Homeostasis Flashcards
(21 cards)
Homeostasis
Describes the relatively constant states maintained by the body
Term homeostasis coined by …..?
American physiologist Walter B. Cannon
Internal environment around body cells remains……..?
Constant
Greek word homoios means…..?
the same
Greek word stasis means……?
standing
homeostasis Simplified
Means a condition that may vary, but which is relatively constant
Examples of Homeostasis
Temperature regulation
Regulation of blood carbon dioxide level
Regulation of blood glucose level
Feedback Control Loops
Devices for maintaining or restoring homeostasis by self-regulation
Basic components of control mechanisms
Sensor mechanism
Integrating, or control, center
Effector mechanism
Feedback
Hormones
Secreted into the blood, and information is transmitted in the control loops
Sensor Mechanism
Specific sensors detect and react to any changes from normal
The Integration Center
information is analyzed and integrated, and then, if needed, a specific action is initiated
The Effector Mechanism
Effectors directly influence controlled physiological variables
Feedback
The process of information about a variable constantly flowing back from the sensor to the integrator.
Negative Feedback Control Systems
Are inhibitory
Stabilize physiological variables
Produce an action that is opposite to the change that activated the system
Are responsible for maintaining homeostasis
Are much more common than positive feedback control systems
Positive Feedback Control Systems
Are stimulatory
Amplify or reinforce the change that is occurring
Tend to produce destabilizing effects and disrupt homeostasis
Bring specific body functions to swift completion
Feed-Forward
Control systems occur when information flows ahead to another process or feedback loop to trigger and change in anticipation of an event that will follow.
Intracellular Control
Regulates functions within cells by use of genes or enzymes.
Intrinsic Control
regulates tissue and organ control by use of chemical signals or other “built-in” mechanisms
Extrinsic control
Regulates from organ to organ using nerve signals or endocrine (hormonal) signals
Homeostatic Mechanisms
May not be as efficient during infancy and early childhood as they are in adulthood
May lose their efficiency even more in advanced old age
