Diagram shows thyroid gland with thyroid follicle (central cavity), follicular cells (surrounding the follicle), and blood capillaries (adjacent vessels).

| List I | List II |
|---|---|
| A. Heart | III. Atrial natriuretic factor |
| B. Kidney | I. Erythropoietin |
| C. Gastrointestinal Tract | IV. Secretnin |
| D. Adrenal Cortex | II. Aldosterone |
