Nutrition and metabolism Flashcards
Hormones that directly activate genes are classified as
lipid soluble
Oxytocin is produced here…
Hypothalamus
What is the effect of PTH (parathyroid hormone)?
- > increase osteoclast activity
- > increase Ca 2+ reabsorption in the kidney
- > increase Ca2+ absorption in the intestine
Which hormone controls the rate of body metabolism and cellular oxidation?
T3/T4 (thyroid hormones)
Nutrient
a substance in food that promotes normal growth, maintenance and repair
Major nutrients
- carbs
- lipids
- proteins
45 essential nutrients- body cannot make
comes from the food you eat
Western diet
high in:
- meat
- sugar
- vegetable oil
- white flour
*60% of diet is fast food and processed food
Carbohydrates
-> main source of energy
Dietary sources:
-STARCH (complex carbs) in grains and vegetables- polysaccharides
-SUGARS in fruits, sugarcane, sugar beets, honey and milk- mono and disaccharides
- FIBER (cellulose):
- Insoluble: cellulose in vegetables; provides roughage (maintains health of colon. feeds useful bacteria in colon)
*soluble fiber: pectin (found in cell wall of plants) in apples and citrus fruits; reduces blood cholesterol levels.
Carbohydrates
Uses:
- > 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
Lipids
Dietary sources:
- Triglycerides (most abundant lipid):
* Saturated fats in meat, dairy foods, and tropical oils
* unsaturated fats in seeds, nuts, olive oil, and most vegetable oils - Cholesterol in egg yolk, meats, organ meats, shellfish, and milk products
- > liver produces about 85% of blood cholesterol
Saturated Fats
usually solid at room temp (butter), only single bonds between carbon atoms
Unsaturated fats
at least one double bond, usually liquids at room temp
Lipids
essential fatty acids:
- Omega-3 and Omega-6; found in most vegetable oils
- must be ingested, liver cannot synthesize
Uses of lipids
- Absorption: fat-soluble vitamins
- Fuel: of hepatocytes and skeletal muscle (triglycerides)
- Cell membranes and myelin sheaths
- Functions of fatty deposits (adipose tissue)
* protection of body organs, insulation, concentrated source of energy - regulatory function of prostaglandins:
* control of BP, smooth MM contractions, inflammation - Function of cholesterol (not used for energy)
* stabilizes plasma membranes
* precursor of bile salts and steroid hormones
proteins
Uses:
1. 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
Proteins
dietary sources:
-> 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
vitamins
- 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 carbs, fats, and proteins are the fuel of a car, vitamins are the ignition
vitamins
2 types, based on solubility:
- 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
Minerals
7 inorganic nutrients required in moderate amounts
-calcium, phosphorus, pottassium, sulfur, sodium, chloride, and magnesium
- others required in trace amounts
- work with nutrients to ensure proper body functioning
Minerals examples
- > 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
Proteins are used primarily to build all of the following except
cell membrane
Metabolsim
-> biochemical reactions inside cells involving nutrients
2 types of reactions:
-Anabolism- synthesis of large molecules from small ones
- catabolism- hydrolysis of complex structures to simpler ones
- cellular respiration: catabolism of food fuels and capture of energy to form ATP in cells
3 stages of metabolism
Processing of nutrients:
1. digestion, absorption and transport to tissues
- Cellular processing (in cytoplasm)
* Anabolism (synthesis) of lipids, proteins, and glycogen
* catabolism (glycolysis) into intermediates - Oxidative (mitochondrial) breakdown of intermediates into CO2, water, and ATP
Oxidation-reduction (redox) reactions
- transfer of electrons from one molecule 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)
ATP synthesis
2 mechanisms:
- substrate-level phosphorylation (fast, low output)
* 1. glycolysis
* 2. Kreb (citric acid) cycle - 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
Carbohydrate metabolism
Oxidation of glucose:
C6H12O6 + 6O2 -> 6H2O + 6CO2 + 32 ATP + heat
- glucose is catabolized in 3 pathways
1. glycolysis
2. krebs cycle (citric acid cycle)
3. electron transport chain and oxidative phosphorylation
glycolysis
- > 10-step pathway- high speed reaction
- > anaerobic, only produces 5% of total ATP
- > occurs in cytosol
- > glucose-> 2 pyruvic acid molecules (6C to two 3C)