This is a working draft for Leslie's review. The dependency edges below are a first pass — the diagram and the prerequisite table are the parts to check hardest, since they drive hold-vs-advance decisions.
The course map shows the eight units as a spine — cells and tissues first, the immune and integumentary systems last. But the real prerequisite structure isn't a straight line: it's a directed graph. Human Anatomy is more strictly cumulative than most subjects — the muscular pump is built from muscle tissue, the nervous system depends on the blood supply that feeds it, the immune system defends every system that came before it. A weak concept early doesn't just lower one grade, it cascades into everything downstream that needs it. This page is the map a guide uses to find the concept that's actually blocking a stuck student.
An arrow means “must be mastered first.” Units 05, 06, and 08 each pull from two upstream units — those are the cascade points where one soft prerequisite quietly breaks several later units.
Prerequisite gating
A unit unlocks when its prerequisites are mastered — demonstrated, not merely seen. "Covered in class" is not the gate; a cleared rubric is. The difference matters most at the cascade points, where a soft prerequisite quietly breaks two or three later units.
| Unit | Must have mastered first |
|---|---|
| 01 Cells, Tissues & Body Plan | — (entry point) |
| 02 Skeletal & Muscular | 01 (bone and muscle are tissues built on the cell) |
| 03 The Cardiovascular System | 02 (the heart and vessel walls are muscle tissue) |
| 04 The Respiratory System | 02 (breathing is driven by the diaphragm & rib muscles) |
| 05 The Nervous System & Senses | 03 (the brain depends on its blood supply) + 04 (respiratory drive is a reflex) |
| 06 The Digestive & Urinary Systems | 03 (absorption & filtration depend on blood transport) + 05 (autonomic & enteric control) |
| 07 The Endocrine & Reproductive Systems | 05 (the hypothalamic–pituitary axis is neural control of hormones) |
| 08 The Immune & Integumentary Systems | 06 (mucosal & gut-associated immunity) + 07 (hormonal regulation of defense) |
Gap-cascade diagnosis
When a student stalls late, the visible symptom is rarely the real problem — the broken concept is usually upstream. Trace the arrows backward. Common cascades:
| Late symptom | Upstream concept to check first |
|---|---|
| Hormone feedback loops won't resolve (Unit 07) | Neural control from Unit 05 — the hypothalamic–pituitary axis sets the endocrine set point. |
| Absorption & filtration don't add up (Unit 06) | Blood transport from Unit 03 — the hepatic-portal and renal circulation, not the organ itself. |
| Immune regulation stalls (Unit 08) | Hormonal control from Unit 07 — endocrine signals tune the immune response. |
| The nervous system's oxygen demand doesn't make sense (Unit 05) | The blood supply from Unit 03 — the brain fails first when perfusion is misunderstood. |
Using the graph to plan a re-attempt
The graph turns a "not yet" into a targeted re-attempt instead of a whole-unit re-teach. When a student fails a downstream demonstration:
- Trace backward to the upstream node the symptom points to.
- Re-attempt the upstream concept first — close the gap at its source, not where it surfaced.
- Then re-run the downstream demonstration. Often it passes without any re-teaching of the downstream unit at all, because the cascade is resolved.
This is also where the integration guide matters: some anatomy concepts depend on an idea from another spoke — the physics of pressure and flow behind blood and breathing, proportional reasoning behind dose and concentration. When the upstream anatomy node looks solid but the student still stalls, check the cross-disciplinary dependency before re-teaching the anatomy.