Principles of homeostasis

Question 1

define homeostasis

Answer 1

the regulation of a cell/organism to maintain a stable internal environment despite changes in the internal or external environment

Question 2

name the two main systems which help maintain an internal environment

Answer 2

• nervous response
• hormonal response

Question 3

name three main factors which homeostasis control?

Answer 3

• body temperature
• blood glucose levels
• water levels

Question 4

what is one consequence of not maintaining a body temperature

Answer 4

enzymes may denature

Question 5

name the key elements of the control system

Answer 5

1. receptor
2. co-ordinator
3. effector

Question 6

define a hormone

Answer 6

they are chemical messages secreted by the endocrine system, which are complimentary to the cells receptors which the hormones are binding to

Question 7

which organ monitors and controls blood glucose concentrations?

Answer 7

the pancreas, the liver

Question 8

describe how insulin controls blood glucose levels when your blood sugar is high

Answer 8

1. pancreas detects the rise in blood glucose
2. the pancreas secretes insulin into the blood stream
3. insulin travels to the liver
4. liver absorbs glucose and converts it into glycogen
5. this results in the blood-glucose level returning to normal

Question 9

describe the process when your blood sugar levels fall?

Answer 9

1. pancreas detects fall in blood-glucose
2. pancreas secretes glucagon into blood stream
3. the glucagon travels to the liver
4. the liver converts glycogen to glucose and releases it into the blood
5. this results in the blood levels returning back to normal

Question 10

what is type one diabetes caused by?

Answer 10

body’s immune system attacking pancreas cells, meaning no insulin is made, resulting in blood sugar levels rising

Question 11

what is type two diabetes caused by?

Answer 11

poor diet and obesity over time, meaning liver does not recognise insulin in the blood, resulting in blood sugar rising

Question 12

what is negative feedback?

Answer 12

where the cycle works to return conditions and levels back to normal levels

Question 13

what is positive feedback?

Answer 13

where an effector causes an increase in levels, driving them away from the optimum.

Question 14

give an example of a negative feedback loop?

Answer 14

thyroxine, as it controls the basal metabolic rate, returning the heart rate to normal conditions

Question 15

name two conditions which can affect the pituitary gland, and affect how it stimulates endocrine glands

Answer 15

• decreased body temperature
• increased levels of stress