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PSL300 > Endocrine pancreas > Flashcards

Endocrine pancreas Flashcards

1
Q

What is metabolism?

A

Sum of all chemical reactions in the body

Includes anabolic (synthesis of large molecules) and catabolic (breakdown of large molecules) processes.

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2
Q

Define anabolic metabolism.

A

Large molecules synthesized from smaller ones. Fed metabolism that occurs immediately following a meal

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3
Q

Define catabolic metabolism.

A

Breakdown of large molecules into smaller ones.
Fasted metabolism state that is usually 3-4 hours following a meal

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4
Q

What is the basal metabolic rate (BMR)?

A

An individual’s energy expenditure when resting, at comfortable temperature, and fasted.

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5
Q

What metabolic state is characterized by using glucose for energy?

A

Fed (absorptive) state.

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6
Q

What metabolic state is characterized by using glucose and fat for energy?

A

Fasted (postabsorptive) state.

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7
Q

List the metabolic processes occurring in the fed state.

A

glycogenesis: creating glycogen from glucose

Lipogenesis: anabolic state where fatty acid are converted into triglycerides

Protein synthesis: amino acids to proteins (muscles

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8
Q

List the metabolic processes occurring in the fasted state.

A

Glycogenolysis: breakdown of glycogen in the liver and muscles into glucose and then into ATP via glycolysis

Lipolysis: catabolic breakdown of triglycerides in adipose tissue into fatty acids and ATP

Protein degradation: protein in muscles breakdown into amino acids

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9
Q

Gluconeogenesis

A

making new glucose through the fast state by non-carbohydrate substrates such as glycerol and amino acids

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10
Q

What transports glucose into cells?

A

Glucose transporters (GLUT).

There are two main GLUT transporters- GLUT2 and GLUT4 transporters

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11
Q

Where is GLUT 2 primarily found?

A

Liver and pancreas

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12
Q

what is the primary role of GLUT 2 transporter

A

it transports glucose and insulin secretion

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13
Q

Where is GLUT 4 primarily found?

A

Adipose tissue, skeletal muscle.

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14
Q

What is the primary role of GLUT 4 transporter

A

storage of glucose and getting glucose into skeletal muscles- with the help of insulin

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15
Q

What is the relationship between insulin and glucagon?

A

There are antagonistic to one another

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16
Q

What is the role of insulin in metabolism?

A

Reduces blood glucose and promotes formation of glycogen, fat, and protein.

it moves glucose out of the bloodstream and into the cell

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17
Q

What happens to glucagon levels immediately following a meal

A

in the fasted states glucagon levels are high to promote the breakdown of stored energy sources, however after a meal when glucose begins to rise as well as insulin, glucagon bill drop

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18
Q

What happens to insulin levels immediately following a meal

A

insulin levels will rise with glucose levels and push glucose into the cells. When enough glucose is pushed into the cell and out of the bloodstream, insulin levels will start to drop

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19
Q

What is the dominant hormone of the fed state?

A

insulin (anabolic)

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20
Q

What is the primary role of insulin

A

increases glucose oxidation, glycogen synthesis, fat synthesis, and protein synthesis

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21
Q

What type of receptor does insulin bind to?

A

Receptor tyrosine kinase.

22
Q

What is the primary stimulus for insulin secretion?

A

Glucose.

23
Q

Mechanism of Insulin Action- GLUT 4 transporters

A
  1. insulin will bind to tyrosine kinase receptor- activating kinase
  2. receptor phosphorylates insulin-receptor substrates (IRS) which stimulates secondary pathways
  3. second messenger pathways alter protein synthesis and existing protein- here GLUT4 receptors will be created and translocate to the plasma membrane via exocytosis where glucose can move into the cell via facilitated diffusion
24
Q

Where are GLUT 4 transporters found?

A

in muscle and adipose tissue

25
Q

What does glucose do for muscle tissues and adipose tissue

A

for muscle tissues, it is used for immediate metabolic use- during exercise GLUT 4 can go to the plasma membrane without insulin

For adipose tissues, glucose is stored and will eventually be turned into fat

26
Q

What are the differences between Glut 4 and GLUT 2 transporters

A

GLUT 4 transporters are dependent on insulin, meaning that they need insulin to move to the plasma membrane and they are found on muscle and adipose tissue

GLUT 2 transporters are independent of insulin and act on liver cells

27
Q

Mechanism of Action- GLUT 2 Transporters

A

GLUT 2 receptors are bound to the plasma membrane even when insulin is not present.

in the liver, there is presence of glucose on the inside

In the presence of insulin- it will activate hexokinase, which phosphorylates glucose into glucose 6 phosphate

this phosphorylation will maintain a high glucose concentration on the outside of the cell, indirectly increasing glucose uptake by liver

