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A & P - The Skeletal System
Tissues, bone formation, structure of bone, axial & appendicular skeleton,
44
Anatomy
Undergraduate 1
08/14/2012

Additional Anatomy Flashcards

 


 

Cards

Term
5 functions of Skeletal System
Definition

Support (for soft tissues and organs)

 

Storage of minerals (eg. calcium) and lipids (eg yellow bone marrow)

 

Blood cell production (eg. red and white in red bone marrow)

 

Protection (eg. skull protects brain)

 

Leverage (change forces generated by skeletal muscle)

Term
6 bone shapes & examples
Definition

Sutural bones (between flat bones of skull)


Irregular bones (eg spinal vertebrae, pelvis)


Short bones (eg carpals & tarsal)


Flat bones (eg roof of skull, sternum)


Long bones (eg humerus)


Sesamoid bones (eg. patella, up to 26 although varies)

Term
4 types of bone cells and describe
Definition

Osteocyte (Most common, mature bone cell that contains the bone matrix)


Osteoblast (Immature bone cell that secretes the organic components of matrix)


Osteoprogenitor (Stem cell whose divisions produce osteoblasts)


Osteoclast (Multinucleate cell that secretes acids and enzymes to dissolve bone matrix)

Term

Compact bone contains:

 

 

Spongy bone contains:

Definition

Compact bones contain parallel osteons

 

Spongy bone contains trabeculae

 

 

Term
How many bones are in the axial and appendicular skeleton?
Definition

An adult skeleton has 206 bones

 

The axial skeleton has 80 bones

 

The appendicular skeleton has 126 bones

Term

Describe the structure of a long bone

 

Definition

Epiphysis (Expanded ends) - spongy bone

 

Diaphysis (Tubular shaft) - compact bone, surrounds medullary cavity

 

Metaphysis (join between diaphysis and epiphysis)

Term
Describe the structure of a flat bone
Definition
Layers of compact bone covering spongy bone
Term
Discuss the general structure of bone
Definition

Cells - osteocytes in lacunae

 

Matrix is dense:

  • calcium phosphate, carbonate and hydroxide
  • hydroxyapatite
  • collagen fibres

Remarkable properties:

  • Calcium hard but brittle
  • Collagen fibres strong but flexible
Term
Discuss mature bone cells (Osteocytes)
Definition
  • Maintain matrix and repair bone
  • In lacunae (compartments)
  • Between layers of matrix (lamellae)
  • Canaliculi are passages through lamella, join lacunae to each other and blood vessels
Term
Describe the structure of spongy bone in more detail
Definition
  • Lamellae arranged in trabeculae (not osteons)
  • Bone marrow around the trabeculae
  • Blood vessels run through bone marrow
  • Nutrients to osteocytes via canaliculi
Term
Why compact and spongy bone?
Definition

Compact bone

  • Thickest where stresses arrive from a few directions
  • Osteons align along these stress lines - strong

Spongy bone

  • Where bones are not heavily stressed
  • Stresses come from many different directions
  • Lighter
Term
Describe the 2 layers of bone
Definition

Periosteum (outside layer)

  • Superficial layer that covers all bones (not in joints)
  • Circulatory and nervous supply
  • Bone growth

Endosteum (inside layer)

  • Growth, repair and remodelling
  • Incomplete cellular layer lines medullary cavity, trabeculae and central canals
Term
3 definitions related to growth of bone
Definition

Osteogenesis: Process of bone formation

 

Ossification: Process of replacing other tissue (eg. cartilage) with bone

 

Calcification: The deposition of calcium salts (anywhere)

Term
Describe the two mechanisms of ossification of bone
Definition

Endochondrial ossification - bone replaces existing cartilage

- most bones begin as hyaline cartilage

- these cartilage models of bone are then ossified

 

 

Intramembranous ossification - bone develops from mesenchymal cells (stem cells)

Term

Endochondrial ossification

 

STEP 1

Definition
  • chondrocytes increase in size
  • matrix is reduced and calcifies
  • Chondrocytes die
Term

Endochondrial ossification

 

STEP 2

Definition
  • Blood vessels grow into perichondrium
  • Mesenchymal cells differentiate into osteoblasts
  • Layer of bone surrounds shaft
Term

Endochondrial ossification

 

STEP 3

Definition
  • Blood supply to centre
  • Fibroblasts differentiate into osteoblasts and spongy bone
  • Primary ossification centre
  • Bone spreads to ends
Term

Endochondrial Ossification

 

STEP 4

Definition
  • Osteoclasts create medullary cavity
  • Increase in length and diametre
Term

Endochondrial ossification

 

STEP 5

Definition
  • Blood supply to epiphyses
  • Secondary ossification centres
Term

Endochondrial ossification

 

