Week 3 Flashcards
What is the main difference between glycogen and dietary fiber?
Glycogen is digestable
dietary fibre is not digestable
What are simple carbohydrates and what are complex carbohydrates?
simple: monosaccarriade, and disarracaride
complex: olygo and polysaccaride
How is glucose produced in plants?
photosynthesis
What is the role of carbohydrates?
- structure in plants
- source of energy and blood glucose homeostasis
- substrate in the biosynthesis of other compounds
- cell to cell regonition
Whatis a glycoprotein?
a carbohydrate cell receptor
Name the 3 main 6-carbon monosaccharides
Glucose
Frutose
Galactose
Name the 2 3-carbon monosaccharides?
ribose
deoxyribose
Draw the structures of glucose, fructose, and galactose
see notes
How is insulin-dependent glucose uptake by the body?
glucose transporter 4 (GLUT4).
What is galactosemia?
Reduction in the metabolism of galactose to glucose due to deficient galactokinase or other metabolism genes
What are the 3 main disaccharides?
Lactose
Maltose
Sucrose
What is lactose made of?
what glycosidic bonds does it have?
Galactose and glucose
beta 1,4 glycosidic bond
What is Maltose made of?
what glycosidic bonds does it have?
Glucose and glucose
alpha 1,4 glycosidic bond
What is sucrose made of?
what glycosidic bonds does it have?
glocose and frutose
alpha 1,2 glycosidic bond
Lactose intolerance is the inability to digest lactose.
What are the primary and secondary type of lactose intolerance?
Primary:
shortage of the enzyme lactase in
adulthood because of lactase non-persistence, which is the “default” program in humans post weaning
Secondary:
in lactase persistence phenotypes (in certain ethnicities and population with dairy farming ancestry), LI is associated with damage of the lactase producing cells
What are the three main polysaccharides?
starch
glycogen
cellulose
What has a higher GI; amylose or amylopectin?
amylopectin
Are Oligosaccharides digestable?
mostly not
What are the two forms of starch?
Amylopectin and amylose
What is amylose?
continuous chain of glucose molecules
linked by α-1,4 glycosidic bonds
What is Amylopectin?
branched chain of glucose molecules linked by α-1,4 and α-1,6 glycosidic bonds.
Why is amylopectin quicker to digest then amylose?
More quickly digested as more sites available to enzymes activity
What is the glycogen storage capacity in the liver and muscle post meal?
liver: 90-120g in average adult
muscle: 300g
What is glycogen?
storage form of glucose in the human body
How is liver glycogen and muscle glycogen used differently?
Liver glycogen: used for BGL homeostasis principally
Muscle glycogen: substrate for energy production in muscle during exercise
What is glycogen storage disease?
Liver cannot convert glycogen to glucose or glucose to glycogen
What enzymes break down maltose, sucrose and lactose?
Maltose: maltase
Sucrose: sucrase
Lactose: lactase
What can excess glucose lead to?
Excess glucose availability can result in fatty acids via acetyl CoA being diverted to lipogenesis (fed state, high insulin conditions)
How are glucose, galactose absorbed?
active, passive and facilitated
how is fructose absorbed?
facilitated
Liver converts fructose and galactose to intermediates of glycolysis for energy production.
True or false?
true
How is blood glucose lowered?
Transfer of glucose from blood vessels into cells for energy production or storage as glycogen in liver and muscle.
Some cells uptake glucose in an insulin- independent manner(e.g. liver).
Some cells take up glucose in an insulin-dependent manner (e.g muscle cells via GLUT4).
How is blood glucose level increased?
Glucagon, cortisol, epinephrine /adrenaline, norepinephrine/noradrenaline and growth hormone: these promote glygogenolysis and gluconeogenesis.
the formation of glucose.
What happens when you have a high sugar diet?
contanst high blood sugar level and insulin secretion may lead to:
- Increase risk of dental caries
- Weight gain and obesity from hyperglycemia and
hyper insulinemia.
- Glucose “intolerance” and “insulin resistance”
- Type 2 Diabetes Mellitus when pancreas becomes
exhausted from high insulin requirement, in the situation of insulin resistance
What is insulin resistance?
Insulin receptors don’t respond to insulin as well anymore.
What happens when there is insulin resistance?
As the blood glucose levels continue to rise the pancreas is signaled to produce more insulin in the attempt to get the glucose inside the cells. eventually, the pancreas becomes exhausted
How do you test if you are insulin resistant?
Glucose tolerance test
What is type two diabetes biologically causes by and what does it lead to?
cause: insulin resistance
leading to pancreatic beta cells exhaustion and failure (stop producing sufficient insulin).
Management for type two diabetes
healthier diet
exercise
insulin injections
medications
Why does type one diabetes occur?
pancreatic beta cells are inexsistant since birth or destroyed (auto immune disease) and dont produce insulin al all
What does uncontrolled type 1 diabetes lead to?
leads to ketoacidosis as a large number of cells are glucose starved and rely on fat alone for energy. This leads to constant ketogenesis
What is the glycemic index rated on?
carbohydrate-containing foods based on their effect on blood sugar levels over about two hours post-ingestion
What are the factors that affect GI of a meal?
