Midterm 2 Flashcards
What cells must use glucose as an energy source?
Neurons and RBCs
In what form is glucose stored in the body
Glycogen
Where is glucose stored in the body
some stored in the liver, a lot is stored in the muscels
Where is glucose released from when needed in the blood
Hydrolyzed from glycogen in the liver, glycogen in the muscle isn’t released back into the blood stream
What happens if excess glucose enters the body
either used for energy or converted to fat in the liver
Def: Gluconeogenesis
conversion of certain amino acids to be used for energy
What occurs in ketosis
fat is used to provide fuel when CHO isn’t low, fat fragments join to from ketone bodies which can be used to fed the brain
What hormones regulate blood glucose homeostasis
Insulin which causes glucose to move into cells and glucagon which promotes glucose from the liver to move into the blood
How do blood glucose hormones promote uptake or release
bind to liver and if uptake muscle cells too
Negative feedback loop of blood glucose homeostasis
- a person eats, blood glucose rises
- High blood glucose stimulates the pancreas to release insulin
- Insulin stimulates the uptake of glucose into the cells to store it as glycogen and the conversion of excess into fat for storage
- As the body’s cells use glucose, blood levels decline
- low blood glucose stimulates the pancreas to release glucagon into the blood stream
- Glucagon stimulates liver cells to break down glycogen and release glucose into the blood
- Blood glucose begins to rise
Def: Type 1 diabetes
Genetic form of diabetes, individual is unable to produce insulin
Def: Type 2 Diabetes
Caused by obesity and certain type of excess fat, individual is unable to respond to insulin creating a positive feedback loop
Def: Hypoglycemia (and what symptoms it causes)
Low blood sugar, caused by an excess of insulin in the blood stream, often a result of poorly managed diabetes. Can cause weakness, rapid heartbeat, sweating, anxiety, hunger, and trembling
Def: Hyperglycemia
High blood sugar, high amount of glucose stuck to RBCs, causes damage to tissues, heart disease and stroke, neural problems, vision and hearing loss, infections, amputations, kidney failure
Def: Oral Glucose tolerance test
Assesses your ability to handle a glucose load and regulate blood sugar
Process of a Oral Glucose Tolerance Test
- Overnight fast
- Ingestion of 75g of glucose as an oral load
- blood glucose response measured over 2-3h
- Often accompanied by hormonal measurements
Def: Glycemic Response
Speed of glucose absorption, blood glucose rise, and speed of return to normal
Def: Glycemic Index
Flood classification based on glycemic response, high index = greater glycemic response = more sugar
Def: Glycemic Load
Glycemic index x carbohydrate amount
What are the common harms of sugar
- Nutrient deficiencies: Displace calories that contain nutrients
- Dental caries: Sugars fermented to acid by bacteria erodes enamel on teeth
Factors that increase negative effects of sugar on teeth
Time in mouth, sticky foods, frequency of consumption
Why is sugar seen to make childern hyperactive
Parental expectations and often associated with events that promote hyperactivity
What are the recommended intakes of sugar
No UL, No more than 25% of total daily intake,
less than 10% is good, less than 5% is better
Def: Artificial Sweeteners
Non-nutritive sweeteners, moderate dose is considered safe, high does may cause protentional negative health effects
Stevia
A herbal sweetener, accepted by health canada
Sugar Alcohols
Nutritive (0.2 to 4 kcal/g), no dental caries, low GI, Side effects in large quantities, absorbed slowly
What is the negative effect of sweeteners
Reduces sensitivity to sweetness causing excess caloric intake in the future
Soluble Fiber
Lowers cholesterol by binding bile, slows glucose absorption, slow transit of food through upper GI tract
What are the health benefits of soluble fiber
lower risk of heart disease, lower risk of diabetes and lower risk of colon cancer
Insoluble Fiber
Increases fecal weight and speed fecal passage through colon, provides feelings of fullness
Health benefits of insoluble fiber
May help with weight management
Harmful effects of fiber
Limit ability to meet caloric intake needs, sudden introduction can cause abdominal discomfort, gas and diarrhea
DRI for Carbohydrates
RDA 130g, AMDR 45-65%
Daily fiber intake
25g/2000kcal, DRI 14g per 1000kcal per day
Fiber intake limits
WHO advises less than 40g
Def: Obesity
One who receives negative health affects due to high body weight and body fat
Obesity as a health indicator
Inaccurate on individual level, good indicator on a average health level
What are Lipids composed of
Carbons, hydrogen and oxygen
What are the uses of fat
Insulation, energy (low intensity), protection, taste for food
What is the structure of fats?
