Chapter 24 Nutrition and Metabolism Flashcards
(84 cards)
1
Q
Hormones that directly activate genes are classified as ______
A
- amino acid based
- water soluble
- lipid soluble
- G proteins
2
Q
Oxytocin is produced here
A
- anterior pituitary gland
- posterior pituitary gland
- hypothalamus
- ovary
3
Q
what is the effect of PTH
A
- increase osteoclast activity
- increase Ca2+ reabsorption in the kidney
- increase Ca2+ absorption in the instestine
- all of the above
4
Q
which hormone controls the rate of body metabolism and cellular oxidation
A
- luteinizing hormone (LH)
- insulin
- T3/T4
- cortisol
5
Q
nutrient
A
a substance in food that promotes normal growth, maintenance, and repair
6
Q
major nutrients
A
-carbohydrates, lipids, and proteins
7
Q
other nutrients
A
- vitamins and minerals (water too)
- 45 essential nutrients the body cannot make
8
Q
western diet
A
- high in:
- meat
- sugar
- vegetable oil
- white flour
- 60% of diet is fast food and processed food
9
Q
carbohydrates
A
- main source of energy
- starch- (complex carbohydrates) in grains and vegetables - polysaccharides
- sugars in fruits, sugarcane, sugar beets, honey and milk - mono and disaccharides
- fiber (cellulose)
10
Q
fiber (cellulose)
A
- insoluble- cellulose in vegetables -> provides roughage and maintains health of colon and feeds useful bacteria in colon
- soluble fiber- pectin (found in cell wall of plants) -> in apples and citrus fruits; reduces blood cholesterol levels
11
Q
uses for carbohydrates
A
- glucose is the fuel used by cells to make ATP
- neurons (nervous system) and RBC -> glucose
- if run low can depress brain function (diabetic coma)
- excess glucose is converted to glycogen (liver/skeletal muscles) or fat and stored
12
Q
lipids
A
- triglycerides (most abundant lipid)
- cholesterol- in egg yolk, meats, organ meats, shellfish, and milk products
- liver produces about 85% of blood cholesterol
13
Q
triglycerides
A
- most abundant
- saturated fats- in meat, dairy food, and tropical oils
- unsaturated fats- in seed, nuts, olive oil, and most vegetable oilss
14
Q
saturated vs unsaturated fats
A
- saturated fats- usually solid at room temperature (butter), only single bonds between carbon atoms
- unsaturated fats- at least one double bond, usually liquids at room temperature (vegetable oils)
15
Q
lipids- essential fatty acids
A
- omega-3 and omega-6
- found in most vegetable oils
- must be ingested because liver cannot synthesize
16
Q
uses of lipids
A
- absorption- fat-soluble vitamins
- fuel- of hepatocytes and skeletal muscle (triglycerides)
- cell membranes and myelin sheaths (fatty covering over nerves)
- fatty deposits (adipose tissue)- protection of body organs, insulation, concentrated source of energy
- regulatory function of PROSTAGLANDINS- control BP, smooth MM contractions, inflammation
- function of cholesterol (not sued for energy)- stabilizes plasma membranes and precursor of bile salts and steroid hormones
17
Q
uses for proteins
A
- structural materials- keratin, collagen, elastin, muscle proteins
- most functional molecules- enzymes, some hormones
- nitrogen balance- rate of protein synthesis = rate of breakdown
- hormonal controls- anabolic hormones (GH, sex hormones) accelerate protein synthesis
18
Q
dietary sources of proteins
A
- animal products; eggs, milk, fish, and most meats contain complete proteins
- legumes (beans/peas) and cereals together contain all essential amino acids
- body can only produce 12/20 amino acids, the other 8 are the essential amino acids, need to be present in diet
19
Q
vitamins
A
- organic compounds
- crucial in helping the body use nutrients
- most function as coenzymes
- vitamins D (skin), some B, and K are synthesized in the body (intestinal bacteria)
- if carbohydrates, fats, and proteins are the fuel of a car, vitamins are the ignition
20
Q
two types of vitamins based on solubility
A
- water soluble vitamins:
- B complex and C are absorbed with water
- not stored in the body, need to be ingested daily
- fat-soluble vitamins:
- A, D, E, and K are absorbed with lipid digestion products
- stored in the body, except for vitamin K
21
Q
minerals
A
- 7 inorganic nutrients required in moderate amounts
- calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium
- others required in trace amounts
- work with nutrients to ensure proper body functioning
22
Q
examples of minerals
A
- calcium, phosphorus, and magnesium salts -> harden bone
- iron is essential for oxygen binding to hemoglobin
- iodine is necessary for thyroid hormone synthesis
- sodium and chloride are major electrolytes in the blood
