Human Anatomy: 2100 Exam 2

The skeletal system is a __ organ system with tissues that grow and change throughout life

dynamic

Cartilage is a __ connective tissue

supporting

Example of cartilage soft tissues

airways in respiratory system, auricle of ear

Gliding surfaces at articulations (joints)

cartilage

Cartilage is _ than bone, but more _ and resilient

weaker; flexible

Parts of cartilage

chondroblasts and chondrocytes

Where do chondroblasts and chondrocytes reside?

lacunae

Mature cartilage is __

avascular (no dedicated blood flow)

Hyaline cartilage

lines end of bones

Fibrocartilage

stronger and more resilient (intervertebral discs)

Elastic cartilae

resistent and flexible (ear lobes)

Interstitial growth

in center of tissue

Appositional growth

at edges of tissue

Hematopoiesis

blood cell production in red bone marrow

Bone General Functions

• Structural support

• Protection of more delicate organs

• Movement

• Hematopoiesis

• Storage of mineral and energy reserves

What minerals are stored in bones?

Calcium and phosphate (ATP/ADP), lipids stored in yellow marrow

Calcification

Extracellular matrix is sturdy and rigid due to deposition of minerals

Bones of the skeleton are complex organs containing __ tissue types

all four

Long bones

long, cylindrical (humorous, femur, etc.)

Short bones

as wide as they are long (tarsal)

Flat bones

broad and thin bones (skull)

Irregular bones

any bones with a weird shape (vertebrae)

Diaphysis

extending all the way through (shaft)

Epiphysis

ends of bone

Metaphysis

epiphyseal plate (growth plate)

__ makes up the majority of the bone

Diaphysis

Articular cartilage

Hyaline cartilage (glassy surface for bones to slide over each other)

Medullary cavity

open space in diaphysis (would be much heavier without)

Spongy bone

contains red bone marrow

• hemopoiesis

Endosteum

inner lining of the medullary cavity (contains a bunch of different cells)

Periosteum

outer lining of medullary cavity

Bone is __ vascularized

highly

Nerves accompany blood vessels through the __

nutrient foramen

Osteoprogenitor cells

stem cells in endosteum and periosteum—turns into osteoblasts

Osteoblasts

secrete osteoid, forming bone matrix

Osteocytes

maintains matrix, detects mechanical stress on bone

• osteoblasts trapped by bone matrix

Osteoclasts

dissolve bone matrix, releasing calcium

• when systemic Ca2+ is needed

Compact bone

relatively dense, external surfaces of long and flat bones

Spongy bone

open lattice of narrow plates called trabeculae, internal surface of bones

The basic unit of compact bone is __

osteon

Osteons are also known as __

Haversian system

Central canal

in center of osteon, containing blood vessels and nerves

Concentric lamellae

rings around central canal

Osteocytes housed in __ between lamellae

lacunae

Canaliculi

tiny interconnecting channels that extend between lacunae (space), allow osteocytes to connect and communicate

Perforating canals

run perpendicular to and help connect multiple central cannals

Spongy bones __ osteons

lack

Trabeculae in spongy bone contains __

parallel lamellae

trabeculae

small, beam-like tissue structures that provide mechanical support and form porous frameworks inside organs and bones

Ossification

the formation of bone connective tissue

Intramembranous ossification

produces flat bones of the skull, some facial bones, mandible, and central portion of clavicle

• bones develop from mesenchyme membrane

Process of intramembranous ossification

• calcification entraps osteoblasts within lacunae in bone matrix

• osteoblasts become osteocytes

Endochondral ossification

Formation of most bones of skeleton: upper / lower limbs, pelvis, vertebrae, ends of clavicles

Where do the bones develop from in endochondrial ossification?

from hyaline cartilage model

First step of endochondral ossification

The fetal hyaline cartilage model develops

Second step of endochondral ossification

Cartilage calcifies, and a periosteal bone collar forms

Third step of endochondral ossification

The primary ossification center forms in the diaphysis

Fourth step of endochondral ossification

Secondary ossification centers form in the epiphyses

Fifth step of endochondral ossification

Bone replaces cartilage, except the articular cartilage and epiphyseal plates

Sixth step of endochondral ossification

Epiphyseal plates ossify and form epiphyseal lines

A long bone’s growth in length

interstitial growth, occurs in epiphyseal

Growth in a bone’s diameter

oppositional growth, occurs in periosteum

Epiphyseal plate

– Site of interstitial growth

– Consists of five distinct microscopic zones

Zone 1 of the epiphyseal plate

zone of resting cartilage

Zone 2 of the epiphyseal plate

zone of proliferating cartilage

Zone 3 of the epiphyseal plate

zone of hypertrophic cartilage

Zone 4 of the epiphyseal plate

zone of calcified cartilage

Zone 5 of the epiphyseal plate

zone of ossificatio

__ stimulates increase in bone density via increased osteoblast activity

mechanical stress

Bones of athletes become thicker and stronger as the result of __

repetitive and stressful exercise

Bones lose mass with age, but this can be slowed or reversed with __

weight bearing exercise

Simple fracture

Compound fracture

Comminuted fracture

a severe type of broken bone where the bone shatters or breaks into three or more pieces

Compression fraction

a collapse or break in a spinal bone, called a vertebra, usually caused by pressure on weakened bone

Spiral fracture

a severe type of broken bone where the fracture line wraps around the bone in a corkscrew shape due to a strong twisting or rotational force

Epiphyseal fracture

a break in the growing tissue near the ends of long bones in children and adolescents

Depressed fracture

occurs when a piece of bone is pushed inward below its normal level due to a high-impact blow or compression

Greenstick fracture

an incomplete break where the bone bends and cracks on only one side instead of snapping completely apart

Stress fracture

a tiny crack or severe bruising inside a bone caused by repetitive force and overuse rather than a single injury

During aging, bones change in two ways:

• Loses the ability to produce organic matrix (mainly collagen)

• Loses calcium and other minerals (bone mineral density)

Osteopenia

a condition where bone mineral density is lower than normal

Osteopenia can result in a decrease in bone mass called __

osteoporosis

Osteoporosis features

• compact bone becomes spongy

• bone tissue deteriorates at a faster rate than it is produced

• bones are more susceptible to fracture

• compression fractures of the vertebrae are common

• common in elderly

• treatment: calcium and vitimin d, hormone replacement

Typically __ bones in the adult skeleton

206

Axial skeleton

• skull

• vertebral column

• thoracic cage

Appendicular skeleton

• bones of the upper and lower extremities

• shoulder and hip bones

General functions of the axial skeleton

• protect organs

• house special senses

• muscle attachments

• hematopoiesis

Unpaired cranial bones

• ethmoid

• frontal

• occipital

• sphenoid

Paired (right and left) cranial bones

• parietal

• temporal

Ethmoid bone

Frontal bone

Occipital bone

Sphenoid bone

Parietal bone

Temporal bone

Unpaired facial bones:

vomer and mandible

Paired facial bones

• maxillae

• nasal

• lacrimal

• zygomatic

• palatine

• inferior nasal conchae

Vomer bone

Mandible bone