Wk8 Lab notebook: CNS, PNS, and brain regions

E1: Sort structures, then explain their roles

The central nervous system, or CNS, consists of the brain and spinal cord. Peripheral nerves and ganglia belong to the peripheral nervous system, or PNS. Ganglia are groups of nerve-cell bodies outside the CNS.

These are anatomical divisions: they describe where structures belong. Sensory input, integration and motor output describe jobs. Both divisions can contribute to one action. A PNS sensory nerve carries information inward; CNS circuits process it. A PNS motor nerve carries output to a muscle.

Use five rows labeled A1 through A5. In each row, name a CNS structure and its processing role. Then name a PNS structure and its relay role. Finish with a sentence explaining why both are involved. Do not force the whole action into just one division. These are simplified pathway accounts, not complete maps of every connection.

A: Five supplied action scenarios

Original paper scenarios: no person performed these tasks and no responses were measured. Each card supplies the pathway information needed for sorting.

A1: Feeling a light touch on a fingertip. Sensory fibers in the finger and arm carry input toward the spinal cord and brain. Brain circuits support conscious recognition of the touch.

A2: Choosing to raise a hand. Motor areas of the cerebrum help form the command. Signals travel through CNS pathways to spinal motor neurons, whose axons extend through peripheral nerves to arm muscles.

A3: Pulling a hand away from a painfully hot surface. Sensory input enters the spinal cord through peripheral fibers. A spinal circuit activates output through peripheral motor fibers to withdrawal muscles. Brain pathways also receive information. The initial spinal response does not require waiting for a conscious decision. Do not test this scenario.

A4: Adjusting balance during a step. Peripheral sensory fibers carry information from muscles and joints. Cerebellar circuits compare movement information with motor commands. Adjusted CNS output reaches muscles through peripheral motor fibers.

A5: Breathing without consciously choosing each breath. Brainstem circuits contribute to respiratory control. Output reaches breathing muscles through peripheral motor nerves. This account identifies nervous-system roles; it does not imply the brainstem or nerves act alone.

E2: Three regions and the actual prior map

Cerebrum: includes areas involved in voluntary movement and information processing. Cerebellum: helps coordinate movement using feedback, including balance information. Brainstem: includes circuits involved in vital functions such as breathing. These are useful associations, not exclusive one-region/one-job rules.

Use your actual brain-region map from Thursday, March 11, 2027. Record the map date and identify where each of the three regions is labeled. Do not state that you examined a specimen if you did not.

Match each region to one function card: FC1, coordinating a movement using balance feedback; FC2, contributing to automatic breathing control; FC3, planning a voluntary hand movement. Explain each match using the region-function descriptions above.

If the actual map is missing, request it or recover your saved work. Use this supplied E2 reference to practice all three matches, labeling them reference recovery. Ask the teacher for the required link to your map. This text supplies function information, not a replacement specimen observation.

E3: Regrowth and recovery are different claims

Regeneration means regrowth of damaged neural structures, such as an axon. Functional recovery means an improvement in what a person can do. These are related but are not identical.

A neuroscience review describes adult mammalian CNS axon regeneration after injury as very limited. Peripheral axon regrowth can occur under suitable conditions. This broad biological contrast does not set one person's outcome.

MedlinePlus explains that stroke rehabilitation can help people relearn movement and daily skills. Effects and recovery pace vary with the affected brain areas, severity and complications. Improvement does not require claiming that every damaged neuron grew back.

AAOS describes how peripheral nerve injury can interrupt signals. Some nerve fibers can regrow, but injury type, location and treatment matter. Lasting loss of function can remain even with treatment. Therefore, neither CNS injury nor PNS injury alone establishes a recovery timetable or a certain outcome.

C1: Repair the injury comparison

Consider an invented comparison: case C has continuing movement loss after a stroke involving the brain. Case P has improved hand function after an injury to an arm nerve. These are stipulated story outcomes, not patient records or measured research results.

