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ENI 2 > intro to metabolism > Flashcards

intro to metabolism Flashcards

1
Q

post prandial means

A

the time right after a meal
- influx of energy, storage nutrients and growth

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2
Q

what is inter-prandial

A

fasting stage between meals
storage is used for energy and growth

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3
Q

what is digestion

A

the process in the alimentary canal by which food is broken up physically as by the action of the teeth and chemically as by the action of enzymes and converted into a substance suitable for absorption and assimilation into the body
- the co-ordinated process that extracts nutrients out of food and makes them availible for absorption inside the gut into the blood stream and lymphatic circulation

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4
Q

discuss the pathway of digestion and absorption from the stomach to the blood stream

A
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5
Q

what are the macronutrient groups

A
  • carbohydrate
  • protein
  • fat (lipid)
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6
Q

what are carbohydrates

A
  • chains made of single units called monosaccharides
  • contain carbon, hydrogen and oxygen
  • each monossacharide has a ring structure made up from C6H12O6
  • monosaccharides are joined together to form carbohydrates or polysaccharaides
  • the products of carbohydrate digestion are glucose, fructose and galactose
  • these are small enough to pass through capillaries (and therefore hepatic portal vein
  • used for producing energy
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7
Q

name the products of carbohydrate digestion

A
  • glucose
  • fructose
  • galactose
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8
Q

name the carbohydrases and where they are found

A
  • amylase (intestinal juices)
  • maltase (ij)
  • sucrase (ij)
  • lactase (ij)
  • amylase (pancreatic secretion)
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9
Q

fructose and glucose are converted to what substance in the liver

A

glucose

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10
Q

in the liver, excess glucose is converted into:

A

glycogen
- liver glycogen acts as a storage which can be used to top up circulating glucose levels when needed
- the liver has a limited capacity to store glycogen

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11
Q

how is glucose supply controlled

A
  • the liver is responsible for regulating blood glucose supply
  • two hormones, insulin and glucagon jointly regulate the storage and recycling of blood sugar
  • insulin/glucagon produced in the islets of langerhan cels
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12
Q

where are insulin and glucagon produced

A

islets of langerhans in the pancreas
- beta cells secrete insulin
- alpha cells secrete glucagon
- gamma cells secrete somatostatin (prevents big swings in bs)

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13
Q

describe 2 non-carbohydrate enrgy substrates and how they are used for energy

A

during exercise, muscle glycogen is broken down to lactate
- lactate enters the blood stream and back to the liver where it becomes a substrate glucose production

during fasting, fat is broken down
- this releases free fatty acids and glycerol which circulate back to the liver
- glycerol is also used to make more glucose by gluconeogenesis

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14
Q

what are proteins

A
  • large molecules which cant be absorbed without being broken down
  • made from monomers called amino acids
  • amino acids are joined in long chains by peptide bonds to make proteins
  • different proteins are created by the number and combination of amino acids in the chain
  • around 10 amino acids are essential and can only be obtained by diet (not manufactured in the body
  • essential in the diet for growth and maintenance of body tissues (can also be used for energy but less efficient than fat or carbs)
  • amino acids are absorbed into the intestinal capillaries and transported to the liver via the hepatic portal vein
  • most amino acids enter the systemic circulation via the caudal vena cava nualtered
  • in the cells amino acids are synthesised int different proteins for intracellular function
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15
Q

what hormone stimulates the secretion of proteases

A

gastrin

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16
Q

name proteases

A
  • hydrochloric acid (stomach)
  • pepsinogen/pepsin (stomach)
  • trypsin (pancreas)
  • chymotrypsin (pancreas)
  • elastase (pancreas)
  • carboxypeptidase (pancrease)
  • aminopeptidase (small intestine)
17
Q

explain the fate of protein

A
  • excess amino acids are disposed of cia deamination
  • deamination releases ammonia which is highly toxic, this is immediately converted to urea by the liver and excreted by kidneys
  • as glycogen levels deplete, skeletal muscle protein is broken down as a substrate for gluconeogenesis
  • amino acids are deaminated to yield ammonium and a carbon skeleton
  • after deamination, amino acids can enter energy production pathways
18
Q

