Life's Organisation: Cells, Matter, and Human Tissues

Organisation and Composition of Life

Levels of Organisation

Abiotic (Non-living) Levels

• Atom Level
• Molecule Level
• Macromolecule Level

Biotic (Living) Levels

• Organelle Level: e.g., Mitochondria
• Cellular Level: The fundamental unit of life
• Multicellular Level:
  • Tissue Sublevel
  • Organ Sublevel
  • Organ System Sublevel

Composition of Matter

• Primary Bioelements: Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur, Phosphorus (CHONSP)
• Secondary Bioelements: e.g., Calcium, Sodium
• Trace Bioelements: e.g., Iron, Zinc

The Building Blocks of Life

Cell Characteristics

Structure and Functions

• Cell Membrane: Surrounds, protects, and regulates the transfer of substances.
• Cytoplasm with Organelles: Carries out vital cellular functions.
• Genetic Material: Contains the instructions for life.

Cell Types

• Prokaryotic Cells: No nucleus; genetic material is dispersed in the cytoplasm (e.g., bacteria).
• Eukaryotic Cells: DNA is contained inside a nucleus.

Human Cell Structures and Organelles

• Cell Membrane
• Cytoskeleton: Gives the cell shape.
• Nucleus: Contains genetic material.
• Mitochondria: Break down glucose for energy (cellular respiration).
• Rough Endoplasmic Reticulum (RER): Stores and transports proteins.
• Smooth Endoplasmic Reticulum (SER): Produces lipids and breaks down toxic materials.
• The Golgi Apparatus: Transports substances made in the RER.
• Lysosomes: Generated by the Golgi apparatus; responsible for digestion.
• Vacuoles: Store a variety of substances.
• Centrioles/Centrosome: Involved in cell division.
• Cilia and Flagella: Allow the cell to move.

Understanding Human Tissues

Connective Tissue

Connects, supports, binds, or separates other tissues or organs.

• Connective Tissue Proper: Surrounds and connects (e.g., tendons, ligaments).
• Cartilaginous Tissue: Supports the skeleton (Cells: Chondrocytes).
• Bone Tissue: Supports the body; stores calcium phosphate (Cells: Osteocytes).
• Adipose Tissue: Stores lipids; provides protection and energy (Cells: Adipocytes).
• Blood Tissue: Liquid plasma containing cells (red blood cells, white blood cells, platelets); transports nutrients, hormones, waste, and provides protection.

Muscle Tissue

Specialized for contraction, producing movement.

• Smooth Muscle Tissue: Involuntary movement; found in hollow organs.
• Cardiac Muscle Tissue: Involuntary movement; pumps blood.
• Skeletal Muscle Tissue: Voluntary movement; attached to the skeleton, keeps bones and joints in place.

Epithelial Tissue

Covers body surfaces, lines body cavities, and forms glands.

• Covering and Lining Epithelium: Covers the outside of the body and lines internal organs and cavities.
• Glandular Epithelium: Forms glands.
  • Exocrine Glands: Secrete substances (e.g., onto a surface or through a duct).
  • Endocrine Glands: Secrete hormones into the blood.

Nervous Tissue

Transmits nerve impulses. Composed of:

• Neurons: Transmit signals.
• Neuroglia (Glial Cells): Support and protect neurons.