Intro to Nutrition Flashcards
Identify the 3 macronutrients and their building blocks.
- Carbohydrates—glucose and other sugars
- Protein—amino acids
- Fats—free fatty acids
Define monosaccharides
-examples
- Made up of chains of simple sugars (monosaccharides; one sugar unit)
- Examples: glucose, fructose, galactose
Define disaccharides
-examples
Two monosaccharides combined to form a new sugar, a disaccharide.
- Glucose + fructose = sucrose
- Galactose + glucose = Lactose
- Glucose + glucose = maltose
Define polysaccharides
Made up of more than 10 monosaccharide units
•Starches = polysaccharides (many sugar units of glucose)
•Examples:
-Storage polysaccharides: glycogen (glucose) and starch (glucose polymer)
-Structural polysaccharides: cellulose (glucose) and chitin (N-acetylglucosamine)
Given a list of foods, identify the ones that are carbohydrates.
- Dairy: milk, yogurt, and ice cream
- Fruit: whole fruit and fruit juice
- Grains: bread, rice, crackers, and cereal
- Legumes: beans and other plant-based proteins
- Starchy Vegetables: potatoes and corn
- Sugary Sweets: soda, candy, cookies, and other desserts
Outline the digestion of carbs
-mechanical and chemical breakdown
- digestion starts in the mouth with mechanical breakdown of the food.
- Chemical digestion also begins with the secretion of saliva:
- -Saliva contains bicarbonate to help neutralize acids
- -Mucus to moisten fee and the oral cavity
- -Antibodies and lysozymes which fights oral bacteria
- -Salivary amylase is in action
Outline the digestion of carbs
-bolus production
- A bolus is produced by chemical and mechanical action of the mouth on food.
- Bolus moves down esophagus to the stomach. In the stomach:
- -Hydrochloric acid denatures proteins and activates pepsin
- -Pepsin, as enzyme to digest protein
- -Gastric lipase is in action
What is function of salivary amylase?
chemical digestion of starch
What is gastric lipase?
an enzyme in the stomach to digest fat
Outline the digestion of carbs
-Production and movement of chyme
- stomach digestive action produces “chyme” (~2 hours)
- chyme moves into the small intestines in small increments: more digestion occurs, absorption of nutrients occurs here as well
Which organs help with digestion?
The pancreas, gall bladder and liver all help with digestion
What enzymes does the pancreas produce and secrete for digestion of carbs?
•Amylase – digests carbohydrates
•Lipases – digests fats
•Proteases- digests proteins
*Pancreas also produces insulin and glucagon that regulate blood glucose
What does the liver produce for digestion of carbs?
- Bile for emulsification of fats (stores in gallbladder)
- Receives products of digestion via the portal vein
- Releases glucose from glycogen stores
Where do the final steps of digestion of carbs occur?
•Final step occurs in small intestinal enterocytes.
- Brush border of enterocytes contains enzymes in the microvilli.
- Dietary starch is digested by α-amylase produced by the pancreas: generates maltose, short oligosaccharides and limit dextrins.
- These cannot be absorbed: requires further hydrolysis.
What happens after the carbs are absorbed from the gut into the bloodstream?
glucose exits the capillary, enters the interstitial space.
- glucose needs presence of insulin to enter cells of some organs (such as muscle, adipose tissue, and liver)
- other organs such as the brain, red blood cells, and the renal medulla do not require the presence of insulin to uptake glucose
State the purpose of carbohydrates
- Glucose can provide energy for immediate needs shortly after a meal and long-term energy needs can be provided by storing insulin in the liver and adipose tissue.
- In presence of insulin, glucose is taken up by cells for immediate use.
State the purpose of proteins
Provide the body with material for building blood cells, body tissue, hormones, muscle, and other structural elements and are also burned to produce energy.
- Repair and maintenance of body tissue and growth in children.
- Energy—can be stored as fat or converted to glucose for energy needs
- Hormones and enzyme synthesis
- Transport and storage of molecules (hemoglobin, ferritin)
- Antibodies
State the purpose of fat
Used to provide and store energy in the body, insulate body tissues, cushion internal organs, transport fat-soluble vitamins, and as integral parts of cell membranes, brain, hormones, hair, and skin.
Identify the organs that store glucose.
- Liver - stored as glycogen
- Muscle - stored as glycogen, used for quick energy needs
- Adipose tissue - unlimited
Identify the purpose of glycogen.
- In the presence of Insulin, extra glucose is taken up by the liver and stored as glycogen.
- Muscles can also store glucose as glycogen and use it for quick energy needs.
Identify the relative impact of carbohydrates, protein, and fats on blood glucose over time.
Percentage of nutrients changes to blood glucose:
• Carbohydrate: up to 100%
• Protein: 50%
• Fat: < 10%
State number of kilocalories in 1 gram of carbohydrates, protein, and fats.
- Carbohydrates - 4kcal/g
- Protein - 4 kcal/g
- Fat - 9 kcal/g
Identify the percent of macronutrients in a normal healthy diet.
-carbohydrates
45- 65% of total calories
Identify the percent of macronutrients in a normal healthy diet.
-proteins
Intake for an adult should be about 0.8 gm/kg of body weight or about 20% of caloric intake.
Identify the percent of macronutrients in a normal healthy diet.
-fats
- < 30% of total calories
- Limit saturated fats to < 10% of total calories (raises LDL)
- Increase amount of monounsaturated fats (increases HDL) and polyunsaturated fats
State the effect of insulin on carbohydrates
- in presence of insulin, glucose is taken up by cells for immediate use.
- in the presence of Insulin, extra glucose is taken up by the liver and stored as glycogen.
- muscles can also store glucose as glycogen and use it for quick energy needs.
- liver and muscle glycogen stores are limited and can be quickly consumed if demand is great.
- adipose tissue is unlimited and can store glucose for future use.
- insulin promotes the conversion of glucose into fat.
State the effect of insulin on proteins
- Amino acids can also stimulate the pancreas to secrete insulin.
- Insulin stimulates the uptake of glucose and amino acids by the muscle cells. It promotes protein synthesis by increasing amino acid transport and stimulating ribosomal protein synthesis.
- Insulin also promotes glycogen synthesis to replace glycogen storage used during muscle activity.
- Insulin accomplishes this by increasing glucose uptake, enhancing glycogen synthase activity, and inhibiting glycogen phosphorylase.
- Muscle stores about 500 to 600 grams of glycogen.
- Muscle lacks the enzyme glucose-6-phosphatase, so it does not contribute to blood glucose.
State the effect of insulin on fats
- Most fats are used for energy or stored for later use with the help of insulin.
- When other fuels are in short supply, such as during a prolonged fast, the level of insulin in the blood falls.
- The reduced level of circulating insulin promotes the removal of fat from the storage depots and helps its entry into the circulation.
- It may then be used by muscle and other organs.
- Insulin stimulates glucose and fatty acid uptake leading to lipogenesis (triglyceride production and storage) and inhibits lipolysis.
- Insulin accomplishes these effects by inducing production of lipoprotein lipase in adipose tissue, increasing glucose uptake to produce alpha-glycerol phosphate, and inhibition of intracellular lipase to decrease lipolysis.
