Unit 4 Skeletal System (no Diagrams)

Osteoblasts

bone forming cells "Builders"

Osteoclasts

cells that break down bone matrix, important for Calcium homeostasis and bone remodeling

Osteocytes

mature bone cells found in lacunae; maintain bone structure; mature osteoblasts

phosphorus and calcium

minerals needed for building bones

Osteoporosis

A condition in which the body's bones become weak and break easily.

Osteosarcoma

malignant tumor of the bone

spongy bone

Layer of bone tissue having many small spaces and found just inside the layer of compact bone.

compact bone

Hard, dense bone tissue that is beneath the outer membrane of a bone

Articulation (joint)

the point at which two bones come together

synovial joints

freely movable joints; filled with synovial fluid

Examples: hinge/pivot, ball and socket, gliding, saddle

hinge joint example

extend and contract; elbow and knee (type of synovial)

saddle joint

type of joint found at the base of each thumb; allows grasping and rotation (type of synovial)

plane joint (gliding joint)

most simple and least mobile articulation between flat surfaces of two bones; metacarpals/metatarpals (type of synovial)

ball and socket joint

circular movement; hip and shoulder (type of synovial)

cartilaginous joints

allow only slight movement and consist of bones connected entirely by cartilage; spine and rib

fibrous joints

consists of inflexible layers of dense connective tissue, holds the bones tightly together; immovable; skull and pelvis

How do bones grow larger?

epiphyseal lines grow cartilage (chondrocytes) which are replaced with Osteoblasts (grow new bone) and then Osteocytes.

closed fracture (simple)

break that does not penetrate the skin

open fracture (compound fracture)

Broken bone has come through the skin

greenstick fracture (incomplete fracture)

bone is only partially broken

Why does your body need calcium besides building bone?

muscle contraction, neuron/heart electrical stimulatin

Explain the feedback loop for LOW CALCIUM

the Parathyroid releases parathyroid hormone which causes OSTEOCLASTS to breakdown bone and release calcium into the blood. This raises the level of calcium back to normal.

Explain the feedback loop for HIGH CALCIUM

the Thyroid releases Calcitonin hormone which causes OSTEOBLASTS/OSTEOCYTES to deposit calcium from the blood INTO the bone matrix. This lowers the level of calcium back to normal.

long bones

longer than they are wide Ex: Femur

short bones

cube shaped bones of the wrist and ankle

flat bones

These bones are thin, flat, and curved. They form the ribs, breastbone, and skull, for example.

Irregular bones

Bones that don't fit into the other categories and include bones of the vertebrae and face