Question 1: Define the term 'reflex arc' and describe its main purpose in the nervous system.

Answer: A reflex arc is a neural pathway that mediates reflex actions, allowing rapid responses to stimuli without conscious brain involvement, primarily to protect the body from harm.

Question 2: List the main components involved in a typical reflex arc.

Answer: Receptor, sensory neuron, coordinator (spinal cord or brain), motor neuron, effector.

Question 3: Explain why reflex actions are faster than voluntary actions.

Answer: Reflex actions are faster because they bypass the brain and involve only the spinal cord or simple neural pathways, reducing the number of synapses and processing time.

Question 1: Describe a simple experiment you could perform to demonstrate the reflex action of the knee-jerk response.

Answer: Use a person sitting with legs hanging freely, tap the patellar tendon just below the kneecap with a reflex hammer, and observe the involuntary extension of the leg. Ensure safety precautions like checking for injuries beforehand.

Question 2: Identify the independent and dependent variables in this experiment.

Answer: Independent variable: the force or location of the tap; Dependent variable: the response time or extent of leg movement.

Question 3: What safety precautions should be taken during the experiment?

Answer: Ensure the person is healthy without knee injuries, avoid excessive force, and perform the experiment under supervision.

Question 1: A person’s reflex response time is measured from stimulus to response as 0.25 seconds. If the stimulus is applied 0.15 seconds after the initial signal, what is the total response duration? Show your calculation.

Answer: Total response duration = 0.25 seconds (response time) + 0.15 seconds (stimulus delay) = 0.40 seconds.

Question 2: Convert a reflex response time of 0.35 seconds into milliseconds.

Answer: 0.35 seconds = 350 milliseconds.

Question 1: A patient shows a delayed reflex response when testing the knee-jerk reaction. List two possible reasons for this delay.

Answer: Possible reasons include nerve damage or impaired neural pathways, or a neurological disorder affecting reflex transmission.

Question 2: In a scenario where the spinal cord is injured, predict how reflex responses might be affected.

Answer: Reflex responses may be weakened or absent because the neural pathway is disrupted, preventing the reflex signal from reaching the effector.

Question 1: Describe how understanding reflex arcs can be useful in medical diagnosis and treatment.

Answer: Understanding reflex arcs helps diagnose nerve damage or neurological disorders by assessing reflex responses. It also guides treatments such as nerve repair and rehabilitation for improving neural function.

Question 2: Explain how reflex actions are utilized in safety devices like car airbags.

Answer: Car airbags deploy rapidly in response to sudden deceleration detected by sensors, mimicking a reflex action to protect occupants from injury by providing immediate cushioning without conscious decision-making.