B 13.2 - Homeostasis Flashcards
(42 cards)
3 internal conditions that are kept constant
-body temperature
-blood glucose concentration
-water potential of the blood
internal environment
whats going on inside an organism (outside of cells)
external environment
whats going on outside an organism’s body (surroundings)
why does the internal environment need to be kept constant?
so cells can work efficiently
what is homeostasis?
maintenance of a constant internal environment
how do mammals maintain a constant internal body temperature?
-insulation
-sweating
-shivering
-vasodilation of arterioles
-vasoconstriction of arterioles
what are cells in blood surrounded by?
plasma
what are other cells surrounded by?
tissue fluid
where are the optimum conditions for the internal environment maintained within?
plasma and tissue fluid
how is homeostasis brought about?
(homeostatic control)
negative feedback:
-sensory receptors send body information to brain continuously
-if level is beyond the normal range, brain initiates a response to bring level back to within set points
-receptors inform brain that the level has been restored
what is negative feedback
detect
–>change from set point
correct
–>triggers response that brings level back to its set point
effect in cells of blood glucose levels are being too high?
cells lose water due to osmosis
–>outside has lower water potential (high concentration of glucose)
–> cell shrivels up / gets crenated
effect of blood glucose levels being too low for cells?
-cells cant respire, can’t release energy needed
-brain cells die quickly
how does glucose get into blood?
-starch broken down into glucose by enzymes (in mouth and duodenum)
-gets absorbed out of small intestines into blood
why is glucose needed when you exercise?
-muscles need to contract more
-more energy is needed
-more respiration needs to happen
-more oxygen + glucose needed
role of pancreas in controlling blood glucose levels
-detects blood glucose levels
-secretes insulin and glucagon
process of homeostasis if blood glucose levels are too high
-detected by pancreas
-insulin is released into blood
-insulin decreases blood glucose levels by:
–>causing cells to take up more glucose for respiration
–>causing glucose to turn into glycogen in liver cells
why does glycogen not affect blood glucose levels?
it’s insoluble so it doesn’t affect osmosis (water potential of cytoplasm or blood)
process of homeostasis if blood glucose levels are too low
-pancreas detects blood glucose levels
-glucagon is released into blood
-glucagon increases blood glucose levels by:
–>making liver change glycogen to glucose
why should body temperature be kept constant? (enzymes)
enzymes work best at optimum temperatures (gets denatured if temperature is too high)
why should body temperature be kept constant? (cell membranes)
membranes become more fragile as temperature increases
why should body temperature be kept constant? (diffusion rates)
rates increase at a higher temperature and decrease at a lower temperature
-affects gas exchange and absorption
why should body temperature be kept constant? (liquids like blood)
liquids become more viscous (thick and sticky, no flow) as temperature decreases
how does the body gain heat? specific examples as well
-metabolism (respiration, chemical reactions in the liver)
-movement (respiration, friction within muscles)
