Metabolism at a Glance

Citation

Salway, J. G. (2017). Metabolism at a Glance (4th ed.). Wiley-Blackwell.

Chapter Summary

The book presents human metabolism in 61 two-page spreads (about 140 pages), each built around a large metabolic chart with a facing page of explanation, now in full colour. The chapters are grouped in eight parts. In the preface Salway describes the fourth edition's changes: a general update, extensive revision of the carbohydrate and fatty acid/triacylglycerol chapters to include glyceroneogenesis, a revised treatment of cholesterol, an extension of the sports-science material, chapters on α- and ω-oxidation of branched-chain fatty acids, and new chapters on the molecular "production line" of fatty acid synthesis and on the "Krebs uric acid cycle", which he describes as almost entirely neglected by textbooks.

Part 1: Energy metabolism (Chapters 1–9)

Chapter 1, "Introduction to metabolic pathways", sets out the book's method. It compares the full metabolic chart to a map of the London Underground: the detail of individual enzymes matters, but to answer a question such as how glucose is turned into fat, the student should recall just enough to follow the overall route. It then shows how pathways are distributed between cytosol and mitochondrion. The rest of Part 1 covers ATP and the mitochondrial respiratory chain, the shuttles that oxidize cytosolic NADH, the yield of ATP from glucose (with a chapter title that asks whether the answer is 31 or 38), anaerobic metabolism of glucose and glycogen, 2,3-bisphosphoglycerate in the red cell, and the oxidation of triacylglycerol.

Part 2: Carbohydrate metabolism (Chapters 10–24)

Glycogen synthesis and breakdown and their regulation (four chapters); the pentose phosphate pathway; regulation of glycolysis, illustrated in cardiac muscle; glycolysis in skeletal muscle and the biochemistry of sport and exercise; regulation of gluconeogenesis and of the Krebs cycle; why mammals cannot make glucose from fatty acids; the "Supermouse" with overexpressed PEPCK in muscle; and the metabolism of sorbitol, galactitol, glucuronate and xylitol, fructose, and ethanol.

Part 3: Fat metabolism (Chapters 25–41)

The largest part, following fat from its synthesis to its oxidation: NADPH production by the pyruvate/malate cycle, the conversion of glucose and protein to fatty acids and triacylglycerol, esterification in liver and adipose tissue, mobilization of fatty acids from adipose tissue, glyceroneogenesis, elongation and desaturation, fatty acid oxidation and the carnitine shuttle, ketone body formation and use, and the oxidation of unsaturated fatty acids in mitochondria and peroxisomes, including α- and ω-oxidation.

Part 4: Steroid metabolism (Chapters 42–43)

Cholesterol, then steroid hormones and bile salts.

Part 5: Amino acid metabolism (Chapters 44–51)

Biosynthesis of the non-essential amino acids, amino acid catabolism, the conversion of amino acids to glucose in starvation and just after refeeding, disorders of amino acid metabolism, the pathways of phenylalanine and tyrosine and of tryptophan (to NAD⁺, serotonin and melatonin), and the urea cycle.

Part 6: Metabolic channelling (Chapters 52–53)

How enzymes are organized so that intermediates pass directly between them, with fatty acid synthase as the example.

Part 7: Purines, pyrimidines and porphyrins (Chapters 54–57)

Folate metabolism and the "1-carbon pool" in purine and pyrimidine synthesis, the Krebs uric acid cycle for disposing of nitrogenous waste, and porphyrin metabolism, haem and the bile pigments.

Part 8: Integration of metabolic pathways and diabetes (Chapters 58–61)

The fasting liver and its disturbance in Reye's syndrome, then three chapters on diabetes: the metabolic changes it causes, types 1 and 2 and MODY with pancreatic β-cell metabolism, and type 2 diabetes and dysfunctional liver metabolism.

Key Concepts

Parts 1–2: Energy and Carbohydrate

• Metabolic map as route map: learning the overall path between start and end products before the enzyme-level detail.
• Compartmentation: the location of pathways in cytosol or mitochondrion, which determines how intermediates must be shuttled.
• ATP yield: how much ATP the complete oxidation of glucose produces, and why the figure is debated.
• Regulation: control of glycogen metabolism, glycolysis, gluconeogenesis and the Krebs cycle by tissue and physiological state.

