EXAM 4 Flashcards
major nutrients
macronutrients: Carbohydrates, lipids, proteins
micronutrients
vitamins + minerals
USDA “my plate” guidelines
-1/2 fruits and vegetables
-1/2 grains and proteins
glass of milk
there are 45-50 essential nutrients
must be in diet for healthy physiology because body doesn’t make enough of it
carbohydrates include
-sugars: mono+disaccharides
—-from fruit, milk, and honey
-polyscaccharides: from grains, fruits, and veg
glucose is used by
-cells for energy
-red blood cells and neurons rely on it
insoluable polysaccharides
-such as cellulose provide fiber that help with intestinal health, defecation
-soluble fibers in some fruit
the most abundant dietary lipid is
-triglycerides: neutral fat
-saturated fat (with hydrogen) in meat+ dairy
-unsaturated: olive oils+seeds
essential fatty acids include
-e.g. linoleic+ linoleic acids are needed in the diet
–in most vegetable oils
cholesterol is found in
-egg yolk, milk, meat
-liver secretions
lipids are used by the body to
-cell membrane stability
-myelin in nervous system
-absorption of fat soluble vitamins
-can provide energy storage+ as an energy source in some conditions
-some chemical messengers: prostaglandins
-make adipose: cushioning and insulation
proteins have all essential amino acids are
-complete proteins : dairy, meat, fish, soybeans
-vs. incomplete proteins: lack four or more of 8 essential amino acids
incomplete proteins:
lack four or more of 8 essential amino acids
amino acids from dietary protein may be used to
-synthesize new proteins or be broken down to make energy
conditions that determine how amino acids are used determine
weather someone is positive in nitrogen balance or negative
to be positive in nitrogen balance (amino acids)
i) all needed amino acids (all 20 of them)
ii) caloric intake of carbs+fats meets energy needs
iii) hormone levels reflect healthy, non stressed states; healthy, low levels of stress hormones and healthy high levels of growth hormones
vitamins mostly serve as
coenzymes (assist in catalysis)
Vitamins A,D,E, and K are
exp for vit a
-fat soluble
-e.g. vitamin A in rhodopsin in rod’s for night vision
water soluble vitamins include
example of a ws vit
B-complex vitamins and vitamin C
folic acid- important for DNA replication in fetal development
water soluble vitamin functions
important in DNA replication
minerals such as Ca+ are used by the body to
-add strength to bones and teeth
-messengers to influence proteins’ function (eg Ca+ binds to calmodulin in smooth m)
-excitability: Ca+ depolarization of heart cells
metabolic processes are either
catabolic: breaking down big molecules
anabolic: building big molecules
catabolic processes
breaking down big molecules
anabolic
building big molecules
In cellular respiration…
food molecules are broken down and their parts are used to make atp
Three stages are involved in processing energy containing nutrients
a) GI system digest nutrients and absorbs them
b) convert small nutrient molecules to a form that can be used for energy production
c) aerobic production of energy in mitochondria
oxidation-reduction reactions are coupled reactions that involve
-transfer of electrons from one molecule to another
-when O added or H is lost it is oxidized
-a molecule that gains an electron is reduced
in the body, oxidation reduction reactions are enzyme catalyzed
-use coenzymes such as FAD and NAD+
-energy from food is transferred to the coenzyme so ATP can be made
ATP synthesis may occur through two mechanisms
-substrate-level phosphorylation
-oxidative phosphorylation
substrate-level phosphorylation
P transferred from one molecule over to ADP to make ATP
oxidative phosphorylation
uses, pushes
-uses electron transport chain in mitochondria
-pushes H+ into intermembrane space
-when H+ diffuses back in energizes the ATP synthase to make ATP
Carbohydrate Metabolism
- glucose enters the cell by….
