2
Cells, Tissues,
Organs, and Organ
Systems of Animals
Cells, Tissues,
Organs, and Organ
Systems of Animals
Chapter Outline
- 2.1 What Are Cells?
- 2.2 Why Are Most Cells Small?
- 2.3 Cell Membranes
- Structure of Cell Membranes
- Functions of Cell Membranes
- 2.4 Movement across Membranes
- Simple Diffusion
- Facilitated Diffusion
- Osmosis
- Filtration
- Active Transport
- Bulk Transport
- 2.5 Cytoplasm, Organelles, and Cellular Components
- Cytoplasm
- Ribosomes: Protein Workbenches
- Endoplasmic Reticulum: Production and Transport
- Golgi Apparatus: Packaging, Sorting, and Export
- Lysosomes: Digestion and Degradation
- Microbodies: A Diverse Category of Organelles
- Mitochondria: Power Generators
- Cytoskeleton: Microtubules, Intermediate Filaments, and Microfilaments
- Cilia and Flagella: Movement
- Centrioles and Microtubule-Organizing Centers
- Vacuoles: Cell Maintenance
- Vaults: A Newly Discovered Organelle
- 2.6 The Nucleus: Information Center
- Nuclear Envelope: Gateway to the Nucleus
- Chromosomes: Genetic Containers
- Nucleolus: Preassembly Point for Ribosomes
- 2.7 Levels of Organization in Various Animals
- 2.8 Tissues
- Epithelial Tissue: Many Forms and Functions
- Connective Tissue: Connection and Support
- Nervous Tissue: Communication
- Muscle Tissue: Movement
- 2.9 Organs
- 2.10 Organ Systems
Because all organisms are made of cells, the cell is as fundamental to an understanding of zoology as the atom is to an understanding of chemistry. In the hierarchy of biological organization, the cell is the simplest organization of matter that exhibits all of the properties of life (figure 2.1). Some organisms are single celled; others are multicellular. An animal has a body composed of many kinds of specialized cells. A division of labor among cells allows specialization into higher levels of organization (tissues, organs, and organ systems). Yet, everything that an animal does is ultimately happening at the cellular level.