Energy Metabolism

Flashcards for Energy Metabolism Lecture Review

Energy Metabolism

All chemical reactions by which the body obtains and spends energy.

Anabolic Process

Building of substances, such as producing glycogen from glucose.

Catabolic Process

Breakdown of substances, such as breaking down glycogen to glucose.

Oxidation

Losing electrons.

Reduction

Gaining electrons.

ATP formation

Oxidation in cellular metabolism results in this energy currency form.

Metabolic Coupling

When one metabolic reaction proceeds only with the reactions it is linked to.

1st Law of Thermodynamics

Energy cannot be created nor destroyed; it can only be transformed.

Steady State (Energy Balance)

Energy intake equals energy expenditure and energy storage for a stable condition.

Positive Energy Balance

More energy is coming into the body than is needed; energy is stored as adipose tissue

Negative Energy Balance

Extra energy comes from storage, where Energy Intake is less than Energy Expenditure

1g of carbohydrate

4 kcal or 17 kj

1g fat

9 kcal = 38kj

1g protein

4 kcal = 17 kj

1g alcohol

7 kcal = 30kg

Calorimetry

Science of measuring heat production to determine energy content of food.

Bomb Calorimetry

Measures kcal in food via C and H bond breakage and energy released as heat.

Direct Calorimetry

Heat provides a measure of food energy composition as kcalories

Indirect Calorimetry

Measure of O2 consumption and CO2 production as an indicator of heat production.

Respiratory Quotient (RQ)

Ratio of moles CO2 produced per moles O2 consumed at the tissue level

2nd Law of Thermodynamics

Chemical transformations always result in a loss of free energy available to drive metabolic processes.

Gibbs Free Energy

Free energy available to drive metabolic processes.

Resting Metabolic Rate

Estimate of energy required while at rest.

Basal Metabolic Rate

Clinical measurement of metabolism under standardized conditions (AM, fasted 12 hours, quiet rest, controlled temperature).

ATP

Adenosine Triphosphate; stores energy from energy-releasing reactions (ADP -> ATP)

Glycolysis

Breaking glucose down to pyruvic acid.

Glycogenesis

Taking glucose and forming glycogen.

Glycogenolysis

Breakdown of glycogen to glucose.

Gluconeogenesis

Creation of new glucose.

Beta Oxidation

Loss of electrons.

Lipolysis

Taking triglyceride and breaking it down to fatty acids and glycerol.

Lipogenesis

Building up lipids.

Proteolysis

Breaking down protein.

Epithelium

Intestine absorptive cells.

Interstitial cells

Intestine absorptive cells moving onto the rest of the body; end product.

Monosaccharides

Simple sugar, small molecules (monomers) directly absorbed by the intestine.

Glucose transporter 5 and 2 (GLUT5 and GLUT2) and Na+/ glucose transporter 1 (SGLT1)

Transport monosaccharides across intestinal cell, into interstitial space.

Saturated (Lipids)

All free C bonds occupied by H atoms (no double bonds).

Unsaturated (Lipids)

C=C double bond (mono), multiple bonds (poly).

Emulsion droplets

Small congregations of lipid molecules held in water

Micelle

A complex of lipids and bile salts that facilitates the absorption of lipids in the small intestine.

Lymphatic Ducts

Transport long chain fatty acids.

Lipoprotein Lipase (LPL)

Exported from cell to endothelium to breakdown circulating trigs for storage.

protein

Proteins folded polymers of amino acids

Pep1 transporter protein

Co-transport: H+.

Insulin receptors

Tyrosine kinase receptor used to detected insulin.

Tyrosine kinase receptors

Adds a phosphate group to tyrosine residues on themselves and other proteins.

Glucokinase

Catalyzes the reaction of glucose to glucose-6-phosphate, the first step of glycolysis.

Glycogen synthase

An enzyme that transfers a glucose molecule to a growing glycogen chain

Gluconeogenesis

Take glucose and make more glucose

Glycogen phosphorylase

Breaks down stored glycogen into glucose and glucose-1-phosphate.

VLDL

Very low density lipoproteins.

Insulin

GLUT4 transport glucose into the cell

Insulin Phases

3 Phases of Insulin Secretion: Cephalic (freedforwards stimulation: Anticipatory), incretion (the helper) + digestive (parasympathetic (vagus)).

Epinephrine

Neurotransmitter epinephrine (adrenaline) released during low blood glucose levels (BGL).

Glucagon

Glucagon (only in liver not muscle) receptor expressed on hepatocyte wall

Ketones fuel

Glucose and fat (ketone bodies) is used CNS during fasting.

Lipid oxidation

FA broken down into 2 carbon segments.

Hormone- Sensitive Lipase

Major determinant of circulating (FA).

Glucagon - Basic role.

Increase blood glucose levels (BGL) -> getting sugar out of cells and into the blood.

Glycolysis - 3 phases

Phase 1: Glucose is activated Phase 2: Fructose is cleaved Phase 3: The 3 carbon fragments are oxidised.

Glucose -> pyruvate

Generates energy without oxygen.

Citric acid cycle -Function

Releases CO2 through the cycle.

Mitochondria -Function

Retrieves energy within FADH2 and NADH (temporary).

Metabolic control - Four steps

Substrate availability, Product accumulation,Enzyme inhibition, Allosteric regulation.

Blood glucose concentrations

Most important single factor (inhibitor).