Metabolism and Nutrition Lecture Notes

Flashcards covering the vocabulary and core concepts of human metabolism, cellular respiration, nutrient types, and thermoregulation based on the provided OpenStax anatomy and physiology notes.

Metabolism

The sum of all energy-requiring and energy-consuming processes of the body.

Anabolism

The set of biochemical reactions that build large molecules from smaller ones.

Catabolism

A set of biochemical reactions that break down complex molecules into simpler ones.

Saturated Lipids

Fats that have single bonds and are solid at room temperature.

Unsaturated Lipids

Fats that have double bonds, causing kinks in their structure, and are liquid at room temperature.

Fat Soluble Vitamins

Vitamins $A$, $D$, $E$, and $K$

can be stored in the body.

Water Soluble Vitamins

Vitamins $C$ and $B$-complex

easily passed through body as waste.

Vitamin $A$

fat-soluble; antioxidant and is essential for eye night vision

Vitamin $D$

fat-soluble; produced in skin by UV light, responsible for calcium absorption and promoting bone growth

Vitamin $K$

fat-soluble; synthesized by bacteria in large intestine, essential for blood clotting protein formation.

Vitamin $B_{12}$

water-soluble; requires intrinsic factor in the stomach for absorption; it acts as coenzyme essential for $DNA$ synthesis.

Oxidation

A chemical reaction where a compound loses electrons ($\text{OIL}$: Oxidation Is Loss).

Reduction

A chemical reaction where a compound gains electrons ($\text{RIG}$: Reduction Is Gain).

Cellular Respiration

The process that oxidizes glucose through glycolysis, the Krebs cycle, and electron transport chain to produce $ATP$.

Glycolysis

A process occurring in the cytoplasm that does not require oxygen; it yields two pyruvate molecules and two $ATP$ from one glucose molecule.

Krebs Cycle

A mitochondrial process requiring oxygen that generates $6 NADH$, $2 ATP$, and $2 FADH_2$ while converting pyruvate into Acetyl $CoA$.

Electron Transport Chain

A mitochondrial process where electrons from $NADH$ and $FADH_2$ are passed to oxygen (the final acceptor) to synthesize the most $ATP$.

Glycogenesis

The formation of glycogen from glucose, stimulated by insulin release when blood sugar is high.

Glycogenolysis

The breakdown of stored glycogen into glucose, stimulated by glucagon and epinephrine.

Gluconeogenesis

The formation of glucose from non-carbohydrate sources such as proteins and fats, stimulated by cortisol and glucagon.

Deamination

The removal of an amino group from an amino acid; the group is converted to ammonia and then urea for excretion.

Lipogenesis

The process where the liver and adipose cells synthesize lipids from glucose, occurring when caloric intake exceeds $ATP$ needs.

Lipolysis

The splitting of triglycerides into glycerol and fatty acids, enhanced by epinephrine and norepinephrine.

Ketogenesis

The formation of ketone bodies in the liver as an alternative energy source during starvation or insulin deficiency.

Ketoacidosis

A condition characterized by high levels of ketones in the blood causing the blood $pH$ to become acidic.

Low-density Lipoproteins ($LDLs$)

Known as "bad" cholesterol, these carry about $75\%$ of total cholesterol and can deposit it in fatty plaques.

High-density Lipoproteins ($HDLs$)

Known as "good" cholesterol, these remove excess cholesterol from arteries and transport it to the liver for elimination.

Absorptive State

A period lasting 2-4 hours after a meal where nutrients enter the blood, glucose is oxidized for $ATP$, and excess nutrients are stored.

Post-absorptive State

A state occurring four hours after a meal where blood glucose levels are maintained through glycogen breakdown, lipolysis, and gluconeogenesis.

Basal Metabolic Rate ($BMR$)

The amount of energy liberated or expended in a given unit of time, affected by age, gender, and hormones.

