormian/sutural bones.
What are Wormian/sutural bones
Tiny bones between cranial bones.
Are there osteoblasts & osteoclasts in the periosteum?
Yes, in the osteogenic layer.
Does the epiphysis have more compact bone or spongy bone?
Spongy bone.
Does the periosteum cover the epiphysis?
No, articular cartilage does.
Which appears thinner, the epiphyseal plate or the epiphyseal line?
The epiphyseal line.
What is yellow marrow?
Adipose tissue that is stored in the medullary cavities of long bones.
Where do you find red marrow in infants?

In adults?
In the medullary cavities.

In the interior of epiphyses.
Does the endosteum cover the trabeculae of spongy bone?
Yes. It also lines the canals of compact bone.
Does the endosteum contain osteoclasts & osteoblasts?
Yes, just as the periosteum does.
As the bone grows in diameter is it being broken down on the inner surface of the compact bone?
Yes, this is how compact bone maintains a constant thickness.
What is an abnormally thin epiphyseal plate indicative of?
Growth retardation.
Where does bone hardness come from?

And flexibility?
Inorganic calcium salts that have been deposited.

Organic elements of the matrix, particularly the collagen fibers.
What are interstitial lamellae, and what are they a result of?
Remnants of circumferential lamellae that have been broken down.

Result of bone remodeling.
What are the 7 most important skeletal cartilages?
1. articular
2. costal (connect ribs to sternum)
3. laryngeal
4. tracheal & bronchial
5. nasal
6. intervertebral discs
7. external ear
What are distinguishing factors of cartilage tissue?
Consists of primarily water. Have no nerves or blood vessels.
What are the 3 divisions of the axial skeleton?
Vertebral column
Bony thorax
What are the 2 sets of bones in the skull?
The cranium
The facial bones
How are all but one of the skull bones connected?
What is the cranial vault/calvaria?
The superior, lateral & posterior walls of the skull.
The cranium is constructed of what?
8 large flat bones.
What is the glabella?
The smooth area between the eyes.