homeostasis

Question 1

what is homeostasis?

Answer 1

-condition of equilibrium in body’s internal environment, we adjust and adapt to changes in our environment

Question 2

how is homeostasis achieved?

Answer 2

dynamically achieved by interactions with regulatory processes

Question 3

what range should the variables operate in and is it independent of another?

Answer 3

should operate in a narrow range and homeostasis of one variable is not independent of another

Question 4

what is the set point regulated by and what does this component have?

Answer 4

regulated variable has sensors or receptors which send afferent signals to the brain

Question 5

what is the differences between efferent and afferent signals?

Answer 5

efferent flows from control centre to effector whereas afferent goes towards control centre and CNS from receptors

Question 6

explain temperature as an example

Answer 6

hypothalamus controls body core temp (37) ; effectors are blood vessels, sweat glands and skeletal muscles which alter temperature when thermoreceptors in skin detect change

Question 7

how would you return to original value when too hot or too cold?

Answer 7

too hot- constriction blood of skin blood vessels to reduce heat loss
too cold- shivering to increase heat production

Question 8

explain maintenance of blood glucose as an example

Answer 8

70-110mg/ di glucose controlled by pancreas, chemosensors detect the change and effectors liver, adipose tissue, skeletal muscle alter storage/ release of glucose

Question 9

what does tight control of a variable mean and give examples

Answer 9

• at any given time the variable will close to predicted
  e.g. blood pH, oxygen content in blood

Question 10

what does looser control of a variable mean and give an example

Answer 10

• may fluctuate in response to diurnal rhythms but will eventually return to normal levels

Question 11

what is meant by gain and how do you work it out?

Answer 11

• precision by which a control system can prevent deviation from homeostasis
  amount of correction needed/ amount of abnormality after correction

Question 12

what does a large gain mean?

Answer 12

more sensitive regulation that better maintains ‘normal’ or closer to ‘normal’ conditions

Question 13

what is negative feedback?

Answer 13

most common feedback loop that acts to reduce an effect

Question 14

what is an example of negative feedback?

Answer 14

concentrations of active product and enzyme A are competing with each other but synthesis of active product depends on presence of enzyme A
- allows active product to self regulate

Question 15

what is a limiting enzyme?

Answer 15

• key enzyme that determines the overall rate of a metabolic pathway; enzymes can be regulated by other molecules that either increase or reduce their activity

Question 16

what does negative feedback signal?

Answer 16

fine tunes body’s response to a stimulus so that homeostasis can be achieved under new conditions

Question 17

what is positive feedback and give an example

Answer 17

• acts to increase an effect
• clotting of blood when you’ve cut yourself

Question 18

what are feedforward loops and give an example

Answer 18

• physiological responses in anticipation of a change in a variable e.g. HR increases prior to a race

Question 19

what is similar between reflex and local responses?

Answer 19

• both are a result of events proceeding from a stimulus

Question 20

what is the difference between a reflex and local response?

Answer 20

in local the entire sequence only occurs in area of stimulus whereas reflex is everywhere