Parts 3–4: Lipids and Steroids

• Triacylglycerol/fatty acid cycle and glyceroneogenesis: the routes by which fat is stored, mobilized and re-esterified.
• Ketone bodies: fuels made from fatty acids by the liver and used by other tissues.
• Peroxisomal, α- and ω-oxidation: alternative pathways for fatty acids that mitochondrial β-oxidation cannot handle.

Parts 5–8: Nitrogen and Integration

• Urea cycle and Krebs uric acid cycle: disposal of nitrogen as urea or uric acid.
• One-carbon pool: folate-carried carbon units used in purine and pyrimidine synthesis.
• Metabolic channelling: direct passing of intermediates between enzymes.
• Metabolism in diabetes: how the integrated pathways are disturbed in diabetes and in the fasting liver.

Critical Analysis

Strengths

• Pathways in context. Each chart shows a pathway within the wider metabolic network, and the author's stated approach, treating the charts as a route map, helps students see how one pathway connects to the next rather than memorizing them one by one.
• Regulation and integration, not just reactions. Many chapter titles are about control (of glycogen metabolism, glycolysis, gluconeogenesis, the Krebs cycle, lipolysis) and about physiological states such as exercise, starvation and refeeding, with a closing part on integration and diabetes.
• Range of use. The publisher presents the book as suitable from introductory to advanced medical and biochemistry courses, as a concise review of inborn errors of metabolism, and as a revision aid for undergraduate examinations and USMLE Step 1. The preface adds postgraduates and specialists in diabetes, metabolic disorders, chemical pathology and sports science.
• Distinctive topics. Chapters on the "Supermouse", the Krebs uric acid cycle, metabolic channelling and α- and ω-oxidation cover material that standard textbooks often treat briefly.

Limitations

• Dense for beginners. Salway concedes in the preface that readers new to biochemistry will need to select what is appropriate to their level using their course notes, and he points them to his companion book Medical Biochemistry at a Glance as a more basic introduction.
• Metabolism only. The book does not cover protein structure, enzyme kinetics, molecular biology or nutrition, which a medical biochemistry course also requires.
• Few clinical chapters. Clinical material is concentrated in the chapters on amino acid disorders, Reye's syndrome and diabetes, and the contents include no chapters on the laboratory investigation of metabolic disease.

Where It Fits in the Course

Salway is a visual companion rather than a course text. Use it alongside a full medical biochemistry book: Marks' Basic Medical Biochemistry teaches metabolism through patient cases, and Lippincott Illustrated Reviews: Biochemistry offers outline text, figures and practice questions across the whole subject. Salway's charts are the place to see how the pathways in those books connect. Crash Course Metabolism and Nutrition is a gentler, clinically framed revision text that adds what Salway leaves out, such as vitamins, minerals, obesity and the thyroid.

For more advanced study, Keith Frayn and Rhys Evans's Human Metabolism: A Regulatory Perspective explains how metabolism is regulated across organs in feeding, fasting and exercise; Salway's preface lists Frayn's earlier book, Metabolic Regulation: A Human Perspective, as further reading. Clinical Biochemistry: Metabolic and Clinical Aspects continues into the laboratory investigation of metabolic disease.

How to Use This Book

The book suits students in medicine, veterinary science and the biomedical sciences who are taking or revising a metabolism course; school chemistry and an introductory biochemistry lecture course are the expected background.

A practical plan:

• Read Chapter 1 first for the route-map approach and the compartment layout, which every later chart assumes.
• Follow your lectures, part by part. Use Parts 1–3 alongside teaching on energy, carbohydrate and fat metabolism, then Parts 5 and 7 for nitrogen metabolism. Read the facing text with the chart open and trace each step on the chart as it is described.
• Core versus optional. For a first course, Parts 1 and 2, the main fat chapters (fatty acid synthesis and oxidation, lipolysis, ketone bodies), the urea cycle and the diabetes chapters are core; peroxisomal, α- and ω-oxidation, metabolic channelling, the "Supermouse" and the Krebs uric acid cycle can wait for later study.
• Revise actively. Cover a chart and redraw the route between two named metabolites, such as glucose to fat or amino acids to glucose in starvation, then check it.

Use Part 8 last as an integration exercise: explain, chart by chart, what changes in the fasting liver and in diabetes. Pair the book with a source of questions, since it is a visual summary rather than a workbook.