Unit 1: AOS 2, DP 4 Flashcards
Homeostasis
condition of a relatively stable internal environment maintained within narrow limits
Hypothalamus
regulates temp and osmotic pressure
Evaporation
of water helps regulate body temperature
Pancreas
regulates blood sugar
Kidney
maintain water balance
Skeletal muscle
contracts and releases heat
Blood
distributes heat throughout the body
Stimulus-response with negative feedback is a key
mechanism for homeostatic regulation of physiological variables
Stimulus
change in external or internal environment (sound of start signal)
Receptor
one-off sensing of the change (ears)
Control centre or modulator
where (brain cortex receives and processes nerve signal from ears and transmits a message about required response)
Effector
physical (skeletal muscles receive the signal)
Response
what (arms/legs push off the starting block)
Feedback loops
- Response of a system that influences ongoing activity
- Mechanism which the output of a process is directed back to and affects the input to the process
Negative feedback loops
key mechanisms of homeostasis that allow for return of a variable to its required range (stimulus too low)
temperature (neg feedback)
1 (decrease in body temp), 2 (decrease detected by thermoreceptors in skin), 3 (hypothalamus sends signals via nerve and hormonal systems), 4 (skeletal muscles), 5 (shivering)
decrease glucose (neg feedback)
1 (decrease in blood glucose), 2 (alpha cells of pancreas), 3 (alpha cells of pancreas secrete the hormone glucagon), 4 (liver cells, body cells), 5 (increase in blood glucose by release of glucose into the blood from the liver)
increase glucose (neg feedback)
1 (increase in blood glucose), 2 (beta cells of pancreas), 3 (beta cells of pancreas secrete the hormone insulin), 4 (skeletal muscle), 5 (decrease in blood glucose by uptake by muscle and adipose tissue)
Positive feedback
not a mechanism of homeostasis, causes an amplification of a stimulus further from a set point (stimulus too high)
increase temp (pos feedback)
1 (increase in body temp), 2 (increase detected by thermoreceptors in skin), 3 (hypothalamus sends signals via nerves), 4 (sweat glands), 5 (initiation of sweating)
Neg v Pos feedback
Both negative and positive feedback loops use the stimulus-response model whereas negative feedback is when a response counteracts the change in a variable, positive feedback instead causes an amplification of a variable.
