HOMEOSTASIS WITHIN THE BODYS ENVIRONMENT Homeostasis is the

HOMEOSTASIS WITHIN THE BODY’S ENVIRONMENT

Homeostasis is the maintenance of a stable internal environment You need to maintain a certain level of oxygen, food, water, sugar, etc… to function properly. So how do you maintain this level of Homeostasis when your environment is constantly changing?

Let’s imagine that when you body systems are in balance. They maintain homeostasis. (Like a see-saw) 1. A Stimulus produces change in the variable. Unb alan Variable Homeostasis ced A stimulus causes a certain body level to fall out of homeostasis, and to an unbalanced level. What do you do then?

The body has developed feedback mechanisms for many systems to maintain body and cell homeostasis. Let’s look at the components of the feedback system.

The three components of the feedback system are: 1. Receptor (sensor) 2. Control center 3. Effector Draw this!! →

The body communicates through neural and hormonal control systems (variable) responds to changes in the environment (stimuli) 3. Sends information to control center (afferent pathway) re fe Af 2. The Receptor nt P at hw ay So let’s say there is a stimulus and we have an unbalanced system.

The Control Center: (Brain or C. nervous system) - Determines the set point (level) - Analyzes information nt -Determines appropriate e r fe f A response. 4. Sends a response to the Effector through a efferent pathway. Ef fe re nt

Effector: Provides a means for response to the stimulus By depressing it (negative feedback) (most) Or enhancing it (positive feedback) re nt A ffe Ef fe re nt

Feedback Mechanisms • Negative feedback • Includes most homeostatic control mechanisms • Shuts off the original stimulus, or reduces its intensity • Works like a household thermostat

Change in Heart Rate (exercise) causes your heart rate to increase. How do you lower it? Stimulus: Increased Heart Rate & blood pressure Artery sensors sense increase in blood Receptor: pressure, send info to brain. Control Center: Brain wants to slow down the heart rate, send message to the heart to beat slower. Effector: Slower heart rate decreases blood pressure.

Change in Osmotic balance (dehydration): Stimulus: Too little water in the body’s blood Receptor: Hypothalamus gland in body senses lack of water, send message to brain. Control Brain tells Pituitary gland to secrete Center: hormone ADH. Effector: ADH reaches make the kidney work harder to reabsorb more water. Corrects Osmotic imbalance.

Change in Body Temperature (Cold or hot): Stimulus: Body temperature too high or low Receptor: Hypothalamus neurons in body senses hot/cold temperature Control Brain: too hot – activate sweating Center: Brain: too cold – activate shivering Effector: Too hot – skin sweats, evaporation of sweat cools body. Too cold – muscles constrict, muscle tremor in shivering releases heat energy

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Change in Glucose levels (too high glucose): Stimulus: Increased glucose levels Receptor: Pancreas Control Center: Pancreas releases insulin into the blood. Effector: -Body cells increase glucose intake - Liver uptakes extra glucose converts it into glycogen

Change in Glucose levels (too low glucose): Stimulus: Decreased glucose levels Receptor: Pancreas receptors Control Center: Pancreas releases glucagon into the blood. Effector: -Liver breaks down glycogen releases glucose into the blood stream.