- large amounts of Na present in processed food or sprinkled on food may contribute to fluid retention and high BP
23
Q
what is a good source of unsaturated fats
A
- nuts*
- meats
- margarine
- dairy
24
Q
proteins are used primarily to build all of the following except
A
- collagen
- enzymes
- cell membrane* -> lipids
- hormones
25
metabolism
-biochemical reactions inside cells involving nutrients
26
two types of metabolic reactions
- anabolism- synthesis of large molecules from small ones
| - catabolism- hydrolysis of complex structures to simpler ones -> using water to breakdown
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cellular respiration
- catabolism of food fuels and capture of energy to form ATP in cells
- energy currency
- ATP must be continually recycled
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3 stages of metabolism
- 1. digestion, absorption and transport to tissues
- 2. cellular processing (in cytoplasm) -> anabolism (synthesis) of lipids, proteins, and glycogen) OR catabolism (glycolysis) into intermediates
- 3. oxidative (mitochondrial) breakdown of intermediates into CO2, water, and ATP
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oxidation-reduction (redox) reactions
- transfer of electrons from one molecules to another
- oxidation- gain of oxygen or loss of hydrogen ion (loss of electron)
- oxidation-reduction (redox) reactions:
- oxidized substances lose electrons and energy
- reduced substances gain electrons and energy
- coenzymes act as hydrogen (or electron) acceptors
- nicotinamide adenine dinucleotide (NAD+)
- flavin adenine dinucleotide (FAD)
30
ATP synthesis
1. substate-level phosphorylation (fast, low output) -> 1. glycolysis 2. kreb (citric acid) cycle
2. oxidative phosphorylation (slow, high output):
- carried out by electron transport proteins
- nutrient energy is used to create H+ gradient across mitochondrial membrane
- H+ flows through ATP synthase
- energy is captured and attaches phosphate groups to ADP
31
carbohydrate metabolism
- oxidation of glucose - C6H12O6 + 6O2 -> 6H2O + 6CO2 + 32 ATP + heat
- glucose is catabolized in three pathways
- 1. glycolysis
- 2. krebs cycle (citric acid cycle)
- 3. electron transport chain and oxidative phosphorylation
32
cellular respiration mechanism
- during glycolysis, each glucose molecule is broken down into 2 molecules of pyruvic acid in the cytosol
- pyruvic acid enters the mitochondrial matrix -> KREBS -> decomposes it to CO2
- during glycolysis and the krebs cycle small amounts of ATP are formed by substrate level phosphorylation
- energy rich electrons picked up by coenzymes are transferred to the electron transport chain, built into the cristae membrane
- ETC carries out oxidative phosphorylation which accounts for most of the ATP
- about 30 ATP product
33
glycolysis
- 10 step pathway
- high speed reaction
- anaerobic
- only produces 5% of total ATP
- occurs in the cytosol
- glucose -> 2 pyruvic acid molecules (6C to two 3C)
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final products of glycolysis
- 2 pyruvic acid -> converted to lactic acid if O2 not readily available
- if O2 is available it enters the aerobic pathways
- 2 NADH to electron transport
- net gain of 2 ATP
IN: glucose
OUT: 2 ATP (net), 2 NADH, 2 pyruvic acid
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lactic acid
- if not enough oxygen, NADH returns its H to pyruvic acid which forms lactic acid
- will allow working muscles to continue at high rates for 1-3 minutes
- lactic acid not responsible for post exercise soreness
- is responsible for muscle burn
36
Krebs (citric acid) cycle
- occurs in mitochondrial matrix
- fueled by pyruvic acid and fatty acids
- pyruvic acid is broken down into CO2 in a series of energy extracting reactions
- breakdown products of fats and proteins can also enter the cycle
- primary roles is to generate electrons (H)
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kreb (citric acid) cycle
- transitional phase- 2 NADH* and 2 CO2
- kreb cycle:
- 2 ATP
- 4 CO2
- 6 NADH*
- 2 FADH*
- * electron transport
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electron transport chain and oxidative phosphorylation
- the part of metabolism that directly uses oxygen
- subtracts NADH + H+ and FADH2 deliver hydrogen atoms
- hydrogen atoms are split into H+ and electrons
- electrons are shuttled along the inner mitochondrial membrane, losing energy at each step
- released energy is used to pump H+ into the intermembrane space
- produces about 28 ATP
39
ETC
electrons are shuttled along the inner mitochondrial membrane from one complex to the next, losing energy with each transfer
