Presentation is loading. Please wait.

Presentation is loading. Please wait.

HOMEOSTASIS DR ROBERT RYAN BUENAVENTURA MEDICAL GROUP APRIL 24, 2006.

Similar presentations


Presentation on theme: "HOMEOSTASIS DR ROBERT RYAN BUENAVENTURA MEDICAL GROUP APRIL 24, 2006."— Presentation transcript:

1 HOMEOSTASIS DR ROBERT RYAN BUENAVENTURA MEDICAL GROUP APRIL 24, 2006

2 Homeostasis From the Greek roots –Homo: alike or the same –Stasis: to stand or posture Term coined by Walter Cannon in 1932

3 Homeostasis Ability or tendency of an organism/cell to maintain internal equilibrium by adjusting its physiological processes – –e.g., temp, pH, blood pressure, PCO 2, etc. Negative or Positive Feedback

4

5 Feedback Negative Feedback – –Slows down process to return to equilibrium Positive Feedback – –Accelerates process away from equilibrium

6 Feedback ( contd) Stock Market Aircraft autopilot Computer modeling Biological systems Genes

7 Feedback ( contd) Control triangle preprogrammed with desired ranges Input arrives and acted upon in control triangle to provide an output Output sampled and fed back to control triangle Output modified to make sure output stays within programmed range for center

8 Types of Feedback Negative Feedback: change in an environment causes response that returns conditions to original state –Thermostat Positive Feedback: response of the system is to change that variable even more in the same direction –Sim City –Two in human body

9 Nervous System Bodys surveillance system – –Blood pressure, temperature, pH, etc. Sensory centers – –Brain or spinal cord – –Barrage of input integrated and response generated Organs convert signal into some form of action – –E.g., movement, changes in heart rate, release of hormones, etc. Reflex arc

10 Cardio-Respiratory System Maintain homeostasis and deliver oxygenated blood to cells Negative Feedback – –Blood Pressure – –pH – –PCO 2 Hyperventilation example

11 Endocrine System Elegant feedback networks Affects activities of cells, tissues, and organs throughout the body Controls slower, longer lasting responses to internal stimuli Self-Regulating Negative Feedback Mechanism – –Hypothalamus – –Anterior Pituitary – –Other Endocrine End Organs

12 Endocrine System (contd) Thyroid hormone

13 Endocrine System (contd) Sex hormones

14 Endocrine System (contd) Steroid hormones

15 Endocrine System (contd) Positive Feedback Loop – –Childbirth Increased rate of contractions causes increased rate of stretch receptor stimulus (feedback) Continues positive feedback loop until baby is delivered

16 Endocrine System (contd) Positive Feedback Loop – –Name the other positive system found in mammals

17 Endocrine System (contd) Blood clotting – –Self-catalytic, self-accelerating effect – –Clotting process begins Runs faster and faster Until bleeding stops – –Positive feedback loop is part of a larger negative feedback loop Activated by bleeding Ultimately works to stop the bleeding

18 Blood Clotting

19 Summary Homeostasis is achieved by – –Mainly negative feedback – –Infrequent cases positive feedback Negative feedbacks goal is to maintain equilibrium Positive feedbacks goal is to accelerate away from equilibrium Endocrine, Nervous and Cardio-Respiratory systems all use feedback to maintain life

20


Download ppt "HOMEOSTASIS DR ROBERT RYAN BUENAVENTURA MEDICAL GROUP APRIL 24, 2006."

Similar presentations


Ads by Google