Even number of Carbons (usually 18) with H attached, carboxylic acid and methyl group
What is considered to be a long, medium and short chain
Long: 12-24
Medium: 6-10
Short: less than 6
Def: Saturated Fatty acids
No double bonds, as many H as possible, solid at room temperature, more stable, longer chain lengths
Def: Unsaturated Fatty Acids
Lose of at least 2 H atoms, liquid at room temperature, unstable, shorter chains
Def: Monounsaturated Fatty Acids
1 double bond
Def: Polyunsaturated fatty acid
2+ double bonds
Stearic Acid
18 Carbon Atoms, 0 Double bonds, saturated, Most animal fats
Oleic Acid
18 Carbon Atoms, 1 Double bonds, Monounsaturated, Olive, canola oils
Linoleic acid
18 C, 2 Double bonds, polyunsaturated, sunflower, safflower, corn and soybean oils
Linolenic Acid
18 C, 3 double bonds, polyunsaturated, soybean, flaxseed, and canola oils, walnuts
Omega Number
Location of double bonds nearest to the methyl end of the carbon chain
Triglycerides
Glycerol backbone + 3 fatty acids
What type of reaction is used to form triglyerides
condensation reaction where H2O is released
Hydrogenation
H atoms added to unsaturated fatty acids, makes liquid fat more solid at room temperature, increases shelf life
Trans Fatty Acids
Derived from the process of hydrogenation, occurs naturally in some animal-based products, behave like saturated fats in the body
Phospholipids
Glycerol + 2 FA + phosphate group, soluble in fat and water, emulsifier
Sterols
Multiple-ring structure, eg. Cholesterol and plant sterols
Lipid Digestion in the Mouth
Lingual Lipase secreted
Lipid Digestion in the Stomach
Lingual Lipase activated by acid and begins to digestion hydrolyze one bond of triglycerides to produce diglycerides and fatty acids, the stomach churning action mixes fat with water and acid
Lipid Digestion in the Small intestine
CCK signals release of bile which emulsified fat, pancreatic lipase hydrolyzes emulsified into monoglycerides, glycerol and fatty acids
Lipid Digestion in the Large intestine
some fat and cholesterol trapped in fiber, exit in feces
Emulsification by bile
- Fat and water separate with enzymes in the water,
- Bile has an affinity for both fat and water allowing it to bring the fat into the water as a micelle
- Bile converts large fat globules into small droplets
- exposes fats to enzymes
How are Triglycerides digested
Pancreatic and intestinal lipases hydrolyze the fatty acids
How are phospholipids digested
Pancreatic and intestinal lipases hydrolyze the fatty acid chains
How are sterols digested
Sterols are absorbed in their whole form
How is Glycerol absorbed
Diffuses directly into the blood stream
How are small lipids absorbed
Diffuses directly into the blood stream
Which forms of lipids can diffuse directly into the blood stream
Glycerol and small lipids
How are monoglycerides and fatty acids absorbed?
