4 5 Feedback Illustrative Examples Period 4 What

4. 5 Feedback Illustrative Examples Period 4

What is Negative Feedback? • Form of homeostasis • Process of the body's activation, communication, and execution of a counter response in response to a bodily stimulus.

Example: Blood-sugar regulation • Blood-sugar levels low: pancreas releases glucagon, which travels to the liver and tells it to release more glucose into the bloodstream • Blood-sugar levels high: pancreas releases insulin which travels inside the bloodstream and tells fat cells to take in the excess glucose • Unless you're diabetic, which in that case insulin does nothing (Type II)

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Teresa Luo Claire Lee P. 4 Lactation The process where milk is synthesized and secreted from the mammary glands Positive Feedback Loop -Brings a greater change in the same direction -Amplifies responses and processes in biological organisms -Stimulus triggers an effect that increases in intensity

Teresa Luo Claire Lee P. 4 Lactation in Mammals Stimulus (Suckling from infant) Releases Hormones Milk is discharged through mammary glands Milk production

Teresa Luo Claire Lee P. 4 Stimulus and Signaling Stimulus -Suckling from infants: -triggers sensory nerve impulses in the areola Response -Lactocytes in mammary alveoli produce milk -Hypothalamus and posterior pituitary releases oxytocin

Teresa Luo Claire Lee P. 4 Release of Hormones Oxytocin -stimulates/relaxes muscles surrounding the breast for milk ejection -triggers myoepithelial cells to squeeze milk from alveoli and transports it into lactiferous ducts Prolactin -stimulates mammary glands to produce milk -triggers milk biosynthesis within alveolar cells

Response-Milk Secretion -Milk is produced by mammary glands: -Local mechanisms within the mammary glands related to the amount of milk removed by the infant are responsible for regulation of milk volume -The amount of milk removed also determines the extent in which the loop is proceeded and the stimulus is increased. Teresa Luo Claire Lee P. 4

Positive Feedback Teresa Luo Claire Lee P. 4 Amplifying process-stimulus is increased: Release of oxytocin and prolactin -More milk secretion triggers more suckling from the infant -Ensures continued milk production as long as infant continues to breastfeed Suckling from infant Milk secretion

What is positive feedback? ● ● ● Sandhya Sridhar & Jade Chi Homeostasis-the tendency for the body to maintain a balance internal condition-is involved in positive feedback Positive Feedback is a response that increases or amplify the action of the original stimulus Positive Feedback can occur in both plants and animals