-facilitated diffusion when insulin causes glucose transporters to go to membrane
Carbohydrate Metabolism
- glucose enters glycolysis
what is it and where does it occur
=sugar splitting, happens in cytosol, no O2 needed
3 phases
Glycolysis Phase 1
investment of 2 ATP to add phosphate groups to glucose
Glycolysis Phase 2
sugar cleavage: the 6-c sugar is split into three carbon fragments
glycolysis phase 3
-3 C fragments are oxidized
-ATP is formed (net of 2 ATP for glycolysis)
-NAD+ is reduced to NADH
two pyruvic acids molecules can follow ____ depending on ____
two distinct pathways depending on the availability of oxygen
pyruvic acid pathways when there is not enough oxygen
pyruvic acid ferments into lactic acid
pyruvic acid pathways when there is adequate oxygen
what (2 things) enters what to start what
pyruvic acid and NADH enter mitochondria to start aerobic cellular respiration
in aerobic pathways, pyruvic acid
enters mitochondria by active transport
pyruvic acid is first converted to
acetyl CoA: One carbon is removed from pyruvate and acetyl CoA is added
Acytyl CoA enters the Krebs Cycle (citric acid cycle)
within…
what combines
what is oxidized
-within mitochondrial matrix
-Acetyl acid combines with oxaloacetic acid to form citric acid
-citric acid is then oxidized
the krebs cycle yields (3)
2 ATP
NADH, FADH2 (reduced coenzymes)
CO2+H+
the electron transport chain
requires, pushes, then what
-requires O2 to take electrons from coenzymes (generates H2O)
-Pushes H+ out of matrix into inter membrane space
-as H+ flows back into matrix, oxidative phosphorylation occurs by ATP synthase
krebs cycle: the net energy gain from one glucose molecule is
30 ATP
cells cannot store large amounts of ATP, and so
they spend it or save its energy in other forms
glycogenesis
whats created
where and when
-creating glycogen from glucose
-occurs in liver and muscle cells when energy levels are high
glycogenolysis
what happens, when
-split glycogen to glucose:6P when energy is low; liver cells can remove the P and release glucose to blood
gluconeogenesis
uses what to make what and when
-use amino acids or glycerol to make glucose in liver when energy is low
energy content of fat molecules is
-very high
-most energy dense type of fuel 9cal/gram
lipolysis
-break down T.A.G. with lipase into glycerol and fatty acids
-followed b-oxidation: breaking off 2-c’s at a time of F.A.; add CoA and enter citric acid cycle
-ketone bodies can be a byproduct
Lipogenesis
-when energy levels are sufficient, energy can be stored as fat
-TAG is built up from smaller molecules
Protein metabolism; amino acids can be used
- to make new proteins
-when all neededamino acids are present
-allows ingested and synthesized a.a.’s to build new proteins
Protein metabolism; amino acids can be used
- for energy
when?
transamination
-when energy levels are low, when stress hormone levels are high, when certain a.a.’s are lacking
-change the amino acid…
–transamination: converts one amino acid into a keto acid
–that keto acid can be modified to enter the citric acid cycle to make ATP
–extra nitrogen can be excreted by kidney at urea
insulin is a key hormone for the…
absorptive state= well fed
during the absorptive state __ exceeds __
anabolism exceeds catabolism
insulins effect on glucose metabolism
-_ glucose uptake by body cells
-__ glucose oxidation in tissue cells
-__ gluconeogenesis
-__storage of glycogen and conversion of carbohydrates to fat
-increase glucose uptake by body cells
-increase glucose oxidation in tissue cells
-decrease gluconeogenesis
-increase storage of glycogen and conversion of carbohydrates to fat
insulins effect on amino acid metabolism
-increase transport of amino acids into cells
-increase protein synthesis
insulin contributes to feelings of
satiety
nuclei (clusters of cells) in the ___ are crucial for eating
hypothalamus
some cells make neurotransmitters or hormones that trigger hunger…
when fasting (i.e. in postabsorbative state)
NPy from arcuate nucleus –> increase orexin from lateral hypothalamic area
other cells make neurotransmitters or hormones that trigger satiety…
after a big meal
POMC+CART from arcute nucleis-> increase CRH from ventromedial nucleus
short-term regulation of food intake
what for hunger and what for satiety?
i) empty stomach secretes ghrelin: hormone that stimulates hunger pathways in brain
ii) full stomach and high blood sugar stimulate vagus nerve and insulin secretion; insulin stimulates satiety pathways in brain
long-term regulation of food intake
i) adipose cells secrete leptin (especially at night)
–leptin inhibits hunger pathways and stimulates satiety pathways