GIM 1 Flashcards
What is nutrient flux?
The measure of activity of a metabolic pathway
What are the 3 metabolic pools?
Functional pool - direct involvement in body function
Storage pool - provides buffer
Precursor pool - provides substrate for nutrient synthesis
What is glycemic index?
The ranking of CHOs in food and how they affect blood glucose level (pure glucose GI = 100)
What the the recommendations for CHO intake?
~50% of dietary energy
Free sugar intake < 5% of calorie intake
What are the anaemia preventing vitamins?
B12 (animal products) and folate (green veg)
What are the sources of vitamin D?
D3 = fish oil, egg yolk, butter
7-dehydrocholesterol = animal fats, plant sterols, UV light
What is the physiologically active form of vitamin D?
Calcitriol (vit. D metabolised by liver and kidney hydroxylation)
What are the actions of vitamin D?
Intestinal and renal absorption of Ca and PO4
Normal bone formation
Neuromuscular and immune functions
What is caused by vitamin D deficiency?
Rickets (children)
Osteomalacia (adults)
What is the toxicity of vitamin D?
> 250micrograms/day
Leads to hypercalcaemia and calcification of soft tissues
What is the use of calcium?
Bones, cell signalling and muscle function
What are the sources of calcium?
Milk and dairy, flour, hard water
What is calbindin?
Intestinal Ca binding protein for Ca absorption (regulated by vit. D)
What is the metabolic response to low plasma Ca
Parathyroid hormone and vitamin D synthesis.
Vitamin D activated to calcitriol
Increased Ca absorption
What is the metabolic response to high plasma Ca
Calcitronin secreted from thyroid gland
Increased Ca excretion and prevention of Ca release from bones
What is the purpose of iron?
Hb and electron transport
Where is iron stored?
Reticulo-endothelial system and bone marrow
What is transferrin?
A plasma transport protein that transfers iron to bone marrow
In what form is iron absorbed?
Fe2+ (absorption enhanced by reducing agents)
What are some examples of positive energy balance?
Obesity, growth, pregnancy, recovery
What are some examples of negative energy balance?
Wasting disease, anorexia, starvation, voluntary weight loss
What processes are involved in basal metabolic rate (BMR)
Heart and resp.
Protein turnover
Fat and CHO turnover
Ion gradient maintenance
What is physical activity level (PAL)
Ratio of energy expenditure to BMR
How do we assess nutritional status?
Anthropometry (height, weight, BMI) Body composition Biochemistry and haematology Function Dietary assessment
What are the causes of undernutrition?
Increased nutrient demand
Reduced nutrient delivery to GI system
Inability for GI system to absorb nutrients
What are the effects of undernutrition?
Decreased insulin Increased amino acid release (proteolysis) Ketone bodies supply brain Gluconeogenesis Eventual protein and tissue breakdown Fatty acids as energy source
What are the different types of undernutrition?
Primary - diet related
Secondary - illness related
Specific - nutrient deficiency
Generalised - calorie deficiency
What are the 2 types of protein-energy malnutrition (PEM)
Dry PEM - Marasmus (no oedema)
> severe calorie and protein deficiency
Wet PEM - Kwashiorkor (oedema)
> severe protein deficiency
> link to low [plasma albumin]
What is refeeding syndrome?
A syndrome of metabolic disturbances resulting from re-nutrition to patients who are starved or severely undernourished
Patient re-nourished
Insulin increases and glucose moves into cells
Electrolytes (especially phosphate) move into cells for metabolism
Hypophastaemia results
What is enteral nutrition support?
Small bowel feeding with pump administration. Results when patients are undernourished for 7 days
What is parenteral nutrition support?
Administration of nutrients through central or peripheral vein. Used when GI tract not functional or accessible.
What are the dietary risk factors of obesity?
Fat overconsumption
Excessive sugar intake
Alcohol - decreases fat oxidation and storage
What is the main focus for obesity treatment/management?
Lifestyle modification
Limited drug therapies and bariatric surgery only used for severe obesity with co-morbidities
For a patient with hypertension, what diet should they be put on?
DASH diet
What are the benefits of a DASH diet?
High fruit and veg (lots of K+ reduces BP)
Reduced Na+ reduces BP
Evidence that diets high in Na+ and low in K+ result in hypertension
What are the dietary benefits of non-starch polysaccharides?
Decrease LDL-C
Bind bile salts and prevent reuptake
High fibre - lower risk of CVD
What are the functions of bile?
Digestion of fats and fat soluble vitamins
Secretion of waste products such as bilirubin
How is bile made/secreted?
Secreted into canaliculi by hepatocytes
Modified by ductal epithelial cell secretions in bile ducts
Further modification in gallbladder (stored there in fasting state)
What is the relationship between bile and cholesterol?
Cholesterol is synthesised in hepatocytes to make bile acids (cholate and chenodeoxycholate)
Cholesterol in diet is converted to bile acids
How does bile aid lipolysis?
Bile salts emulsify lipids and break them down into little droplets - larger SA for easier digestion
How does enterohepatic recirculation of bile work?
Venous blood travels from ileum to the liver through portal vein
Hepatocytes extract bile acids from sinusoidal blood
Re-secretion into canaliculi
How do fish oils decease CVS risk?
Eicosapentaeonic acid (EPA) competes with arachidonic acid and reduces COX- to TXA3 instead of COX to TXA2. TXA3 has less platelet activating activity. Decreased risk of thrombosis by inhibited platelet aggregation
