NUTR1023 Lecture Notes - Lecture 4: Sausage Roll, Short-Chain Fatty Acid, English Muffin
NUTR1023 Health and Fitness Through Diet and Exercise
Summer Semester 2017
Module 4 – Macronutrients
Objectives
At the end of this module students will be able to do the following:
• List the functions of carbohydrates, proteins and fats in the body.
• Describe how carbohydrates, proteins and fats are digested and absorbed.
• Describe the chemical structures and classifications of carbohydrates, proteins and
fats.
• List some rich food sources of carbohydrates, proteins and fats.
• Briefly describe the effect of manipulating dietary macronutrient intake on body
weight and other risk factors for chronic disease.
Study Tasks
1. Watch the videos Carbohydrates, Protein and Fats. Then read chapters 4, 5 and
6 of the Tapsell textbook (pages 53-76 and 127-137 in these chapters
discuss Micronutrients which we will cover in Module 5) before completing the
following activities:
• Which hormone regulates the passage of glucose into cells?
Insulin (removes glucose from blood and puts into cells) and Glucagon (stimulates
liver to release glucose into blood stream). Low glucose levels (not enough energy
– particularly to the brain), High glucose levels (particularly over long periods of
time, causes damage to blood vessels and tissues).
• Which enzyme digests carbohydrate in the mouth?
Amylase
• Where does most carbohydrate digestion occur?
Small intestine (enzymes released from pancreas), polysaccharide >
monosaccharide.
• What happens to carbohydrates that resist digestion in the small intestine?
They move to the large bowel and become fermented by bacteria of the colon to
produce short chain fatty acids that are rapidly absorbed and used for energy.
• How are carbohydrates stored in the body?
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Via glycogen (polysaccharide)
• What are the two main classes of dietary lipids?
Dietay holesteol steol ad tiaylglyeol’s glyeol hai ith thee fatty
acids attached). Absorbed in the GIT and packaged into chylomicrons.
• What are the main types of fatty acids in dietary fat?
They can be saturated, monounsaturated or polyunsaturated, and help to make
up the three fatty acids chains that are part of a triacylglycerol.
• How are dietary lipids packaged after absorption?
Absorption: directly into bloodstream (glycerol and short/medium chain fatty
acids) or lymphatic system (long chain fatty acids: micelles diffuse into intestinal
cells, reassembly of triglycerides, packed with proteins into chylomicrons, bypass
liver).
• Explain lipid digestion
Complex due to insolubility in water, do not easily dissolve in the body for
availability for digestive enzymes. Occurs in small intestine, fat molecules are
emulsified with aid of bile (secreted from gall bladder) and then broken down by
pancreatic enzymes into monoglycerides, glycerol and fatty acids.
• What are the four main proteins in the body?
Collagen, haemoglobin, myosin, actin.
• Briefly describe how protein is digested in the body.
Denaturation: disruption of stability, uncoil and lose shape, induced by stomach
acid. Can change properties (eg/ cooking an egg).
Stomach digestion: HCl denatures proteins. Conversion of enzyme pepsinogen to
pepsin.
Small intestine: Hydrolysis reactions. Peptidase enzymes.
Amino acids are then transported through the blood stream to the liver to
undergo protein synthesis or released into the general blood stream for other
functions. Very little protein is wasted.
• List some foods that are sources of carbohydrate.
Grain, milk, sweets, vegetables, fruits
• List the three most common dietary monosaccharides.
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find more resources at oneclass.com
Glucose, Fructose, Galactose
• List the two most common dietary disaccharides.
Sucrose, Lactose
• Describe the difference between amylose and amylopectin.
Both types of starch. Amylopectin have lots of branches (digested and absorbed
rapidly) and Amylose is usually a straight chain (slow digestion).
• Describe why people unable to digest lactose experience uncomfortable
gastrointestinal symptoms.
Undigested lactose, that cannot be absorbed in the blood), will reach the large
intestine where the microbiota will ferment the lactose, creating irritating acid
and gas. The lactose itself will draw water into the large intestinal lumen and
cause bloating and diarrhoea.
• What are fatty acids?
Usually long chain molecules that are composed hydrogen and carbon. Saturated
(maximum amount of hydrogen atoms, thus only single bonded carbons eg/
meat) and unsaturated (lacks hydrogen atoms, thus includes one or more double
bonds i is H’s o sae side of od; et oleule; liuid at oo tep o
tas H’s o opposite side of od; liea; siila health effets as satuated
fats) configuration eg/ oil).
Triglycerides (3 fatty acids joined by a glycerol; primary fat storage).
Phospholipids (solubility in fat and water, part of cell membranes, emulsifiers –
hydrophilic head, hydrophobic tail).
Sterols (ring based structure found in cholesterol and plant sterol, creates many
body compounds such as hormones and vitamins)
Lipoproteins (transport fats and cholesterol into the blood, classified due to
density: VLDL, LDL (delivery system, increase risk of cardiovascular disease due to
the potential of oxidation around blood vessel membrane to cause build-up of
plaque), HDL)
• List the two essential fatty acids.
Ca’t e sythesised y the ody ad hae NRV utiet efeee alues fo
needed intake, depending on age.
Linoleic (18 carbon, omega 6)
Alpha-linolenic (18 carbon, omega 3)
• What is the role of fats in the body?
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Nutr1023 health and fitness through diet and exercise. At the end of this module students will be able to do the following: List the functions of carbohydrates, proteins and fats in the body: describe how carbohydrates, proteins and fats are digested and absorbed, describe the chemical structures and classifications of carbohydrates, proteins and fats. List some rich food sources of carbohydrates, proteins and fats: briefly describe the effect of manipulating dietary macronutrient intake on body weight and other risk factors for chronic disease. Study tasks: watch the videos (cid:858)carbohydrates(cid:859), (cid:858)protein(cid:859) and (cid:858)fats(cid:859). Insulin (removes glucose from blood and puts into cells) and glucagon (stimulates liver to release glucose into blood stream). Dieta(cid:396)y (cid:272)holeste(cid:396)ol (cid:894)ste(cid:396)ol(cid:895) a(cid:374)d t(cid:396)ia(cid:272)ylgly(cid:272)e(cid:396)ol"s (cid:894)gly(cid:272)e(cid:396)ol (cid:272)hai(cid:374) (cid:449)ith th(cid:396)ee fatty acids attached). Absorption: directly into bloodstream (glycerol and short/medium chain fatty acids) or lymphatic system (long chain fatty acids: micelles diffuse into intestinal cells, reassembly of triglycerides, packed with proteins into chylomicrons, bypass liver): explain lipid digestion.
