Effects of Nutrition Flashcards
what percentage of your diet should these major nutrients make up:
- CHO
- FAT
- PRO
CHO: 45-65%
FAT: 20%
PRO: 10-15%
why does muslce mass remain constant in healthy weight bearing humans that feed normally?
this is because of the dynamic equilibrium in protein turnover, as MPB is greater than MPS when fasted, but MPS is greater than MPB when fed, so everything balances out.
what 2 macronutrients stimulate insulin secretion
CHO and PRO
is exercise anabolic or catabolic?
it is BOTH. It is more catabolic than anabolic though
what amino acid can inhibit catabolism via the insulin pathway?
Leucine
what amino acid has a unique anabolic signalling capability to drive Muscle protein synthesis and what does it act as to do this?
Leucine
- to do this it can act as a substrate
what are 3 internal structures are glucose-dependent in the body during a fed (postprandial) state?
- brain
- blood cells
- renal medulla
what percentage of available glucose does the brain use
50%
what are 3 examples of preferential users of glucose during the postprandial state (they want to use glucose but if they can’t isnt detrimental to function)
- heart
- renal cortex
- white skeletal muscle (type II muscle fibres)
what does the redness of a muscle fibre indicate and what type of fibres are red and what type of fibres are more white in colour?
how glycolitic the muscle fibre is
Red: type I
white: type II
name 2 examples of internal structures that use fatty acids as a fuel source in the postprandial state
- liver
- red skeletal muscle
when are protein used as a fuel source?
if there is excessive intake of it
what is the main functions of:
- glucose
- Amino acids (protein)
in the postprandial state
glucose:
- converted to glycogen to be stored for later use
- used for triglyceride synthesis
Amino Acids:
- protein synthesis in skeletal muscle mainly
what are 5 consequences of protein calorie malnutrition?
- poor wound healing
- higher rate of infections
- greater length of stay at the hospital
- greater costs at hospital
- increased morbidity and mortality
Define Fasted state
- exculsion of all food energy
define starvation
Prolonged inadequate intake of protein and/or energy
define cachexia
muscle wasting induced by metabolic stress
when does the fed state end and what happens in terms of hormones when it ends
- when the last nutrient is absorbed
- when fed state ends, there is decrease level of insulin and increase in glucagon
what are 3 endogenous fuel sources that are used when the fasted/postabsorptive state starts?
- release, transfer and oxidation of fatty acids
- release of glucose from liver glycogen
- release of amino acids in proteins from muscle as a source of fuel
how long does the post-absorptive state last?
12 hours
in the post-absorptive/fasted state what are the 3 sources of energy used and how long before they are all used up?
- short term reserves to maintain blood glucose levels for glucose dependent tissues
- release and oxidation of fatty acids from adipose tissue/ectopic stores
- release of glucose from liver glycogen
these are all used up within 24 hours
what is the liver glycogen capacity in kcal and what is this equivalent to in grams of CHO/glucose
- 1000 kcal
- equivalent to 250g of Carbohydrates/glucose
state 4 things that happen when you fast for longer than 24 hours
think insulin and glucagon, amino acids and proteins usage, lipases, glucose production
- further decrease in insulin and increase in glucagon
- proteolysis and release of amino acids from muscle as a source of fuel
- activation of hormone sensitive lipase to increase lipolysis and circulating FFA and TG
- increase in gluconeogenesis
where does the cori cycle occur?
in the skeletal muscle and the liver
gluconeogenesis
outline how gluconeogenesis occurs through the cori cycle
- glucose is converted in skeletal muscle to lactate
- this pyruvate/lactate travels back to the liver for conversion back into glucose
is the Cori cycle anaerobic or aerobic mostly?
- mostly anaerobic
outline 5 steps of how gluconeogenesis occurs in the Gluose-alanine (Cahill) cycle
- Glucose (from glycogen/GNG) in skeletal muscle is broken down to pyruvate
- pyruvate is transaminated to produce alanine
- alanine returns to the liver via absorption through hepatocytes for deamination, where pyruvate and NH2 is produced
- after demination in the liver, NH2 is used in urea for excretion
- pyruvate in the liver is converted to glucose via gluconeogenesis, ready to be transfered and used in the muscle again
where does the cahill cycle occur?
in the skeletal muscle and liver
where doe the glutamine cycle happen
in the kidneys
outline the 3 steps of the glutamine cycle for gluconeogenesis
- muscle glutamine goes to kidney
- glutamine is converted to glutamate + excess ammonia (NH3)
- this is then converted to a-ketoglutarate and is sent through the Krebs/TCA cycle to be converted back into glucose to create more glucose
what process occurs if you fast for longer than 2-3 days?
ketosis
what characterises ketosis and what molecule causes smelly breath that is found in people on a keto diet?
- characterized by presence of ketone bodies
- acetone causes the smelly breath
what are ketone bodies and what can they be used for?
- ketone bodies are bi-products of fatty acid oxidation in the liver
- can be used by all tissues with mitochondria to allow for energy release
when is there significant muscle protein loss during the fasted state?
in the first 7-10 days
how much protein is lost in urination when someone is in the fasted state for 7-10 days and what is this equivalent to in Lean body mass (LBM) per day intially and over first 7 day period
urinary loss:
- 10-12 g urinary Nitrogen/day
- 360g LBM per day initally
- 1-2kg LBM over first 7 days
what happens if you consume more protein that needed?
- oxidation of the excess amino acids and then excretion out the body
- used to make new glucose and fatty storage
