Nutrition Flashcards
What is nutrition
Nutrition: the process by which the body obtains and uses certain components of food
It includes digestion , absorption, transportation and cell metabolism
What is a nutrient
Nutrient: chemicals taken into the body and used to produce energy, provide building blocks for new molecules, and function in other chemical reactions
6 nutrients
Macronutrients
Water , carbohydrates, lipids and proteins
Micronutrients
Vitamins and minerals
Essential nutrients
Minerals, most vitamins, nine amino acids, and 1-3 of the fatty acids must be consumed in diet
Calorie
Amount of energy (heat) necessary to raise the temperature of 1g of water by 1 degree
Kilocalories
Calorie x 1000
1 kilocalories
= 4.184 kilojoules (KJ)
Carbohydrate and protein
4 kcal/g
Fats
= 9kcal/g
Alcohol
= 7.1kcal/g (empty calories- no nutritional benefits)
Recommend daily intake
Depends on sex, age, weight and activity ~ 2000Cal women and 2500Cal men
Carbohydrates
Primary source of energy
~ 440g in body (325 muscles , 90-100 liver and 15-20 blood)
Accounts for ~ 45-65% of total kilojoules
Erythrocytes and neurons can not mobilise fats or amino acids therefore need to rely on carbohydrates
Homeostasis regulates by insulin and glucose
Excess amount of carbohydrates leads to dental , obesity
Deficient amount of carbohydrates leads to metabolic acidosis
Monosaccharides ( type of carbohydrates)
Carb in there simple form known as simple sugars
Three types
Glucose( veg)
Fructose ( fruits, berries and honey)
Galactose ( milk)
Diasaccharides
Two aided together two carbs added together
Sucrose( table sugar) -composed of glucose molecule and fructose molecule ( sugar cane, sugar beets, honey)
Lactose (milk sugar) - glucose and galactose molecule
Maltose( germinating cereals- two glucose molecules
Polysaccharide
Many carbs together
Complex carbohydrates- numerous glucose molecules combined to create a chain
• starch ( primarily vegetables, fruits and grains
• glycogen ( muscle and liver)
- insulin released post meal
- muscles hoard ~ 2/3
• fibre - cellulose ( plant cell walls) indigestible
Dietary fibres
Held together by bonds our digestive enzymes cannot break = no energy
• Found in all vegetables, fruits and legumes
• Cellulose = constituent of plant cell walls
• Hemicellulose = cereal fibres; pectins = vegetables and fruits; gums similar/ used as additives
Excessive dietary fibre
Can interfere with absorption of iron , calcium, magnesium, phosphorus and some trace elements
Proteins
Chains of amino acids
In the body 20 different kinds of amino acids :
Two categories
1. Essential only obtained through the diet
2. Non essential body can synthesis and make there own
Complete protein
Food that contain adequate amount of all 9 essential proteins
Eg meat, fish poultry cheese and eggs
Incomplete proteins
Don’t contain all nine essential proteins
Eg leafy greens veg, grains, legumes
Required 46-56g age and sex training status different
Use of protein in the body
Amino acids synthesis proteins
Create tissues that are structural strong like collagen and keratin
Play a role in blood change pH , promote blood clotting and gas transportation
Form actual transport proteins
Receptor molecules
Energy source- when there isn’t enough carbohydrates or fats
Lipids
95% of lipids are triglycerides
Aka fats when solid at room temp and oils liquid at room temp
• 3 fatty acids attached to a glycerol molecule
• aka fats (solid at room temperature) or oils (liquid at room temperature)
• Subcategorised
Saturated - single covalent bonds between the carbon atoms of their fatty acids (fats of meat, diary products, eggs, coconut oil, and palm oil)
• Unsaturated -one or more double bonds between carbon atoms
• Short chains soft, long chains hard at room temp
Remaining 5% are-
• Cholesterol (liver and egg yolks)
• Phospholipids (lectithin) - plasma membranes
Cholesterol
Fat like substance produced in our body and is found in food
Produced by the liver -75%
Function break down lipids in small intestine and important in bile
High density lipoproteins (hDL)
Low density lipoproteins ( ldl)
The liver and small intestines produce
HDLs
• Contains the least amount of total lipids (20%) and cholesterol (20%) and the highest protein (50%) of the lipoproteins
Degradation in the liver of a very-LDL (VLDL)
produces LDLs
• Formed from fats, carbohydrates, alcohol and cholesterol
• Contains high percentage of lipids (95%) of which 60% consists of triglycerides
Lipids
it can be used for first as an energy source to produce Atp. so we can obviously store energy from fats. and we can use them to make energyThey’re quite energy dense.
