The Skeletal System

Formation of Bone When you are developing as a baby, your bone starts as cartilage. As development continues, blood vessels stimulate cartilage and turn it into potential bone cells. These potential bone cells are called OSTEOBLASTS! Cells secrete hormones that make the bone harden.

OSTEOBLASTS

Bone Structure COMPACT BONE = Outside layer = Dense, hard bone –Supplies oxygen and nutrients to bone cells SPONGY BONE = Inside layer –Less dense bone –Lots of holes and spaces (like a sponge) BONE MARROW = Innermost layer Spongy Bone Bone Marrow Compact Bone

Bone Structure

What is the purpose of bone? Framework upon which muscles and organs rest Protection Helps with movement by linking muscles and bones with joints Helps the immune system Warehouse for minerals Purpose Video

How can bones help your immune system? Bone marrow has many useful cells! –Red marrow produces red blood cells which carry oxygen throughout the body. –Red marrow also produces white blood cells to fight disease! –Yellow marrow helps store fats and produces red blood cells during major injury.

The Skeletal System More Bones and Joints!

Lots of Bones! The human skeleton has 206 bones! These bones are divided into two sections on the skeleton. –Axial –Appendicular

Axial Skeleton –Skull and bones that support it Skull Vertebral Column RibsSternum

AXIAL SKELETON

Appendicular Skeleton APPENDICULAR = the bottom half! –arms –legs –pelvic girdle –shoulders

APPENDICULAR SKELETON

Bringing it all together… JOINTS are the hinges that connect bones to one another. Most joints are moveable, but… Stationary joints are called fixed joints. –Ex: Skull Joints are held together by LIGAMENTS –Ligaments are tough bands of tissue The ends of bones are covered with cartilage to ensure smooth motion.

JOINTS

MORE ON JOINTS LIGAMENTS = Thin bands are tissue that connect bone to bone TENDONS = Thick bands of tissue that connect muscle to bone BURSA = Fluid-filled sac that absorbs shock and prevents bones from rubbing together.

LIGAMENTS

TENDONS

BURSA

Arthritis -itis means inflammation Arthro- means joint Arthritis, therefore, means… More than 100 types of arthritis About 37 million people have arthritis in the US ~ 1 out of 7 people

Arthritis

Popping Your Knuckels All joints are surrounded by synovial fluid, a thick, clear liquid Stretching or bending the finger causes the bones of the joint to pull apart which causes the connective tissue capsule to stretch increasing its volume Increasing the volume decreases the pressure of the synovial fluid. The synovial fluid pressure drops, gases dissolved in the fluid become less soluble, forming bubbles through a process called cavitation. When the joint is stretched far enough, the pressure in the capsule drops so low that these bubbles burst, producing the pop that we associate with knuckle cracking. It takes about minutes for the gas to redissolve into the joint fluid. During this period of time, your knuckles will not crack. Once the gas is redissolved, cavitation is once again possible, and you can start popping your knuckles again.

Damage from Popping Knuckles Only one in-depth study 300 people No correlation between popping knuckles and arthritis Problems they did have: soft tissue damage to the joint capsule and a decrease in grip strength Probably because of the stretching of ligaments when creating the popping Professional Baseball players experience similar effects to their pitching arm

Osteoporosis Osteoporosis means porous bone A disease in which bones become less dense and fragile. Painless until bone breaks Can happen in any bone Happens typically in hip, spine, and hand Women are 4 times more likely then men 10 million people in US – –8 million = women –2 million = men

Osteoporosis