Thermoregulation

The body's maintenance of a core temperature of approximately $37^\circ\text{C}$ ($98.6^\circ\text{F}$) using the hypothalamus as a control center.

Vasoconstriction

A mechanism to conserve heat during low body temperature by narrowing cutaneous blood vessels.

Vasodilation

A mechanism to release heat during high body temperature by widening blood vessels.

Main classes of nutrients

Water, Protein, Carbohydrate, Fat, Vitamins, Minerals

Water (nutrient)

dissolves and carries nutrients, removes waste, and regulates body temp

Protein (nutrient)

builds new tissues, antibodies, enzymes, hormones, and other compounds

Carbohydrate (nutrient)

provides energy

Fat (nutrient)

provides long term energy, insulation, and protection

Vitamins (nutrient)

facilitate use of other nutrients; involved in regulating growth and manufacturing hormones

Minerals (nutrient)

helps build bones and teeth; aid in muscle function and nervous system activity

Effects of low body temperature (Thermoregulation)

vasoconstriction, shivering, increase thyroid hormone and catecholamines

Types of carbohydrates

simple carbohydrates and starches or ‘complex carbohydrates’

Dietary sources of carbohydrates

Pasta breads cereals, grains, rice, fruits, milk, yogurt, and sweets

Dietary source of lipids(fats)

butter, margarine, oils, creams, fatty meats, cheeses, and egg yolks

types of lipids

saturated fats and polyunsaturated fats

dietary sources of proteins

Animal sources: milk, eggs, meat, fish, cheese, etc.

plant sources: pulses, cereals, beans, nuts, soya beans, etc.

types of vitamins

fat soluble and water soluble vitamins

Vitamin E

fat-soluble; antioxidant that helps protect cell membranes from oxidative damage

Vitamin C

Water-soluble; important for the synthesis of collagen, immune function, and acts as an antioxidant.

Vitamin B1 (Thiamine)

Water-soluble; essential for carbohydrate metabolism and proper nerve function.

Vitamin B2 (Riboflavin)

Water-soluble; plays a key role in energy production, fat metabolism, and the maintenance of healthy skin and eyes.

Vitamin B6 (Pyridoxine)

Water-soluble; involved in amino acid metabolism, neurotransmitter synthesis, and red blood cell production.

Folic Acid (Vitamin B9)

Water-soluble; crucial for DNA synthesis, repair and methylation, as well as proper cell division and growth.

Anabolic reactions

glycogenesis, which is the formation of glycogen from glucose

protein synthesis, where amino acids are assembled into proteins

Catabolic reactions

glycolysis, where glucose is broken down to produce pyruvate and ATP,

lipolysis, where triglycerides are broken down into glycerol and fatty acids.

Oxidation-reduction reaction

OIL-RIG

oxidation, which is a chemical reaction where a compound loses electrons

reduction, where a compound gains electrons. These reactions are essential for energy production in biological systems.

Glucose catabolism (cellular respiration)

oxidizes glucose molecules through glycolysis, the Krebs cycle, and electron transport chain (oxidative phosphorylation) to produce ATP.

Formation of acetyl CoA

pyruvate is converted into two Acetyl CoA molecules through Krebs cycle

function of NAD (metabolism)

acts as a coenzyme in redox reactions, functioning as an electron carrier

function of FAD (metabolism)

acts as a coenzyme in various metabolic reactions, particularly in the Krebs cycle. It accepts electrons during reactions, becoming reduced, and then carrying electrons to ETC to contribute to ATP production

initial substrates and products (glycolysis)

The initial substrates are one glucose molecule, while the products are two pyruvate molecules, two ATP, and two NADH molecules from the breakdown of the glucose

initial substrates and products (Krebs cycle)

The initial substrate is Acetyl CoA, the products of one turn include 3 NADH, 1 FADH2, 1 ATP (or GTP), and 2 CO2 as byproducts, while regenerating oxaloacetate to continue the cycle.

