Biologi - 8 Grade - Skeletal. Muscle, Joint-2

Skeletal and Muscular System Overview

Skeletal System

  • Definition: The framework consisting of bones that provides support, movement, and protection of internal organs.

  • Total Bones: Adult skeleton has 206 bones (infants have ~300).

  • Divisions:

    • Axial Skeleton: Skull, vertebral column, ribs, sternum.

    • Appendicular Skeleton: Bones of shoulders, arms, hips, legs.

Bone Classification

  • Long Bones: Limbs (arms & legs).

  • Short Bones: Wrist & ankles.

  • Flat Bones: Shoulder blades & skull.

  • Irregular Bones: Face & vertebrae.

Functions of the Skeletal System

  • Support: Provides body shape and structure.

  • Protection: Shields internal organs (e.g., ribcage protects lungs).

  • Movement: Muscles attach to bones, facilitating motion.

  • Storage: Stores minerals (calcium, phosphorus) and produces blood cells in bone marrow.

Skeletal System Details

  • Skull:

    • Cranium: 8 bones protecting the brain.

    • 14 facial bones, including mandible.

  • Vertebral Column: 33 vertebrae in children, 26 in adults (7 fuse).

  • Ribs: 12 pairs; upper 7 true ribs, lower 2 floating ribs.

Muscular System

  • Purpose: Provides motion, maintains posture, and pumps blood.

  • Muscle Types:

    • Skeletal Muscle: Voluntary; striated; attached to bones.

    • Smooth Muscle: Involuntary; non-striated; located in walls of hollow organs.

    • Cardiac Muscle: Involuntary; striated; found in the heart.

Joints Classification

  • Ball-and-Socket Joints: Shoulders & hips (multi-directional movement).

  • Hinge Joints: Elbows & knees (one direction).

  • Gliding Joints: Wrists & ankles (limited movement).

  • Pivot Joints: Between vertebrae (rotational movement).

  • Fixed Joints: Skull (no movement).

Skeletal System Health and Injuries

  • Common Conditions:

    • Fractures: Different types (e.g., hairline, complete, greenstick).

    • Osteoporosis: Bone weakening due to mineral loss.

    • Scoliosis: Curvature of the spine.

    • Bone Cancer & Leukemia: Symptoms include pain, swelling, and fatigue.

    • Arthritis: Inflammation of joints leading to pain.

Activities and Assessment

  • Classify bones/joints in journals.

  • Discuss functions of the skeletal system.

  • Reflect on living without bones.

  • Model Creation: Build a skeletal model, explaining its functions.