Homeostasis

Question 1

What enters a cell?

Answer 1

nutrients and oxygen

Question 2

what exits a cell?

Answer 2

waste and carbon dioxide

Question 3

name some systems that interact with the external environment and expend energy

Answer 3

nervous system, locomotor system and reproductive system

Question 4

name some systems that interact with the internal environment and help to achieve homeostasis

Answer 4

cardiovascular, respiratory, excretory and alimentary

Question 5

name some systems that control other systems

Answer 5

nervous system and endocrine system

Question 6

why is homeostasis important?

Answer 6

cells function most effectively under optimal environmental conditions. basic cellular functions tend to alter their immediate environment. homeostasis operates to correct any changes in the cellular environment

Question 7

what is the optimum pH for pepsin?

Answer 7

3

Question 8

what is the optimum pH for trypsin?

Answer 8

7

Question 9

name the 2 mechanisms of homeostasis control

Answer 9

feedback control and feed-forward control

Question 10

how does negative feedback work?

Answer 10

a change in the variable activates mechanisms that alter the level of that variable so as to counteract the change

Question 11

what detects changes in the core body temperature?

Answer 11

thermoreceptors

Question 12

what part of the brain are the thermoreceptors found?

Answer 12

hypothalamus

Question 13

what is circadian rhythm?

Answer 13

daily rhythm of things such as body temperature

Question 14

what is feedforward control?

Answer 14

altering a behaviour before there is an obvious error signal. an anticipatory action

Question 15

give 3 examples of anticipatory actions

Answer 15

stop eating before full, increasing heart rate, probably learned behaviours

Question 16

what is positive feedback?

Answer 16

a change in a variable activates mechanism that alter the level of that variable so as to increase the change

Question 17

where is positive feedback used?

Answer 17

blood clotting, childbirth and action potentials

Question 18

what type of feedback is it when a small change is amplified and converted to a larger one?

Answer 18

positive feedback

Question 19

what are extracellular fluids?

Answer 19

interstitial fluids and plasma

Question 20

what is the difference between extracellular and intracellular fluids?

Answer 20

ionic composition

Question 21

what can move between intracellular and extracellular fluids?

Answer 21

water and some ions

Question 22

with regards to ECF and ICF what happens when we drink lots of water?

Answer 22

ECF volume increases and ECF osmolarity decreases

Question 23

what happens if the ECF is more dilute than the ICF?

Answer 23

water moves from the ECF to the ICF until the osmolarities of ICF and ECF are equal. the extra water is dispersed in ECF and ICF

Question 24

what is osmosis?

Answer 24

diffusion of water along its concentration gradient

Question 25

what does hypotonic mean?

Answer 25

red blood cells burst in low concentrations of NaCl

Question 26

what is isotonic?

Answer 26

neutral concentrations of NaCl

Question 27

what is hypertonic?

Answer 27

red blood cells shrivel in high concentrations of NaCl

Question 28

why does homeostasis not keep every variable at a constant level all the time?

Answer 28

there is a delay in operating the control systems and each variable is not maintained at the same value in different individuals