Metabolism Flashcards

1
Q

How long is the pancreas

A

~ 12 - 15 cm long.

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2
Q

Where does the pancreas sit?

A

Below and behind the stomach.

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3
Q

What are the three regions of the pancreas?

A

Head, body and tail.

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4
Q

Is the largest section of the pancreas, near the duodenum

A

Head

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5
Q

Is the central section of the pancreas

A

Body

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6
Q

Is the tapered section of the pancreas

A

Tail

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7
Q

How is the pancreas connected to the duodenum?

A

Via two ducts, the main pancreatic duct and the Accessory duct.

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8
Q

What type of cells does the pancreas have clusters of?

A

Glandular epithelial cells.

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9
Q

Makes up 99% of the glandular epithelial cell clusters

A

Acini/

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10
Q

What do the cells within acini do?

A

Produce and secrete the components of pancreatic juice.

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11
Q

acini secrete

A
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12
Q

cells secrete

A
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13
Q

How much pancreatic juice is produced each day?

A

1 - 1.5 litres

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14
Q

What is the pH of pancreatic juice?

A

between 7.1 and 8.2

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15
Q

Where does pancreatic juice flow?

A
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16
Q

Where does pancreatic juice drain?

A
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17
Q

How is digestive enzyme secretion activated?

A

By cholecystokinin (CCK)

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18
Q

What activates bicarbonate secretion?

A

Secretin

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19
Q

What are the enzymes of pancreatic juice for protein digestion?

A

Trypsin, chymotrypsin, carboxypeptidase, elastase.

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20
Q

What are the enzymes of pancreatic juice for carbohydrate digestion?

A

Pancreatic amylase.

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21
Q

What are the enzymes of pancreatic juice for lipid digestion?

A

Pancreatic lipase and phospholipase.

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22
Q

What are the enzymes of pancreatic juice for nucleic acid digestion?

A

Ribonuclease and deoxyribonuclease.

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23
Q

What are the two main secretory cells?

A

Alpha islet cells (17%)
Beta islet cells (70%)
Delta cells (7%)
F cells (6%)

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24
Q

What do alpha islet cells secrete?

A

Glucagon

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25
Q

What do beta islet cells secrete?

A

Insulin

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26
Q

What do delta cells secrete?

A

Somatostatin, which inhibits the secretion of both glucagon and insulin.

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27
Q

What do F cells secrete?

A

Pancreatic Peptide, which inhibits somatostatin

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28
Q

What does glucagon do?

A
  • Promotes glycogenolysis and gluconeogenesis.
  • which increases blood glucose concentration
  • Promotes the release of fatty acids via lipolysis.
  • Main target is the liver and adipose tissue.
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29
Q

What does insulin do?

A
  • Promotes glucose uptake into skeletal muscle and adipose tissue via GluT 4.
  • Promotes glycogenesis in muscle and liver.
  • Increases amino acid uptake and protein synthesis.
  • Increases formation of triglycerides.
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30
Q

What is the largest gland in the human body?

A

The liver

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31
Q

What is the second largest organ?

A

The liver, only second to the skin.

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31
Q

What is the liver composed of?

A

Hepatocytes, Bile Canaliculi, Hepatic sinusoids, Stellate reticuloendothelial cells.
* Hepatic macrophages that phagocytise ageing red and white blood cells and bacteria.

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31
Q

How much does the liver weigh?

A

1.4 g

32
Q

What is Bile Canliculi?

A

Network of ducts between laminae.

33
Q

What is the main cell of the liver?

A

Hepatocytes (80%)

34
Q

What tasks do hepatocytes do?

A

Metabolic, secretory and endocrine.

35
Q

What is hepatic laminae?

A

Forms. 3D layers

36
Q

What do Bile Canaliculi do?

A
  • Carry bile secreted by hepatocytes to bile ducts.
  • These ducts converge into the common hepatic duct.
  • Bile can be stored in the gall bladder.
37
Q

What surrounds hepatic laminae?

A

hepatic sinusoids, which are very permeable blood capillaries.

37
Q

What are the key components of bile?

A

Bilirubin and Bile salts

37
Q

What is Bilirubin?

A

Main bile pigment derived from haem

37
Q

Does carbohydrates maintain blood glucose concentration?

A

Yes

38
Q

What are bile salts?

A
  • Salts of bile acids
  • responsible for emulsifying lipids.
  • Breaking them down and suspending them
  • Also aid absorption via formation of micelles.
  • Micelles allow for more efficient lipase action.
38
Q

What does carbohydrates do in liver metabolism?

A
  • Stores glucose molecules such as glycogen.
  • driven by insulin
  • breaks down glycogen to glucose.
  • driven by glucagon.
  • Conversion of some amino acids and lactic acid to glucose.
  • Converts fructose and galactose to glucose.
39
Q

What is the liver’s metabolic role in regards to lipids?

