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:

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


  • 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


  • 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!


  • 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


  • 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)


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.

Comments (6)

  1. Tara

    That little fact about lactose intolerance is so interesting! I’m so glad I’m not lactose intolerant, though my family is from southern europe. I love my yogurt and cheese!! I would say that protein probably satisfies me the most, but carbs are my favorite.

  2. Alexa @ Simple Eats

    I need a combo! Fat and carbs (peanut butter on toast) always satisfies me the most!

  3. Matt @ The Athlete's Plate

    That just went way over my head! Fat definitely keeps me the fullest :)

  4. livinglearningeating

    I feel satisfied with a combo of all three (especially carbs & fat).

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