- combine with bile to form micelle
- Diffuse across membrane
- Reform triglycerides
- Combined with other lipids (cholesterol, phospholipids) and protein to form chylomicrons
- Chylomicrons enter the lymph
What types of fats are absorbed via combination with bile to form micelles
Monoglycerides and fatty acids
Def: Chylomicrons
Clusters of lipids and proteins that act as transport vehicles for fat called lipoproteins
Types of lipoproteins
Chylomicrons - large and least dense
VLDL (very-low-density lipoprotein) - bad
LDL (Low density lipoprotein)
HDL (high density lipoprotein) - good
Structure of a typical lipoprotein
The interior is composed of triglycerides and cholesterol and is surrounded by phospholipids
Phospholipids are organized similar to membranes (heads on the outside, tails on the inside)
Composition percentage of Chylomicron
Primarily triglycerides very little protein
Composition percentage of VLDL
Half triglycerides, relatively equal composition of other nutrients
Composition percentage of LDL
lots of cholesterol relatively equal composition of other nutrients
Composition percentage of HDL
Lots of proteins, least amount of triglycerides, equal parts of cholesterol and phospholipids
Similarities in VLDL and HDL
Same percentage composition of cholesterol and phospholipids in both
Function of Chylomicrons
Transport diet derived lipids to cells
Function of VLDL
Produced in liver, Deliver lipids to body (from GI tract and chylomicron remnants)
Functions of LDL
VLDL that has many triglycerides removed, High in cholesterol (delivers it to tissues)
Functions of HDL
Produced by liver to remove cholesterol from body tissues and back to liver for recycling, also has an anti-inflammatory property
Lipoprotein lipase
Enzyme that is activated in response to insulin, hydrolyzes triglycerides to glycerol and fatty acids, allowing TG to move into the cells on the endothelial cell lining of the capillaries around muscle adipose and heart tissue
Factors that lower LDL and/or raise HDL
Weight control (body composition) Monounsaturated or polyunsaturated fat in diet (instead of saturated) Soluble dietary fibers Phytochemicals (e.g. plant sterols) Moderate alcohol consumption Physical activity (mainly raise HDL)
Blood Cholesterol effects of heart attacks
Accumulates in arteries, restricts blood flow, leads to heart attack or stroke
Process of Atherosclerosis
- Damage to artery wall
- Deposition f oxidized LDL
- Inflammatory response
- Recruitment of monocytes to damages area with inflammatory response turning them into macrophages to ingest the LDL cholesterol
- Macrophages accumulate in arterial intima (take up lots of cholesterol turning them into foam cells
- Collagen deposition around foam cells ( thickening and hardening of the intimal medial layer of artery)
- Migration of smooth muscle cells forming a fiberous cap
- Artery becomes hard and non-elastic
Effects of Saturated Fat, trans fats and cholesterol consumption
Increased risk of heart disease
Effects of mono- and poly- unsaturated fat consumption
decreased risk of heart disease, larger chylomicrons/ VLDL preventing them from crossing the endothelium layer
Fat DRI
20-35%
Daily values for various fats
65g or 30% of total energy intake fats
20g or 10% of total energy intake for saturated and trans fats - low as possible
300mg cholesterol
Roles of Adipose tissue
Stores fat - creating unlimited energy store
Secrets hormones: adipokines - regulates energy balance and influence body functions
Insulation
shock absorption
structural material for membranes
Essential Fatty Acids
Linoleic Acid
Linolenic Acid
Eicosanoids
Linoleic Acid
Omega-6 - component of membrance phospholipids, required for nerves, makes arachidonic acid
Linolenic Acid
Omega-3 - Component of membrane phospholipids make EPA and DHA - needed in eyes and brain
Eicosanoids
Made from n-6 and n-3 long-chain fats, inflammatory mediating compounds (n-6 inflammatory and n-3 anti-inflammatory
Olive Oil
Low total and LDL cholesterol, low LDL oxidation, Lower blood clotting factors, Phytochemicals that acts as antioxidants, Lower BP, Lower inflammation
Nuts
Energy dense, mono- and polyunsaturated fats, Fiber, protein, and other compounds, phytochemicals that act as antioxidants, plant sterols
Fish
EPA and DHA -long chain fats
Reduce blood TG, Lower blood pressure, preventing blood clots, defending against inflammation, precursors for eiosanoid
Mediterranean Diet
High fat, low saturated fat, very low in trans fat
Effects correlations of a Mediterranean diet
lower risk of heart disease, lower risk of cancer
Functions of proteins
Building blocks of the body
Enzymes
Hormones
Where can you get protein from
Meat, eggs, milk, legumes, grains, vegetables
Amino acid structure
Contain C,H,O, & N, central carbon with an acid group (COOH) and an amino group (NH2), a unique side chain and hydrogen saturation
