Page 3: Synapses, Reflexes, and Reaction Time

This section covers important concepts for Homeostasis GCSE Biology AQA questions:

• Synapses: Connection points between neurons
• Reflexes: Rapid, automatic responses to stimuli
• Reflex arc: Pathway of information in a reflex action
• Reaction time: Speed of response to a stimulus

Example: A reflex arc when touching a hot object involves:

1. Stimulation of pain receptors
2. Sensory neuron activation
3. Signal transmission through relay neurons
4. Motor neuron activation
5. Muscle contraction to withdraw hand

Highlight: Reflexes are crucial for reducing the chances of injury by providing rapid responses without conscious thought.

Page 1: Introduction to Homeostasis

Homeostasis is the regulation of internal body conditions to maintain a stable environment. This section explores:

• Definition and importance of homeostasis
• Controlled conditions (e.g., body temperature, blood glucose)
• Components of control systems (receptors, coordination center, effectors)
• Negative feedback homeostasis mechanisms

Definition: Homeostasis is the maintenance of a stable internal environment in response to internal and external changes.

Example: When blood glucose levels rise, the body releases insulin to bring them back down, demonstrating negative feedback homeostasis.

Highlight: Automatic control systems use negative feedback to maintain stability by counteracting changes in internal conditions.