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Biology Revision Year 2 > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

what is homeostasis?

A

physiological control systems that maintain a constant internal environment

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2
Q

describe positive feedback

A

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

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3
Q

describe negative feedback

A

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

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4
Q

what cells secrete insulin?

A

beta cells in the islets of Langerhan

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5
Q

what is the role of insulin?

A

to decerase bllod sugar conc.

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6
Q

describe 3 ways insulin decreses blood sugar conc.

A

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

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7
Q

what cells secrete glucagon?

A

alpha cells in the islets of langerhan.

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8
Q

how does glucagon restore normal blood sugar level?

A

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

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9
Q

what is glycogenesis?

A

the conversion of glucose to glycogen

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10
Q

what is glycogenolysis?

A

the hydrolysis of glycogen into glucose

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11
Q

what is gluconeogenesis?

A

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

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12
Q

which hormone decreases blood sugar levels?

A

Insulin

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13
Q

which hormone increases blood sugar levels?

A

glucagon

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14
Q

when is glucagon secreted?

A

when the blood sugar is low

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15
Q

when is adrenaline secreted?

A

low

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16
Q

when is insulin secreted?

A

when the bloood sugar is HIGH

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17
Q

where does glucagon attach to receptors?

A

liver

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18
Q

where does adrenaline attach to receptors?

A

liver

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19
Q

where does insulin attach to receptors?

A

liver and muscle

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20
Q

what are the mechanisms of glucagon?

A

decreases rate of respiration, glycogenolysis, gluconeogenesis

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21
Q

what does adrenaline activate?

A

glycogenolysis, secretion of glucagon

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22
Q

what does adrenaline inhibit?

A

glycogenesis, and insulin secretion

23
Q

what are the mechanisms of insulin?

A

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

24
Q

how does insulin increase cell permeability?

A

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
Q

Define diabetes

A

an illness where blood glucose levels are not fully controlled

26
Q

Describe Hyperglycaemia

A

dangerously high blood glucose concentration

27
Q

Describe hypoglycaemia

A

dangerously low blood glucose concentration

28
Q

What causes Type I diabetes

A

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

29
Q

What age does Type I diabetes affect?

A

Children and adolescents

30
Q

What affect does Type I diabetes have on blood glucose concentration

A

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

31
Q

how can we treat Type I diabetes?

A
  • Insulin injections/ pump
  • avoid sugars
  • eat at regular intervals
  • regular exercise
32
Q

What causes Type II diabetes?

A

Obesity/ lack of exercise

B don’t make enough insulin or liver and muscle stop responding to insulin

33
Q

What age does Type II affect?

A

adults and elderly

34
Q

What is the affect of Type II on blood glucose conc?

A

hyperglycaemia

35
Q

What is the treatment for Type II diabetes/

A
  • eat healthy, lose weight, regular exercise
  • drugs - which increase sensitivity to insulin, produce more insulin
  • insulin injections
36
Q

describe how secondary messengers aid Glycogenolysis.

A
  • The hormone (first messenger) eg) adrenaline or glycogen is complementary to the receptor protein on the target cell
  • The enzyme Adenyl Cyclate converts ATP to cAMP
  • cAMP activates protein kinase A by altering the tertiary structure
  • cAMP is the secondary messenger
37
Q

What are the 2 parts of the kidney?

A

medulla and the cortex

38
Q

Describe the process of ultrafiltration

A

takes place in between the capillaries and the bowmans capsule
high hydrostatic pressure forces small molecules out to form the filtrate

39
Q

What is the larger capillary entering the glomelurus?

A

Afferent arteriole (lArge)

40
Q

What is the smaller capillary entering the glomelurus?

A

Efferent arteriole

41
Q

What three layers are the small molecules filtered through between the blood and the Bowman’s capsule?

A

capillary membrane, basement membrane, podocyte

42
Q

Define selective reabsorbtion

A

useful products are reabsorbed by the nephron from the glomerular filtrate.

43
Q

Describe the process of selective reabsorption

A

Ultrafiltration makes glomerular filtrate
capillaries wrap around nephron and useful substances are reabsorbed into the blood
Proximal Convuluted Tube (PCT) absorbs most of the molecules (including water)

44
Q

How is the PCT adapted for reabsorption

A

microvilli increase SA for absorption

45
Q

How are Glucose and Amino acids reabsorbed

A

Facilitated diffusion

46
Q

How is Urea reabsorbed

A

simple diffusion

47
Q

How is water reabsorbed?

A

osmosis

48
Q

What is reabsorbed by Active transport using ATP?

A

glucose, amino acids, and ions

49
Q

describe what happens at the ascending limb of the loop of Henle (stage one) `

A

Na+ and Cl- are pumped out
This decreases the water potential of the medulla
water cannot move out of the ascending limb because it is impermeable to water

50
Q

Describe what happens at the descending limb of the LoH (stage two)

A

the descending limb is permeable to water
water moves out by osmosis
this is absorbed by the capillaries that wrap around the nephron
water leaving the nephron at the descending limb increases the concentration of the urine

51
Q

How would the length of the LoH be different in a camel?

A

The loop would be longer
increasing the conc of the medulla
increasing the amount of water leaving the nephron
therefore the urine is more concentrated

52
Q

What is the affect of ADH binding to the receptor at the collecting duct of the nephron?

A

ADH increases the permeability to water so water moves out by osmosis because the medulla has a more negative water potential

53
Q

describe the process of osmoregulation when dehydrated. (6 steps)

A

1) dehydration means the water potential of blood is more negative
2) this is detected by osmoreceptors in the hypothalamus
3) posterior pituitary secretes ADH into the blood stream
4) ADH binds to the specific receptor at the collecting duct
5) this increases the permeability to water
6) water moves out by osmosis because the medulla is more negative

Biology Revision Year 2 (13 decks)

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