initial substrates and products (Electron Transport Chain)

The initial substrates are NADH and FADH2, which donate electrons. The main products are ATP

location of glycolysis

occurs in the cytoplasm of the cell, where it does not require oxygen to break down glucose into pyruvate.

location of Kreb’s cycle

occurs in the mitochondrial matrix, where it requires oxygen to metabolize Acetyl CoA and produce energy-rich molecules like NADH and FADH2.

location of electron transport chain (ETC)

occurs in the inner mitochondrial membrane, where it utilizes electrons from NADH and FADH2 to synthesize ATP

initial substrates and products (glycogenesis)

The initial substrate for glycogenesis is glucose, while the main product is glycogen, which is formed when glucose molecules are linked together, primarily in the liver and muscle cells.

initial substrates and products (glycogenolysis)

The initial substrate for glycogenolysis is glycogen, while the products include glucose-1-phosphate and free glucose, which are released into the bloodstream when the body needs energy.

initial substrates and products (gluconeogenesis)

The initial substrates for gluconeogenesis are non-carbohydrate sources such as proteins and fats, while the main product is glucose, which is synthesized to maintain blood sugar levels during fasting or low-carb intake.

function of cortisol (carbohydrate C&A)

promotes gluconeogenesis, the formation of glucose from non-carbohydrate sources (catabolism)

influences carbohydrate metabolism by increasing blood glucose levels and inhibiting insulin's action, which affects both anabolism and catabolism processes.

function of insulin (carbohydrate C&A)

facilitates glucose uptake into cells, promoting carbohydrate anabolism by stimulating glycogenesis

&

inhibits gluconeogenesis and glycogenolysis, thus preventing excessive breakdown of carbohydrates and maintaining stable blood glucose levels.

function of glucagon (carbohydrate C&A)

promotes glycogenolysis, the breakdown of glycogen into glucose (catabolism)

&

stimulates gluconeogenesis, which helps to increase blood glucose levels during fasting or low-energy states.

function of norepinephrine (carbohydrate C&A)

enhances lipolysis, can also promote glycogenolysis (catabolism)

&

helps to mobilize energy stores during stress or low-energy states, impacting carbohydrate metabolism.

Favorable state of glycogenesis

fed (absorptive) state, Blood glucose levels are high, and insulin stimulates the liver and muscles to store excess glucose as glycogen.

Favorable state of glycogenolysis

fasting (post-absorptive) state, Blood glucose levels are falling, and glucagon (and epinephrine during exercise or stress) stimulates the breakdown of glycogen to release glucose.

Favorable state of gluconeogenesis

prolonged fasting, starvation, or extended exercise, The liver (and kidneys during prolonged fasting) synthesizes glucose from amino acids, lactate, and glycerol under the influence of glucagon and cortisol.

the effect of protein metabolism on ammonia and urea production

During protein metabolism, amino acids undergo deamination, where amino groups are removed and converted to ammonia.

Ammonia is further converted into urea in the liver through the urea cycle, allowing for safe excretion in urine.

types of lipoproteins

Chylomicrons, very low-density lipoproteins, low-density lipoproteins, high density lipoprotein

Chylomicrons

Transport dietary lipids from GI to adipose tissue

Very low-density lipoproteins (VLDLs)

•Form in hepatocytes

Transport lipids from liver to adipocytes for storage

Low-density lipoproteins (LDLs)

“bad” cholesterol

Carry 75% of total cholesterol in blood

Can deposit cholesterol in fatty plaques

High-density lipoproteins (HDLs)

“good” cholesterol

Remove excess cholesterol from arteries to liver for elimination

function of liver in metabolism

converts amino acids into substances that can enter Krebs cycle to produce ATP

What is metabolic rate?

the amount of energy expended by the body over a specific period, influenced by factors such as age, gender, and hormonal levels.

factors that affect BMR

age, gender, diet, exercise, body temp and hormonal levels