Chapter 6: Skeletal System Flashcards

Four types of connective tissue

Cartilage, Bone, Bone Marrow, Periosteum

Tissue that makes up MOST of the skeleton

osseous(bone) tissue

Functions of bone are

movement, protection, support, mineral storage, hemopoeisis, energy storage


provides leverage for muscle contraction


protects internal organs from physical injury


supports soft tissue and provides a point of attachment for skeletal muscles

Mineral storage

Calcium and phosphate in bone is available when needed elsewhere in
the body


Blood cell production occurs in red bone barrow

Energy storage

Yellow bone marrow contain lipids, an important source of energy

2 Divisions of the skeletal system

Axial & Appendicular portion

Axial portion

80 bones that are arranged along the longitudinal axis of the body

Appendicular portion

126 bones (mostly right & left sides)
ex. appendages, shoulder, pelvic(hip) bones

Examples of Appendages

Arms, legs, hands feet

Examples of shoulder

clavicle, scapula

Examples of pelvic(hip)

os coxae

Classifcation of bones

long bones, short bones, flat bones, irregular bones, suture bones,
sesamoid bones

Long bones

longer than they are wide

Example of long bone


Longest & heavies bone in the body


Short bones

cube shaped

Example of short bones

Tarsals in ankle

Flat bone examples

ribs, sternum, scapula, cranium

Irregular bones are

complex in shape

Irregular bone example


Suture bones are

complex in shape

Example of suture bones

found in cranium
ex. coronal suture

Sesamoid bones are

small bones embedded in tendon/extra bones

Example of sesamoid bone

Patella(knee cap)

Proximal Epiphysis

End of a long bone which is spongy(cancellous) bone arranging in a
latticework of thin plates called TRABECULAE.


shaft of long bone which is compact(dense) bone tissue

Distal Epiphysis

distal end of long bone which the same structure as the proximal epiphysis

Epiphyses are usually ____than the long bone



area where the diaphysis joins the epiphysis. Includes the epiphyseal
plate in growing long bones; a layer of hyaline cartilage that allows
the diaphysis to grow in length

Medullary cavity

where yellow bone marrow is found

Articular cartilage

found where two bones come together(joint)

function of articular cartilage

reduce friction as joint and absorb shock


thin layer of dense CT membrane around the surface of the bone

function of periosteum

repair and nutrition of the bone. tendons and ligaments attach.


membrane that lines the medullary cavity of the bone. Contains
osteoprogenitor cells and osteoclasts.

Four main types of cells in bone tissue

osteoprogenitor, osteoblast, osteocyte, osteoclast


found in the inner portion of the periosteum, in the endosteum and
canals in bone that contain blood vessels.

Function of osteoprogenitor

undergo mitosis and become osteoblasts(immature)


cells that form bone tissue. secrete collagen and matrix which
calcifies to build bone tissue.


mature bone cells.
Maintain bone tissue by exchanging nutrients and wastes with the blood


cell that's important in the development, growth, maintenance, and
repair of one.

Function of osteoclast

resorption of bone (breaking down of bone tissue)

Living bone is

bone cells and collagen fibers

non living bone=

calcium, phosphorus, and chemical components of the matrix

Bones become more _____ as we age


Bone remodeling

continuous ongoing replacement of old bone tissue with new bone tissue

Osteoblasts are constantly ___

forming new bone tissue

Osteoclasts are constantly_____

destroying old bone tissue

Bone is a major storage area for _____


Calcium is important for

heart, nerve, enzyme, and blood physiology

Bone vs blood calcium levels are regulated by

Parathyroid glands and throid gland

Parathyroid gland secretes

PTH(parathyroid hormone)

Thyroid gland secretes

hormone calcitonin

If blood calcium levels are HIGH ____

calcitonin is released by the thyroid gland and osteoblasts are
stimulated to build more bone. This uses calcium so the blood calcium
levels decrease to normal

If the blood calcium levels are LOW______

PTH is released by the parathyroid gland and osteoclasts are
stimulated to break down bone to release calcium ions and blood
calcium levels increase to normal.

Fracture is

break in bone

4 sequence of events for repair

fracture hematoma, fibrocartilageinous callus, bony callus, remodeling

Fracture hematoma

formation of a blood clot

Fibrocartilaginous callus

organization of the fracture into granulation tissue called procallus

Bony callus

fibrocartilaginous(soft) callus becomes bony(hard) callus


restoration of the bone to near original structure and form

Colle's fracture

break in the distal end of the radius

Potts fracture

break in the distal end of the ribia

Most frequently broken bone in the body


Compact(dense bone)

consists of osteons with very little space between them, composes
bone tissue of the diaphysis

Function of compact(dense) bone

protect and support

Spongy(Cancellous) bone

does not contain osteons, consists of trabeculae surrounding many
red-marriw filled spaces, found in short, flat, and irregulkar bones
and in the epiphyses of long bones

Spongy(cancellous) bones function

store red marrow and provide some support

ossification is

bone formation

2 types of bone formation(ossifiossificationcation)

Intramembrane ossification, endochondrial

Intramembranous ossification

occurs within fibrous membranes. Mesencyhaml ceels become
osteoprogenitor cells which then become osteoblasts which secrete bone matrix.

Endochondroial oossification

occurs within a hyaline cartilage model

Primary ossification center of a long bone is in the


Secondary ossification centers develop in the

Epiphyses, where bone replaces cartilage except for the epiphyseal plate

Epipuseal plate

layer of hyaline cartilage in the metaphysis of growing bone

4 zones(epiphysis to diaphysis)

resting cartilage, proliferating cartilage, hypertrophic(maturing
cartilage), calcified cartilage

Resting cartilage

anchor the epiphyseal plate to the bone of the epiphysis

Prolifterating cartilage

layer of chondrocytes stacked like coins in columns

hypertropic(maturing) cartilage

larger chondrocytes, stacked in columns

Calcified cartilage

only a few cells thick. Calcified matrix; cements epiphyseal plate to
the bone of the diaphysis.

at 20 years of age bones stop growing in length because of

sex steroids (mainly estrogens in male/females) & shut down at
the epiphyseal plate