- at the end combine with O2 to form water
- cyanide poisoning reacts with final cytochrome preventing electron transfer preventing ATP formation
40
the primary function of cellular respiration is ____
- to synthesize proteins
- to store energy
- to produce ATP*
- to provide oxygen to the cells
41
which of the following processes is likely to occur in the skeletal muscle cells during sprinting
- glycolysis
- oxidative phosphorylation
- the Krebs cycle (citric acid cycle)
- lactic acid oxidation to pyruvic acid*
42
glycogenesis
- glycogen formation when glucose supplies exceed need for ATP synthesis
- mostly in liver and skeletal muscle
43
glycogenolysis
- glycogen breakdown in response to low blood glucose
| - unable to store ATP, so glucose needs to be stored for later use
44
atheletes and carbohydrates
- complex carbohydrates -> more glycogen storage in muscle; more effective than high protein meal for intense muscle acitivty
- carbo loading:
- carbohydrate rich diet for 3-4 days
- decreased activity -> muscles store more glycogen -> improved performance and endurance
45
gluconeogenesis
- glucose formation from noncarbohydrate (glycerol and amino acid) molecules
- mainly in the liver
- protects against damaging effects of hypoglycemia - especially important for nervous system
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lipid metabolism
- fat catabolism yields 9 kcal per gram (vs 4 kcal per gram of carbohydrate or protein)
- most concentrated source of energy
- blood glucose- energy for a few minutes
- glycogen stores- energy for a day
- lipid stores- 30-40 days
- lipolysis "fat splitting" into fatty acids and glycerol
- glucose C6H12O6 produces 32 ATP
- common fat C57H110O6 produces 463 ATP
- only triglycerides are routinely oxidized for energy
- the 2 building blocks are oxidized separately
- glycerol pathway- glycerol enters into glycolysis
- fatty acid pathway- fatty acids enter the kreb (citric acid) cycle
47
lipogenesis
- triglycerides synthesis occurs when cellular ATP and glucose levels are high
- glucose is easily converted into fat
- stored in subcutaneous or adipose tissues
- even with a low fat diet, carbohydrate intake can provide raw material to make triglycerides
48
lipolysis
- the reverse of lipogenesis
- stores fat- > glycerol and fatty acids for fuel
- preferred by liver, cardiac muscle, resting skeletal muscle
- "fat burns in a carbohydrate flame"
- without it, acetyl CoA is converted by ketogenesis in the liver into ketone bodies (ketones)
49
homeostatic imbalance
- accumulation of ketones in blood -> ketosis
- ketones acidic -> metabolic acidosis
- low blood pH, can lead to coma/death
- breathing rapid to release CO2 to raise pH
- common in starvation, unwise dieting, diabetes mellitus
- ketone bodies excreted in urine
50
glycerol is metabolized at what stage of cellular respiration
- glycolysis*
- acetyl CoA
- kreb (citric acid) cycle
- oxidative phosphorylation
51
protein metabolism
- proteins deteriorate, so continually broken down and replaced
- amino acids recycled -> new proteins or different compound
- protein not stored in body
- when dietary protein in excess, amino acids are oxidized for energy OR converted to fat for storage
52
oxidation of amino acids
- to use protein as fuel
- first deaminated (NH2 removed) then its converted to:
- pyruvic acid
- keto acid intermediate of krebs cycle
- events include transamination, oxidative deamination, and keto acid modification
- deamination of AA is necessary for the carbon skeleton to enter catabolic pathways
- the nitrogenous compounds are metabolic waste products
53
oxidation of amino acid mechanism
- transamination- an amine group is switched from an amino acid to a keta acid
- oxidative deamination- the amine group of glutamic acid is removed as ammonia and combined with CO2 to form urea
- keto acid modification- the keto acids formed during transamination are altered so they can easily enter the krebs cycle pathways
- waste substance is urea
54
protein synthesis
- amino acids most important anabolic nutrients -> form all proteins; bulk of functional molecules
- hormonally controlled
- requires complete set of amino acids
- essential amino acids required in diet
55
catabolic-anabolic steady state of the body
- absorptive state and postabsorptive state
- absorptive state (fed state)- lasts 4 hours after eating begins; absorption of nutrients occurring
- postabsorptive state (fasting state)- morning (before breakfast), later afternoon (before dinner), all night; GI tract empty; energy sources supplied by breakdown of reserves