A
  • Triglycerides
  • Excess energy store and use as fuel source for ATP production.
  • Converts excess carbohydrate and protein to triglycerides.
  • Synthesises cholesterol and phospholipids.
  • Produces lipoproteins for transportation of triglycerides and cholesterol to other cells.
  • VLDL
  • LDL
  • Nascent HDL protein
39
Q

What is the liver’s metabolic role in regards to protein

A
  • Deamination of amino acids
  • Removal of amino groups (NH2)
  • Transamination of amino groups.
  • Synthesis of non-essential amino acids.
  • Conversion of ammonia (NH3) to urea.
  • Synthesis of most plasma proteins.
  • Albumin
  • Alpha and Beta Globulins
  • Prothrombin
  • Fibrinogen.
40
Q

Internal toxins

A
41
Q

External toxins

A
42
Q

How many phases are there in liver detoxification?

A

2

43
Q

What does Phase I of liver detoxification do?

A
  • Driven by specific enzymes
  • Involves oxidation, peroxidation and reduction.
  • Process produces less harmful substances.
44
Q

What does Phase II of liver detoxification do?

A
  • Converts phase I metabolites into a water-soluble form.
  • Involves powerful antioxidants such as glutathione.
  • Allows excretion in urine.
45
Q

What does the liver store?

A
  • Glycogen
  • Vitamins A, B12, D, E and K
  • Minerals including iron and copper.
46
Q

How is Vitamin D activated by the liver?

A
  • Converts inert vitamin D from sun exposure, foods or supplements to calcidiol.
  • This is then processed by the kidneys to form the active form of Vitamin D - calcitriol.
46
Q

What is the absorptive state?

A
  • Recently digested and absorbed nutrients are available
  • Including glucose for ATP Production
47
Q

What is the postabsorptive state?

A
  • No New nutrients are available
  • Metabolic needs of the cells must be met by mobilising nutrients stored in the body.
48
Q

How long do we spend in each metabolic state?

A

~ 12

49
Q

What are the main characteristics of absorptive state?

A
  • Nutrients from the GI tract enrich the blood.
  • Glucose and amino acids transported to the liver via the hepatic portal vein.
  • Most absorbed lipids encased in chylomicrons
  • Absorbed into lacteals
  • Transferred to blood via thoracic ducts.
  • Arrive at the liver via hepatic artery.
  • Nutrients can be used immediately or stored.
50
Q

How is Glucose metabolised in the absorptive state?

A
  • 50% is oxidised and used for ATP production via glycolysis, Kreb’s cycle and electron transport chain.
  • 40% converted to triglycerides and stored mainly in adipocytes.
  • 10% converted to glycogen in liver and skeletal muscle.
50
Q

When does the absorptive state happen?

A

up to ~ 4 hours after a meal.

51
Q

How are lipids metabolised in the absorptive state?

A
  • Most triglycerides and fatty acids are stored in adipocytes.
  • Lipids are delivered to adipocytes by:
  • Chylomicrons from the digestive system.
  • VLDL from the liver.
  • Adipocytes also synthesises triglycerides from excess glucose.
52
Q

How is glucose produced in post-absorptive state?

A
  • Glycogen is catabolised into free glucose molecules.
  • Triglycerides are broken down to permit the conversion of glycerol to glucose.
  • Gluconeogenesis
  • Lactic acid produced during glycolysis can be converted to glucose in the liver.
  • Amino acids can be used for glucose production by the liver.
52
Q

How are proteins metabolised in the absorptive state?

A
  • Amino acids absorbed for the manufacture of proteins.
  • Deaminated by the liver to produce keto acids.
  • Keto acids can either:
  • Enter the Kreb’s Cycle for ATP Production
    *Used to make glucose or fatty acids.
53
Q

How is the absorptive state regulated?

A
  • Insulin secretion increases after a meal.
  • Driven by glucose-dependent insulinotropic peptide (GIP) and rising blood glucose.
  • Insulin has many metabolic effects, promoting:
  • GluT 4 production and entry of glucose in skeletal muscle and adipocytes.
  • Anabolism of glucose to glycogen.
  • Formation of triglycerides in adipocytes and liver.
  • Amino acid absorption and protein synthesis.
    > Also requires thyroid hormones and insulin-like growth factor (IGF).
54
Q

What are the post-absorptive state processes for glucose sparing?

A
  • Fatty acid oxidation for ATP production
  • Oxidation of lactic acid by cardiac muscle
  • Oxidation of amino acids by the liver to produce ATP
  • Oxidation of ketone bodies for ATP production.
55
Q

What does cortisol stimulate in the post-absorptive state?

A
  • Promotes gluconeogenesis
  • stimulates protein catabolism and lipolysis for use as fuel for ATP production.
56
Q

What does glucagon stimulate in the post-absorptive state?

A

Glycogenolysis and gluconeogenesis.

57
Q

What does epinephrine and norepinephrine stimulate in the post-absorptive state?

A
58
Q

What is fasting?

A
59
Q

What is Starvation?

A
60
Q

How long can humans survive without food? and how?

A
61
Q
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62
Q
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63
Q
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63
Q
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64
Q
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64
Q
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65
Q
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66
Q
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67
Q
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68
Q
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69
Q
A