Introduction to physiology DR Arwa rawashdeh Objectives Describe

Introduction to physiology DR. Arwa rawashdeh

Objectives • Describe homeostatic mechanisms of the major functional systems. • Describe control systems of the body • Examples of control mechanisms • Characteristics of control mechanism

What is homeostasis? Hemeo: same Stasis: standing Dynamic equilibrium Process that occurs in all living things All organ systems work together to achieve homeostasis Ability of an organism to maintain its internal environment, despite changes to its internal or external environment How does homeostasis work? • Feedback pathways – A cellular relay race – Specific organs and structures must communicate with each other in response to changes in the body • Keeps levels of certain processes within a normal range

What things in your body need to be kept within a range? • • • Body Temperature Blood pressure Blood p. H O 2 and CO 2 concentration Osmoregulation-Water balance Blood glucose

Cellular relay race • • • Stimulus Receptor Integrating center Effector Response – Reverses the stimulus

Why is feedback important in living things? • Allows baseline to be regained • Conserves resources – Cellular Materials – Energy (ATP)

Principles of feedback

Negative feedback pathways • Way in which most homeostatic mechanisms work • The product of the pathway inhibits, or shuts down, the original signal

Examples of Negative feedback pathways

Positive feedback pathways

Feed- back control Planned output and actual output are compared and subsequent action is taken if necessary Feedforward control Based on forecast result If the forecast is bad the control is taken well in advance of actual result