Nutrition and Metabolism

energy

capacity to work can be electric, heat and nuclear

calorie

unit of heat energy, amount of heat necessary to raise temp , so tiny kCal

laws of thermodynamics

energy cannot be created or destroyed only converted of transferred from one for to another, large portion of original energy always ends up as heat, even when doing nothin, heat is being lost to the environment

carbs

primarily from plants such as starch (complex carbs) in grains and vegetables, sugars mono and disaccharides in fruits sugarcane, sugar beets, honey and milk, polysaccharides provide fiber

insoluble fiber

cellulose in vegetables provides roughage

soluble fiber

pectin in apples and citrus fruits reduces blood cholesterol levels

carbs uses in body

glucose fuel most used for cells to make ATP, some cells use fat, neurons and rbcs rely entirely on glucose, excess glucose is converted to glycogen or fat then stores, fructose and galactose are converted by liver before circulating

dietary requirements of carbs

should consist of mostly complex caarbs (whole grains and veggies), simple carbs should be limited

lipid uses in body

adipose tissue mechanical and thermal insulation, fuel storages, phospholipids needed for myelin sheath and cell membranes, cholesterol stabilizes membranes make steroid hormones, major fuel of hepatocytes and skeletal muscle, absorb fat soluble vitamins

lipid dietary sources

triglycerides - saturated fats and unsaturated fats

saturated fats

from animal products (meat and dairy), tropical oils, or hydrogenated oils (“trans fat” horrible for health) limit

unsaturated fats

found in seeds, nuts, olive oil, and most vegetable oils

saturated fatty acids

solid at room temp (animal fats and butter), linear molecules

unsaturated fatty acids

liquid at room temp (plant oils and olive oils) disney knees kinked, omega 3 fatty acids

trans fat

artifically hydrogenated, increases food shelf life, bad for you, margarine, shortening, some peanut butter and baked products

lipids: cholesterol

found in egg yolk, meats, organ meats, shellfish, and milk products, not required in diet cause liver makes it

what is cholesterol?

not used as energy source, basis of steroid hormone, 15% from diet 85% from liver acetyl CoA, lost from body from poop

lipoproteins

combos of lipid and protein complexes

triglycerides and cholesterol are transported to and from tissue cells by

lipoproteins

LDL

low density lipoproteins, highest cholesterol content, lower density lipid proteins, higher lipid precentage

HDL

high density lipoproteins, highest protein content,

recommended total cholesterol HDL and LDL levels

total cholesterol 200mg/dL or less, HDL >60 good <40 not good, LDL 100 or less good, 130 or above not good

proteins use in body

structural materials, keratin collagen and elastin CT and muscle proteins, enzymes some hormones regulate body function

protein dietary sources

animal products eggs milk fish most meats, as well as soybeans are considered complete proteins, legumes, nuts and cereals contain incomplete proteins (lack some essential amino acids

three factors of proteins

1.) all or none rule, 2.) adequacy of caloric intake, 3.) hormonal controls

all or none rules

all amino acids are needed and must be present from protein synthesis to occur, if not all are present then amino acids are used for energy, whatever not used immediately are oxidized to cabs or fats

adequacy of caloric intake

protein is used as fuel if insufficient carbs or fat is available

hormonal controls

anabolic hormones (GH , sex hormones ) accelerate protein synthesis and growth, adrenal glucocorticoids (released during stress) promote protein breakdown and conversion of amino acids to glucose

vitamins

need a tiny amount, organic compounds crucial in helping body use nutrients

most vitamins function as a coenzyme

act with particular function to accomplish a task, ex B-vitamins are coenzymes for converting glucose to energy

most come from diet except

Vitamin D - made by skin, some B and K synthesized by intestinal bacteria, Beta-carotene (from carrots) converted to vitamin A in body

water soluble vitamins

B complex and C are absorbed with water, B12 requires intrinsic factor (RBC maturation), not stored in body, B9 folic acid neurodevelopment, C for bone, cartilage antioxidant

fat soluble vitamins

A,D,E and K are absorbed with lipid digestion, stored in body except K, excessive consumption causes health problems

minerals

seven minerals required in moderate amounts: phosphorus, potassium, sulfur, sodium, magnesium, chlorine, calcium

fat are the

most important form of stored energy

when we take in too little food we start to metabolize stored food

starts with glycogen and far then if all depleted goes to protein, proteins not stored by can be used for energy, leads to tissue damage or death

kwashiorkor disease

chronic protein deficiency, characterized by edema (abdominal mostly) and muscle loss

metabolism

once inside body cells, nutrients become involved in an incredible variety of biochemical reactions known as metabolism

anabolism

synthesis of large molecules from small ones (example: synthesis of proteins from amino acids) builds up and consumes energy

catabolism

hydrolysis of complex structures to simpler ones (example: breakdown of proteins into amino acids) break down and release energy

absorptive state

once in jejunum nutrients have been broken down and con now be absorbed into our bloodstream → portal vein → liver

3 major stages of in processing energy

1.) digestion/absorption (GI tract), 2.) newly delivered nutrient built up into lipids protein and glycogen via anabolic pathways or broken down by catabolic pathways (tissues/cytoplasm of), 3.) almost entirely catabolic (needs O2 mitochondria)

catabolism: cellular respiration

end result energy, glycolysis, citric acid cycle, oxidative phosphorylation

glycolysis

cells in body take up circulating glucose in response to insulin and through series of reactions, transfer some energy in glucose to ADP to form ATP, produces pyruvate

gluconeogenesis

forming new glucose from noncarb source, occurs in liver , formed from glycerol and amino acids when blood glucose levels drop, protect from hypoglycemia

lipolysis

obtain energy from fat, triglyceride must break down by hydrolysis to fatty acid and glycerol, fatty acid oxidized into acetyl CoA in krebs cycle, glycerol goes to glycolysis, 3 fatty acids 16 or more carbons = fat yield more energy reserve than carbs

glycolysis

converts glucose to pyruvic acid

glycogenesis

polymerizes glucose to form glycogen

glycogenolysis

hydrolyzes glycogen to glucose monomers

gluconeogenesis

forms glucose from noncarb precursors

ketogenesis

when glucose scarce, the liver begins converting fatty acids into ketone bodies

ketone bodies as fuels

ketones are released into bloodstream and used as alternative energy source by tissues especially the brain

problem with this

brain only wants glucose for energy, if starved of glucose (atkins diet) ketone kicks in to create ATP but ketones are acidic so not great for your body

accumulation of ketones

can lead to ketosis, common in starvation or diabetes mellitus, ketone bodies are also excreted in pee

ketoacidosis

uncontrolled diabetes (T1D) especially, body produces lots of ketones, if no inulin glucose cant use energy for cells which causes liver to keep producing ketones, ketones are acidic and make blood acidic, life threatening

metabolic acidosis

cause dangerous pH levels, ketones are acidic, fruity breath from vaporizing acetone, breathing becomes rapid as lungs try to produce CO2 to raise pH