lecture 3: nutrition Flashcards
why do we need food
chemicals for energy and components to build biomass
what types of molecules does food give us
organic and inorganic
why is food required
maintain favourable internal conditions
like growth, physiological processes, reproduction, regulation, maintenance and repair
describe inorganic molecules
minerals –> bones, enzymes, cofactors etc
describe organic molecules
vitamins –> coenzymes etc
carbs, fats, proteins –> energy for work (ATP), carbon and nitrogen skeletons for biosynthesis
what happens to organic fuel molecules
oxidized to produce ATP
cellular respiration is stepwise oxidation of carbs, fats and proteins
what things are oxidized for energy before proteins
carbs and fats
kcal conversions for carbs, fats and proteins
1g carbs = 4kcal
1g fat = 9kcal
1g protein = 4kcal
what are proteins broken down into
amino acids which are mainly used for biosynthesis
what is metabolic rate
amount of energy an animal uses in a unit of time (sum of all the energy that requires biochemical reactions occurring over a time)
measured in cals or kcals
what is BMR
basic metabolic rate - metabolic rate of a non growing endotherm at rest on an empty stomach and absence of stress
BMR adult male and female
male = 1600-1800kcal/day
female = 1300-1500kcal/day
what will increase metabolic rate above BMR
any activity that is not a basic physiological process to keep us alive
name factors affecting metabolic rate (15)
physical activity
stress
mental activity
pregnancy
illness
hormones
lack of sleep
biological sex
age
genetics
temperature
weight
muscle mass
frequency of eating
type of food
when we take in more calories than are required for metabolic rate
excess fuel stored in body
name and describe the 2 locations of excess fuel storage in body
glycogen in liver and muscle - short term storage
fat in adipose tissue - long term storage, glucose will be converted into fat if glycogen stores are full
name and describe the 3 energy stores that can be used when needed
liver glycogen - used to maintain blood sugar levels
muscle glycogen - used to provide muscles with energy during exercise
fat - used when glycogen stores have depleted
what are essential nutrients
elements or molecules we must obtain from diet
cannot synthesize these
balanced diet includes all the essentials
name the 4 categories of essential nutrients and their quantities
essential amino acids (9)
vitamins (organic molecules, 13)
minerals (inorganic, 15)
essential fatty acids (2)
what 2 essential nutrients are required in very small amounts
vitamins and minerals
why are 9/20 amino acids essential in diet
body can synthesize other 11
name vitamins (essential nutrient)
ascorbic acid (vitamin c)
etc
name minerals (essential nutrient)
calcium, phosphorus (bones)
iron (hemoglobin, cytochromes)
sodium, potassium, chloride (electrolyte balance)
etc
name essential fatty acids (essential nutrient)
omega 3 and 6 (unsaturated)
skin, cardiac health, inflammation
describe undernourished
diet does not have enough calories
glycogen used –> fat used –> body will break down proteins for fuel –> lose muscle mass –> brain becomes protein deficient –> death
if you survive can lead to irreversible damage
describe overnourishment
excessive calorie intake (common in affluent nations)
once glycogen stores are full - excess fuel molecules stored as fat
leads to being overweight and obesity
describe malnourishment
diet missing one or more essential nutrient
more common than undernourishment
can you be overnourished and malnourished at the same time
YUHH
what is protein deficiency
most common type of malnutrition
occurs when diet does not include all of the essential amino acids
are animal products a complete source of proteins
yesss has 9 essential amino acids
describe an example of protein deficiency
kwashiorkor - poor food supplies
symptoms = distended abdomen, enlarged liver, loss of teeth, impaired mental and physical development, severe = death
describe hormones that regulate appetite (def)
hormones that act on the satiety center in the brain (hypothalamus) to regulate long term and short term appetite
name one reason it is difficult to lose weight (set point)
feedback mechanisms regulate body weight around a set point
name the 4 hormones that regulate appetite
leptin
PYY
insulin
ghrelin
describe leptin (source and effect)
source = adipose tissue
decreases appetite
increases energy expenditure
describe PYY (source and effect)
source = small intestine
decreases appetite
describe insulin (source and effect)
source = pancreas
decreases appetite
describe ghrelin (source and effect)
source = stomach wall
increases appetite
how would a decrease in body fat affect hormones that regulate appetite
affects leptin
leptin decreases - appetite increases and metabolism decreases
why is it difficult to lose weight (hormones)
adipose tissue decreases
leptin decreases
appetite increases
metabolism decreases
