Overview
This lecture explains homeostasis, its importance for enzyme and cell function, and the key features of automatic control systems that regulate internal body conditions.
Homeostasis Definition and Importance
- Homeostasis is the regulation of internal conditions in a cell or organism to maintain optimum conditions for function.
- Stable internal conditions are essential because enzymes and cells cannot function well if conditions change too much.
- Homeostasis responds to both internal and external changes to keep conditions constant.
Internal Conditions Maintained by Homeostasis
- Blood glucose concentration, body temperature, and water levels are kept constant in the human body.
- Exercise can affect these conditions by lowering glucose, raising temperature, and causing water loss through sweating.
Automatic Control Systems
- Automatic control systems use either the nervous system or hormones to regulate internal conditions.
- These systems operate without conscious thought to maintain stability in the body.
Key Features of Automatic Control Systems
- Receptor cells detect changes (stimuli) in the environment, which can be internal (blood glucose) or external (skin temperature).
- Stimulus: a change detected by receptors, can be from inside or outside the body.
- Receptors send information to a Coordination Center (brain, spinal cord, or pancreas).
- The Coordination Center processes this information and sends instructions to effectors.
- Effectors (muscles or glands) carry out responses to restore optimum internal conditions.
Key Terms & Definitions
- Homeostasis — Regulation of internal conditions to maintain optimum function.
- Stimulus — A change in the environment detected by receptors.
- Receptor — Cells that detect changes in the environment.
- Coordination Center — Processes information from receptors; examples include the brain, spinal cord, and pancreas.
- Effector — Muscle or gland that carries out responses to restore balance.
Action Items / Next Steps
- Learn and memorize the definition of homeostasis and the key features of automatic control systems.
- Be prepared to identify and describe examples of stimuli, receptors, coordination centers, and effectors.
- Review questions on homeostasis in the revision workbook as assigned.