Nutrition Basics Quiz

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Questions and Answers

What is the recommended daily intake percentage of carbohydrates for maintaining a balanced diet?

10–20%

45–65% (correct)

70–80%

25–35%

Which type of carbohydrates should be prioritized in a diet?

Refined sugars

Artificial sweeteners

Simple carbohydrates

Complex carbohydrates (correct)

What is a common dietary source of saturated fats?

Fish

Coconut (correct)

Avocados

Olive oil

Which of the following fatty acids is an omega-3 fatty acid that the liver cannot synthesize?

Linolenic acid Signup and view all the answers

What role does the liver play in cholesterol levels in the body?

It synthesizes about 85% of blood cholesterol. Signup and view all the answers

What is the primary role of vitamins in the body?

To facilitate the use of macronutrients. Signup and view all the answers

Which vitamin can be synthesized in the body instead of requiring external intake?

Vitamin D Signup and view all the answers

What distinguishes water-soluble vitamins from fat-soluble vitamins?

Water-soluble vitamins are absorbed with water and not stored significantly. Signup and view all the answers

Which of the following statements about antioxidants is true?

Vitamins A, C, and E function as antioxidants by neutralizing free radicals. Signup and view all the answers

What is a consequence of excessive intake of fat-soluble vitamins?

It can cause health problems due to their ability to be stored in the body. Signup and view all the answers

Which vitamin is primarily associated with coenzyme functions in amino acid metabolism?

Vitamin B6 Signup and view all the answers

What is the primary source of Vitamin B9?

Green vegetables and legumes Signup and view all the answers

Which vitamin deficiency can lead to symptoms such as irritability, convulsions, and anemia?

Vitamin B6 Signup and view all the answers

Which vitamin is known for its role in collagen synthesis?

Vitamin C Signup and view all the answers

What is a common symptom of biotin (Vitamin B7) deficiency?

Scaly skin inflammation Signup and view all the answers

Which vitamin can mask a deficiency of Vitamin B12?

Vitamin B9 Signup and view all the answers

What type of foods primarily provide Vitamin B12?

Meats, eggs, and dairy products Signup and view all the answers

What deficiency is characterized by symptoms such as gastrointestinal upset and delayed wound healing?

Vitamin C Signup and view all the answers

What is the desirable total cholesterol level for adults, measured in mg/dl of blood?

200 mg/dl or lower Signup and view all the answers

What is a significant consequence of high LDL levels (≥160 mg/dl)?

Cholesterol deposits in artery walls Signup and view all the answers

Which dietary fatty acids are associated with increasing blood cholesterol levels?

Trans fats Signup and view all the answers

How does the liver regulate cholesterol production in relation to dietary intake?

It has a basal production rate regardless of dietary intake Signup and view all the answers

What recent finding has emerged regarding HDL levels and cardiovascular disease?

High HDL levels do not consistently protect against CV disease Signup and view all the answers

What effect do unsaturated omega-3 fatty acids have on platelets?

They prevent spontaneous clotting. Signup and view all the answers

Which body shape is associated with higher levels of cholesterol and LDLs?

Apple shape Signup and view all the answers

Which lifestyle factor is known to lower HDL levels?

Cigarette smoking Signup and view all the answers

What is now believed to be a more accurate indicator of the need for treatment in cardiovascular disease?

Non-HDL cholesterol levels Signup and view all the answers

What medication is commonly prescribed to lower LDL cholesterol levels?

Statins Signup and view all the answers

What primarily occurs during the fed state after eating?

Nutrients are stored and ATP synthesis is predominant. Signup and view all the answers

Which of the following is the major fuel for ATP synthesis during the fed state?

Glucose Signup and view all the answers

How are monosaccharides like fructose and galactose processed after absorption?

They are converted to glucose in the liver. Signup and view all the answers

What happens to excess dietary nutrients regardless of their source during the fed state?

They are transformed to fat. Signup and view all the answers

Where is glycogen primarily stored in the body during the fed state?

Liver and muscle tissue Signup and view all the answers

What is the role of very low-density lipoproteins (VLDLs) in the fed state?

To package fats with proteins for transport. Signup and view all the answers

During the fed state, how does glucose enter the cells?

It requires insulin for cell uptake. Signup and view all the answers

Which of the following statements is true about dietary amino acids in the fed state?

They are used to remake degraded body proteins. Signup and view all the answers

Study Notes

Chapter 24: Nutrition, Metabolism, and Energy Balance

Video: Why This Matters (Career Connection)
- Understanding body's nutrient conversion to energy helps advise patients on diets for peak performance.

