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Endocrine physiology > hormone regulation of metabolism > Flashcards

hormone regulation of metabolism Flashcards

(52 cards)

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1
Q

what are the different energy reserves in humans & where are they located?

A
  • fat (adipose tissue)
  • protein (muscle)
  • glycogen (muscle)
  • glycogen (liver)
  • glucose (ECF)
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2
Q

in what organs or tissues is glycogen stored?

A

the liver and muscle

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3
Q

can glycogen be rapidly metabolised?

A

yes - it can be ‘instant’ glucose

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4
Q

what kind of energy reserve are fatty acids?

A

they are medium to long term energy reserves

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5
Q

what occurs as a result of endogenous fatty acid synthesis exceeds the energy requirements?

A

the stores expand over time and lead to obesity

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6
Q

Describe glucose as a metabolic fuel?

A
  • excellent fuel
  • yields a significant amount of energy upon oxidation
  • can be utilised by virtually all cells
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7
Q

How does the brain utilise glucose?

A
  • the brain consumes 25% of all the glucose that is oxidised in the body
  • glycogen is not stored in the neurons so it requires a constant supply of glucose
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8
Q

what are the main sources of glucose?

A
  • through diet
  • glycogen reserves (180-200g) - 1 day supply
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9
Q

what are the 4 major pathways of glucose metabolism?

A
  1. glycogenesis
  2. glycogenolysis
  3. gluconeogenesis
  4. glycolysis
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10
Q

what is glycogenesis?

A

making glycogen from glucose for storage

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11
Q

what is glycogenolysis?

A

breaking down glycogen to use for energy

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12
Q

what is gluconeogenesis?

A

making new glucose from non carbohydrate sources eg fatty acids

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13
Q

what is glycolysis?

A

breaking down glucose for energy

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14
Q

is glycogen a short term or long term energy reserve?

A
  • short term energy reserve
  • plays essential role in maintaining blood glucose between meals
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15
Q

what is the main enzyme that activates glycogenesis?

A

glycogen synthase

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16
Q

what is the main enzyme that controls glycogenolysis?

A

glycogen phosphatase

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17
Q

Describe the** opposing effects that phosphorlyation by protein kinases** has on glycogen synthase and glycogen phosphotase

A
  • **phosphorylation of GS inactivates it **/ dephosphorylation activates it
  • phosphorylation of GP activates it/ dephosphorylation inactivates it
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18
Q

What hormone stimulates glycogenesis?

A

insulin

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19
Q

what does insulin signal?

A

energy abundance - ie too much energy

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20
Q

how does insulin stimulate glycogenesis?

A
  • activates protein phosphatase
  • this phosphatase** activates glycogen synthase** and dosent activate glycogen phosphatase
  • **decreases the activity of phosphorylase kinase **
  • therefore the** net effect of insulin stimulation **causes an increase in glycogen synthesis and a decrease in glycogenolysis
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21
Q

what 2 hormones stimulate glycogenolysis?

Study These Flashcards
A
  1. glucagon
  2. epinephrine
22
Q

what does glucagon signal to the body?

Study These Flashcards
A

glucagon signals that glucose is running low

23
Q

what does epinephrine signal to the body about glucose?

Study These Flashcards
A

it signals that glucose is** urgently needed**

24
Q

how does glucagon and epinephrine stimulate glycogenolysis?

Study These Flashcards
A
  • activates glycogen phosphatase - by activating phosphorylase kinase
    * inhibits glycogen synthase - mediated by protein kinase A
  • therefore the net effect is an** increase in glycogenolysis **and a decrease in glycogenesis
  • opposite effect to insulin
25
when is gluconeogenesis most active?
* it is most active in fasting state * during prolonged exercise * conditions of carbohydrate starvation
26
where does gluconeogenesis mainly occur?
* organs that rely least on glucose for energy - the liver
27
what are the **raw ingredients t**hat the liver uses to **synthesise glucose** and what is an example?
* supplied by the muscle and other tissues * eg RBC's
28
what is the starting molecule of gluconeogenesis?
pyruvate
29
what is a** critical enzyme **that allows **glucose to leave the cell** and that is** not found in muscle**?
* glucose 6 phosphatase
30
During fasting what 2 hormones are prevalent and what actions do they have?
* glucagon and cortisol * they induce gluconeogenic enzymes and inhibit glycolytic enzymes - ie they favour gluconeogenesis
31
during the feeding stage, what hormone is prevalent and what actions does it have?
insulin * insulin induces glycolytic enzymes * inhibits gluconeogenic enzymes * favours glycolysis
32
what are fatty acids?
they are a long hydrocarbon chains (C10-24) with a terminal COO- group
33
how are fatty acids mainly stored in the body?
triglycerides
34
where does Beta oxidation ( FA metabolism) occur?
occurs in mitochondria
35
what occurs in beta oxidation?
* FA chains broken down to a 2C compound - acetyl CoA * when glucose and FA metabolism are balanced, acetyl Co A is oxidised in the TCA cycle * if acetyl CoA is in excess, the surplus is converted to ketone bodies
36
what is an important enzyme involved in fatty acid synthesis?
acetyl CoA carboxylase
37
What **2 hormones** **regulate ACC **by** controlling the activity** of **protein kinases and phosphatases**?
* glucagon * insulin
38
how does glucagon influence ACC?
* glucagon **activates protein kinases** which phosphorlyate and therefore **inhibit acetyl CoA carboxylase** * **glucagon signals that energy is low** and **lipid metabolism** should switch from **FA synthesis to oxidation**
39
How does insulin influence ACC?
* insulin activates** protein phosphatase** which **dephosphorylates (ie activates) ACC** * insulin** signals energy abundance** and lipid metabolism **should switch from FA oxidation to synthesis **
40
what hormones stimulate lipolysis & why?
* epinephrine - energy needed immediately * glucagon - no more glucose, switch to fatty acids as energy source
41
how do epinephrine and glucagon stimulate lipolysis?
they activate** hormone sensitive lipase **which hydrolyses TG's to FA's and glycerol
42
what hormone inhibits hormone sensitive lipase and what does it favour?
insulin * favours triglyceride synthesis
43
what is the anorexigenic pathway in the brain?
a pathway which leads to a feeling of being full - and signals that you should stop eating
44
what is the orexigenic pathway in the brain?
a pathway in the brain that stimulates appetite
45
what **hormone stimulates the anorexigenic pathway**? (ie the pathway that leads to the feeling of fullness)
insulin
46
what** hormone produced in the stomach **stimulates the orexigenic pathway (ie favours appetite)?
GHRELIN
47
what is **GLP-1** and what is it's** function**?
**glucagon like peptide 1** * function : causes the glucose induced secretion of insulin from the pancreatic beta cells
48
what pathway does GLP-1 favour?
the anorexigenic pathway
49
what is leptin?
hormone predominantly made by** adipose cells** and enterocytes in the small intestine that helps to** regulate energy balance** by **inhibiting hunger**, which in turn **diminishes fat storage in adipocytes**
50
what pathway does leptin favour?
the anorexigenic pathway
51
what is the **1st metabolic priority** in prolonged starvation?
* to provide sufficient glucose to brain and other tissues that are dependent on it
52
what is the **2nd metabolic priority** in prolonged starvation?
* a shift from the **utilization of glucose to utilization of fatty acids/ ketone bodies** & **preserve protein**

Endocrine physiology (19 decks)

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