Week+7+Phylum+Chordata+and+Bones

Introduction

• K103 Lab Week 7

• Presenters:

  • Lynda Bonewald, PhD

    • Musculoskeletal biologist

    • Research focus: osteocytes and bone to muscle crosstalk in aging

    • Over 200 publications

    • Founding director of Indiana Center for Musculoskeletal Health (ICMH)

  • Lilian Plotkin, PhD

    • Bone biologist from Argentina

    • Expertise: osteoblasts and bone histology

    • Current research: sex differences in the skeleton, chromosomal and hormonal contributions

Organism Overview

• Overview of various organism classifications and developmental biology concepts.

Organization of Animal Kingdom

• Key Concepts:

  • Parazoa and Eumetazoa:

    • Distinction based on levels of tissue organization and symmetry.

  • Symmetry Types:

    • Radial symmetry (ex. Cnidaria)

    • Bilateral symmetry (ex. Bilateria)

  • Developmental Concepts:

    • Gastrulation

    • Body cavity types:

      • Acoelomates, Pseudocoelomates, Coelomates

      • Protostomia vs. Deuterostomia

Chordata Phylum

• Key Characteristics:

  • Notochord -> precursor to backbone

  • Dorsal nerve cord -> spinal cord

  • Closed circulatory system

  • Subphylum: Cephalochordata:

    • Closest living relatives of vertebrates

    • Help reconstruct evolutionary steps from invertebrate to vertebrate

    • Early chordate lineage: 650-700 million years ago

    • Example: Pikaia, a finned swimming organism

• Subphylum: Vertebrata:

  • Distinct head and trunk structure

  • Supported by cartilage and vertebrate structures

  • Well-developed brain and sensory organs

  • Examples: reptiles, mammals, birds, amphibians

Skeletal System

• Functions:

  • Support

  • Protection

  • Movement

  • Mineral homeostasis

  • Blood cell production

  • Triglyceride storage

• Bone Anatomy Concepts:

  • Axial vs. Appendicular skeleton

  • Anatomical terms: anterior, posterior, etc.

  • Bone classification:

    • Long, flat, short, irregular, sesamoid

Sesamoid Bones

• Definition: small, round, flat bones found in tendons near joints

  • Example: patella (kneecap)

Bone Structure

Bone Hierarchy

• Macrostructure to Nanostructure:

  • Whole Bone

  • Cortical Bone

  • Trabecular Bone

  • Osteons (functional unit of compact bone)

  • Haversian Canals – nerve and blood supply

Bone Microstructure

• Components of Osteon:

  • Central canal

  • Lamellae (concentric layers)

  • Interstitial system (space between osteons)

Bone Cells

• Types of Bone Cells:

  • Osteoblasts: bone-forming cells

  • Osteocytes: mature bone cells

  • Osteoclasts: bone-resorbing cells

  • Osteoprogenitor cells and bone-lining cells

Joint Classification

Basic Joint Categories

• Synovial Joints:

  • Full range of motion; examples include knee, elbow

• Cartilaginous Joints:

  • Examples: pubic symphysis, vertebrae

• Fibrous Joints:

  • Examples: sutures, syndesmosis

Advanced Joint Classification

• Types of Joints:

  • Synovial Joints:

    • Examples of movements: gliding, angular, rotation

  • Types of Cartilaginous Joints:

    • Synchondroses: united by hyaline cartilage

    • Symphyses: united by fibrocartilage

Types of Cartilage

• Hyaline Cartilage: found in joints, contains chondrocytes

• Elastic Cartilage: provides flexibility

• Fibrocartilage: provides tensile strength and rigidity

Cartilage Components

• Tendon & Ligament Composition:

  • Fibroblasts generate collagen

  • Main component of connective tissue

Rib Distinction

• Divided into:

  • True ribs

  • False ribs (8, 9, 10)

  • Floating ribs (11, 12)

Pelvic Girdle

• Composed of:

  • Os Coxa (hip bone)

  • Sacrum

  • Coccyx

Tasks Ahead

• Identify bones (left/right, anterior/posterior)

• Review bone features if time allows

• Prepared slides on various structures including:

  • Amphioxus immature adult

  • Hyaline cartilage

  • White fibrous tissue

  • Decalcified bone

  • Ground mammal bone