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Define a calorie both in physics terms and how calories are used in nutrition.
Physics: One calorie is the amount of heat needed to warm one gram of water one degree celsius.
Food calories are expressed as Kcals or 1,000 calories.
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Describe how we can directly determine the caloric content of foods. What apparatus is used to do this, how does it work?
Bomb calorimetry.
"Blow up food in water and measure the change in the water's temperature"
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What is the difference between the gross energy contained in foods compared to the digestible and metabolizable energy in foods and how do these values differ for fat, carbohydrates, and protein?
The gross energy value is measured with the heat of combustion using bomb calorimetry.
Digestible energy
Metabolizable energy
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What is the difference between kinetic and potential energy. Which type of energy is typically contained in foods?
Kinetic energy means through motion do active work.
Chemical energy is a form of potential energy related to the breaking and forming of chemical bonds.
Food has potential energy that is used to run the ATP producing machine to enable kinetic work.
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Define and give an example of both endergonic and exergonic reactions.
Exergonic releases energy.
Endergonic requires energy imput.
Biochemical pathways (glycoloysis etc.) tend to be both exergonic and endergonic. Often it requires less energy to push a ball uphill than downhill and more energy is obtained as the ball goes down the hill. The sum of the entire process is the key.
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Describe in chemical terms the relationship between photosynthesis and cellular respiration.
The sun --> energy in plants --> energy in animals --> Respire CO2 --> CO2 + H2O + Sun --> Plants --> Turn into Glucose --> Lather, rinse, repeat...
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Define digestion and absorption.
Digestion is the chemical breakdown of foods to most basic chemical constituents (nutrients) in preparation for absorption.
Absorption is how we get the nutrients throughout the body. (Simple diffusion, protein dependent transport, active transport, pinocytosis)
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Starting at the mouth and progressing to the colon describe each digestive organ with respoect to unique anatomical features, secretions, roles in digestion and diseases specific to each organ.
1. mouth - mechanical chewing, chemical release of amylase and saliva
2. Esophagus - Transit (GERD)
3. Stomach - Storage, H+/peptic digestion & intrinsic factor (vital for B12) -- Peptic Ulcers
4. Small Intestine - Most digestion occurs here. (Celiac)
4a. Duodenum - fat, protein, carbohydrate digestion and absorption excretes bile. Most macro nutrients focus here.
4b. Jejunum - water and electrolyte transport
4c. Ileum - Bile salt transport (reabsorption - recycle bile)
5. Large Intestine
5a. Colon - Storage water and electrolyte transport and reabsorption (a bacterial infection affects water absorption = diarrhea)
5b. Rectum and Anus - Defecation (the majority of waste is bacteria)
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What organs are considered accessory organs to digestion; describe any secretions from these organs and their specific roles in aiding digestion.
The pancrease, liver, and gallbladder facilitate digestive and absorptive processes in the small intestine.
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Describe at least five factors which can interfere with nutrient absorption.
GERD: reflux or backward flow of gastric contents (acidic chyme) from the stomach to the esophagus can damage and inflame the esophageal mucosa and result in reflux esophagitis (inflammation of the esophagus caused by the refluxed gastric contents)
IBDs: Inflammatory Bowel Diseases are characterized by acute, relapsing, or chronic inflammation of various segments of the GI tract, especially the intestines. Nutrient malabsorption is a significan problem because nutrient digestion is impaired and nutrient transit time is typically decreased and malabsorption occurs.
Celiac Disease, also called gluten- or gliadin-sensitive enteropathy or celiac sprue, results from an intolerance to gluten (rye, wheat, barley, and sometimes avenin in oats). Manifestations of celiac disease include diarrhea, abdominal pain, malabsorption, and weight loss.
Chronic Pancreatitis: the exocrine portion of the pancreas produces several enzymes needed to digest all nutrients. A person with chronic pancreatitis experiences severe pain, especially with eating, as well as nausea, vomiting, and diarrhea.
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How do oats lower cholesterol?
A decrease in the bile acids returned to the liver and decreased cholesterol absorption lead to a decreased cholesterol content of liver cells. Decreased hepatic cholesterol promotes removal of LDL cholesterol from the blood.
Oats have soluble fiber (pectin). Soluble fiber makes a jelly-like matrix that binds up the bile salts so now we make new bile in the liver from cholesterol (LDL) in the blood.
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What is the chemical definition of a carbohydrate?
Polyhydroxy aldehydes and ketones
- Empirical Formula: Cn(H2O)n
- Constructed from C, H, O atoms
- Occur in proportions that approximate a hydrate of carbon
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How has fiber and complex carbohydrate consumption changed in the USA since the turn of the century?
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How has simple consumption changed?
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What are the four main classes of carbohydrates and what distinguishes each class?
Monosaccharides: simplest form of CHO e.g. glucose, fructose, galactose
Disaccharides: two monosaccharides joined by a covalent bond
Oligosaccharides: short chains of monosaccharides
Polysaccharides: long chains of monosaccharides e.g. starch, cellulose, glycogen, dietary fiber
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Describe a condensation reaction in respect to making a disaccharide.
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Compare and contrast amylose and amylopectin.
Amylose: straight chain
Amylopectin: branched
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