3.1.2 Reflex Actions

• Reflex actions involve a neural pathway called the reflex arc
• The receptor in a reflex arc detects the stimulus and initiates a nerve impulse
• The motor neuron carries the nerve impulse from the spinal cord to the effector
• Where is the nerve impulse transferred from the sensory neuron to the motor neuron in a reflex arc?

  Spinal cord
• Match the neuron type with its role in the reflex arc:

  Sensory Neuron ↔️ Carries impulse from receptor to spinal cord

  Motor Neuron ↔️ Carries impulse from spinal cord to effector

  Interneuron ↔️ Connects sensory and motor neurons
• A sensory neuron carries the nerve impulse from the receptor to the spinal cord.


  True
• Motor neurons transmit impulses from the spinal cord to effectors in a reflex arc.

  True
• Reflex actions allow the body to respond quickly to environmental changes without conscious thought.


  True
• Sensory neurons convert sensory stimuli into electrical signals called nerve impulses.
• Match the neuron type with its role in the reflex arc:

  Sensory neuron ↔️ Carries impulse from receptor

  Interneuron ↔️ Transfers impulse within spinal cord

  Motor neuron ↔️ Carries impulse to effector
• What is a reflex action?

  Involuntary, rapid response
• Interneurons coordinate the motor response in reflex actions.


  True
• Motor neurons have long axons to reach effectors.

  True
• Relay neurons in the spinal cord allow reflex actions to occur without brain involvement.

  True
• Steps of the reflex arc in the correct order:

  1️⃣ Stimulus detected by receptor

  2️⃣ Nerve impulse travels through sensory neuron

  3️⃣ Impulse transferred by relay neuron in spinal cord

  4️⃣ Motor neuron carries impulse to effector

  5️⃣ Effector executes response
• Where are sensory neurons located?

  Sensory organs and tissues
• What is the primary function of sensory neurons?

  Transmit sensory information
• Where are interneurons located in the reflex arc?

  Spinal cord
• Match the neuron type with its role in the reflex arc:

  Sensory Neuron ↔️ Carries impulse from receptor

  Interneuron ↔️ Transfers impulse to motor neuron

  Motor Neuron ↔️ Carries impulse to effector
• In a reflex arc, motor neurons transmit impulses from the spinal cord to effectors.


  True
• Arrange the steps of the pupillary light reflex:

  1️⃣ Light shines in the eye

  2️⃣ Photoreceptors in the retina detect light

  3️⃣ Sensory neuron carries impulse to spinal cord

  4️⃣ Relay neuron transfers impulse

  5️⃣ Motor neuron carries impulse to iris muscles

  6️⃣ Iris muscles contract, pupil constricts
• What are reflex actions in biological terms?

  Involuntary, rapid responses
• How many components are in a reflex arc?

  Five
• Relay neurons ensure quick signal transfer without brain involvement.

  True
• Order the steps in the path of a reflex action:

  1️⃣ Receptor detects stimulus

  2️⃣ Sensory neuron carries impulse to spinal cord

  3️⃣ Relay neuron transfers impulse within spinal cord

  4️⃣ Motor neuron carries impulse to effector

  5️⃣ Effector responds (e.g., muscle contraction)
• What is the primary function of sensory neurons?

  Transmit sensory information
• What is the role of interneurons in the reflex arc?

  Relay the nerve impulse
• Interneurons are located in the spinal cord and are also known as relay neurons.
• Interneurons integrate sensory input and coordinate the motor response, allowing the body to execute a rapid, involuntary reflex action.
• In a reflex arc, the receptor detects the stimulus and sends an impulse.
• Where is the nerve impulse transferred to a relay neuron in the reflex arc?

  Spinal cord
• What type of signals do motor neurons transmit to effectors?

  Efferent signals
• Match the neuron type with its role in the reflex arc:

  Sensory Neuron ↔️ Carries impulse from receptor to spinal cord

  Interneuron ↔️ Transfers impulse within spinal cord

  Motor Neuron ↔️ Carries impulse from spinal cord to effector
• Motor neurons transmit nerve impulses from the CNS to effectors
• Effectors execute the response by muscle contraction or gland secretion
• Reflex actions take about 50 milliseconds, while voluntary actions take about 0.5 seconds
• Reflex actions allow the body to react swiftly to environmental changes without conscious thought.


  True
• Match the neuron type with its role in the reflex arc:

  Sensory Neuron ↔️ Carries impulse from receptor to spinal cord

  Interneuron ↔️ Transfers impulse within spinal cord

  Motor Neuron ↔️ Carries impulse from spinal cord to effector
• Sensory neurons convert sensory stimuli into electrical nerve impulses.

  True
• Interneurons integrate sensory input and coordinate motor responses in the reflex arc.


  True