Homeostasis Feedback Loops Homeostasis is the maintenance of

Homeostasis & Feedback Loops

Homeostasis is the maintenance of a constant internal environment. A. Homeostasis works to maintain the organism's internal environment within tolerance limits (the narrow range of conditions where cells are able to function).

B. Homeostasis is a self-adjusting mechanism involving feedback where a response alters the internal conditions based on a stimulus. C. Feedback is when the response to a stimulus has an effect of some kind on the original stimulus.

Negative feedback is a control system that helps the body maintain homeostasis by sending a signal to decrease or stop a response. Negative feedback is the most common type.

Negative Feedback Examples: a. Blood Glucose Levels:

b. Body Temperature:

c. Blood Pressure:

c. Water Level:

Positive feedback is a control system that sends a signal to enhance or increase a response. Positive feedback is not very common.

Positive Feedback Examples: a. Breastfeeding - a baby begins to nurse (the stimulus) and a few drops of milk are released. This releases a hormone in the mother which further stimulates the release of milk (the response). The baby continues to nurse, stimulating more milk release until nursing stops.

b. Childbirth:

c. Blood clotting – an open wound stimulates the release of platelets to the site of the open wound.

Negative Feedback vs. Positive Feedback ® increases or ® slows down, stops continues the or reverses the activity ® wants to return levels back to normal