- primary goal during postabsorptive state is to maintain blood glucose levels
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absorptive state
-anabolism exceeds catabolism
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absorptive state: carbohydrates
- glucose major cellular energy fuel
| - glucose converted in liver to glycogen or fat
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absorptive state: triglycerides
- most glycerol and fatty acids converted to triglycerides for storage
- triglycerides are sued by adipose tissue, skeletal and cardiac muscle cells and liver cells as primary energy source
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absorptive state: amino acids
- most amino acids used in protein synthesis
| - excess deaminated -> stored as fat or used for ATP
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absorptive state: hormonal control
- absorptive state primarily controlled by insulin
| - insulin secretion stimulated by elevated blood levels of glucose and amino acids
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insulin effects on metabolism
- insulin, a hypoglycemic hormone
- insulin effects:
- moves glucose into muscle and adipose cells (brain and liver take up glucose without insulin)
- glucose oxidation for energy
- glycogen and triglyceride formation
- active transport of amino acids into tissue cells
- protein synthesis
- inhibits glucose release from liver, and gluconeogenesis
62
diabetes mellitus
- inadequate insulin production or abnormal insulin receptors
- glucose unavailable to most body cells
- blood glucose levels high
- glucose lost in urine
- fats and proteins used for energy
- metabolic acidosis, protein wasting, weight loss
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post absorptive state
- GI tract empty
- catabolism of fat, glycogen, and proteins exceeds anabolism
- goal- maintain blood glucose between meals
- makes glucose available to blood
- promotes use of fats for energy (glucose sparing- save glucose for organs that need it most)
- during starvation , the body will utilize glycogen and fat stores first, then move to muscle protein first before other tissues
- the heart is primarily muscle protein and when severely catabolized the result is death
64
sources of blood glucose
- glycogenolysis in liver and skeletal muscle
- lipolysis in adipose tissues and liver
- glycerol used for gluconeogenesis in liver
- catabolism of cellular protein- major source during prolonged fasting
- amount of fat in body determines how long can survive without food
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post absorptive state: hormonal and neural controls
- glucagon- hyperglycemic hormone
- glucagon release is stimulated by declining blood glucose and rising amino acids levels
- SNS interacts with hormones to control event in post absorptive state (epinephrine)
66
effects of glucagon
- glucagon promotes:
- glycogenolysis and gluconeogenesis in the liver
- lipolysis in adipose tissue -> fatty acids and glycerol to blood
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the process whereby excess glucose is stored in cells is called _____
- glycogenesis*
- glycogenolysis
- gluconeogenesis
- glycolysis
68
hyperglycemic hormones include glucagon and ____
- insulin*
- epinephrine
- ADH
- aldosterone
69
what is the true function of molecular oxygen acquired by the lungs
- O2 catalyzes the breaking of bonds in the glucose molecule
- O2 catalyzes the synthesis of ATP
- O2 serves as the final electron acceptor for the oxidation of food molecules
- O2 drives energy dependent processes in our cells
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hepatocytes
- about 500 metabolic functions
- process nearly every class of nutrient
- play major role in regulating plasma cholesterol levels
- store vitamins and minerals
- metabolize alcohol, drugs, hormones, and bilirubin
- mechanical contraptions can stand in our heart, lungs, or kidney, but nothing can do the work of the liver
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postabsorptive state
- proteins -> amino acids
- glycogen -> glucose
- triglycerides -> glycerol and fatty acids
- glucose and fatty acids and ketones are the major energy fuels
- amino acids are converted to glucose in the liver
- amino acids -> keto acids -> glucose
72
cholesterol
- structural basis of bile salts, steroid hormones, and vitamin D
- major component of plasma membranes
- 15% of blood cholesterol ingested; rest made in body, primarily liver
- lost from body when catabolized or secreted in bile salts
- not used as an energy source!
