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Homeostasis: maintaining an internal balance. SBI 4U, December 12 th , 2012. Maintaining an Internal Balance. Ray Zahab vs. Fennec Fox Fennec fox ears allow for efficient hearing and act as radiator. Maintaining and Internal Balance. - PowerPoint PPT Presentation
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HOMEOSTASIS:MAINTAINING AN INTERNAL BALANCESBI 4U, December 12th, 2012
Maintaining an Internal Balance Ray Zahab vs. Fennec Fox Fennec fox ears allow for efficient
hearing and act as radiator
Maintaining and Internal Balance Homeostasis: the physiological state of
the body in which the internal physical and chemical conditions are maintained within an acceptable or tolerable range that is suitable for essential biological processes
Dynamic state
Maintaining an Internal Balance Body has several conditions that must be
monitored. Such as:-internal temperature-hormone levels-pH-flow and concentration of glucose and
other solutes *some tolerable ranges are narrow, while
others are more broad*
The Internal Environment Purpose of homeostasis: to maintain internal physical
and chemical conditions that are appropriate for the cells to function properly
Internal environment: the extracellular fluid, which consists of the fluid that surrounds the cells and tissues in the body and the plasma portion of the blood
Focus on fluid outside of the cells
Organ Systems Involved in Homeostasis
Nervous System Endocrine System Muscular System Integumentary System Excretory System Reproductive System
Organ Systems Involved in Homeostasis
All of the organ systems are coordinated to carry out the tasks necessary for the survival of the organism. No matter how simple or complex the animal, these functions include:
1. Taking in nutrients and other required chemicals, processing and excreting
2. Synthesizing proteins, fats and carbs3. Sensing and responding to changes in
external environment4. Protecting body 5. Reproducing, protecting and feeding offspring
Organ Systems Involved in Homeostasis
Homeostatic Mechanisms: a system that monitors internal and external conditions and changes bodily functions to maintain homeostasis
Ex: shivering in response to cold weather
Negative Feedback Mechanisms
Primary mechanism of homeostasis Negative feedback: the response of a system that acts to maintain
equilibrium by compensating for any changes made to the system 3 components: sensor, integrator and effector
Negative Feedback Mechanisms Sensor: consists of tissues or organs
that detect any change in external or internal factors
Info transmitted to integrator acts as a processing or control centre. Compares environmental conditions with the optimal function conditions called set points
Integrator activates the effector the element of a feedback system that acts to return the system to its optimal state
Negative Feedback Mechanisms
Antagonistic effects response opposite to change Ex: thermostat1. Sensor measures temperature2. Integrator compares the measures temperature to
set point3. Integrator activates electrical effector (furnace or
air conditioner)4. Temperature returned to normal state
Negative Feedback in Animals Ex: humans1. Neurons in preoptic region of
hypothalamus receive info from thermoreceptors
2. Hypothalamus compares info to set point
3. Hypothalamus activates effectors that induce vasoconstriction in skin. Less thermal energy lost. Body temperature increases
Positive Feedback Mechanisms Positive Feedback: the response of a
system that acts to increase the effect of any changes made to the system
Do not result in homeostasis Operate when a continuous increase in
some internal variable is required (ex: fight or flight)
Ex: childbirth contractions release of oxytocin