How many essential and none essential amino acids are there
9 essential, 11 non-essential
What is the bond between amino acids called when forming a chain
peptide bond
Primary Structure
Sequence of amino acids
Secondary Structure
Determined by week electrical attractions within chain, resulting in either a twisting or folding of protein
Tertiary Structure
Complex structures as a result of side chain properties
Quaternary sturcture
Interactions between polypeptide chains
Protein Denaturation
A proteins stability is disturbed causing it to uncoil and lose their shape along with a loss of functional ability - could be caused by heat or acid
Digestion of protien in the mouth
Mechanical digestion through mastication
Digestion of protein in the stomach
Hydrochloric acid denatures protiens and activates pepsinogen to pepsin where cleaves proteins into smaller polypeptides
Digestion of protein in the small intestine
Pancreatic and intestinal proteases turn polypeptides into tripeptides, dipeptides and amino acids, surface enzymes such as intestinal tripeptidases and dipeptidases further break down into amino acids
Protien Absorption
Amino acids transported into intestinal cells -Specific carriers for amino acids and small peptides
Once in the enterocyte they are used for energy and synthesis of other proteins
Unused AA are sent to the liver via the bloodstream
Transcription
DNA acts as a template for mRNA which copies the information
Translation
mRNA leaves the nucleus and attaches amino acids in sequence based on mRNA until completed chain is released as a protein
Roles of proteins
Building materials, Hormones, enzymes, transporters, fluid balance, acid-base balance, antibodies, provide glucose and energy, other
Role of protein as a building material
For growth, maintenance or repair, muscle, bone, skin
Role of protein as a hormone
Messenger molecules, released in response to stimuli, travel in bloodstream to tissues, elicit appropriate responses
Role of protein as an enzyme
Proteins that facilitate or help a reaction to completion - Build substances, break them down transform one substance into another
Role of protein as transporters
Transport solutes across cell membranes
Def: Gluconeogeneses
Conversion of proteins to glucose
Def: Transamination
Conversion of an amino acid to anther amino acid
What can amino acids be used to make?
Other compounds - neurotransmitters
Energy and glucose
Deamination
Removal of the N-containing amino groups, resulting in Ammonia (NH3) and keto acid
What happens when ammonia is removed form an amino acid
Ammonia is combined with CO2 in the liver to make urea since ammonia is toxic, urea is released into the blood and passes through the kidneys where it is filtered out
Protein Turnover
Continual making and breaking of proteins, turnover rate is about 1-2%/day
Amino Acid pool
Floating amino acids that are cycled through protein turnover or used for energy
Nitrogen balance
N intake - N output = N Balance
Positive Nitrogen Balance
Used to gain muscle of build tissues, when more N is going in than coming out, pregnant mom, growing child
Nitrogen Equilibrium
Equal N in and out, regular nongrowing individual
Negative Nitrogen balance
More N out than in, lose muscle mass, surgical patient or astronaut
Factors effecting nitrogen balance
Protein consumption, nitrogen in urine, feces, hair, nails, sweat, skin debris, breath
How is nitrogen balance often miscalculated
overestimated N intake, underestimated N output, overall overestimated N balance
Protein turnover cycle
- Eating acts as an anabolic stimulus
- Muscle protein synthesis rate increases and MP breakdown decrease
- without stimulus MSP will eventually drop and MPB will eventually rise
How does age effect protein turnover cycle
Elderly exhibit the same MPB as adults but lower MPS
How does resistance training effect protein turnover cycle
Increases MPS overall for the rest of the day
Do athletes require more protein for energy
Amino acid oxidation contributes to less than 5% of energy production during exercise in trained athletes, protein consumption during exercise does not improve performance
Do athletes who do resistance training need additional protein
At 0.8g/kg/d in negative protein balance, at 1.4g/kg/d in positive protein balance, at 2.4g/kg/d in very positive protein balance, there is seen to be a significant improvement in strength gains in trained athletes with higher protein intake and overall athletes
Optimal Protein intake for resistance training
at least 1.6g/kg/d with a confidence interval of 1.1 - 2.2
Protein RDA for endurance athletes
1.2-1.4g/kg/d
Protein RDA for team sports
1.2-1.7g/kg/d
Protein RDA for power
1.5-1.7g/kg/d
Protein RDA for strength
1.6-1.7g/kg/d
Protein for Energy restriction
2.0g/kg/d (lose weight while building muscle mass)