Part 1 - Nutrients

Nutrient: substance in food needed for growth, maintenance, and repair.
Five categories.
Three macronutrients form most of our diet: carbohydrates, lipids, and proteins.
Two micronutrients (vitamins and minerals) are important but needed in smaller amounts.
Most nutrients act as metabolic fuel, some build molecules and cells.
Water accounts for ~60% of food volume.
~40 molecules are essential nutrients.
Cells (especially liver cells) have the ability to convert one type of molecule to another, adapting to varied food intakes.
Energy value: measured in kilocalories (kcal).
- One kcal raises 1 kg of water by 1°C.
- 1 kcal = one Calorie (C).
- Carbohydrates and proteins have 4 kcal/g, lipids have almost 9 kcal/g.
USDA's MyPlate: guidelines represented as portions on a dinner plate.
- Includes fruits, vegetables, grains, protein, and dairy.
Basic dietary principles:
- Eat only what is needed.
- Eat plenty of fruits, vegetables, and whole grains.
- Avoid junk food,

Part 2 - Metabolism

Metabolism: sum of all biochemical reactions in the body involving nutrients.
- Substances are constantly built (anabolism) and broken down (catabolism).
- Even at rest, the body uses energy for essential activities like breathing and nutrient absorption.

24.3 Metabolism as the Sum of Biochemical Reactions in the Body

Anabolism: reactions that build larger molecules/structures from smaller ones.
- Example: protein synthesis from amino acids.
Catabolism: reactions that break down complex structures into simpler ones.
- Example: protein hydrolysis to amino acids.
Three major stages in processing energy-containing nutrients:
- Stage 1: digestion and absorption in the gastrointestinal tract.
- Stage 2: in cytoplasm, nutrients are built into macromolecules (anabolism) or partially broken down (catabolism) with glycolysis as the main path.
- Stage 3: in mitochondria, complete breakdown of stage 2 products (mostly converted to acetyl CoA). This uses oxygen and produces ATP, carbon dioxide, and water.

Cellular Respiration

Catabolic reactions involving glycolysis, citric acid cycle, and oxidative phosphorylation.
- Convert chemical energy of nutrients (e.g., glucose) into usable energy (ATP).

Phosphorylation

Transfer of high-energy phosphate groups from ATP to another molecule.
Primes molecules for activity, motion, or work.

Oxidation-Reduction Reactions and the Role of Coenzymes

Many reactions in cells are oxidation reactions.
- Oxidation involves either gaining oxygen or losing hydrogen atoms (with their electrons).
- Oxidized substances lose electrons.
- O2 is the final electron acceptor; it joins with removed H atoms to form H2O.
Dehydrogenases: catalyze removal of hydrogen atoms
Oxidases: catalyze the transfer of oxygen
NAD+ and FAD: important coenzymes in oxidative pathways.

ATP Synthesis

Two mechanisms capture energy to produce ATP:
- Substrate-level phosphorylation: direct transfer of high-energy phosphate groups from a substrate to ADP, producing ATP.
- Oxidative phosphorylation: more complex process; mostly produces ATP via an electron transport chain and chemiosmosis.

24.4 Carbohydrate Metabolism

Body converts carbohydrates to glucose, which enters cells via glucose transporters.
The process is enhanced by insulin.
Glucose is phosphorylated within the cell to prevent it from leaving.
Only in cells of the intestine, kidney, and liver is glucose released back in.
This keeps intracellular concentrations low, which facilitates continued glucose entry via facilitated diffusion.

Oxidation of Glucose

Glucose is catabolized through glycolysis, citric acid cycle, and oxidative phosphorylation.
- Glycolysis: occurs in the cytosol, requires ten chemical steps, produces pyruvate molecules anaerobically, yields 2 ATP molecules, and 2 NADH+H+.
- Citric acid cycle: occurs in the mitochondrial matrix, generates 2 molecules of CO2, 3 NADH + H+, 1 FADH2, and 1 ATP (as GTP).
- Oxidative phosphorylation: process mostly occurs in mitochondria through electron transport chain and chemiosmosis. This generates 28 ATP per glucose.

Glycogenesis, Glycogenolysis, and Gluconeogenesis

Glycogenesis: The synthesis of glycogen, a large polysaccharide used to store carbohydrate in animals. Most active in liver and skeletal muscle.
Glycogenolysis: The breakdown of glycogen to release glucose. Active in liver and some kidney and intestinal cells, releasing glucose into the bloodstream.
Gluconeogenesis: The formation of new glucose molecules from noncarbohydrate sources like glycerol and amino acids. It is triggered by low blood glucose, and occurs primarily in the liver and some kidney and intestinal cells.

