Homeostasis Flashcards
(29 cards)
Define homeostasis:
An internal condition maintained by internal responses that compensate for changes in the external environment; and dynamic condition
Define active hyperemia
-increased blood flow through a tissue
What are intrinsic controls?Give an example
Vasodilators
What is an example of a vasodilator and how does it work?
NO; when blood oxygen levels fall, endothelial cells in blood vessel walls synthesize and release NO; No activates an enzyme that relaxes neighboring smooth muscles; This dilates blood vessels, increases blood flow
What is the primary mechanism of homeostasis?
negative feedback
In the negative feedback mechanism, the response of the system..
cancels or counteracts the effect of the original environmental change
Break down the process of sensory transduction
stimulus is converted into an AP
-AP is transmitted along axons towards the CNS where it is integrated
How do baroreceptors work?
they send signals (AP) to the brainstem and the brain stem sends signals via autonomic nervous system to elicit changes
Baroreceptors decrease/increase their rate of firing when blood pressure drops
decrease (example when a person stands up blood pressure drops)
What are chemoreceptors and where are they found?
found in the aorta and carotid arteries(and other locations)
-can detect O2 content in the blood
What is respiratory acidosis:
decreased or obstructed respiration causes increase blood CO2 and decreased pH
What is metabolic acidosis:
occurs if the kidneys are not removing enough acid from the body
What is ketoacidosis and what are some examples?
the body fails to adequately regulate ketones
-diabetes (type 1) and alcoholic ketoacidosis
What is an example of Alkalosis
hyperventilation
Ectotherms obtain heat from… while endotherms…
obtain heat from the environment
-can generate heat metabolically
How else does an animal change its conductance to heat?
-redirect blood flow; if the temp outside is cold the blood can be directed to avoid the surface which results in the body being more insulated because the blood is flowing beneath a fatty layer of skin
-the body temp is warmer the blood can be redirected to the surface and heat can flow out more easily which would increase conductance
When you feel hot your blood vessels… and when you feel cold your blood vessels
dilate, constrict
What concept occurs so the isolated part of the body doesn’t change the temperature of the rest of the body?
-Counter-current flow
Countercurrent exchange ensures…
gradients that facilitate the maximal amount of heat retention
Temperature regulation is controlled by…
triggered by thermoreceptors
-integrated by the hypothalamus
What thermoreceptors receive signals when there’s a change in skin temperature
peripheral thermoreceptors in the skin
What thermoreceptors receive signals when there’s a change in core temperature
central thermoreceptors in the hypothalamus, abdominal organs, and elsewhere
What happens when environmental temperatures go to the extreme?
-below freezing: lipid bilayer changes from liquid to frozen gel, disrupts cell function and destroys organelles
-high temp: proteins and nucleic acids unfold due to an increase in kinetic energy of molecules
When there is vasoconstriction this means..
less heat is conducted from the blood, thru the skin, to the environment, which means heat loss is reduced
