Body Systems Homeostasis - SchoolWorld：人体系统与平衡- schoolworld.ppt

Homeostasis Homeo Greek ‘Like’ Stasis Equilibrium Homeostasis Homeostasis The tendency toward a relatively stable equilibrium. Body has the ability to keep internal conditions and activities stable, even when outside world keep changing. Homeostasis Examples... Running Shivering Main Body Systems Involved in Homeostasis 1. The Nervous System Responsible for directing immediate responses to stimuli, usually by coordinating the activities of other organ systems. Main Body Systems Involved in Homeostasis 2. The Endocrine System (hormones) Directing long-term changes in the activities of other organ systems. Mechanisms of Homeostasis 3 interacting Components Mechanisms of Homeostasis 3 interacting Components A. Sensor Mechanisms Senses disruptions in homeostasis Mechanisms of Homeostasis 3 interacting Components B. Control Center Regulates the body’s response to disruptions in homeostasis Mechanisms of Homeostasis 3 interacting Components C. Effector Acts to restore homeostasis! Try this! Determine the 3 mechanisms of homeostasis involved in maintaining internal equilibrium when you walk from a warm building to outside on a cold day Answer! A. Sensor Mechanism Nerve endings of the integumentary system - sense the change in temperature. B. Control Center The brain - determines the appropriate response of the body. C. Effector Your muscles! As you act to shiver to increase you internal body temperature. KEY TERM Homeostatic Balance The body maintains “stable” internal environment (conditions necessary for cell survival) even though external environment (conditions outside the body or body cells) is always changing. Two Feedback Mechanisms Ways of Responding Positive Feedback - Occurs when hormone secretions triggers more hormone secretions - Indicates a trend away from homeostasis Negative Feedback - Works to restore homeostasis by correcting a deficit within the system - Trend towards homeostasis Body Systems Homeostasis Anatomy Physiology Key Terms Anatomy The