Chapters 9, 14, 15 & 11 – Energy, Water/Minerals, and Exercise

90 question-and-answer flashcards summarizing key concepts from chapters on energy metabolism, water & mineral balance, trace minerals, and exercise physiology.

What is energy metabolism?

Deriving energy from macronutrients. Multisteps series of energy transforming reactions.

Define a metabolic pathway.

A coordinated series of enzyme-catalyzed chemical reactions that convert a starting compound into an end product.

What are metabolic intermediates?

compounds formed in any steps along a metabolic pathway.

What is an anabolic pathway?

A pathway that uses energy to build larger molecules from smaller ones.

What is a catabolic pathway?

A pathway that breaks large molecules into smaller ones, releasing energy.

Name the three stages of overall metabolism.

(1) Digestion and absorption, (2) Conversion to acetyl-CoA or other intermediates, (3) Citric acid cycle & electron transport to produce ATP.

What is the body’s immediate source of energy?

Adenosine triphosphate (ATP).

From which nutrients is cellular energy primarily derived?

Carbohydrates, fats, proteins (and to a lesser extent alcohol).

How do oxidation-reduction (redox) reactions transfer energy?

By moving electrons (and H+) from one molecule to another, capturing energy in NADH and FADH2.

What happens to a substance when it is oxidized?

It loses electrons (and often hydrogen).

What happens to a substance when it is reduced?

It gains electrons (and often hydrogen).

Which B-vitamin coenzymes carry electrons in redox reactions?

Niacin (NAD⁺/NADH) and riboflavin (FAD/FADH2).

List the four stages of aerobic cellular respiration.

Glycolysis, Transition reaction (pyruvate → acetyl-CoA), Citric acid (TCA) cycle, Electron transport chain (ETC).

How many net ATP are produced in glycolysis?

2 ATP (plus 2 NADH).

Glycolysis: starting & ending compounds and cellular location?

Starts with glucose, ends with 2 pyruvate; occurs in the cytosol.

Which step of aerobic respiration yields the most ATP?

Electron transport chain/oxidative phosphorylation (~28 ATP).

Why is oxygen essential for the ETC?

It is the final electron acceptor, allowing NADH/FADH2 to be re-oxidized and ATP to form.

What is anaerobic metabolism and when does it occur?

ATP production without oxygen, used during intense, short-duration activity or limited O2 supply.

During anaerobic glycolysis, pyruvate is converted to what?

Lactate (lactic acid).

Which enzyme regenerates NAD⁺ during anaerobic glycolysis?

Lactate dehydrogenase.

What is the Cori cycle?

Lactate from muscle travels to liver, is reconverted to glucose, then returned to muscle.

Where does the Cori cycle take place?

Muscle (lactate production) and liver (glucose synthesis).

What is β-oxidation?

The stepwise removal of two-carbon units from fatty acids to form acetyl-CoA in mitochondria.

Approximate ATP yield from complete oxidation of a 16-carbon fatty acid (palmitate)?

~106–108 ATP.

Why do fats yield more ATP than glucose?

They contain more reduced (H-rich) carbons, providing more electrons for the ETC.

Under what conditions does ketogenesis occur?

Very low carbohydrate intake, uncontrolled diabetes, or prolonged fasting.

Name the primary ketone bodies produced.

Acetoacetate, β-hydroxybutyrate, and acetone.

Give two consequences of ketosis.

Loss of lean tissue and electrolyte imbalance; fruity breath or ketoacidosis in diabetes.

Where does most protein catabolism occur?

In the liver (and to a lesser extent muscle).

Which cofactor removes amino groups from amino acids?

Vitamin B-6 (pyridoxal phosphate, PLP).

What is the urea cycle?

Liver pathway that converts toxic ammonia to urea for kidney excretion.

Define gluconeogenesis.

Formation of glucose from non-carbohydrate precursors (e.g., amino acids, lactate, glycerol).

Why can’t fatty acids serve as carbon for gluconeogenesis?

β-oxidation yields acetyl-CoA, which cannot be converted back to pyruvate or oxaloacetate in humans.

What is the main alcohol-metabolizing pathway?

Alcohol dehydrogenase (ADH) pathway in the liver.

List the enzymes of the ADH pathway.

Alcohol dehydrogenase → acetaldehyde dehydrogenase → acetate formation.

Give three key metabolic roles of the liver.

Regulates blood glucose, synthesizes bile/proteins, detoxifies and processes nutrients.

How does insulin influence energy metabolism?

Promotes glucose uptake, glycogen and fat synthesis, and inhibits catabolic pathways.

What metabolic changes occur during prolonged fasting?

Glycogen depletion, increased lipolysis & ketone production, protein breakdown for gluconeogenesis.

What metabolic changes occur during feasting?

Elevated insulin, glycogen and triglyceride synthesis, inhibition of fat oxidation.

List three primary functions of water.

Solvent/transport medium, temperature regulation, lubricant/cushion for tissues.

Approximately what percent of adult body weight is water?

About 50–60%.

Which tissue holds more water: muscle or adipose?

Muscle (≈ 75%) versus adipose (≈ 10–20%).

