Unit 1: AOS 2, DP 4

Question 1

Homeostasis

Answer 1

condition of a relatively stable internal environment maintained within narrow limits

Question 2

Hypothalamus

Answer 2

regulates temp and osmotic pressure

Question 3

Evaporation

Answer 3

of water helps regulate body temperature

Question 4

Pancreas

Answer 4

regulates blood sugar

Question 5

Kidney

Answer 5

maintain water balance

Question 6

Skeletal muscle

Answer 6

contracts and releases heat

Question 7

Blood

Answer 7

distributes heat throughout the body

Question 8

Stimulus-response with negative feedback is a key

Answer 8

mechanism for homeostatic regulation of physiological variables

Question 9

Stimulus

Answer 9

change in external or internal environment (sound of start signal)

Question 10

Receptor

Answer 10

one-off sensing of the change (ears)

Question 11

Control centre or modulator

Answer 11

where (brain cortex receives and processes nerve signal from ears and transmits a message about required response)

Question 12

Effector

Answer 12

physical (skeletal muscles receive the signal)

Question 13

Response

Answer 13

what (arms/legs push off the starting block)

Question 14

Feedback loops

Answer 14

• 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

Question 15

Negative feedback loops

Answer 15

key mechanisms of homeostasis that allow for return of a variable to its required range (stimulus too low)

Question 16

temperature (neg feedback)

Answer 16

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)

Question 17

decrease glucose (neg feedback)

Answer 17

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)

Question 18

increase glucose (neg feedback)

Answer 18

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)

Question 19

Positive feedback

Answer 19

not a mechanism of homeostasis, causes an amplification of a stimulus further from a set point (stimulus too high)

Question 20

increase temp (pos feedback)

Answer 20

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)

Question 21

Neg v Pos feedback

Answer 21

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.