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Week 12 - Nutrition & Metabolism

Terms in this set (36)

Fibre = animal or plant carbohydrate that resists digestion
24 g/day
Excess fibre interferes with mineral absorption - iron, calcium
Effects of fibre:
Absorbs water into the intestines
Softens stool
Provides bulk so speeds up transit time
Lipid transport
Non-soluble in water
Transported in the blood as lipoprotein droplets:
Core = cholesterol & triglycerides
Outer coating = protein & phospholipids
Lipoproteins transport
Chylomicrons - protein coated lipid droplets
Very-low density lipoproteins (VLDLs)
Low density lipoproteins (LDLs)
High density lipoproteins (HDLs) - good
Density = protein:fat so HDLs have more protein and less fat
Chylomicrons transport triglycerides and cholesterol from....
The small intestine to the liver (and adipocytes)
Via the lymphatic vessels
VLDLs transport triglycerides and cholesterol from....
The liver to adipocytes
Triglycerides are stored in the adipocytes (fat cells)
LDLs transport cholesterol to tissues (blood vessels)
HDLs are empty shells that are made up in the liver
They are transported to the tissues (blood vessels)
HDLs remove cholesterol and return it to the liver for elimination
Metabolism
The combination of chemical & physical reactions through which an organism builds up or breaks down materials for growth and healthy functioning
Anabolism
Constructive metabolism; the process of building up larger molecules from smaller ones
Glucose into glycogen or triglycerides for storage
Catabolism
larger molecules are broken down into smaller ones; releases energy
Glucose is used to form ATP by glycolysis or TCA (Krebs) Cycle
1 kcal = 1000 calories = 4.184 kJ
Amount of heat required to heat 1 litre of water by 1°C
Metabolic rate
Amount of energy released from a cell per unit time
Hormone thyroxine increases metabolic rate
Basal metabolic rate
Energy release required to support vital organs at rest
Glycolysis in the cytoplasm - no oxygen required
Yield = 2 ATP
2 Pyruvic acid
In the absence of oxygen - pyruvic acid is converted into lactic acid
In the presence of oxygen, pyruvic acid passes into the mitochondrion to enter the TCA cycle and the electron transport chain
Yield = 36 ATP
So total = 38
Protein metabolism
Anabolism: amino acids make new proteins

Catabolism: amino acids enter TCA cycle; NH2 removed (deaminated); becomes ammonia NH3 which is toxic so converted into urea by the liver and excreted in the urine

Excess dietary amino acids are not excreted but converted into glucose (gluconeogenesis) or triglycerides (lipogenesis)
Lipid metabolism
Anabolism: three fatty acids + glucose = triglyceride = amino acid + glucose (lipogenesis)

Catabolism: lipolysis = fat breakdown for fuel
Glycerol >> glycolysis
Fatty acids >> acetyl-CoA >> TCA cycle
Normal blood plasma glucose = 3.5 - 8.0 mmol/L (mM)
Fasting = 3.5 - 5.5 mmol/L (mM)
^ Pre diabetes = 4 mmol/L
During absorptive state (up to 4 hours)
Blood glucose is high
Insulin secreted by the beta cells of the pancreas:
Stimulates glycogenesis
Stimulates protein and fat synthesis
Increases entry of glucose into cells = increases amount of carrier proteins for facilitated diffusion
Inhibits gluconeogenesis
During post absorptive state (less than 4 hours)
Glucagon is secreted by pancreatic alpha cells:
Stimulates glycogenolysis, gluconeogenesis and lipolysis
Adrenaline is released by the SNS and adrenal medulla:
Stimulates glycogenolysis and lipolysis
Glucocorticoids (cortisol & cortisone) is released from the adrenal cortex:
Stimulates gluconeogenesis
If glucose is not used, amino acids are used more
This causes a saturation of acetyl co-enzyme A
Leads to the formation of ketones
Breath and urine smells like pear-drops
Diabetes
Type I = not enough insulin
Type II = cells do not respond to insulin
Causes: stress; diet; genetic
Gestational diabetes (pregnancy): renal threshold for glucose falls secondary to an increase in GFR
Tests for diabetes
Urinalysis - glycosuria = excess sugar in the urine
Oral glucose tolerance test:
Fast overnight; measure before & after 75g of glucose
Fasting > 7 mM/L
2 hrs > 12 mM/L
Glycated haemoglobin HbA1C
Diabetic Retinopathy (proliferative)
Development of new vessels as a result of anoxic stimulation, vessels grow out of the retina toward the vitreous humour
High blood sugar levels damage blood vessels in the retina
Aneurysms develop in the blood vessels = bleed slightly but do not affect vision background retinopathy
More severe and widespread changes affect the blood vessels = more bleeding
New scar tissue & new blood vessels are weak, bleed easily = loss of vision
^proliferative retinopathy
Glutamine
Amino acid that is a precursor for neurotransmitter glutamate
Glutamate
A major excitatory neurotransmitter; involved in memory
Gluconeogenesis
Formation of glucose from non-carbohydrate sources
Glycogen
Storage form of glucose in the liver
Glucagon
A protein hormone secreted by pancreatic endocrine cells that raises blood glucose levels; an antagonistic hormone to insulin.
Glycogenolysis
Breakdown of glycogen to glucose
Insulin
A protein hormone secreted by the pancreas that is essential for the metabolism of carbohydrates and the regulation of glucose levels in the blood
Glucose
The form of sugar that circulates in the blood and provides the major source of energy for body tissues. When its level is low, we feel hunger.
Glucocorticoids
Raises blood sugar levels (adrenal cortex)
Promotes glycogen deposition and has anti-inflammatory effects
Glycolysis
The breakdown of glucose by enzymes, releasing energy and pyruvic acid.
Hormones secreted from the adrenal cortex = steroids
Glucocorticoids - cortisol
Mineralocorticoids - aldosterone, which causes sodium retention and potassium excretion by the kidney
Hormones secreted by the adrenal medulla are amines
Epinephrine
Norepinephrine
THIS SET IS OFTEN IN FOLDERS WITH...