Nutrition, Metabolism & Energy Balance Flashcards by Alyssa St.Cyr

What is a nutrient?

A substance in food that body uses for growth, maintenance and repair

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What 2 groups can nutrients be subdivided into?

Macro- and micronutrients

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What are in macronutrients?

Carbohydrates, proteins and lipids

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What are in micronutrients?

Vitamins and minerals

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What is the difference between essential and non-essential nutrients?

Essential nutrients must be provided by the diet, while non-essential nutrients can be produced by the body

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What is the purpose of soluble fiber?

Lower cholesterol levels by binding to cholesterol and not allowing it to enter circulation

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What is the purpose of insoluble fiber?

Can not be digested and facilitates defecation

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What is the purpose of glucose in the body?

Is needed for the production of ATP

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What is the most abundant dietary lipid?

Triglycerides

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What are the types of fats?

Unsaturated and saturated (includes trans) fats

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What 2 essential fatty acids can the liver not synthesize?

Linolenic and linoleic acid

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Complete vs incomplete proteins

Complete proteins contain the greatest amount of essential amino acids

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All-or-none rule for protein synthesis

All amino acids to make a certain protein must be present and in sufficient amounts for the protein to be made

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Adequacy of caloric intake

Proteins should not be used as an energy source, thus there must be fat and carbs for ATP production

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3 factors that affect protein synthesis or degradation

1)All-or-none rule
2)Adequacy of caloric intake
3)Hormonal controls

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Nitrogen balance

Can be +, neutral or -, relates to the amount of protein left in the body after consumption/excretion

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2 types of vitamins

Water and fat soluble

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7 minerals needed by the body

Ca2+, P, K+, S, Mg2+, Na2+, Cl-

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Anabolism

Buildup of larger molecules from smaller ones (aa to proteins)

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Catabolism

Breakdown of large molecules to smaller ones (proteins to aa)

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3 Step catabolic process of cellular respiration

1)Glycolysis (Tissue cells)
2)Krebs Cycle (Mitochondria)
3)Oxidative Phosphorylation (Mitochondria)

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Oxidation

Loss of electrons/gain of oxygen

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Reduction

Gain of electrons/loss of oxygen

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What are the 2 types of phosphorylation mechanisms to form ATP?

Substrate-level & oxidation

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What are the 3 phases of glycolysis?

Sugar activation Sugar cleavage Sugar oxidation

What are the products from glycolysis?

2 pyruvic acid, 2 NADH + H+, 2 ATP

Where does glycolysis occur?

Cytosol

Where does the kreb's cycle occur?

Mitochondrial matrix

What occurs in the transitional phase between glycolysis and the krebs cycle?

Pyruvic acid is converted to acetyl CoA; through the removal of a C and then oxidation through NAD+, leaving acetic acid and coenzyme A

After 1 cycle of the krebs cycle what are the products?

2 CO2, 3 NADH + H+, 1 FADH2, 1 ATP (doubled bc of 2 pyruvic acids, include transition phase)

What are the 2 phases of oxidative phosphorylation?

Phase 1: Creation of proton gradient Phase 2: Chemiosmosis (uses proton gradient to create ATP)

How much ATP is created after glucose metabolism?

~30 ATP

Glycogenesis

Glycogen formation

Glycogenolysis

Glycogen breakdown

Gluconeogenesis

Creation of new glucose molecules from non-carbohydrates (glycerol/amino acids)

2 parts of lipid metabolism

Glycerol breakdown Fatty acid breakdown

Glycerol breakdown in lipid metabolism

Glycerol converted to glyceraldehyde (1/2 glucose molecule) functions the same as glucose in glycolysis

Fatty acid breakdown in lipid metabolism

Beta oxidation, converts fatty acids to acetyl coA, goes straight to krebs cycle

Lipolysis

Breakdown of triglycerides (from storage) into glycerol and FAs Mainly used if carbohydrates are limited

Lipogenesis

Synthesis of triglycerides from glycerol and FAs, so it can be stored

Formation of ketone bodies

When there is no oxaloacetic acid, acetyl CoA accumulates

What are the 3 steps of protein metabolism?

1)Transamination 2)Oxidative Deamination 3)Keto acid modification

Which pancreatic cells release insulin?

Beta cells

Which pancreatic cells release glucagon?

Alpha cells

During what state is insulin released?

Absorptive state

Type 1 diabetes

Destruction of the beta cells that produce insulin; high blood-glucose levels

Type 2 diabetes

Target cell receptors do not respond to insulin ; high blood-glucose levels

Function of lipoproteins

Transport water-soluble cholesterol/triglycerides through the blood

Types of lipoproteins

HDLs, LDLs, VLDLs, chylomicrons

2 forms of thyroid hormone (TH)

T4 (2 tyrosine molecules & 4 iodine atoms) and T3 (2 tyrosine molecules & 3 iodine atoms)

What is the purpose of TH?

To bind to intracellular receptors in DNA to trigger transcription of various metabolic genes

What forms can be made when iodine attaches to tyrosine?

Monoiodotyrosine (MIT) or diiodotyrosine (DIT)

What occurs when TH levels are low?

Hypothalamus release TRH to the anterior pituitary gland, which release TSH to the thyroid gland

Graves disease

Hypersecretion of TH; mimic of TSH

Myxedema

Hyposecretion of TH usually due to iron deficiency and unusable thyroglobulin caused thyroid enlargement Cretinism in infants

Body Mass Index (BMI)

Used to determine obesity based on a person's weight relative to heigh

5 factors that are seen in those with metabolic syndrome

Increased: -Waist circumference -Blood pressure -Blood glucose -Blood triglycerides Decreased: -Blood HDL cholesterols

Arcuate nucleus (ARC)

Contains 2 opposing types of neurons (hunger & satiety promoting neurons)

What are the hunger-promoting neurons?

NPY/AgRP from the lateral hypothalamic area (LHA)

What are the satiety-promoting neurons?

POMC/CART from the ventromedial nucleus (VMN)

Short-term regulation of food intake

Neural signals, nutrient signals and hormones

Long-term regulation of food intake

Leptin; keeps your body at a normal body weight

Direct measure of metabolic rate

Calorimeter (heat liberated)

Indirect measure of metabolic rate

Respirometer (oxygen consumption)

Basal metabolic rate (BMR)

Energy body needs to perform its most essential activities

Total metabolic rate (TMR)

Energy needed to fuel all ongoing activities

Radiation

Heat loss by infrared rays

Conduction

Heat transfer due to direct contact

Convection

Heat transfer due to surrounding air/water

Evaporation

Heat loss due to evaporation of water from body surfaces

Main integrating center for thermoregulation

Hypothalamus