Classify the injured structure in each case as CNS or PNS. Explain how E3 makes the different outcomes possible without making them inevitable. Name one missing clinical detail that would matter, such as injury severity or treatment.

Self-check the statement: location alone explains everything; every stroke deficit is permanent and every cut arm nerve fully heals. Correct both absolute claims with E3. If you only rename CNS and PNS, revise by separating possible regrowth from functional recovery. Do not diagnose either fictional case or prescribe care.

R1: Restart with one complete pathway

First name the two CNS structures, then identify peripheral nerves as part of the PNS. Before reading E3, explain why a finger-nerve injury and brain injury might recover differently. After reading, revise any claim that the division alone guarantees the outcome.

If sorting is difficult, practice first on an action that is not on the cards: lifting a bare foot off a sharp tack. Trace sensory leg fibers, spinal circuit and motor leg fibers. Classify the fibers outside the spinal cord as PNS and the spinal circuit as CNS. Brain processing is CNS too. Do not test this scenario.

Then use E3 to explain that peripheral regrowth can occur under suitable conditions, while CNS regrowth is limited. Neither statement predicts complete recovery. Return to all five action rows and three matches. If unfinished, label the missing parts; the one-row restart does not waive the full product.

X1: Optional crossed-pathway extension

The corticospinal pathway carries commands related to voluntary movement from cerebral motor areas toward spinal motor circuits. Many of its fibers cross to the opposite side in the lower brainstem.

A right-sided brain injury affecting this pathway before the crossing can therefore impair left-sided limb movement. This is a conditional pathway explanation, not a rule that every right-sided stroke causes the same deficit.

If assigned the extension, sketch right motor area, crossing and left-side movement pathway. Explain the possible opposite-side effect and name what is missing before predicting an individual deficit. The exact damaged pathway and extent of injury are not supplied.

S1: Practice, official work and weekly checks

The 25–45-minute block remains official work time. Today’s official work is the CNS/PNS analysis in Activity 2.1.1 Mind Matters and Activity 2.1.2 Mapping Brain Function, finishing the assigned Lesson 2.1 activities. Ask for the exact screens, assigned portion, stopping point and completion evidence.

Complete that confirmed portion if available. Otherwise record the missing input and continue the supplied pathway practice. Do not mark myPLTW complete because this record is finished. The earlier brain-region task and actual map are not assumed complete.

The weekly brain structure-function check, tracker and online evidence through Activity 2.1.2 remain separate requirements. The teacher-posted data/model packet is a separate asynchronous route; request it if missing. Supplemental Khan or BioDigital access does not establish that packet.

Today is Friday, March 12. The prior map is dated Thursday, March 11. No homework is due before this class. Follow today’s teacher-confirmed requirements; this practice record does not finish the week.

Start with location and recovery

Name the two CNS structures. Predict why finger-nerve and brain injuries might recover differently, then revise your prediction using E3.

Use a possible difference, not a guaranteed outcome. R1 supplies a restart.

Five-action CNS/PNS sorting

For A1–A5, name a CNS structure and role, a PNS structure and role, and justify how they participate together.

Use E1 and the supplied card details. Do not assign the whole action exclusively to one division.

Three region-function matches

Match cerebrum, cerebellum and brainstem to FC1 through FC3. Explain each match and cite its location on your actual March 11 map.

If you cannot find your map, label the work E2 reference practice and ask the teacher how to recover the assigned map.

Injury comparison and self-check

Classify case C and case P in C1 by division. Explain why outcomes are not guaranteed, correct both absolute claims and name a missing clinical detail.

The cases are fictional. Use E3; do not diagnose or prescribe.

Final check and remaining work

Check all five rows and three matches. Identify the map you used and ask for any missing official or weekly materials. If assigned, add X1's crossed-pathway explanation.

Save or submit one document. A finished practice page does not mark the official tasks complete.