Nervous System Overview
State what PNS stands for.
Describe what the PNS includes.
1. PNS stands for the Peripheral Nervous System.
2. The PNS includes all the nerves outside the brain and spinal cord ( CNS)
Identify the type of neuron that carries impulses from a receptor to the CNS.
Sensory neuron
Name one part of the brain.
Frontal Lobe, Occipital Lobe, Parietal Lobe, Temporal Lobe, Cerebellum
Identify which nervous system first detects the hot mug and starts the rapid withdrawal response.
The Peripheral Nervous System (PNS), because sensory nerves in the skin detect the heat and send the signal to the CNS.
Define a synapse.
A synapse is the small gap between two neurons (or a neuron and an effector) where signals are passed using neurotransmitters.
State the two divisions of the PNS.
The PNS is divided into the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS).
Compare the dendrite and the axon terminal in a neuron.
Dendrites receive signals into the neuron (from other neurons/receptors).
Axon terminals send signals out of the neuron by releasing neurotransmitters to the next cell at a synapse.
State the number of main parts of the brain typically taught at this level.
5
Define a stimulus
A stimulus is a change in the internal or external environment that can be detected and causes a response.
Predict what happens to response time if the myelin sheath is damaged.
Response time increases (responses become slower) because impulses travel more slowly along the neuron.
Distinguish between the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS).
The SNS controls voluntary actions, mainly movement of skeletal muscles.
The ANS controls involuntary/automatic functions.
Describe the job of the axon in a neuron.
The axon carries electrical impulses away from the cell body toward the axon terminals.
P__________ is responsbile for perception of senses such as taste, pain, pressure, temperature, and touch
Parietal Lobe
Arrange the following parts in the correct order for a reflex arc: motor neuron, receptor, sensory neuron, effector, relay neuron.
Receptor → sensory neuron → relay neuron → motor neuron → effector.
Describe what must happen next for the signal to cross the synapse after an impulse reaches the axon terminal.
Vesicles release neurotransmitters into the synaptic cleft; the neurotransmitters diffuse across and bind to receptors on the next cell to trigger a new impulse.
Identify one example of an action controlled by the Autonomic Nervous System (ANS).
Heart rate (or digestion, pupil size).
Explain what a relay neuron does in a reflex arc.
In a reflex arc, the relay neuron in the spinal cord passes the impulse from the sensory neuron to the motor neuron, helping produce a fast response without using the thinking part of the brain.
Describe one main function of the temporal lobe.
Temporal lobe is responsbile for recognition of sounds and smells
Explain why it is useful that reflexes happen before you fully feel pain.
Reflexes protect you by making you move away from danger quickly, which reduces injury, because the response is coordinated by the spinal cord before the brain processes the pain fully.
Predict what happens at the synapse if a toxin stops vesicles from releasing neurotransmitters.
The neurotransmitter is not released, so it cannot cross the synaptic cleft and the signal is not passed on to the next neuron (the impulse stops/weakens).
Identify which nervous system is mainly responsible for an increased heart rate during a scary movie.
Automatic Nervous System
Analyse the evidence: A student has slower reflexes but normal thinking speed. Deduce whether the motor neuron or relay neuron is more likely to be slow, and justify your answer.
The motor neuron is more likely to be slow. Reflex speed depends on how quickly the impulse travels from the spinal cord to the effector muscle. If thinking speed is normal, the brain’s processing isn’t the issue, so a slower motor pathway to the muscle best explains delayed reflexes.
Deduce which part of the brain Jackson may have injured if he started to lose his vision after a car accident.
He may have injured the occipital lobe, which is mainly responsible for processing visual information.
Suggest one possible reason, using the stimulus–response model, why a student burns their finger but does not pull away quickly.
The sensory neuron may not be sending impulses properly from the receptor to the CNS, so the signal doesn’t reach the spinal cord quickly and the motor neuron/effector isn’t activated fast.
Predict what happens to the nerve signal if a drug blocks receptors on the postsynaptic neuron.
Neurotransmitters can’t bind, so ion channels don’t open properly and the postsynaptic neuron is less likely (or unable) to fire. The signal is reduced or stops.