- Amylose to amylopectin ration
- degree of processing
- fat content of food
- acidicity ( gastric emptying/ amylase activity)
- sugar content and type of sugar
- other macronutrient in the meal
- ripeness of the fruit
- fibre content
What is the difference between glycemic index and glycemic load?
GLycemic index:
- Score based on 50g carbohydrate serving of the test food
- Blood glucose response to the test food compared with a standard (glucose or white bread GI=100)
Glycemic Load:
- Amount of carbohydrate in the food serving consumed, multiplied by its GI value and divided by 100
- More accurately reflects impact on blood glucose, insulin secretion and health of that specific food serving
How do you calculate glycemic load?
- Find out the GI of the food of interest
- Find out how many grams of digestible carbohydrates (CHO) are in the service being consumed (=total CHO on NIP)
- Multiply the GI by the amount of CHO in grams in that specific serve of food
- Divide by 100
what is the acceptable macronutrient distribution range for carbohydrates?
45-65% of total energy intake
how much energy does 1g of carbohydrates give?
4 kcal or 16kj
What is the definition of fiber?
The part of the edible part of a plant, or their extracts, or similar carbohydrates, that is resistant to digestion & absorption in the human intestine, usually with complete or partial fermentation in the large intestine by bacterial colonies
What is the total fibre made of?
dietart fibre (the actual plant) functional fibre (supplement)
What are some sourcse of fibre?
- cell walls of plants
- seed coats (brains) of cereals
- structural compounents of vegetables, nuts and fruits,
roots vegetables, Microbiological, fungal or animal components
What are some soluble fibres?
pectins, some hemicellulose, gums and mucilages
what is the physiological effect of soluble fibers?
lowers blood glucose levels, delays gastric emptying and decreases blood glucose levels
What are some insoluble fibers?
cellulose, hemicellulose. lignins
what are some physiological effects of insoluble fibers
decreased intestinal transit time, decreases constipation,
lower risk for diverticular disease, lower risk for colon cancer
what are the physiological functions of fibre?
- promoting bowel health by increasing bulk and laxation
- reducing obesity and weight gain risk
- assisting in blood glucose control
- reducing plasma cholesterol
- substrate for gut bacteria
What is a diverticulum?
A diverticulum is a small pouch with a narrow neck that sticks out from (protrudes from) the wall of the gut (intestine)
What is diverticulum disease?
Chronic insufficient bulk accompanying a low-fiber diet
What happens to the gut in a fiber-rich diet? how is this different to a fiber-free diet?
Fiber-rich: mature mucus layer: complete barrier function
Fibre- free: microbiota eroded mucus layer: barrier dysfunction
What is the adequate intake of fiber in men, women and in pregnancy?
Men: 30
women: 25
pregency: 25-28
Where does alcohol come from?
The product of carbohydrates fermentation micro-organisms (yeast) convert sugars to ethanol and CO2 in
anaerobic conditions at room temperature
Explain in simple terms the absortion of acohol in the body?
absorption is rapid, as it does not require digestion: in the stomach (~20%) and small intestine (80%) by simple diffusion
•Cannot be stored: has priority over all other energy sources in metabolism (is toxic for the body)
How much energy is produced per gram of alcohol?
7kcal or 29kJ
How much alcohol is in a standard drink?
10 grams of alcohol
Describe the main metabolic pathway for alcohol metabolism
alcohol ->
acetaldehyde ->
(co2 + water + energy) and fatty acid
Where does alcohol metabolism occur?
liver
What are the 3 alcohol metablism pathways
- ADH
- MEOS
- Catalase
Where does the alcohol dehydrogenase (ADH) pathway occur?
grastic cells (20%) hepatocytes (80%)
What is the end product of the ADH pathway? what is it used for?
Acetyl- CoA used for CAC ketone bodies production lipogenesis
The ADH enzyme reaction is the main enthanol metabolic pathway, which does what?
converts ethanol to acetaldehyde
What is MEOS?
The microsomal ethanol oxidizing system
When is MEOS activated?
when the ADH pathway cannot keep up with moderate to excessive intake of alcohol
Where does the catalase mediated pathway occur?
hepatocytes and other cells
when does the catalase mediated pathway occur?
When alcohol consumption is excessive
What does the catalase mediated pathway use to for acetaldehyde and water?
hydrogen peroxides
What are the factors that affect alcohol metabolism?
- Ethnicity, gender, age
- low /poor aldehyde dehydrogenase activity
- Alcoholic content, amount consumed
- individual’s usual intake
- nutrition status (micronutrients are important cofactors in ethanol metabolism)
What is the result of acetaldehyde build up?
dizziness, nausea, headaches, rapid heartbeat, rapid breathing Chronic build up - promotes protein and DNA adduct formation - impairment of enzymes - DNA damage and mutagenesis - ischemia - heart failure - coagulation disorders
Explain blood alcohol content?
expressed as a percentage of ethanol in the blood.
A BAL of 0.05 means that there is 0.05g of alcohol in 100mL of the person’s blood
What blood alcohol content caused coma or death?
above 0.3
What are the 4 gudlines to reduce health risk of drinking alcohol?
- reduce risk of alcohol related harm over a life time
- reduce the risk of injury on a single occasion of drinking 3. childern and people under the age of 18, not to drink
- dont drink during pregnacy and breastfeeding
