How is homeostasis maintained?
Organ systems work together to maintain
homeostasis-
maintenance of stable internal conditions
Negative feedback-
reduces or shuts off certain stimulus. Receptor senses a change, Control center (brain) evaluates the change, Effector corrects the condition. ex–muscle
look up at light and pupils constrict
Positive feedback-
intensifies a stimulus. ex–childbirth, lactation,
Ectotherms/ poikilotherms-
cold-blooded. obtain body heat from environment, therefore, their body temperature changes with a changing environment. fish, amphibians, reptiles.
Endotherms/ homeotherms-
warm-blooded. generate their own body heat and are able to maintain stable internal temperature
hypothalamus
The hypothalamus is a section of the mammalian brain that contains centers that help control the body temperature
Peripheral vasodilation-
diameter of blood vessels in skin increases, bringing more heat to the skin that can be given up to surroundings
Heat stress causes the following
Peripheral vasodilation, Evaporative heat loss, panting
Evaporative heat loss-
sweating produces liquid on the surface of the skin that uses heat to cause its evaporation, cooling the body
Panting-
shallow, rapid breathing that causes evaporative heat loss from the mouth, respiratory tract, and
nasal cavity
Peripheral vasoconstriction-
hypothalamus signals arterioles in skin to contract, causing less blood (with less metabolic heat) to reach the body surfaces
cold stress causes the following
Peripheral vasoconstriction, Pilomotor response, shivering
Pilomotor response-
hair or feather stand up, creating a layer of still air next to skin. This reduces heat loss
shivering
hypothalamus tells skeletal muscles to contract ten to twenty times each second, increasing heat production as a waste product
