BIO 201 Lecture Exam 2 Latest updated questions and answers + rationales - Grand Canyon University

Study of Bones

Osteology

Field of medicine that involves bones, joints, ligaments, ect

Orthopedics

Skeletal System is composed of (4)

bones, cartilage, tendons, ligaments

Ligaments

connect bone to bone

Tendons

connect muscle to bone

Functions of Skeletal System

support, protection, movement, balance, blood formation, rigidity

Shapes of bones (4)

long, short, flat, irregular

Long Bones

bones of extremities, metatarsals, metacarpals

Short Bones

carpals, tarsals

Flat Bones

clavicle, scapula, ribs, skull, pelvis, sternum

Irregular Bones

vertebrae, 3 middle ear bones, facial bones (some), sometimes patella

Diaphysis

shaft of lone bones, gives leverage to bones

Epiphysis

ends of long bones strength, surfaces for attachment

mineralization/ calcification of bones

matrix is hardened by calcium phosphate (and other minerals) being deposited

Characteristics of Compact Bone

denser, makes up 3/4 of total skeleton, outermost layer, makes up most of diaphysis, made up of inversion systems (canals), has medullary cavity in middle with bone marrow

Characteristics of Spongy Bone

makes up 1/4 of skeleton, no osteons, has trabecule, found at epiphysis, found in middle of other bones (skull), covered/ surrounded by compact bone

General Features of Bones

medullary cavity, articular cartilage, periosteum, endosteum, nutrient foramina, epiphyseal plate, and epiphyseal line

Medullary Cavity

surrounded by compact bone, contains bone marrow

Articular Cartilage

made up of hyaline cartilage, found where bone meets bone (knee), reduces friction

Nutrient Foramina

very small holes where blood vessels enter bones

Periosteum

external covering of bone, none where articular cartilage is

Endosteum

lines internal surfaces of bone

Epiphyseal Plate/ Epiphyseal Line

found at ends of long bones between diaphysis and epiphysis where long bones grow in length

Histology of Bone

osteogenic cells, osteoblasts, osteocytes, and osteoclasts

Osteogenic Cells

stem cells that will become bone, already differentiated, undergo mitosis

Osteoblasts

form bone matrix, secrete collagen (protein)

Osteocytes

mature bone cells, help maintain cell activities, do not undergo mitosis, found in lacunae

Osteoclasts

are found, more so, on the surface of bone, break down bone

Bone Marrow

soft tissue in medullary cavities of long bones, between trabeculae of spongy bone, in central canals (osteons) and in some of the flat bones (sternum); 3 types: red, yellow, gelatinous

Red Bone Marrow

myeloid/ hemopoietic, produces red blood cells; in children

Yellow Bone Marrow

fatty does not produce red blood cells, can transform back into red bone marrow if needed

Gelatinous Bone Marrow

turns with age

Matrix of Bone

has both a protein and mineral portion

Protein Portion

made primarily of collagen, 1/3 of the organic matter of bones, gives bones their flexibility

Mineral Portion

85% calcium hydroxiappetite, enables bone to support body weight (compression forces)

Ossification/ Osteogenesis

intramembranous, endochondral

Intramembranous Steps

1. embryonic mesenchyme (comes from mesoderm and turn into sheets of soft tissue

2. trabecular form, osteogenic cells (turn into osteoblasts)

3. trabeculae get thicker

4. some osteoblasts get trapped in lacunae (now become osteocytes)

5. trabeculae become calcified and become spongy bone

6. trabeculae at surface become calcified and become compact bone

7. mesenchyme on surface becomes periosteum

Intramembranous

two layers of compact bone with spongy bone in the middle, produces bones in skull and clavicles, does not have cartilage model

Endochondral

cartilage model, begins 6 weeks post fertilization; embryonic mesenchyme produces chondroblasts which produce hyaline cartilage; cartilage is broken down, reorganized, and recalcified into bone, primary and secondary ossification centers

Primary Ossification Center

in diaphysis/ middle of cartilage model; before birth, chondrocytes hypertrophy and undergo hyperplasia; perichondrium cells become osteogenic cells, osteoblasts form bony collar around cartilage model (periosteum); chondrocytes enlarge and lacunae calcify; chondrocytes do not receive nutrients and die; lacunae fuse together and form cavity in middle of cartilage model (primary marrow cavity); osteoblasts line cavity and deposit osteoid tissue that will calcify and will form bony trabaculae (spongy bone); cartilage begins to die; osteoclasts break down bony trabeculae and marrow cavity is enlarged (diaphysis of long bones); ends of long bones are still hyaline/ articular cartilage; chondrocytes hypertrophy and then die

Primary Ossification Center Summarized

occurs before birth in diaphysis of long bones, gives rise to primary marrow cit

Secondary Ossification Center

forms at birth in epiphysis; cartilage is broken down from center of bone outward;some cartilage trabeculae calcify and form spongy bone; hyaline cartilage remains at epiphyseal