Tissues and supporting systems: in animals and plants.

1. Tissues and Supporting Systems: Skeleton and Supporting Systems in Animals

1.1 Biological Significance of Skeletons

• Definition: The skeleton is a framework that provides structure and support to the body of an organism.
• Significance:
  • Supports the body’s shape and form.
  • Facilitates movement in conjunction with muscles.
  • Protects vital organs (e.g., skull protects the brain, ribcage protects the heart and lungs).
  • Assists in respiratory movements (e.g., rib cage expands during breathing).

1.2 Skeletal Materials

1. Bone:

   • Features: Hard, rigid, and mineralized tissue composed primarily of calcium phosphate.
   • Function: Provides structural support, protection, and storage of minerals.
   • Example: Femur (thigh bone).

2. Cartilage:

   • Features: Flexible, elastic tissue made of chondrocytes and collagen.
   • Function: Reduces friction at joints, provides flexibility and cushioning.
   • Example: Ear cartilage.

3. Chitin:

   • Features: Tough, fibrous polysaccharide found in invertebrates.
   • Function: Forms exoskeletons in arthropods like insects and crustaceans.
   • Example: Shell of a crab.

1.3 Types of Skeletons

1. Exoskeleton:

   • External hard covering.
   • Found in arthropods (e.g., insects, crabs).
   • Provides protection and prevents water loss.

2. Endoskeleton:

   • Internal skeletal structure.
   • Found in vertebrates (e.g., humans, fish).
   • Supports the body internally and facilitates movement.

3. Hydrostatic Skeleton:

   • Fluid-filled cavities that provide support.
   • Found in soft-bodied animals like earthworms and jellyfish.
   • Facilitates movement by changing the shape of the body.

1.4 Bones of the Vertebral Column, Girdles, and Appendicular Skeleton

• Vertebral Column:

  • Divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.
  • Protects the spinal cord and supports body weight.

• Girdles:

  • Pectoral Girdle: Connects forelimbs to the axial skeleton.
  • Pelvic Girdle: Connects hind limbs to the axial skeleton.

• Long Bones:

  • Found in the appendicular skeleton (e.g., humerus, femur).
  • Facilitate locomotion and movement.

1.5 Mechanism of Support in Animals

• The skeleton provides a rigid framework for muscles to attach.
• Muscles contract to move bones at joints, enabling locomotion and flexibility.

1.6 Functions of Skeleton in Animals

1. Protection: Shields delicate organs (e.g., skull protects the brain).
2. Support: Maintains the body’s shape and posture.
3. Locomotion: Works with muscles to enable movement.
4. Respiratory Movement: Facilitates breathing through the expansion and contraction of the rib cage.

2. Supporting Tissues in Plants

2.1 Main Features of Supporting Tissues in Plants

1. Turgid Parenchyma:

   • Living cells with thin walls.
   • Store water and nutrients, contributing to turgidity and support.

2. Collenchyma:

   • Living cells with thickened cell walls at corners.
   • Provide flexibility and mechanical support.

3. Sclerenchyma:

   • Dead cells with lignified walls.
   • Offer rigidity and strength.

4. Xylem (Wood):

   • Conducts water and minerals.
   • Provides mechanical support through lignified tissue.

2.2 Functions of Supporting Tissues in Plants

1. Strength and Rigidity:
   • Prevent collapse against external forces like wind and water.
2. Flexibility:
   • Allow bending without breaking (e.g., collenchyma).
3. Resilience:
   • Enable recovery after stress.

3. Location and Arrangement of Skeletal and Supporting Tissues

3.1 In Animals:

• Bones are strategically located to support the body's framework.
• Cartilage is found in joints, ear, nose, and intervertebral discs.
• Chitin forms the exoskeleton in arthropods.

3.2 In Plants:

• Supporting tissues are distributed throughout the stem, roots, and leaves.
• Epidermis: Protects the plant’s outer surface.
• Cortex: Provides support and storage.
• Stele: Contains vascular tissues (xylem and phloem).

4. Real-World Applications

1. Skeletal System in Medicine:

   • Bone grafts and cartilage repair for injuries.
   • Artificial joints for mobility restoration.

2. Plant Supporting Tissues in Agriculture:

   • Enhancing crop resilience against environmental stressors.

5. Common Misconceptions

• Misconception: "All skeletons are made of bone."
  • Fact: Exoskeletons and hydrostatic skeletons are made of other materials like chitin or fluid-filled structures.
• Misconception: "Plants do not have structural support systems."
  • Fact: Supporting tissues like sclerenchyma and collenchyma provide rigidity and flexibility.

6. Key Diagrams

1. Skeleton of a Mammal:

   • Label vertebral column, girdles, and long bones.

1. T.S. of Herbaceous Plant Stem:

   • Include labeled sections of epidermis, cortex, and stele.

Summary

• Skeletons in animals provide protection, support, and locomotion, while supporting tissues in plants ensure rigidity, flexibility, and resilience.
• Understanding the interplay between structure and function in these systems highlights their critical role in survival and adaptability.