STEP 6

Definition
  • Epiphysis becomes filled with spongy bone
  • Some cartilage remains (articular)
  • Epiphyseal plate forms
Term
Discuss bone increase in length
Definition
  • Bone grows as long as the epiphyseal cartilage continues to grow
  • On the epiphyseal side new cartilage is added continuously
  • On the shaft side osteoblasts invade the cartilage and turn it into bone
  • As the osteoblasts make bone and are moving towards the epiphysis, the bone continues to grow as long as the epiphyseal cartilage continues to expand
Term
Discuss bone increases in diametre
Definition
  • Appositional growth
  • Osteoblasts in the inner layer of the periosteum deposit bone matrix
  • Osteoblasts become surrounded in matrix and differentiate into osteocytes
  • Layers of circumferential lamellae
  • Deepest layers become replaced with osteons
  • Osteoclasts remove matrix at the inner surface
  • Medullary cavity enlarges with increased diametre
Term
3 Steps of Intramembraneous ossification
Definition
  • Mesenchymal cells aggregate, differentiate into osteoblasts, and begin the ossification process. The bone expands as a series of spicules that spread into surrounding tissues
  • As the spicules interconnect they trap blood vessels within the bone
  • Over time, the bone assumes the structure of spongy bone. Areas of spongy bone may later be removed, creating medullary cavities. Through remodelling, spongy bone formed in this way can be converted to compact bone
Term
4 steps when a bone is fractured
Definition
  • Immediately after the fracture, extensive bleeding occurs. Over a period of several hours, a large blood clot, or fracture hematoma, develops
  • An internal callus forms as a network of spongy bone unites with the inner edges, and an external callus of cartilage and bone stabilizes the outer edges
  • The cartilage of the external callus has been replaced by bone, and struts of spongy bone now unite the broken ends. Fragments of dead bone and the areas of bone closest to the break have been removed and replaced
  • A swelling initially marks the location of the fracture. Over time, this region will be remodelled, and little evidence of the fracture will remain
Term
Describe the structure of cartilage
Definition
  • Matrix - firm gel
  • Cartilage cells - Chondrocytes
  • Avascular (unusual)
Term
Describe the two types of cartilage growth
Definition

Interstitial growth

  • Chondrocytes undergo cell division and the daughter cells produce more matrix
  • Enlarges cartilage from within (interstitial)
  • Important for development from embryo to puberty

Appositional growth

  • New layers of cartilage are added to the surface (under the perichondrium)
  • Fibroblasts (stem cells) differentiate into immature chondrocytes that add to the matrix
Term
Name & describe three types of cartilage
Definition

Hyaline (eg. nasal, join ribs to sternum)

 - most common, closely packed collagen fibres make it tough

 

Elastic (eg. epiglottis, auricle)

- elastic fibres make it resilient and flexible

 

Fibrous (eg. between pubic bones)

- densely interwoven collagen fibres, extremely durable and tough

Term
Name the components of bone and the % of composition
Definition

 

Calcium 39%

Potassium 0.2%

Sodium 0.7%

Magnesium 0.5%

Carbonate 9.8%

Phosphate 17%

 

plus

 

Organic compounds (mostly collagen) 33%

Term

Which two hormones regulate storage, absorption and excretion of calcium ions?

 

And what are the three target sites?

Definition

Parathyroid hormone

Calcitonin

 

 

Bones (storage)

Digestive system (absorption)

Kidneys (secretion)

Term
Describe hormone activity when calcium concentrations fall below normal
Definition

Parathyroid hormone (PTH) released

  • Stimulates osteoclasts which releases stored calcium
  • Increases absorption in intestine
  • Decrease excretion at kidneys

Calcium concentrations increased and homeostasis restored

Term
Describe hormone activity when calcium concentrations rise above normal
Definition

Calcitonin released (thyroid gland)

  • Inhibits osteoclasts and osteoblasts continue to store calcium in bone
  • Decreases absorption in intestine
  • Increased excretion at kidneys

Decreased calcium ion concentration and homeostasis is restored

 

Term

Describe Osteopenia & Osteoporosis

 

Definition

Osteopenia - inadequate ossification causing loss of skeletal mass, normal to a certain extent

 

Osteoporosis - when the reduction in bone mass is sufficient to compromise normal function

  • Osteoblasts (add matrix) reduce activity
  • Osteoclasts (remove matrix) continue same level of activity
Term
Describe 3 classifications of joints (articulations)
Definition

Synarthrosis - Immovable joint

- Fibrous, cartilaginous, or bony fusion

- Bones of the skull, teeth, epiphyseal cartilages

 

Amphiarthrosis - slightly movable joint

- Fibrous or cartilaginous

- Between tibia and fibula and between pubic bones

 

Diarthrosis - freely movable joint

- Synovial joint (further divided into types)

Term
Name and describe 6 types of synovial joints
Definition
  • Gliding
  • Hinge
  • Pivot
  • Ellipsoid (condyloid)
  • Saddle
  • Ball & socket

 

Term
Describe and give examples of a gliding joint
Definition

Slight nonaxial or multiaxial movement

 

  • Acromioclavicular and claviculosternal joints
  • Intercarpal and intertarsal joints
  • Vertebrocostal joints
  • Sacroiliac joints
Term
Describe and give examples of a hinge joint
Definition

Monaxial movement

 

  • Elbow joint
  • Knee joint
  • Ankle joint
  • Interphalangeal joint
Term
Describe and give examples of pivot joints
Definition

Monaxial (rotation)

 

  • Atlas / axis
  • Proximal radio-ulnar joint

 

 

Term
Describe and give examples of ellipsoid (condyloid) joints
Definition

Biaxial movement

 

  • Radiocarpal joint
  • Metacarpophalangeal joints 2-5
  • Metatarsophalangeal joints
Term

Describe and give examples of saddle joints

 

 

Definition

Biaxial movement

 

  • First carpometacarpal joint
Term
Describe and give examples of ball and socket joints
Definition

Triaxial movement

 

  • Shoulder joint
  • Hip joint
Term
Describe movement of synovial joints at different parts of the body
Definition

Wrist - gliding

Neck - flexion, extension and hyperextension

Vertebral column - angular movements - flexion, extension and hyperextension

Shoulder and knee - angular movements - flexion and extension

Shoulder - abduction, adduction and circumduction

Head, neck and lower limbs - rotation

Term
Name special body movements at synovial joints
Definition
  • Supination and Pronation
  • Dorsi flexion and Plantar flexion
  • Inversion and Eversion
  • Protraction and Retraction
  • Elevation and Depression
  • Opposition
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