Feedback regulation adjusts hormone secretion when downstream hormone levels or physiological effects inhibit or stimulate earlier control steps, linking signal detection to a specific target-cell response.
Coverage 2022–2022 · Updated 15 Jul 2026
Feedback occurs when a response alters the signal pathway, either reducing further activation or amplifying it under defined conditions.
Negative feedback restores a variable toward a set range; positive feedback reinforces a change until a limiting event stops it. Receptors, hormones and downstream products can all participate.
Classify the loop:
Rising thyroid hormone suppresses hypothalamic and pituitary stimulation, whereas oxytocin-driven contractions can intensify until birth.
Calling any delayed response feedback is incomplete; the direction of the loop must be identified.
This objective is assessed through multiple choice.
Build the answer around this relationship: Negative feedback reduces upstream signalling when a response is already sufficient.
Representative question
What is an example of negative feedback in the menstrual cycle?
High levels of estrogen inhibit FSH secretion.
High levels of LH stop progesterone secretion.
High levels of FSH delay ovulation.
High levels of progesterone make follicles less receptive to FSH.
A ligand only affects target cells with the matching receptor. Quorum sensing uses autoinducers and thresholds for group behaviour. Animal signals differ by source, distance, speed, target-cell response, and chemical class. Hydrophilic ligands use transmembrane receptors and relays; steroid and thyroid hormones use intracellular receptors that affect transcription. Named pathways then show the logic: acetylcholine opens sodium channels, GPCRs switch G proteins through GDP-GTP exchange, epinephrine uses cAMP and kinase cascades, insulin RTKs use dimerisation/autophosphorylation to move GLUT4 and promote glycogenesis, steroid hormones change gene expression, and feedback either amplifies or restores stability.