28
Q

effects of insulin

A

increase glucose transport into insulin-sensitive cells

activates enzymes involved in glycogenesis, lipogenesis, and protein synthesis

inhibits enzymes for glycogenolysis, gluconeogenesis, and lipolysis

increases uptake of amino acids into muscle and protein synthesis

promote lipogenesis and inhibits oxidation

enhance cell proliferation

29
Q

What stimulates insulin release

A

glucose in the blood will bind to transporter which will increase ATP

ATP will cause K channels to close, causing the cell to depolarize, opening calcium channels that will will cause the release of insulin in vesicles

30
Q

What are incretin hormones?

A

GIP-1
GLP-1.

31
Q

Why is there more insulin secreted when glucose is in intestine

A

because of incretin hormones

32
Q

What is the role of GLP-1?

A

Stimulates insulin secretion and increases beta cell mass.

this is done when it travels through the bloodstream to the pancreas and binds to G-coupled receptor

after it is bound, adenyl cyclase will cause increase cAMP and exchange protein activated by Adenyl cyclase (EPAC) which will cause increase of calcium

33
Q

What are stimulators and inhibitors of insulin?

A

Stimulators:

increased glucose
intestinal hormones- GIP-1 GLP1
amino acids
parasympathetic nervous system

Inhibitors:

sympathetic nervous system (fight or flight)

34
Q

What stimulates glucagon secretion?

A
  • Decreased plasma glucose
  • Increased plasma amino acids
  • Sympathetic nervous system.
35
Q

Glucagon

A

secreted by pancreatic alpha cells

36
Q

What effects do glucagon have on the body

A

increase breakdown of glycogen (glycogenolysis)

creates new glucose (gluconeogenesis)

37
Q

What is the primary function of glucagon?

A

Prevents hypoglycemia (too little glucose)

38
Q

How does glucagon prevent hypoglycaemia?

A

in the fasting state, glucagon triggers activation of a cascade sequence that will breakdown down glucose-1-phosphate into glucose

39
Q

Stimulators and inhibitors of glucagon

A

stimulators:
decreased glucose
increased amino acids- protein ingestion enhances glucagon and insulin release, allowing cells to store glucose without severely dropping blood glucose level
sympathetic nervous system

Inhibitors:
GLP1

40
Q

True or False: Type 1 diabetes is often treated with insulin injections.

A

True.

41
Q

Type 1 diabetes

A

insulin dependant diabetes where insulin secretion is reduced or absent

42
Q

Type 2 diabetes

A

non-insulin dependant
there is a defect in insulin secretion and target cell responsiveness to insulin is reduced

43
Q

What characterizes uncontrolled Type 1 diabetes?

A

No insulin production means no GLUT 4 transporters,
decreasing glucose uptake to muscle and adipose- causes hyperglycaemia (high blood sugar) and decrease in glucose utilization will cause the body to sense starvation which causes liver to breakdown glycogen in to glucose

in protein metabolism; increase in protein breakdown and tissue loss

in fat metabolism: increase in fat breakdown and decrease in fat storage causing weight loss

leads to hyperglycemia

high blood sugar gets filtered into the kidney and we urinate lots of glucose and water- leads to low blood volume, which can can cause ADH secretion

Increase in osmolarity

no insulin which means you can’t use glucose for fuel, use fats which release ketones (acidic) as biproduce can result in acidosis

blood volume and blood pressure decreases, as well as urine acidification and hyperkalemia which can lead to coma and death

44
Q

Fill in the blank: GLP-1 helps to stimulate further _______.

A

insulin release.

45
Q

What is the role of the sympathetic nervous system in insulin secretion?

A

Inhibition.

46
Q

What happens to glucose levels in the blood during fasting?

A

They decrease, prompting glucagon release.

47
Q

What is the treatment approach for Type 2 diabetes?

A
  • Diet
  • Exercise
  • Oral hypoglycemics
  • Sometimes insulin injections.
48
Q

how can sulfonylureas help treat type 2 diabetes

A

they can also close K channels leading to further release of insulin

49
Q

How can GLP1 treat type 2 diabetes

A

help beta cell proliferation and prevent apoptosis

reduce gastric emptying- stomach slows glucose being released in bloodstream which can also reduce appetite

50
Q

What other therapeutic affects do GLP1 have on the body

A

it can reduce cardiovascular complications such as myocardial infarction some neurological diseases such as Alzheimers and Parkinson’s as well as neuropsychiatric disorders like substance use disorders and compulsive behaviours

PSL300 (10 decks)

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