| A | B |
|---|
| epidermis | outermost later of skin that is composed of live and dead cells |
| keratin | dead skin cell layer that is waterproof |
| melanin | skin pigment that protects us from UV radiation |
| dermis | thick inner portion of the skin that contains blood vessels, sweat glands, and nerves |
| hair follicle | portion of skin that hair grows out of |
| axial skeleton | portion of the skeleton that includes the skull, ribcage, and spinal column |
| appendicular skeleton | portion of the skeleton that includes the arms, legs and pelvis |
| joint | a junction between two bones |
| ligament | connective tissue that connects bone to bone |
| bursa | a "shock absorber" in your joints |
| tendon | connective tissue that connects muscle to bone |
| compact bone | repeating units of osteons make up this protective layer of bone |
| spongy bone | internal bone that is not as strong as the outer layer |
| osteocyte | a bone cell |
| osteoblast | a cell that builds bone |
| osteoclast | a cell that destroys bone |
| red marrow | this substance produces Red Blood Cells in bone |
| yellow marrow | this substance stores fat in bone |
| voluntary muscle | muscle we can control |
| involuntary muscle | muscle we cannot control |
| smooth muscle | muscle found in the lining of our gut and blood vessels |
| cardiac muscle | muscle found only in the heart |
| skeletal muscle | muscle we control in order to move around |
| myofibril | unit of muscle fiber that is made up of repeating sarcomeres |
| myosin | thick filament in the sliding model |
| actin | thin filament in the sliding model |
| sarcomere | the basic functional unit of contraction |
| sliding filament theory | idea that muscle contraction is based on actin and myosin sliding against each other |
