Homeostasis

homeostasis

maintenance of a stable of internal environment

homeostatic mechanisms

self regulating systems that monitor aspects of the internal environment and correct them as needed

what are the three parts of the homeostatic mechanism

• receptor

• control center

• effector

receptor

detects and provides information about the stimuli

control center

decision maker that maintains the set point

effector

muscle or gland that responds to the control center and causes the necessary change in the internal environment

homeostatic mechanisms cycle

stimulus → receptors → control center → effectors → response

stimulus

a change occurs in the internal environment

negative feedback loop

effectors return conditions toward normal range, and the deviation from the set point settles

why is the negative feedback loop negative

because the response to the change moves the variable in the opposite direction of the deviation from the set point

what does the negative feedback loop prevent

sudden, severe changes in the body

what is the most common type of homeostatic mechanism

negative feedback loop

examples of the negative feedback loop

• body temperature

• blood pressure

• glucose level in the blood

positive feedback loop

activity of effector is initially increased instead of decreasing to produce unstable conditions that seem like they will not lead to homeostasis, it is short lived

which homeostatic mechanism is uncommon

positive feedback loop

examples of positive feedback loop

• pregnancy

• blood clotting

homeostatic imbalance

disturbance of homeostasis

what does homeostatic imbalance result in

• an increased risk for disease

• contributes to changes associated with aging because control systems become less efficient

what is an example of a homeostatic imbalance

heart failure

how is heart failure a homeostatic imbalance

because the heart is not pumping like it should → less blood ejected → blood pressure drops → blood vessels constrict and kidneys retain water → already weak heart is trying to pump through constricted vessels and is now working even harder

what happens if negative feedback mechanisms are overwhelmed

destructive positive feedback mechanisms may take over (ex: heart failure)

in negative feedback is the orginal change increased or decreased

decreased

is blood clotting an example of negative feedback

no

where is the control center for homeostasis mechanisms located

the brain (hypothalamus, brain stem)