Question 1: Define a reflex arc and explain its purpose in the human body.

Answer: A reflex arc is a neural pathway that mediates a reflex action, allowing the body to respond quickly to stimuli without conscious brain involvement, thus protecting the body from harm.

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

Answer: Receptor, sensory neuron, relay neuron (interneuron), motor neuron, effector.

Question 3: Explain how a reflex action differs from a voluntary action.

Answer: A reflex action is automatic and involuntary, occurring rapidly without conscious thought, whereas voluntary actions involve conscious decision-making by the brain.

Question 1: If a person’s finger is observed to fall 15 centimeters after a stimulus is applied, and the reaction time is 0.2 seconds, calculate the average speed of the finger’s movement in cm/sec. Use the formula: Speed = Distance / Time.

Answer: 75 cm/sec

Question 2: A reflex test shows a reaction time of 0.15 seconds. If the nerve conduction velocity is 60 meters per second, estimate the distance between the receptor and the spinal cord in meters.

Answer: 9 meters

Question 1: Describe a simple experiment to test the reflex response of the knee-jerk reflex. List the variables involved and safety precautions.

Answer: An experiment involves tapping the patellar tendon with a reflex hammer while the subject’s leg is relaxed. The independent variable is the force of the tap, the dependent variable is the response time or leg movement, and controlled variables include the position of the leg and the type of hammer used. Safety precautions include ensuring the subject is seated securely and avoiding excessive force to prevent injury.

Question 1: In a study, the average reaction time of 20 individuals to a light stimulus was recorded as 0.25 seconds with a standard deviation of 0.05 seconds. Interpret what this data suggests about the reflex response in the population.

Answer: The average reaction time indicates a relatively quick reflex response in the population, with most individuals responding within a similar timeframe. The small standard deviation suggests low variability among individuals' reflex speeds.

Question 1: Explain how the reflex arc helps protect the body from injury. Include in your answer the speed of response and the pathway involved.

Answer: The reflex arc allows for a rapid response to potentially harmful stimuli by bypassing the brain and directly sending signals through sensory and motor neurons. This quick pathway enables the body to withdraw from danger immediately, preventing injury. The rapid response is due to the involvement of only a few neurons and the absence of conscious processing.

Question 2: A person touches a hot object and quickly pulls their hand away. Describe the sequence of events in the reflex arc that occurs during this action.

Answer: The skin receptors detect heat, activating sensory neurons which send impulses to the spinal cord. Interneurons in the spinal cord process this information and activate motor neurons. Motor neurons then send impulses to the muscles of the hand, causing them to contract and pull the hand away from the hot object.

Question 1: Discuss how reflex testing is used in medical diagnostics and the importance of reaction time measurements in assessing nervous system health.

Answer: Reflex testing helps diagnose neurological conditions by assessing the integrity of neural pathways. Measuring reaction times can indicate nerve damage or diseases affecting the nervous system. Faster or slower responses can help identify specific issues and guide treatment.