Reflex arc and myelin
Trace a reflex arc and explain how myelin speeds signal conduction.
Labeled reflex-arc diagram (all five components, signal-direction arrows, spinal-cord shortcut marked) plus a two-sentence saltatory-conduction explanation.
- 1Do thisTrace a reflex arc and explain how myelin speeds signal conduction.
- 2Use this resource
- 3Submit thisNotebook check: Labeled reflex-arc diagram (all five components, signal-direction arrows, spinal-cord shortcut marked) plus a two-sentence saltatory-conduction explanation.
- 4Submit it here
- 1CMSD website. Go to clevelandmetroschools.org and click the Clever button.
- 2Clever. Clever opens. Sign in if it asks.
- 3Microsoft (district) login. Use your district Microsoft account (the one for school).
- 4Schoology. Open Schoology, then your class, then Assignments, and find the file named below.
The file to submit is named: Human Anatomy & Physiology (Human Body Systems) › Unit 2.1 Reflexes: Drug impacts on neuron signaling, reflex and reaction time, patient diagnosis challenge. › Notebook checkOpen Schoology
- CER:
- Claim, Evidence, Reasoning — make a claim, back it with evidence, explain your reasoning.
- SOP:
- Standard Operating Procedure — the exact steps to follow (especially in a lab).
- Tracker:
- Your PLTW progress log where you record completed evidence.
- myPLTW:
- The PLTW course site where you do the online activities — you open it through Schoology.
Minute-by-minute · 80-minute block
💡 Big idea: A reflex arc bypasses the brain by processing the response at the spinal cord level; myelin dramatically increases conduction velocity by allowing saltatory conduction.
- 0-8Intro: why reflexes are faster than voluntary movement
- 8-25Notes: five reflex-arc components and saltatory conduction
- 25-45PLTW online task: reflexes and conduction speed
- 45-62Label reflex-arc diagram: all five components with signal-direction arrows; mark spinal-cord shortcut
- 62-75Write two-sentence myelin explanation: saltatory conduction and speed comparison
- 75-80Submit diagram and explanation; preview Wednesday reaction-time lab
- • A reflex happens faster than conscious thought because the signal never goes to the brain. It turns around at the spinal cord.
- • Today you trace that shortcut step by step. Five components in the arc. Each has a name and a job.
- • Myelin is why the signal is so fast. We will connect that to a real disease where myelin is destroyed and reflexes fail.
- • Your labeled arc diagram and myelin explanation are the artifacts. Signal direction must be marked on the diagram.
- 1Read the notes on the reflex-arc parts: receptor, sensory neuron, interneuron, motor neuron, effector.
- 2Label a reflex-arc diagram and mark the spinal-cord shortcut.
- 3Complete the PLTW online task on reflexes and conduction speed.
- 4Explain in two sentences how myelin makes signals travel faster.
- 5Submit your labeled reflex-arc diagram and myelin explanation.
- • You can trace the parts of a reflex arc in order.
- • You can explain how myelin affects conduction speed.
- • Reflex arc sequence: stimulus, receptor, sensory (afferent) neuron, interneuron (spinal cord), motor (efferent) neuron, effector (muscle or gland).
- • Saltatory conduction: the action potential jumps between nodes of Ranvier on a myelinated axon, traveling up to 70 m/s compared to 0.5 m/s in unmyelinated fibers.
- • Demyelinating diseases (such as multiple sclerosis) slow conduction velocity and disrupt reflexes, connecting myelination directly to pathophysiology.
Your PLTW work today
Unit 2.1 Reflexes: Drug impacts on neuron signaling, reflex and reaction time, patient diagnosis challenge. · Reflex arc and myelin
Day 2 of this lesson. Open this exact section in myPLTW (reached through Schoology), then do the work below.
Do this: Complete the reflex-arc and myelin task in Lesson 2.1 Getting Nervous on myPLTW; work through all screens on signal propagation and myelination speed.
Mark the reflex-arc task complete after submitting your labeled reflex-arc diagram.
Introductory task is done; today the reflex-arc task should show complete.
myPLTW completion status plus your submitted diagram.
All PLTW activities are completed inside the PLTW course environment — this page only gives direction. Submit producibles on Schoology.
Today's PLTW tracker
Check things off as you work, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible on Schoology.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
Unit 2.1 Reflexes: Drug impacts on neuron signaling, reflex and reaction time, patient diagnosis challenge. · Reflex arc and myelin
Complete the reflex-arc and myelin task in Lesson 2.1 Getting Nervous on myPLTW; work through all screens on signal propagation and myelination speed.
Introductory task is done; today the reflex-arc task should show complete.
This is how Mr. Mendoza sees the class keeping pace with PLTW. Be honest, it only helps if it is accurate.
🎯 Trace a reflex arc and explain how myelin speeds signal conduction.
- Read the notes on the reflex-arc parts: receptor, sensory neuron, interneuron, motor neuron, effector.
- Label a reflex-arc diagram and mark the spinal-cord shortcut.
- Complete the PLTW online task on reflexes and conduction speed.
- Explain in two sentences how myelin makes signals travel faster.
- Submit your labeled reflex-arc diagram and myelin explanation.
Notebook check: Labeled reflex-arc diagram (all five components, signal-direction arrows, spinal-cord shortcut marked) plus a two-sentence saltatory-conduction explanation.
Submit on SchoologyUpload by 11:29 PM for full credit.
| Task | Who |
|---|---|
| Read the notes on the reflex-arc parts: receptor, sensory neuron, interneuron, motor neuron, effector. | _______ |
| Label a reflex-arc diagram and mark the spinal-cord shortcut. | _______ |
| Complete the PLTW online task on reflexes and conduction speed. | _______ |
| Explain in two sentences how myelin makes signals travel faster. | _______ |
| Submit your labeled reflex-arc diagram and myelin explanation. | _______ |
Working solo? Put your own name in "Who" for every row.
- You can trace the parts of a reflex arc in order.
- You can explain how myelin affects conduction speed.
Resources & readings
Vetted readings and references for this unit. Use them to prepare, to catch up if you were absent, or to go deeper on today's target.
Lab & supplies
WebXam practice
Cumulative WebXam review
A quick mixed-review pulling questions from earlier units plus today, so the WebXam material stays fresh.
Where this leads — careers
What today's skills lead to. These are real health-science careers this course builds toward. Tap one to see, on the US Department of Labor's O*NET site, what the job actually involves, what it pays, and how fast it is growing.
What to do if you were absent
Today is individual PLTW work, so do exactly what we did in class, from home: complete the same PLTW target above, then submit your Notebook check.
Open Schoology (CMSD) and keep goingHow to get there: open the CMSD website, click Clever, sign in with your Microsoft (district) account, then open Schoology from Clever.
Class still runs. Complete the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
Khan Academy: Neurons and Synapses- CompleteEvery required part of the artifact is present, nothing left blank.
- AccurateThe science and the data are correct and match the evidence.
- Scientific reasoningYou explain your claim with evidence and reasoning (CER), not just an answer.
- Professional communicationClear, organized, labeled, and written the way a clinician or scientist would.
- SubmittedTurned in the right way (Schoology for routine work) and confirmed.
Drop your Thu, Oct 15, 2026 · Reflex arc and myelin here. Use a clear file name (your initials + project). Routine work still goes to Schoology (via the CMSD portal).
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