AP Biology Study Notes: Organismal Regulation

Homeostasis

The process of maintaining internal stability within an organism.

Dynamic Homeostasis

A state of internal balance that allows for fluctuations within a viable range around a set point.

Feedback Loop

A self-regulatory system where the output of a process affects the input.

Receptor (Sensor)

Component of a feedback loop that detects changes in the internal environment.

Control Center

Processes the signal in a feedback loop and compares it to the set point.

Effector

The organ or tissue that carries out the response to adjust the condition in a feedback loop.

Negative Feedback

A mechanism that reduces or opposes a stimulus to maintain homeostasis.

Set Point

The ideal value for a condition that the body maintains through feedback loops.

Thermoregulation

The process by which the body maintains its core internal temperature.

Vasodilation

The widening of blood vessels to increase blood flow and decrease body temperature.

Insulin

A hormone that decreases blood glucose levels by facilitating the uptake of glucose by cells.

Glucagon

A hormone that increases blood glucose levels by promoting glycogen breakdown in the liver.

Positive Feedback

A mechanism that amplifies a response until a specific outcome occurs.

Oxytocin

A hormone that stimulates uterine contractions during childbirth.

Ethylene

A plant hormone that promotes ripening in fruits.

Diabetes Mellitus

A condition resulting from the failure of the negative feedback loop regulating insulin.

Type 1 Diabetes

An autoimmune disorder where the body cannot produce insulin.

Type 2 Diabetes

A condition where the body's cells become resistant to insulin signals.

Graves' Disease

An autoimmune disorder that leads to hyperthyroidism due to the failure of the negative feedback mechanism.

Osmoregulation

The process of maintaining the proper balance of water and electrolytes in the body.

Childbirth (Labor)

A process exemplifying positive feedback, leading to increased oxytocin release as contractions intensify.

Blood Glucose Regulation

A negative feedback mechanism involving insulin and glucagon to maintain blood sugar levels.

Graph Pattern of Negative Feedback

Oscillation around a flat set point line.

Graph Pattern of Positive Feedback

Exponential growth or a sharp spike followed by a drop-off.

Common Mistake - Positive vs. Negative Feedback

Students often misinterpret positive feedback as 'good' and negative feedback as 'bad' when both serve critical roles in biological systems.

Stop Signal in Positive Feedback

Positive feedback processes must have a definitive endpoint to prevent resource exhaustion.