Skeletal System Functions: 1) Supports body 2) Protects internal organs 3) Provides for movement 4) Stores mineral reserves 5) Provides a site for blood cell formation

Skeletal System Has 206 bones Divided into two sections: 1) Axial: skull, vertebral column, ribs, and sternum 2) Appendicular: all other bones

Structure of Bones Bones are living tissue!! Periosteum – tough layer of connective tissue surrounding bone Compact bone – beneath the periosteum (dense but not solid) Haversian canals– tubes that run through compact bone and contain blood vessels and nerves

Structure of Bones Spongy bone – inside outer layer of compact bone Osteocytes – digest away old bone Osteoclasts – maintain healthy bone Osteoblasts – make new bone

3-D Section of Bone Tissue

Bone Homeostasis 1.Most of our skeleton is constantly being broken down, and built back up 2.Amount of bone built up = amount of bone broken down 3.This balance of breakdown and buildup is called bone homeostasis

Bone marrow – soft tissue center of bone Maintains the balance of minerals Serves as a storage for minerals (Ca, P) Two Types: 1) Yellow – made mostly of fats, aids in Red Blood Cell (RBC) production 2) Red – produces RBCs, white BC, and cells to help clotting

Skeletal Development The skeleton of the embryo is made of cartilage Bone begins to replace cartilage by 9th week of development (known as ossification)

Joints Joints – where two or more bones meet Most allow movement Some are fixed (no movement): skull

Pelvis, Sexual Dimorphism

Types of Joints Five types: Ball and socket: allows rotational movements (shoulder, hip) Ball and Socket Movement

Types of Joints, Cont’d 2) Pivot: bones twist against each other (atlas and axis of your vertebrae) Pivot Joint in Arm

Types of Joints Cont’d 3) Hinge: back and forth movements much like a door (elbow, knee)

Types of Joints 4) Gliding: bones slide against each other (wrist) 5) Saddle: Freely moveable joint found only in the thumb

Joint support Ligaments: bands of tissue that connect bone to bone Surrounds joints with wide range of motion and little skeletal support Cartilage: covers bone ends and allows for smooth movement. Can also be found in joint to provide cushion (meniscus) Bursa: sacs of fluid that act as shock absorbers Tendons: bands of tissue that connect muscle to bone (patella tendon, Achilles)

Problems with Skeletal System - Breaks Complete/Incomplete (Greenstick) Displaced Simple/Compound (breaks skin) Impacted or Comminuted Spiral Hairline

Breaks - Complete & Displaced

Breaks - Incomplete/Greenstick

Breaks - Spiral

Breaks - Compound

Breaks - Comminuted

Breaks - Hairline

Osteoporosis

Problems with Skeletal System -Rheumatoid arthritis Inflammation in joints Redness, warmth, swelling, pain, fatigue Occurs on both sides of body Genetic, environmental, hormonal factors; immune system attacks the joints and other organs

Rheumatoid arthritis

Problems with Skeletal System - Dislocation Normal Dislocated

Dislocation Normal Dislocated