24.5 Lipid Metabolism

Fats are the most concentrated source of energy, yielding twice the energy as carbohydrate or protein.
Products of fat digestion are transported in lymph via chylomicrons and enter capillaries for various uses.
Glycerol: converted into glyceraldehyde-3-phosphate (a glycolysis intermediate), and eventually to acetyl CoA. Yields about 15 ATP.
Fatty acids: undergo beta oxidation in the mitochondria to break down into two-carbon fragments which are reduced, producing FADH2, and NADH+H+, which are used to produce ATP. Each fragment binds with coenzyme A to form acetyl CoA to enter the citric acid cycle.

Lipogenesis and Lipolysis

Lipogenesis: Synthesis of triglycerides; stimulated by high glucose levels.
Lipolysis: Breakdown of stored fat into glycerol and fatty acids; utilized when carbohydrate intake is insufficient.
The breakdown of fatty acids produces acetyl CoA that can be used in the citric acid cycle or in ketogenesis.

24.6 Amino Acids

Proteins have a limited life span and must be broken down and replaced.
- Amino acids are recycled into new proteins or different N-containing compounds (like nucleotides).
- Cells constantly take up dietary amino acids for tissue protein replacement at rates of ~100g per day.
If dietary amino acids are in excess, they are oxidized for energy or converted to fat or glycogen storage.
Deamination: removal of the amino group (-NH2). The resulting molecule is converted into pyruvate or a keto acid. Important molecule in these conversions is amino acid glutamate.
Three Degradation Events
Transamination: transfer of amine groups between molecules.
Oxidative deamination: removal of the amine group and its conversion to urea.
Keto acid modification: altering of keto acids so they can enter the citric acid cycle.

24.7 Energy Storage

Energy is stored in the fed state as glycogen and fat.
In the fasting state, energy is released through glycogenolysis and gluconeogenesis from the liver, and lipolysis and ketogenesis from adipose tissues.

24.8 The Liver

The liver carries out over 500 metabolic processes. – Carbohydrate metabolism (blood glucose homeostasis). – Fat metabolism (beta oxidation, fatty acid synthesis, lipoproteins, cholesterol). – Protein metabolism (urea synthesis, amino acid metabolism, protein synthesis).

24.9 Neural and Hormonal Control of Food Intake

For body weight to remain stable, energy intake must equal energy output.
Neural and hormonal factors regulate food intake to maintain energy balance.
Short-term regulation: (neural signals from digestive tract, nutrient signals in blood, gut hormones, and other hormones).
Long-term regulation: (hormone leptin, and/or other hormones).

Obesity

Body mass index (BMI) is a measure used to determine obesity.
- The clinically defined BMI range for obesity is >30.
Obesity is associated with chronic diseases (e.g., inflammation, insulin resistance, type 2 diabetes mellitus, cardiovascular disease, and some types of cancers, etc.).

24.10 Thyroxine and Basal Metabolic Rate

Basal metabolic rate (BMR): rate of energy output for essential activities in a fasting, relaxed state at a normal temperature
Metabolic rate is affected by several things: – Age and gender – Body temperature – Stress – Thyroxine hormone levels.

24.11 The Hypothalamus and Thermoregulation

The hypothalamus is the primary regulatory center for thermoregulation.
Receives afferent sensory input from peripheral and central thermoreceptors and initiates appropriate heat-promoting or heat-loss mechanisms.

Mechanisms of Heat Exchange

Body uses four mechanisms of heat transfer:
- Radiation: loss of heat in the form of infrared waves.
- Conduction: transfer of heat through direct contact.
- Convection: transfer of heat via movement of fluids (air).
- Evaporation: heat loss as water turns to vapor from skin. This is sensible (noticeable) or insensible (unnoticeable) depending on whether the rate of evaporative heat loss matches body's heat production.

Clinical-Homeostatic Imbalances

Hyperthermia: occurs when the body's heat loss mechanisms fail. This is a serious medical condition which can lead to heat stroke, which can cause multiple organ failure, including brain damage. Often happens after prolonged or extreme heat exposure.
Hypothermia: occurs when body temperature falls below normal and can lead to decreased cellular activities. This condition can lead to a decline in vital signs like blood pressure, respiration rate, and heart rate; and is a medical emergency. Can be caused by prolonged cold exposure.
Fever: a regulated increase in body temperature triggered by chemicals called pyrogens as a response to infection that promotes healing, inhibits bacterial growth, and enhances immune response.

Developmental Aspects of Nutrition

Good nutrition is essential for all phases of life, particularly during fetal development where sufficient calories, proteins, and vitamins are needed for brain growth.
In older adults, medication use can influence nutrient absorption and utilization.

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Test your knowledge on essential nutrition concepts with this quiz. Explore questions about carbohydrate intake, healthy fats, and the liver's role in cholesterol management. Perfect for anyone looking to enhance their understanding of dietary guidelines.