The skeletal system
1.SUPPORT Attachment for tendon, framework for body 2.PROTECTION Ex: cranial bones protect brain 3.ASSISTANCE IN MOVEMENT Work with muscles 4.MINERAL HOMEOSTASIS calcium 5.BLOOD CELL FORMATION in red bone marrow of select bones 6.TRIGLYCERIDE STORAGE Potential energy reserve in adipose cells of yellow bone marrow
1. diaphysis: shaft 2. epiphyses: ends 3. metaphysis: between diaphysis and epiphysis. Contains hyaline cartilage in growing bone.
4. Articular cartilage: covers ends of bone to reduce friction 5. periosteum: surrounds bone; –serves as an attachment point for ligaments and tendons
6. marrow cavity: inside diaphysis that contains fatty yellow bone marrow
Compact bone tissue Strong/light Makes up most of diaphysis (shaft)
Parts of compact bone OSTEON: repeating unit of compact bone 1.Perforating canals: transverse, for blood vessels and nerves 2. Central canals: runs longitudinally through middle of osteon; for blood vessels and nerves
3. Concentric lamellae: rings around central canals 4. Lacunae: spaces between lamellae 5. Canaliculi: fluid-filled; radiating from lacunae in all directions.
Spongy bone tissue Located on ends of long bones and irregularly shaped bones Looks spongy; is not soft Sometimes contains red bone marrow
Calcium in bone
Bones, neurons, muscle cells, blood clotting, depend on Ca +2 in blood. Too high – heart stops Too low – osteoporosis, breathing stops
Stimulus: low blood calcium levels Receptors: cells of parathyroid gland Control center: nucleus of parathyroid cells (parathryoid hormone – PTH) Effectors: osteoclasts activated – releases calcium from bone A negative feedback system Calcium homeostasis
Stimulus: high blood calcium levels Receptors: Cells in thyroid gland Control center: nucleus of thyroid cells (secrete calcitonin - hormone). Effectors: osteoclasts inhibited: bone absorbs calcium What type of feedback system?
SUMMARY Thyroid controls high blood calcium Parathyroid controls low blood calcium
Axial/Appendicular divisions of the nervous system