Homeostasis
- Created by: Liv Scott
- Created on: 06-03-15 10:18
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- Homeostasis
- Negative feedback
- Blood glucose regulation
- Islets of Langerhans
- Drop in blood glucose conc.
- Alpha cells secrete glucagon
- Inhibit insulin secretion
- Glycogenolysis - converts glycogen to glucose
- More fatty acids used in respiration
- Gluconeogenesis- conversation of amino acids & fats to glucose
- Alpha cells secrete glucagon
- Rise in blood glucose conc.
- Beta cells secrete insulin
- Inhibits glucagon production
- Binds to receptors on hepatocytes
- Activates adenyl cyclase
- Converts ATP to cAMP
- More glucose channels in the cell surface membrane
- More glucose enters cells
- Glycogenesis- glucose converted to glycogen
- More glucose channels in the cell surface membrane
- Converts ATP to cAMP
- Activates adenyl cyclase
- Beta cells secrete insulin
- Drop in blood glucose conc.
- Islets of Langerhans
- Brings about a reversal of a change back to the norm
- Blood glucose regulation
- Communication system
- Hormonal
- Slow response, long term
- Neural
- Quickly, through neurons
- Hormonal
- Thermoregulation
- Endotherms
- Use internal sources of heat to maintain body temp within a narrow range
- Advantages
- Constant internal temp, regardless of external temp
- Activity possible in cold weather
- Can live in cold climates
- Disadvantages
- More energy used up producing heat
- More food needed
- Less energy from food can be used for growth
- Adaptations
- Sweat
- Alter breathing pattern
- Alter body shape
- Alter body shape
- Move into/away from sun
- Hair (lies flat or erect)
- Advantages
- Use internal sources of heat to maintain body temp within a narrow range
- Ectotherms
- Relies on external sources of heat to regulate body temp
- Advantages
- Constant internal temp. independent of external temp.
- Activity possible in cold conditions e.g. winter
- Can live in cold climates
- Disadvantages
- More energy used in producing heat energy
- More food needed to make heat energy
- Less of the energy from food used for growth
- Adaptions
- Move into/out of the sun
- Change breathing movements
- Alter body shape
- Advantages
- Relies on external sources of heat to regulate body temp
- Endotherms
- Cell signalling
- Cells need to communicate with each other
- Positive feedback
- Response is to increase the original change
- E.g. hypothermia & labour contractions
- Response is to increase the original change
- The maintance of the internal environment in a stable state
- Negative feedback
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