Skeletal 1

bones, cartilage, ligaments

What is the Skeletal system composed of?

support, protection, movement,mineral homeostasis, blood cell formation (hemopoiesis)

Functions of Skeletal System

Support

provides a scaffold or framework to support soft tissues

Protection

protects many internal organs from injury

Mineral homeostasis

stores calcium and phosphorus--minerals are released into the blood when needed

movement

skeletal muscles attach to bones by tendons

Hemopoiesis

blood cell formation in red bone marrow

Osteocytes

mature bone cells, maintain bone matrix

Osteology

The study of anatomy, structure, and function of the bones.

long bones, short bones, flat bones, irregular bones

Classification of bones

long bones

bones that are longer than they are wide

Short bones

cube shaped bones of the wrist and ankle

flat bones

These bones are thin, flat, and curved. provide both protection and surfaces for muscle attachment

irregular bones

Have complex shapes. examples: spinal vertebrae, pelvic bones

Diaphysis

shaft of a long bone

Epiphysis

End of a long bone

epiphyseal line

found between diaphysis and epiphysis. remnant of the epiphyseal plate, seen in adult bones

articular cartilage

thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber

Periosteum

A dense fibrous membrane covering the surface of bones, contains blood vessels and nerves that enter bone

medullary cavity

marrow cavity within the diaphysis containing yellow marrow

Endosteum

membrane lining the medullary cavity of a bone

osseous tissue

bone tissue

spongy bone and compact bone

two types of bone

cancellous bone

another term for spongy bone

porous

inner layer of bone appears?

Short, flat, and irregular bones

Spongy bone is found mostly in what kind of bones

trabeculae

the irregular latticework of thin bony plates in spongy bone tissue filled with marrow and blood vessels

compact bone

dense, hard outer layer of bone tissue that lie underneath the periosteum

epiphysis

spongy bone makes up the bulk of \___ of bones

diaphysis

compact bone makes up the bulk of \___ of bones

Extracellular matrix (minerals and collagen fibers) and cell types

Bone tissue consists of

Osteoblasts

Bone building cells

ossification

process of bone formation

osteocytes

osteoblasts become \____ once surrounded by bone matrix

Lacunae

spaces occupied by their cell bodies. In bones, small spaces between the lamellae which contain osteocytes

Concentric lamallae

rings around the central canal, sites of lacunae

Canaliculi

spaces occupied by their processes or extensions. little channels that connect lacunae. allows passage of wastes and nutrients

Osteoclasts

Bone-destroying cells responsible for resoprtion or breakdown of bone

Osteon

A structural unit of compact bone. looks like a circular target in cross section

Haversian Canal

central canal in compact bone containing blood vessels and nerves; surrounded by lamellae.

Volksmann's canal

Perforating Canals that come off the Haversian canal and run horizontal. They also contain arteries, veins, and nerve fibers.

intramembranous ossification

process by which bone forms directly from mesenchymal tissue. produces flat bones of skull, clavicle, and part of the mandible in fetus; thickens long bones throughout life

3rd month

what month in embryonic development does intramembranous ossification start?

1st step of intramembranous ossification

Mesenchymal cells cluster & differentiate into osteoblasts. An ossification center is formed.

2nd step of intramembranous ossification

Osteoblasts secrete bone matrix. Matrix calcifies (hardens). Trapped osteoblasts become osteocytes

3rd step of intramembranous ossification

Trabeculae develop. Blood vessels grow in spaces. Mesenchyme condense & form periosteum.

4th step of intramembranous ossification

Trabeculae thicken & its surface layers become compact bone. Vascular tissue become red marrow

endochonral ossification

Bone formation where existing cartilage is replaced by bone

8th week of embryonic development

cartilage is formed during?

2nd month of embryonic development & continues until early adulthood

cartilage begins to ossify during?

1st step of endochondral ossification

Cartilage model is formed.

2nd step of endochondral ossification

Cartilage model grows.

3rd step of endochondral ossification

Primary ossification center is developed.

4th step of endochondral ossification

Medullary cavity is developed.

5th step of endochondral ossification

Secondary ossification centers appear in the epiphyses.

6th step of endochondral ossification

formation of articular cartilage and epiphyseal plate

bone remodeling

ongoing replacement of old bone tissue by new bone tissue

bone resorption

the removal of minerals and collagen fibers from bone by osteoclasts

bone deposition

the addition of minerals and collagen fibers to bone by osteoblasts

Heredity, nutrition, hormones, and exercise

What four factors affect bone growth and maintenance?

Ca2+, phosphorus and protein

forms part of bone matrix. Healthy bones require adequate ingestion of this

Vit D

needed for absorption of Ca++ & phosphorus in the small intestine

Vit A

needed for normal activity of osteoblasts

Vit C

needed for collagen synthesis

growth hormone

hormone secreted by anterior pituitary gland that stimulates growth of bones

thyroid hormone

increase rate of protein synthesis

Estrogen

promotes closure of epiphyseal discs; inhibits osteoclasts

Testosterone

promotes closure of epiphyseal discs; inhibits osteoclasts promotes Ca++ retention which cause stronger bone matrix

parathyroid hormone

increase bone resorption and calcium absorption and levels in blood

Calcitonin

decrease bone resorption which lowers blood calcium levels

Joint

A place in the body where two bones come together

Articulation

Another term for joint

synarthrosis joint

immovable joint (sutures)

amphiarthrosis joint

slightly movable joint (vertebrae)

diarthrosis joint

freely movable joint (synovial); largest category of joints

articular cartilage, joint capsule, synovial membrane, bursae

Parts of a synovial joint

joint capsule

The fibrous sac that encloses a joint.

synovial membrane

The lining of a joint that secretes synovial fluid into the joint space.

Bursae

small sacs of synovial fluid between the joint & the tendons that cross over the joint. permit the tendons to slide easily as the bones are moved

Flexion

type of movement that decrease in angle bet. the bones, bringing them closer together

Extension

Straightening of a joint

Hyperextension

extension beyond anatomical position

Abduction

Movement away from the midline of the body

Adduction

Movement toward the midline of the body

Rotation

moving a bone around its longitudinal axis

Internal Rotation

Rotation of a joint toward the middle of the body.

External Rotation

Rotation of a joint away from the middle of the body.

Circumduction

circular movement of a limb at the far end

Elevation

lifting a body part superiorly

Depression

lowering a body part

Protraction

moving a body part anteriorly

Retraction

moving a part backward

Supination

movement that turns the palm up

Pronation

turning the palm downward

opposition

Movement of the thumb to touch the fingertips

Inversion

Turning the sole of the foot inward (medially)

Eversion

turning the sole of the foot outward (laterally)

Dorsiflexion

bending of the foot or the toes upward

plantar flexion

bending of the sole of the foot by curling the toes toward the ground

brittle bones and cartilages of joints erode

Effects of aging on bones