Name four routes of daily water loss.

Urine, sweat, exhaled air, and feces.

Describe how the Renin-Angiotensin system responds to low fluid.

Renin → angiotensin II → vasoconstriction & aldosterone release → sodium/water retention ↑ blood pressure.

Give two common causes of dehydration.

Inadequate intake, excessive sweating/vomiting/diarrhea.

List two signs of water intoxication.

Hyponatremia, headache/confusion or seizures.

What is the action of antidiuretic hormone (ADH)?

Increases kidney water reabsorption, reducing urine output.

How does aldosterone regulate electrolytes?

Stimulates kidneys to retain sodium (and water) and excrete potassium.

Why does dehydration lower urine output?

ADH and aldosterone signal kidneys to conserve water and sodium.

Which two minerals are central to fluid balance?

Sodium and potassium.

What role does sodium play in nerve transmission?

Depolarization: sodium rushes into neurons, creating an action potential.

What percentage of table salt is sodium?

About 40% sodium, 60% chloride by weight.

How does the body lower excess blood potassium?

Aldosterone signals kidneys to excrete potassium in urine.

Why do potassium-rich diets help prevent hypertension?

Potassium promotes vasodilation and counters sodium’s blood-pressure-raising effect.

What blood pressure defines Stage 1 hypertension?

Systolic 130–139 mmHg or diastolic 80–89 mmHg.

Name two organs commonly damaged by prolonged hypertension.

Heart and kidneys (also brain, eyes).

Which vitamin is essential for calcium homeostasis?

Vitamin D (calcitriol).

Give one factor that reduces calcium bioavailability.

High oxalate or phytate intake, low vitamin D, or high fiber.

Which populations absorb calcium most efficiently?

Children, adolescents, and pregnant women.

How is heme iron different from non-heme iron in absorption?

Heme iron (animal foods) is absorbed intact (~25%); non-heme (plant/animals) requires reduction and is less absorbed (~2–15%).

What protein transports iron in blood?

Transferrin.

In which protein is excess iron stored in cells?

Ferritin (and hemosiderin when stores are high).

Name one enhancer and one inhibitor of non-heme iron absorption.

Enhancer: vitamin C or meat factor; Inhibitor: phytates, polyphenols, or calcium.

At what point does iron deficiency become anemia?

When hemoglobin production declines and blood Hb falls below normal range (Stage 3).

Which compounds decrease iodine bioavailability?

Goitrogens in cruciferous vegetables, cassava, millet, soy.

Name the two classic iodine deficiency disorders.

Goiter and cretinism.

What is the selenium deficiency disease?

Keshan disease (cardiomyopathy).

List two key functions of zinc.

Enzyme cofactor for protein synthesis & DNA/RNA; immune function; wound healing; taste perception.

What is a common non-dietary source of fluoride?

Fluoridated drinking water (and some toothpaste).

Give three benefits of regular exercise.

Improved cardiovascular health, weight management, and enhanced mental well-being.

What are the three pillars of a good fitness program?

Variety (mode), overload/progression, and consistency.

How does ATP supply energy for contraction?

Myosin heads hydrolyze ATP, releasing energy to slide actin filaments.

Which high-energy compound rapidly regenerates ATP during short bursts?

Phosphocreatine (PCr).

Which energy pathway dominates in the first 30 s of intense exercise?

Anaerobic glycolysis (lactate system).

Which tissue stores more total glycogen?

Muscle (larger mass) exceeds liver in total content.

What is “hitting the wall” in endurance sports?

Severe fatigue from muscle & liver glycogen depletion (bonking).

At what intensity is fat the main fuel source?

Low to moderate (≈ 25–65% VO2 max).

Which muscle fiber type is recruited for sprinting?

Type IIx (fast-twitch glycolytic) fibers.

Define muscular atrophy.

Loss of muscle size and strength from inactivity or undernutrition.

Why do athletes practice carbohydrate loading?

To maximize muscle glycogen stores for endurance performance.

How does a ketogenic diet typically affect high-intensity athletes?

May impair high-intensity/anaerobic performance due to limited glycogen.

Recommended protein intake for strength athletes?

About 1.6–2.0 g/kg body weight per day.

Differentiate sports anemia from true anemia.

Sports anemia is temporary plasma expansion lowering Hb concentration; true anemia involves depleted iron stores and low Hb mass.

What does RED-S stand for?

Relative Energy Deficiency in Sport.

Give two symptoms of heat exhaustion.

Profuse sweating and dizziness (others: weakness, rapid pulse).

Fluid to replace each pound lost during exercise?

About 2–3 cups (16–24 fl oz; ~475–700 mL).

What causes water intoxication in endurance events?

Excessive plain water intake diluting blood sodium (hyponatremia).

When are sports drinks preferable to water?

Activities >60 min or very hot/humid conditions to replace carbs & electrolytes.

General carbohydrate intake within 30 min post-exercise?

≈1.0–1.5 g carbohydrate per kg body weight.

Are most ergogenic aids proven effective and how are they regulated in the U.S.?

Few have solid evidence; supplements are regulated as foods, not drugs—manufacturers, not FDA, ensure safety/effectiveness.