Overview of Biological Systems

Definition: A biological system is a complex network of biologically relevant entities that interact together to maintain life and carry out biological functions.

Cellular Systems
- Basic unit of life; consists of organelles (nucleus, mitochondria, etc.)
- Processes: metabolism, reproduction, and response to stimuli.
Organ Systems
- Groups of organs working together for specific functions.
- Examples:
  - Circulatory System: transports nutrients, gases, and waste.
  - Respiratory System: gas exchange; oxygen in, carbon dioxide out.
  - Digestive System: processes food and absorbs nutrients.
Ecosystems
- Communities of living organisms (biotic) interacting with their physical environment (abiotic).
- Energy flow and nutrient cycling are key processes (e.g., food chains, food webs).

Homeostasis
- The ability to maintain internal stability despite external changes.
- Involves feedback mechanisms (e.g., body temperature regulation).
Classification of Systems
- Based on function: e.g., physiological, ecological, or molecular systems.
- Can be open (interact with environment) or closed (isolate from environment).
Interaction and Dependency
- Different systems rely on each other; for example, the digestive system provides nutrients for cellular respiration in cells.

A biological system is a complex network of interacting biological entities that work together to maintain life.
All biological systems are comprised of smaller parts that work together to form a larger whole.
This network of interacting parts can be found at all levels of organization, including cells, organs, organisms, and ecosystems.

The basic unit of life is the cell.
Cells contain organelles, which are specialized structures that perform specific functions.
Some examples of organelles include the nucleus (contains genetic material), mitochondria (powerhouse of the cell), and ribosomes (protein synthesis).
Cells carry out important functions like metabolism (all chemical processes in the body), reproduction, and responding to stimuli. ### Organ Systems
Groups of organs work together to perform specific functions.
For example, the circulatory system is responsible for transporting blood, nutrients, gases, and waste products throughout the body.
The respiratory system is responsible for gas exchange, taking in oxygen and releasing carbon dioxide.
The digestive system is responsible for breaking down food and absorbing nutrients.

Ecosystems are made up of communities of living organisms (biotic) interacting with their physical environment (abiotic).
Key processes in ecosystems including energy flow and nutrient cycling.
Food chains and food webs are examples of how energy flows through ecosystems.

Homeostasis is the ability of an organism to maintain a stable internal environment despite external changes.
This is accomplished through feedback mechanisms, such as regulating body temperature.

Systems can be classified by their function such as physiological, ecological, or molecular systems.
Systems can be open, meaning they interact with the environment, or closed, meaning they are isolated from the environment.
Systems depend on each other. For example, the digestive system provides nutrients for cellular respiration in cells, which are essential for life.

Understanding how biological systems work is essential for understanding disease and developing effective treatments.
Conservation of ecosystems is essential for sustainability.
Advances in biotechnology often rely on our knowledge of cellular systems.

Systems biology is a field of study that seeks to understand biological processes holistically.
Systems biology has applications in medicine, agriculture, and environmental science.
Modeling biological systems can help us predict outcomes and design interventions.