Kaap 309: Introduction to Skeletal System

Primary Functions of Bones: What does it do?

1. Support

2. Protection

3. Movement (Anchorage)

4. Storage

5. Hematopoiesis

6. Hormone production

Support

Architecture for the body

• Lower extremity (pillars)

• Thoracic cage (walls)

• Skull (enclosed room)

Protection

Bones protect vital organs:

• Skull → brain

• Thoracic cage → lungs & heart

• Vertebrae → spinal cord

Movement

• Bones serve as levers, and muscles attach via tendons

• Type of movement is determined by joint types

Storage

• Fat storage:

  • Stored as triglycerides in yellow bone marrow

• Mineral storage:

  • Calcium and phosphate reservoirs

Hematopoiesis

Production of blood cells and platelets

• Occurs in red bone marrow

Hormone production

• Production of osteocalcin which regulates:

  • Insulin secretion

  • Glucose homeostasis

  • Energy expenditure

• important for diabetes

Classification of the Skeleton

Two Primary Regions:

1. Appendicular Skeleton

• Limbs (upper/lower)

• Limb girdles

• Upper: scapula, clavicle

• Lower: pelvis

• Function: Movement and locomotion

2. Axial Skeleton (CORE)

• Skull, vertebral column, rib cage

• Function: Support and protection

Acronym: S.P.M.S.H.H. → “Some Powerful Moms Save Happy Homes.”

Function	Key Idea	Memory Image
Support	Architecture for the body (pillars, walls, room)	Imagine bones as a house frame — legs are pillars, rib cage are walls, skull is a room
Protection	Shield organs (skull → brain, ribs → heart/lungs, spine → spinal cord)	Think of armor protecting soft parts
Movement (Anchorage)	Bones = levers, muscles = pulling ropes, joints = hinges	Picture a robot arm
Storage	Stores fat (yellow marrow) + minerals (Ca²⁺, phosphate)	Think of bones as a pantry full of energy + minerals
Hematopoiesis	Makes blood cells in red marrow	Red = blood!
Hormone Production	Makes osteocalcin, regulates insulin, glucose, energy → links to diabetes	Picture a bone “chef” cooking up hormones for blood sugar control

Acronym: “A for Arms, Ax for Axis.”

Skeleton	Includes	Function	Mnemonic
Appendicular	Limbs + limb girdles (arms, legs, scapula, clavicle, pelvis)	Movement & locomotion	“Appendages help you move”
Axial	Skull, vertebral column, rib cage	Support & protection	“Axis keeps your body upright”