Metabolism Flashcards
1
Q
How long is the pancreas
A
~ 12 - 15 cm long.
2
Q
Where does the pancreas sit?
A
Below and behind the stomach.
3
Q
What are the three regions of the pancreas?
A
Head, body and tail.
4
Q
Is the largest section of the pancreas, near the duodenum
A
Head
5
Q
Is the central section of the pancreas
A
Body
6
Q
Is the tapered section of the pancreas
A
Tail
7
Q
How is the pancreas connected to the duodenum?
A
Via two ducts, the main pancreatic duct and the Accessory duct.
8
Q
What type of cells does the pancreas have clusters of?
A
Glandular epithelial cells.
9
Q
Makes up 99% of the glandular epithelial cell clusters
A
Acini/
10
Q
What do the cells within acini do?
A
Produce and secrete the components of pancreatic juice.
11
Q
acini secrete
A
12
Q
cells secrete
A
13
Q
How much pancreatic juice is produced each day?
A
1 - 1.5 litres
14
Q
What is the pH of pancreatic juice?
A
between 7.1 and 8.2
15
Q
Where does pancreatic juice flow?
A
16
Q
Where does pancreatic juice drain?
A
17
Q
How is digestive enzyme secretion activated?
A
By cholecystokinin (CCK)
18
Q
What activates bicarbonate secretion?
A
Secretin
19
Q
What are the enzymes of pancreatic juice for protein digestion?
A
Trypsin, chymotrypsin, carboxypeptidase, elastase.
20
Q
What are the enzymes of pancreatic juice for carbohydrate digestion?
A
Pancreatic amylase.
21
Q
What are the enzymes of pancreatic juice for lipid digestion?
A
Pancreatic lipase and phospholipase.
22
Q
What are the enzymes of pancreatic juice for nucleic acid digestion?
A
Ribonuclease and deoxyribonuclease.
23
Q
What are the two main secretory cells?
A
Alpha islet cells (17%)
Beta islet cells (70%)
Delta cells (7%)
F cells (6%)
24
Q
What do alpha islet cells secrete?
A
Glucagon
25
What do beta islet cells secrete?
Insulin
26
What do delta cells secrete?
Somatostatin, which inhibits the secretion of both glucagon and insulin.
27
What do F cells secrete?
Pancreatic Peptide, which inhibits somatostatin
28
What does glucagon do?
- 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.
29
What does insulin do?
- 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.
30
What is the largest gland in the human body?
The liver
31
What is the second largest organ?
The liver, only second to the skin.
31
What is the liver composed of?
Hepatocytes, Bile Canaliculi, Hepatic sinusoids, Stellate reticuloendothelial cells.
* Hepatic macrophages that phagocytise ageing red and white blood cells and bacteria.
31
How much does the liver weigh?
1.4 g
32
What is Bile Canliculi?
Network of ducts between laminae.
33
What is the main cell of the liver?
Hepatocytes (80%)
34
What tasks do hepatocytes do?
Metabolic, secretory and endocrine.
35
What is hepatic laminae?
Forms. 3D layers
36
What do Bile Canaliculi do?
- 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
What surrounds hepatic laminae?
hepatic sinusoids, which are very permeable blood capillaries.
37
What are the key components of bile?
Bilirubin and Bile salts
37
What is Bilirubin?
Main bile pigment derived from haem
37
Does carbohydrates maintain blood glucose concentration?
Yes
38
What are bile salts?
- 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
What does carbohydrates do in liver metabolism?
- 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
What is the liver's metabolic role in regards to lipids?
- 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
What is the liver's metabolic role in regards to protein
- 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
Internal toxins
41
External toxins
42
How many phases are there in liver detoxification?
2
43
What does Phase I of liver detoxification do?
- Driven by specific enzymes
- Involves oxidation, peroxidation and reduction.
- Process produces less harmful substances.
44
What does Phase II of liver detoxification do?
- Converts phase I metabolites into a water-soluble form.
- Involves powerful antioxidants such as glutathione.
- Allows excretion in urine.
45
What does the liver store?
- Glycogen
- Vitamins A, B12, D, E and K
- Minerals including iron and copper.
46
How is Vitamin D activated by the liver?
- 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
What is the absorptive state?
- Recently digested and absorbed nutrients are available
- Including glucose for ATP Production
47
What is the postabsorptive state?
- No New nutrients are available
- Metabolic needs of the cells must be met by mobilising nutrients stored in the body.
48
How long do we spend in each metabolic state?
~ 12
49
What are the main characteristics of absorptive state?
- 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
How is Glucose metabolised in the absorptive state?
- 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
When does the absorptive state happen?
up to ~ 4 hours after a meal.
51
How are lipids metabolised in the absorptive state?
- 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
How is glucose produced in post-absorptive state?
- 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
How are proteins metabolised in the absorptive state?
- 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
How is the absorptive state regulated?
- 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
What are the post-absorptive state processes for glucose sparing?
- 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
What does cortisol stimulate in the post-absorptive state?
- Promotes gluconeogenesis
- stimulates protein catabolism and lipolysis for use as fuel for ATP production.
56
What does glucagon stimulate in the post-absorptive state?
Glycogenolysis and gluconeogenesis.
57
What does epinephrine and norepinephrine stimulate in the post-absorptive state?
-
-
58
What is fasting?
59
What is Starvation?
60
How long can humans survive without food? and how?
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