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Biology Revision Year 2 > Homeostasis > Flashcards

Flashcards in Homeostasis Deck (53)
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1

what is homeostasis?

physiological control systems that maintain a constant internal environment

2

describe positive feedback

a response that amplifies a change eg) voltage gated channels Na +

3

describe negative feedback

receptors detect change away from normal/optimum and affectors return to normal/ optimum eg) blood temp.

4

what cells secrete insulin?

beta cells in the islets of Langerhan

5

what is the role of insulin?

to decerase bllod sugar conc.

6

describe 3 ways insulin decreses blood sugar conc.

binds to liver and muscle causing increased permeability to glucose……more glucose is absorbed by facilitated diffusion………… glycogenesis…..increased rate of respiration

7

what cells secrete glucagon?

alpha cells in the islets of langerhan.

8

how does glucagon restore normal blood sugar level?

gluconeogenesis - non carbs are converted to glucose……glycogenolysis…..decrease rate of respiration.

9

what is glycogenesis?

the conversion of glucose to glycogen

10

what is glycogenolysis?

the hydrolysis of glycogen into glucose

11

what is gluconeogenesis?

the conversion of non carbs eg)lipids/ amino acids into glucose

12

which hormone decreases blood sugar levels?

Insulin

13

which hormone increases blood sugar levels?

glucagon

14

when is glucagon secreted?

when the blood sugar is low

15

when is adrenaline secreted?

low

16

when is insulin secreted?

when the bloood sugar is HIGH

17

where does glucagon attach to receptors?

liver

18

where does adrenaline attach to receptors?

liver

19

where does insulin attach to receptors?

liver and muscle

20

what are the mechanisms of glucagon?

decreases rate of respiration, glycogenolysis, gluconeogenesis

21

what does adrenaline activate?

glycogenolysis, secretion of glucagon

22

what does adrenaline inhibit?

glycogenesis, and insulin secretion

23

what are the mechanisms of insulin?

icrease rate of respiration, glycogenesis, increasing cell permeability to glucose

24

how does insulin increase cell permeability?

glucose carrier molecules are in vesicles in L + M cells, insulon binds with specific receptors on the cell membrane, causing the fusion of the vesicles with the cell membrane, carrier proteins join the cell membrane (fluid mosaic), so glucose is absorbed by fac dif.

25

Define diabetes

an illness where blood glucose levels are not fully controlled

26

Describe Hyperglycaemia

dangerously high blood glucose concentration

27

Describe hypoglycaemia

dangerously low blood glucose concentration

28

What causes Type I diabetes

immune system destroys B cells on the Islets of Langerhan so cannot make insulin

29

What age does Type I diabetes affect?

Children and adolescents

30

What affect does Type I diabetes have on blood glucose concentration

rise after eating carbohydrates
hyperglycaemia - stays high
glucose present in urine