what are lipids

A
  • fats made up form small units called triglycerides
  • comprise carbon, hydrogen, oxygen in a long chain structure
  • each triglyceride/triglycerol (TAG) is made from a molecule of glycerol and 3 fatty acid chains
  • the fatty acid chains give the fat its properties (saturated vs unsaturated)
  • saturated fatty acids have less uses as they have fewer double bonds in their structure which makes them less reactive
  • triglycerides are too large to be absorbed and must be broken down by digestion into monoglycerides and then into glycerol and free fatty acids
  • first, bile salts emulsify the lipif to then by hydrolysed by enzymes into monoglycerides which are dissolved into micelles
  • micells freely enter the intestinal cells where triglycerides are re-synthesised from glycerol and three fatty acids, together with cholesterol and packaged into lipoproteins particles call chylomicrons
  • chylomicrons are carried by lacteals into the lymphatic system and then into the bloodstream to be stored in adipose tissue without first going to the liver
  • some chylomicrons will circulate back to the liver where that are stored, converted to other molecules or used as an energy substrate
  • fatty acids are stored primarily in adipocytes as triglycerol
19
Q

under what circumstance will fat be stored in the liver

A

when there is an overwhelming influx

20
Q

fatty acids are stored primarily as:

A

in adipocytes as triacylglycerol (adipocytes found mostly in the abdominal cavity and subcutaneous tissue)

21
Q

how are lipids used as an energy source

A
  • in the absence of glucose, fat is broken down into TAG which circulates to the liver to be used as a source of energy (ketone bodies then produced as bi product from liver)
  • ketones are also a source of energy but may accumulate in the blood and pass into the urine
  • ## if very high concentrations of ketons formed ketosis occurs
22
Q

list lipases

A
  • lingual lipase
  • gastric lipase
  • pancreatic lipase
  • co-lipase
23
Q

name metabolic lipase enzymes and how they work

A

hormone sensitive lipase
- hydrolyses either fatty acid from a triacylglycerol molecule, freeing a fatty acid and diglyceride OR a fatty acid from a diacylglycerol molecule freeing a fatty acid and monoglyceride
- mechanism of release of lipid from storage

lipoprotein lipase
- degrades circulating triglycerides in the bloodstream to be taken up by tissues

24
Q

explain how metabolism is controlled

A
  • metabolic rate (rate at which living organisms expend energy or convert energy into food)
  • the thyroid under hypothalamus and pituitary influence regulates basal metabolic rate
25
Q

explain hoe the thyroid regulates basal metabolic rate

A
  • speeding up metabolism and development
  • increasing metabolic use of energy
  • increasing digestion rate in the intestine
  • down regulating insulin receptors
  • increasing glycogenolysis ad gluconeogenesis
26
Q

carbohydrates are absorbed as

A

monosaccharides

27
Q

carbohydrates are stored as what? where?

A

glycogen in the liver, muscle or adipose tissue

28
Q

what is the name for the process of building the storage form of carbohydrates

A

glycogenesis
process of creating glycogen from glucose (carbohydrate)

29
Q

how are carbohydrates used in the interprandial period

A

glycogen converted back to glucose for energy (facilitated by insulin)

30
Q

what is the name for the process of releasing carbohydrates from sotrage form

A

glycolysis

31
Q

proteins are absorbed as what

A

amino acids

32
Q

proteins are stored as what? where?

A

not really stored. they are either used by cells or deaminated
after deamination, enter energy pathways as pyruvate, acetyl CoA, or components of TCA cycle or converted to fat

33
Q

what is the name for the process of building the storage form of proteins

A

deamination

34
Q

lipids are absorbed as what

A

small subunits of lipids are call triglycerides
- triglycerides are too large to be absorbed and must be broken fown by digestion into monoglycerides and then into glycerol and free fatty acids

35
Q

lipids are stored as what? where

A

chylomicrons (re-synthesised triglycerides, packaged with cholesterol)
stored in adipose tissues (skips liver) or liver (but only when overwhelming influx)

36
Q

what is the name for the process of building the storage form of lipids

A

lipogenesis

37
Q

what is the name for the process of releasing lipids from storage

A

lipolysis

ENI 2 (83 decks)

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