Overview
This lecture covers the structure and functions of skeletal systems, focusing on differences between exoskeletons and endoskeletons, bone classifications, and bone marrow types in humans.
Skeleton Types
- Arthropods (e.g., ladybugs) have an exoskeleton, meaning their skeleton is outside their body ("exo" = outside).
- Humans have an endoskeleton, located inside the body ("endo" = within).
Functions of the Human Skeleton
- Supports the body and provides a framework for movement through bones and joints.
- Protects vital organs; e.g., the skull shields the brain, the ribcage guards the heart and lungs.
- Performs physiological roles such as calcium storage and hematopoiesis (blood cell production in bone marrow).
Skeleton Divisions
- Axial skeleton: includes the skull, ribcage, and vertebral column; forms the body's central axis.
- Appendicular skeleton: consists of limb and pelvis bones, attaching to the axial skeleton.
Bone Classifications
- Flat bones: found in the skull, ribs, and pelvis; contain inner spongy (cancellous) bone and outer compact bone; provide organ protection and site for hematopoiesis.
- Long bones: examples include the humerus and femur; structure features:
- Diaphysis: long middle section.
- Epiphysis: bone ends.
- Metaphysis: region between diaphysis and epiphysis, contains the growth plate.
- Long bones also have inner spongy and outer compact layers and support movement and hematopoiesis.
Bone Marrow Types
- Red bone marrow: main site for hematopoiesis; abundant in flat bones and epiphyses of long bones.
- Yellow bone marrow: primarily fat storage (adipocytes); found mainly in the diaphysis of long bones.
Key Terms & Definitions
- Exoskeleton — skeleton outside an organism's body.
- Endoskeleton — skeleton inside an organism's body.
- Hematopoiesis — formation of blood cells within bone marrow.
- Axial skeleton — central bones (skull, ribcage, vertebral column).
- Appendicular skeleton — limb and pelvis bones.
- Flat bone — bone with inner spongy and outer compact layers, protective function.
- Long bone — elongated bone with diaphysis, metaphysis (growth plate), and epiphyses.
- Red bone marrow — tissue in bones producing blood cells.
- Yellow bone marrow — fatty tissue in bones storing fat.
Action Items / Next Steps
- Review diagrams of skeletal divisions and bone classifications.
- Memorize key bone structures and their functions.