Homeostasis: temperature regulation Flashcards
What is homeostasis
Refers to maintaining a constant internal environment despite changing internal/external conditions
Some factors that have to be controlled near or at a constant level include
-blood ph at 7.4
-blood pressure at 120/80 mm Hg
-body temperature at 37.5 degrees (Celsius)
What is dynamic equilibrium
The internal environment inside any animal actually fluctuates slightly. Therefore homeostasis actually exists in a state of dynamic equilibrium. (Dynamic meaning changing and equilibrium meaning balance). This means that there is a constant interplay between outside forces that change inside conditions and internal control mechanisms that oppose outside forces.
-example: regulation of body temperature
When body temperature drops below optimal (37.5 degrees Celsius) what happens
The body’s heating mechanisms kick in. These include
Vasoconstriction: blood vessels near the skin contract to limit blood flow and reduce heat loss from the blood, extremities feel cold and look blue due to reduced blood flow
Shivering to generate heat
Goosebumps (hair traps air that acts as insulation)
When body temperature increases above optimal (37.5 degrees Celsius) what happens
Vasodilation: blood vessels near the skin open up to promote heat lose (look flushed)
Sweating (water evaporates, cooling the body)
What is a negative feedback mechanism
A feedback system that results in a variable being brought back to normal levels (counteracts fluctuations from normal box constants)
What are the three parts of negative feedback mechanism (and their functions)
Sensory receptors: a special cell that detects changes in an organisms internal or external environment and signals the integrator (sensory receptors in skin)
Integrator/control center: interprets the signal send a message to the effector telling it what to do (brain)
Effector: counteracts the change (muscles and gland that respond to the change)
How does the body’s reactions to temp change work
As temp rises, blood vessels open up releasing heat and sweat is produced, which evaporates from the body, cooling it
As temp lowers blood vessels contract to conserve heat and muscles shiver to generate heat, causing it to warm
What is a positive feedback mechanism
A feedback system that results in a variables level being continually increased or continually decreased
What are examples of positive feedback mechanisms
Uterine contractions during birth: the more intense contractions, the more the hormone Oxytocin is produced which further increase contractions. ends when the baby is born
Blood clotting: when blood vessels break chemicals are released to attract platelets. As platelets plug the injury, more of the chemicals are released that attract even platelets to the site of the clot. it will continue until the clot is large enough to stop the bleeding
