The skeletal system. 1.SUPPORT Attachment for tendon, framework for body 2.PROTECTION Ex: cranial bones protect brain 3.ASSISTANCE IN MOVEMENT Work with.

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/Appendiculardivisions of the nervous system