Page 2: Synapses, Central Nervous System, and Reflexes
This page delves deeper into the nervous system, focusing on synapses, the central nervous system (CNS), and reflexes. These topics are essential for AQA GCSE Biology Homeostasis past papers and exam questions.
The page begins by explaining the structure and function of synapses:
- Electrical impulses travel along the first axon
- Neurotransmitters are released from nerve endings
- Chemicals diffuse across the synapse
- Receptor molecules on the second neuron bind to specific neurotransmitters
- The second neuron may then transmit electrical impulses
Highlight: Synapses are gaps between neurons where chemical signals (neurotransmitters) are used to transmit information from one neuron to another.
The central nervous system's role in processing information from receptors is described, emphasizing the pathway from stimulus to response:
Stimulus → Receptor → Sensory Neuron → CNS → Motor Neuron → Effector
Reflexes are introduced as rapid responses to certain stimuli that bypass conscious control:
- Receptors in the skin detect stimuli
- Sensory neurons send electrical impulses to relay neurons in the CNS
- Motor neurons send electrical impulses to effectors
- Effectors produce a response
Example: The knee-jerk reflex is an example of a reflex action that doesn't involve conscious thought.
The page concludes with Required Practical 7, which investigates reaction time. This practical is crucial for Homeostasis exam questions Combined science. The procedure involves:
- Setting up a ruler-drop experiment
- Measuring the distance the ruler falls before being caught
- Calculating reaction time based on the distance
- Repeating the test and calculating the mean
Highlight: Using a computer to measure reaction time provides more precise and accurate results, as it eliminates human error and can record times in milliseconds.
