Exercise Science Notes 4

Posted by Nicole

I’m so excited today because Lauren is arriving!  She will be here in two hours and I’m super excited :)

She better be as excited as I am. PS- I’m so happy I grew out of my awkward stage…. circa 2003

On a different note, it’s that time again!

In case you missed it:

• Exercise Science Notes 1
• Exercise Science Notes 2
• Exercise Science Notes 3
• In addition, notes are posted on our Fitness page!

All notes come from my class lectures:

Exercise Science 202 — Principles of Nutrition and Exercise

Digestion and Absorption - Anatomy and Function

• Digestive System: GI Tract, liver, gallbladder, pancreas
• Gastro-intestinal Tract (GI): mouth, esophagus, stomach, small and large intestine
• Mouth: point of entry, mastication, salivary amylase, starch → maltose; other ways of getting food without mouth include liquid food through IV or feeding through the nose.  Chewing food causes the food to have a larger surface area so the enzymes can work more effectively
• Esophagus: tube from the mouth to GI Tract
• Cardiac Sphincter: valve between the esophagus and stomach
• Stomach: mixing, storage, secretion of HCP, Pepsin, Mucus
• Pyloric Sphincter: ring of muscle between the stomach and duodenum
• Small Intestine: Duodenum → Jejunum → Ileum; digestion of fats, proteins, and carbs; absorption through the villi and microvilli. Increased surface area by 600 times
• Liver: bile emulsifies food
• Gallbladder: aids mainly in fat digestion and concentrating bile produced by the liver
• And then my teacher stopped explaining digestion…. but you kinda know what happens…

Speed of absorption: Carbs (fastest) → Protein → Fats

Caloric Cost (Thermogenics): Protein → Carbs → Fats.  It takes the most calories to digest protein.
Efficiency: Fats 96-97% → Carbs 95-96% → Protein 92%

Ulcers: erosion or hole; common for those who were bulimic; excessive HCL and pepsin; pH around 2-3

Different Nutrients – Carbohydrates, Protein, Fats

Carbohydrates

• function as an energy source
• recommendations 55% or more of calories
• so, if 2000 calories x 0.55 = 1100 calories from carbs
• three types of carbs: polysaccharides—starches (grains, nuts, legumes), disaccharides—double sugars (sucrose, lactose, maltose), monosaccharides—single sugars (glucose, fructose)
• caloric sweeteners can lead to a little less than ½ lb/day (600-800 cals/day come from caloric sweeteners)
• if you must choose a caloric sweetener, use blackstrap molasses because it at least has some iron and potassium
• it’s important to note that all caloric sweeteners have no nutritional value (white sugar, brown sugar, raw sugar, high fructose corn syrup, maple syrup, honey)
• 1 level tsp = 5 g of sugar = 20 cal (8 tsp of sugar in a 12 oz. can of soda)
• the US threshold for sugar is a getting higher and higher
• humans are predisposed to want sugar — experiments with babies show positive responses when given sweet substances
• there are many problems resulting from high consumption of sweeteners: dental problems (cavities, periodontal disease; don’t consume sugar at night—salivary flow is down and it stays on teeth all night), obesity, diabetes
• non-caloric sweeteners: saccharin (brand Sweet ‘n Low), acesulfane, splenda, aspartame (made from two amino acids, brand Equal), cyclamate
• Delaney Clause—FDA shall not approve of any chemical food additive found to induce cancer in man or animals, but sweeteners are somehow okay for sell
• lactose is “milk sugar” → Lactase → Glucose and Galactose
• lactose intolerance (50% of all people)—if parents are from southern Europe, the chances of being partially/totally lactose intolerant are very high; northern Europe has low chances of being lactose intolerant

Proteins

• functions: cell replacement, enzyme and hormone replacement, plasma proteins
• recommended 0.8g/kg of body mass/day
• want N2 balance—N2 In vs. N2 Out.  You want In = Out or In > Out
• If In < Out, you have an N2 imbalance – using protein for energy, decreases muscle mass
• If In > Out – N2 balance – building muscles
• 2.2g/kg of body mass/day can help guarantee N2 balance
• make sure you eat complete protein foods — need to have all 9 Essential Amino Acids in the right amount and right balance.  Found in animal products only: eggs, meats, fish, milk, cheese
• food combinations can result in full amino acid profiles, such as wheat and legumes combined → rice and beans!

Fats = Lipids

Fatty acids—chains of carbons with COOH at one end and CH3 at the other end

• differ in chain lengths (differ in the amounts of carbons)
• 7-10 medium
• 11+ long
• fatty acid chain lengths affect their physical structure – liquid vs. solid (oil vs. butter)
• saturated – no double bonds
• monounsaturated – one double bond
• polyunsaturated – more than one double bond
• cis/trans – hydrogenation of fats (“partially hydrogenated”)
• essential fat—omega-3 (healthy) omega-6 (unhealthy).  body cannot produce these
• 20-35% of our diets ideally consist of fat
• can’t have too much because it will create plaque build up in arteries; makes it hard for blood to flow through

All fats are triglycerides

• lipids in the diet and body
• formed by 3 fatty acids joined together through a glycerol molecule
• serve many functions: energy source, energy reserves (adipocytes), insulation and cushion, carries vitamins A, D, E, K and other nutrients, tastes good!

Sterols

• cholesterol makes cell membranes, lines nerves, brain tissues
• found in foods made from animals
• brain has the highest amount of cholesterol
• egg yolks and breast milk are high
• liver and other visceral organs (kidneys)
• muscles only have a moderate amount

Lipid Digestion (break down)

• must break down fats to absorb them
• chewing and some enzymes (lipases)
• fats move to stomach
• 2-4 hours in stomach, only about 30% broken down
• bile from gallbladder helps emulsify and separate fats
• small intestine, FAs are absorbed
• absorbed as beach ball structures called chylomicrons
• then they are put into adipose cells
• adipose cells get bigger and bigger
• taken in to muscle and liver as well

Lipoproteins

• VLDL releases fat into body cells
• IDL collects cholesterol and brings it to the liver
• LDL lethal cholesterol, delivers cholesterol to body cells, part of arteriosclerosis
• HDL healthy cholesterol, picks up cholesterol from plaques in the arterial wells, helps protect heart (more dense—better)

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Okay sorry the formatting is kind of weird and I abbreviate a lot, but hopefully you get the gist!  Let me know if you want clarification about anything because I take notes in gibberish.

Have a good day!

Q4U: What satisfies you the most in terms of satiety– Carbs, Protein, Fats?

I know a lot of people say that protein and fats are the best for satiety, but I will argue that carbs make me feel the fullest/most satisfied.