73
lipoproteins
- transport water-insoluble cholesterol and triglycerides in blood
- higher percentage of lipids -> lower density, hence VLDLs - very low-density lipoproteins
- LDLs- low density
- HDLs- high density
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VLDLs
-transport triglycerides from liver to peripheral tissues (mostly adipose)
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LDLs
- bad cholesterol
| - transport cholesterol to peripheral tissues for membranes, storage, or hormonal synthesis
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HDLs
- good cholesterol
- transport excess cholesterol from peripheral tissues to liver to be broken down and secreted into bile
- also provide cholesterol to steroid producing organs
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plasma cholesterol levels
- ratio of saturated/unsaturated fatty acids affects blood cholesterol levels
- saturated fatty acids stimulate liver synthesis of cholesterol and inhibit cholesterol excretion from body
- unsaturated fatty acids enhance excretion of cholesterol and enhance cholesterol catabolism to bile salts
- trans fats (partially hydrogenated vegetable oil)- healthy oils forced to be solids (margarine)
- trans fats- increased LDLs and reduce HDLs
78
unsaturated omega-3 fatty acids
- found in cold water fish
- plasma cholesterol
- lower proportions of saturated fats and cholesterol
- make platelets less sticky -> help prevent spontaneous clotting
- lower blood pressure
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non dietary factors affecting cholesterol
- stress and cigarette smoking lower HDL levels
- aerobic exercise and estrogen increase HDL levels and decrease LDL levels
- body shape:
- apple- fat carried on upper body correlated with high cholesterol and LDL levels
- pear- fat carried on hips and thighs correlated with lower cholesterol and LDL levels
80
metabolic syndrome
- 5 risk factors that increase the chance of heart disease, stroke, and type 2 diabetes
- increased waist circumference
- increase BP
- increase blood glucose
- increase blood triglycerides
- decreased blood HDL cholesterol
81
obesity
- body mass index (BMI) = wt x 705/height in inches^2
- weight= 133 ht = 5'5 -> 65"
- BMI= 133 x 705/65^2 = 22.2
- considered overweight if BMI 25-30
- considered obese if BMI greater than 30
- higher incidence of atherosclerosis, type 2 diabetes mellitus, hypertension, heart disease, and osteoarthritis
- more adults and children overweight than 20 years ago
- 100 years ago ingested 4 ibs sucrose/year -> today 115ibs/year
82
short term regulation of food intake
- neural signals GI tract- vagus nerve suppresses hunger center
- blood level of nutrients- increased nutrients in blood suppress eating
- ingesting sugar sets of the brains reward (pleasure) center releasing dopamine, this may be genesis for overeating
- GI tract hormones- gut hormones (e.g. insulin and CCK) depress hunger
83
long term regulation of food intake: leptin
hormone secreted by fat cells in response to increased body fat mass
- increased fat cells = increased leptin
- high leptin lowered appetite
- resining leptin -> some weight loss but to a point; not magic bullet for obese patients
- high leptin levels in obese patients; resistant to its action
- main function- protects against weight loss in tomes of nutritional deprivation
84
additional factors in regulation of food intake
- temperature- cold activates hunger
- stress- depends on individual "survival mode"- store fuel, increase COH, increase serotonin, calming effect
- psychological factors
- sleep deprivation
