Hierarchy of Structure in Animals

Hierarchy of Structure in Animals

• Animals are multicellular, meaning they are made of many specialized cells.
• Specialized animal cells cannot survive independently, requiring cooperative groups of cells to form tissues, organs, and organ systems.
• Large animals can comprise trillions of individual cells.

Multicellular Organisms

• Animals are composed of many different specialized cells.
• These specialized cells work together as part of a larger group, forming the organism's body.
• Complex organisms may include trillions of cells.

Complexity in Animals

• Animals display varying degrees of complexity. Visual examples (images) of animal complexity are shown.

Hierarchy of Animals

• Cells form a hierarchy, with increasing levels of complexity.
• An arrangement or classification of things by order of increasing complexity in animals.
• Functioning in organisms depends on the hierarchy of organization within the animal.

Hierarchy in Animals: Example

• Cell: A basic unit of life (e.g., heart muscle cell).
• Tissue: Groups of similar cells (e.g., heart muscle tissue).
• Organ: Structures composed of tissues (e.g., heart).
• Organ system: Multiple organs working together (e.g., circulatory system).
• Organism: A complete living thing (e.g., human).

Organ System

• Organ systems consist of one or more organs and structures operating together for essential life functions.
• Examples include the digestive, circulatory, and respiratory systems.
• Diagrams (illustrations) depict the respiratory and digestive systems.

Organ

• Organs are made of two or more tissue types working together for complex life processes.
• Specific organ examples are shown: heart, lungs, and stomach.

Tissue

• Tissues are collections of similar cells that perform specific, though limited, functions.
• Types of tissue include: epithelial, connective, muscle, and nerve tissue
• Examples of specific tissues are provided, such as lining of digestive system, tendons, smooth muscle, and nerves in sensory organs.
• Additional detail on epithelial tissue: (example provided).
• Additional detail on connective tissue: (example provided).
• Additional detail on muscle tissue (example provided).
• Additional detail on nerve tissue (example provided).

3.2 Stem Cells and Cell Differentiation

• Stem Cells: Undifferentiated cells capable of differentiating into various cell types.
• Stem cells give rise to all the specialized cell types in the body.
• A diagram illustrates the connection between stem cells and various differentiated cells (muscle, blood, nerve, cardiac).

Cellular Differentiation

• Differentiation is the process that creates specialized cells to carry out particular functions.
• Genetic material (DNA) directs differentiation and is passed on through generations.
• A diagram illustrates the process of differentiation, showing the expression of specific genes to generate distinct cell types.

Stem Cells: Types

• Embryonic Stem Cells: Pluripotent (able to differentiate into many cell types).
• Tissue (Adult) Stem Cells: Multipotent (capable of differentiating into limited cell types).

Stem Cells: Sources

• Embryonic stem cells: Derived from embryos. Can differentiate into many cell types.
• Tissue (adult) stem cells: Found in adult tissue. Can differentiate into a limited range of cell types.
• Examples include stem cells from bone marrow, umbilical cord.

Regeneration or Repair

• In complex animals, some tissues can regenerate or repair after damage (e.g., muscle, skin, bone).
• Other tissues cannot regenerate (e.g., nerve tissue).
• A diagram (illustration) shows the regeneration of a starfish arm.

How Cells Become Specialized

• This section provides a visual representation of how cells become specialized.

Homework

• Specific pages and questions in a textbook are assigned for homework.

Answers

• Solutions to assigned textbook questions regarding organ systems and cells are provided.
• Detailed explanations of those solutions are included (cell differentiation and regeneration).