So they’re more dense
than carbohydrates
they can be used for energy storage. Obviously we store fat on our body for high energy needs
They can also physically pad our body. So we have fat on the outside. It provides some padding, and also provides some insulation
include cholesterol, and we talked about some of the positive benefits of cholesterol. So cholesterol is needed for plasma membrane to to make plasma membranes themselves. It adds in fat digestion, like we said, working with bile acids, and is also involved in synthesizing steroid hormones.
Eicosanoids
signalling molecules that are derived from fatty acids that help minimize inflammation, aid in blood, clotting and tissue repair and also aid in smooth muscle contraction.
last point you have up there is that lipids are und in the myelin sheet. So to remind you what myelin sheet is. That’s that outer bit of our urons that allows electrical impulses to be otected and facilitated and neurons.
Vitamins
Organic molecules that exist in minute quantities in food but essential to normal metabolism
If we think of vitamin as being essential. Again, this word coming out an essential vitamin is something that can’t be produced by the body, and therefore needs to be ingested through your dietthey’re only needed in small amounts and can potentially even be toxic in excessive quantities.
Vitamin. K is one that’s unique that it’s produced by intestinal bacteria
Pro- vitamin
- part of a vitamin that the body can assemble or modify into a functional vitamin
•Beta carotene
“ Vitamin
Vitamins are generally used in their original or slightly modified form
Nutrition
Macronutrients: Must be consumed in relatively large quantities
• Water
• Carbohydrates
• Lipids
• Proteins
Micronutrients: Only small quantities are required
• Vitamins
• Minerals
Essential Nutrients
•Cannot be synthesized in the body
• Must be consumed in the diet
Carbohydrates
Monosaccharides (simple sugars)
-Glucose
-Fructose
-Galactose
(Building blocks)
Disaccharides (Formed when two monosaccharides
combine)
-Sucrose (glucose + fructose)
-Lactose (glucose + galactose)
-Maltose (glucose + glucose)
Polysaccharides (formed from many sugar molecules)
-Starch
-Glycogen
-Cellulose( dietary fibre bonds can’t be broken down by enzymes)
Carbohydrate Chemical Digestion in the Mouth and stomach
Mouth
• Salivary Amylase
• Breaks starch into maltose
• Optimal pH: 6.7-7.0
• Incomplete due to short time in the mouth
Stomach
• Highly acidic (pH 1.5 to 3.5) due to hydrochloric acid (HCI)
• Inactivates salivary amylase
• Halts carbohydrate digestion initiated in the mouth
•No specific enzymes for carbohydrate digestion are secreted in the stomach
Pancreatic a-amylase
• Secreted by the pancreas into the small intestine
• Polysaccharides such as starch - + oligosaccharides and disaccharides
Brush border enzymes
•
.
In microvilli of the small intestine epithelial cells
Sucrase
• Sucrose - › Glucose and fructose
• Lactase
• Lactose - › Glucose and galactose
• Maltase
• Maltose - › Two glucose molecules
CHO Chemical Digestion the Large Intestine
Most carbohydrates are digested by this stage apart from resistant complex carbohydrates
Microbial Fermentation
• The large intestine houses a diverse microbiota that can ferment undigested carbohydrates
•Undigested carbohydrates -* short-chain fatty acids + gases (hydrogen, methane, and carbon dioxide)
Starch glycogen
Which of the following enzymes is primarily responsible for carbohydrate digestion?
Amylase
Which of the following carbohydrates is considered to be indigestible by human digestive enzymes?
Cellulose
What is the primary end product of carbohydrate digestion?
Monosaccharides
Which organ secretes enzymes that are essential for carbohydrate digestion?
Pancreas
Fructose is absorbed in the small intestine via which process?
Facilitated diffusion
The absorption of which monosaccharide is not sodium-dependent?
Fructose
What role does the sodium-potassium pump play in the absorption of monosaccharides?
It helps maintain the sodium gradient that facilitates the transport of glucose
Which transport protein is responsible for moving glucose from the intestinal lumen into epithelial cells?
SGLT1
