Unit 6: Homeostasis and blood glucose Flashcards

1
Q

What is homeostasis?

A

physiological control systems that maintain the internal environment within restricted limits

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2
Q

What is homeostasis important to maintain

A
  • stable core temperature
  • stable blood pH
  • stable blood glucose
  • water potential of blood
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3
Q

what mechanism does homeostasis rely on

A

negative feedback

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4
Q

what are hormones

A

secreted by glands which secrete the hormones into the blood

carried in blood plasma

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5
Q

What are target cells

A

cells with receptors complementary to hormones

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6
Q

Why does a stable temperature need to be maintained

A

to provide optimum temp for enzyme activity.
Low temps dont provide sufficient KE for optimum enzyme activity and if temp is too high enzymes denature

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7
Q

why does a stable pH need to be maintained

A

to provide an optimum pH for enzyme activity
extreme changes in pH cause denaturation

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8
Q

why does a stable blood glucose concentration need to be maintained

A

to provide sufficient substrate for respiration to release energy for metabolic processes in the body

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9
Q

why does the water potential of blood need to be maintained

A

so excess water doesnt enter/leave cells causing them to burst/dehydrate/shrivle

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10
Q

what is glycogenesis

A

conversion of glucose to into glycogen

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11
Q

what is glycogenolysis

A

hydrolysis of glycogen into glucose

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12
Q

what is gluconeogenesis

A

conversion of glycerol and amino acids into glucose

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13
Q

how is glucose sourced from your diet

A

by the hydrolysis of carbohydrates (starch) it is then absorbed into the small intestine

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14
Q

How is glucose sourced from stores

A

glycogen is stored in the liver and muscle cells when excess glucose from the diet undergoes glycogenesis

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15
Q

How is glucose sourced by making new glucose

A

from non carbohydrate sources
the liver can make glucose from glycerol and amino acids (gluconeogenisis)

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16
Q

What is negative feedback

A

restores systems to their original level

17
Q

How does the liver maintain blood glucose concentration

A

converts excess blood glucose into insoluble storage compound glycogen

18
Q

What is insulin

A

globular protein made of 51 amino acids

19
Q

How does insulin enter the blood

A

pancreas detects rise in blood glucose and pancreas beta cells secrete insulin

20
Q

How does insulin work when theres an increase in blood glucose

A
  • attaches to receptors on target cells (liver/muscle)
  • increases permeability of target cells to glucose by stimulating the inclusion of more specific channel proteins
  • allows glucose to enter by diffusion reducing the blood glucose concentrarion
21
Q

How is glucose converted to glycogen (glycogenesis)

A

Insulin activates enzymes in the liver/muscles that convert glucose into glycogen
- excess glucose is converted to fat when glycogen stores are full

22
Q

How does the pancreas work when blood glucose decreased

A
  • detected by pancreas and alpha cells secrete glucagon
23
Q

How does glucagon work when blood glucose decreases?

A
  • glucagon attaches to receptors on target cells and activates enzymes which hydrolyse glycogen into glucose
  • glucose is released into the blood increasing blood glucose concentration
24
Q

How is glucose produced when the glycogen store is full?

A

(during extensive exercise or starvation etc)
glucagon activates enzymes which convert glycerol and amino acids into glucose (gluconeogenesis) which is released into blood

25
Q

What gland releases adrenaline

A

adrenal gland

26
Q

How does adrenaline produce glucose

A
  • attaches to receptors on target cells and activate enzymes that hydrolyse glycogen into glucose
27
Q

Why does adrenaline increase glucose production

A

to provide glucose to cells for respiration and increase blood glucose to normal

28
Q

What is a first messenger ?

A

Hormones adrenaline and glucagon don’t enter target cells directly but bind to surface receptors

29
Q

Outline how adrenaline/glucagon increases glucose

A
  • binds to receptors on target cells
  • this activates enzyme adenly cyclase
  • adenlyate cyclase converts ATP into cyclic AMP (acts as second messenger)
  • AMP activates enzyme protein kinase
  • stimulates hydrolysis of glycogen to glucose and its released into blood
30
Q

What is Type 1 diabetes

A
  • cells in the pancreas responsible for production of insulin are destroyed
  • individual produces no insulin at all
31
Q

What is Type 2 diabetes?

A
  • cells have fewer insulin receptors or they are faulty and dont respond to insulin
  • so take up less glucose and convert less into glycogen so blood glucose remains high
32
Q

How is type 1 diabetes managed

A

individual injects themselves with insulin

33
Q

How is type 2 diabetes managed?

A

individual controls their blood glucose by controlling their diet - avoiding foods that cause rapid surge in blood glucose and by regular exercise