Unit 05 · The Nervous System & Senses
The nervous system is the body's signaling network, and you can watch it work. This unit builds from the single neuron and the electrochemical signal that races down its axon, across the synapse to the next cell, out to the divisions of the brain and spinal cord, and into the reflex arcs and special senses you can test on a partner. Mastery means you can run a reflex or sensory test and trace the signal through the arc, not just recite the parts of a neuron.
| Criterion | Not yet | Approaching | Mastered |
|---|---|---|---|
| Neuron structure & the nerve signal | Cannot label a neuron's main parts or say what a nerve signal is. | Labels dendrites, cell body, and axon but cannot explain how the signal travels along the axon. | Labels the neuron and explains the action potential as an electrochemical signal traveling down the axon, at the level of ions crossing the membrane. |
| Synapses & neurotransmission | Thinks the signal jumps directly from one neuron into the next. | Knows a gap exists but cannot describe how the signal crosses it. | Explains the chemical synapse — a neurotransmitter released across the gap to the next neuron — and why signals travel one way. |
| CNS & PNS: brain and spinal cord | Cannot separate the central from the peripheral nervous system or locate the major brain regions. | Divides CNS from PNS but confuses the major brain regions or their jobs. | Distinguishes CNS from PNS, locates the major brain regions and the spinal cord on a model, and states what each region does. |
| Reflex arcs & the special senses | Cannot trace a reflex or name the special senses. | Names the parts of a reflex arc but cannot put them in order, or names the senses without their receptors. | Traces a signal through a reflex arc in order — receptor, sensory neuron, integration, motor neuron, effector — and links each special sense to its receptor. |
| Lab technique (reflex & sensory testing) | Cannot elicit a reflex or run a sensory test cleanly. | Gets a response but cannot control the stimulus or read the result consistently. | Elicits a reflex with proper technique, runs a sensory-response test, and interprets what the response reveals about the pathway. |
| Integration (cross-domain) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“When I tapped below the knee, the stretch fired a sensory neuron into the spinal cord, which drove a motor neuron straight back to the thigh muscle — a reflex arc, no brain required. The signal itself is an action potential, ions crossing the axon membrane, then a neurotransmitter carrying it across the synapse.”
“You hit the knee and the leg kicks. Nerves send signals to the brain. A neuron is a brain cell, I think.”
You demonstrate this unit on Lab Day by running reflex and sensory-response tests on a partner and tracing the signal through the reflex arc aloud in an anatomy identification defense — not a multiple-choice test. A criterion counts as mastered only when you can both perform the test at the bench and defend the pathway the signal takes. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.