Week 13 — Count the Map, Read the Loop: A Central Nervous System Report — Traditional alternative (no AI)

Instructors: publish this instead of the adaptive version if you prefer, and unpublish or delete the adaptive one.

Assignment 12 of the term — count the central nervous system's map, put the reflex arc in order, and explain a reflex in plain words for someone new to anatomy and physiology.

This week you learned the CNS and the PNS, gray matter and white matter, the four lobes and their jobs, the cerebellum, the thalamus and hypothalamus, the brainstem, the spinal cord, the meninges and cerebrospinal fluid, and the reflex arc in order. Week 1 gave you the control center of every feedback loop, and Week 12 opened a single neuron; this week those ideas become a map of the brain and spinal cord. In this assignment you work four short problems, interpret each one, and explain a reflex to someone who has never studied anatomy and physiology. This week's lecture tutorial, quiz, discussion, and A&P Lab & Inquiry practise the same ideas from other angles.

The task

This week's shared dataset is the CNS key: canonical regions, layers, and orders, not measured data. Each side of the cerebrum has 4 lobes (frontal, parietal, temporal, occipital); the brainstem has 3 parts (midbrain, pons, medulla oblongata); the meninges are 3 layers (dura mater, arachnoid mater, pia mater, outer to inner); the brain has 4 ventricles (two lateral, a third, and a fourth); and the reflex arc has 5 parts (receptor, sensory neuron, interneuron, motor neuron, effector).

Work these four problems, showing your arithmetic:

1. The brain has 2 lateral ventricles, 1 third ventricle, and 1 fourth ventricle. How many ventricles does it have?
2. The week's CNS key holds 4 lobes, 3 brainstem parts, 3 meninges, 4 ventricles, and 5 reflex-arc parts. How many items does the key hold?
3. A reflex arc runs through 1 receptor, 1 sensory neuron, 1 interneuron, 1 motor neuron, and 1 effector. How many parts does the arc have?
4. The meninges are 3 layers, and a lumbar puncture's needle stops short of the 1 innermost layer, the pia mater. How many layers does the needle cross?

Beside each answer, add one brief interpretation:

• Problem 1: name the four ventricles and the tissue in each that makes cerebrospinal fluid, and then give the fluid's three jobs and explain why carrying oxygen is not one of them.
• Problem 2: give the brainstem's three parts in order from top to bottom and say what the medulla oblongata helps regulate, and then pair each of the four lobes with its place and its main job.
• Problem 3: give the five parts in order and say where the interneuron sits, and then explain why the hand moves before the pain reaches awareness and what the inhibited antagonist adds.
• Problem 4: name the meninges from outer to inner and the space where cerebrospinal fluid circulates, and then tell the cerebrum's job from the cerebellum's and the thalamus's job from the hypothalamus's.

Explain it to a non-expert

A friend who cooks for a living asks why their hand jumped off a hot pan handle before they even felt the burn. Write a 3–5 sentence message that explains the path the signal took, why the spinal cord and not the brain made the first move, and what that buys them. Name one limit, for example that this is a picture of how the nervous system is built and not advice about any burn. Put any technical term in everyday words. More than one good message is possible.

For a different, ungraded example, imagine a friend who asks how they stay upright when a bus lurches. Model answer: "Your cerebellum, a region of the brain that works on every move, compares what your muscles were told to do with what your body actually feels. When the bus lurches, that feedback says you tilted, and the cerebellum adjusts the move so you stay upright. The cerebrum, the large folded part of the brain, made the plan to stand; the cerebellum keeps the plan on course. This explains how the brain is organized, not why any one person might lose balance."

Use that pattern for the message to your friend, with your own wording and evidence.

Show your arithmetic. A reader should be able to rebuild every number you report from the values given, without guessing which values you used or which operation you chose.

Deliverables

Submit a single report containing:

• the four answers, each with the arithmetic shown and the brief interpretation the task names for that problem;
• your message to your friend, explaining the path the signal took when their hand jumped off a hot pan, why the spinal cord made the first move, what that buys them, and one limit; and
• a one-line restatement of the values you used, so your results are reproducible.

Keep it to roughly one page.

Choose how you show it. Present your report as written text, or as a recorded audio or video explanation of about three minutes with a transcript, or as a labeled sketch of the brain and the reflex arc with a short note. Every form is graded by the same scoring criteria. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

This version is designed to be completed without AI: do the computations, the interpretations, and the writing yourself, without a chatbot or other AI tool. You may use a calculator or a spreadsheet for the arithmetic. Submitting AI-generated work as your own, or copying another student's work, is an integrity violation under the course policy.

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