HUMB1000 – Compendium 3: Are You What You Eat?

1. What is an abdominal quadrant?

One of 4 regions of the abdomen, defined by a transverse umbilical plane and a mid-sagittal plane (RUQ, LUQ, RLQ, LLQ).

2. What is an abdominopelvic region?

One of 9 regions of the abdomen, defined by two vertical (parasagittal) and two horizontal (transverse) planes.

3. What is the appendix?

A small pouch attached to the caecum; can become inflamed (appendicitis), sometimes treated by surgical removal.

What is Body Mass Index (BMI)?

A measure calculated from weight and height (kg/m²) used to estimate whether someone is in a healthy weight range.

What is a calorie?

A unit of energy; 1 Calorie = 4.18 kilojoules (kJ). Used in the USA; Australia uses kilojoules.

6. What is a carbohydrate?

A macromolecule built from monosaccharides; the body's primary and quickest energy source.

7. What is digestion?

The process of breaking down large food molecules into smaller building blocks (e.g. polysaccharides into monosaccharides).

8. What is an enzyme?

A protein that increases the rate of a chemical reaction but is not permanently changed by the reaction.

9. What does 'extrinsic' mean (re: muscles)?

Originating outside the structure it acts on, e.g. extrinsic tongue muscles.

10. What is the gallbladder?

An accessory digestive organ that stores bile produced by the liver and delivers it to the duodenum.

. What does 'intrinsic' mean (re: muscles)?

Originating inside the structure it acts on, e.g. intrinsic tongue muscles originate inside the jaw (per compendium).

12. What is a kilojoule?

The unit Australia uses to express food energy; 1 Calorie = 4.18 kJ.

13. What is the large intestine?

The ~1.5 m wide final section of the GI tract; absorbs water, hosts bacteria that synthesise vitamins B and K, and forms faeces.

14. What is a lipid?

A macromolecule built from fatty acids and glycerol; used for energy storage, insulation, hormones and cell membranes.

15. What is the liver?

An accessory organ that produces and secretes bile and processes nutrients absorbed from the small intestine.

16. What are macromolecules?

Large molecules such as carbohydrates, lipids and proteins, built from smaller repeating building blocks.

17. What is mastication?

The act of chewing food.

18. What is the mediastinum?

The space between the lungs, through which the oesophagus travels.

19. What are minerals?

Inorganic nutrients the body needs in small amounts for normal function (e.g. iron, calcium).

20. What is nutrition?

The process of obtaining and using food/nutrients for growth, energy and health.

21. What is the oesophagus?

A muscular tube that carries food from the pharynx to the stomach, posterior to the trachea.

22. What is the oral cavity?

The mouth; where mechanical digestion (chewing) and initial chemical digestion (salivary amylase) begin

23. What is the pancreas?

An accessory organ that secretes pancreatic juice (digestive enzymes + bicarbonate) into the duodenum.

24. What is peristalsis?

Involuntary, wave-like muscular contractions that propel food through the digestive tract.

25. What is a protein?

A macromolecule built from amino acids; used for structure, enzymes, hormones and antibodies.

26. What are salivary glands?

Glands (three pairs) that secrete saliva, containing water, mucus and salivary amylase, into the oral cavity

27. What are the small intestines?

A ~6 m long tube (duodenum, jejunum, ileum) where most chemical digestion and nutrient absorption occurs.

28. What is the stomach?

A muscular, acidic, J-shaped organ that stores food, mechanically churns it, and begins protein digestion.

29. What is the uvula?

A continuation of the soft palate; closes off the nasopharynx during swallowing.

30. What does 'visceral' mean?

Relating to the internal organs, e.g. the visceral surface of the liver where vessels/ducts and the gallbladder attach.

31. What is a vitamin?

An organic compound needed in small amounts for normal body function; deficiency causes specific disorders.

Name the six classes of nutrients.

Carbohydrates, lipids, proteins, water, vitamins and minerals.

Give an example of a monosaccharide.

Glucose, fructose or galactose.

3. Give an example of a disaccharide.

Sucrose (table sugar) or lactose (in milk).

4. Give an example of a polysaccharide.

Starch or cellulose.

5. What makes up a triglyceride?

Glycerol and 3 fatty acids.

6. What is the difference between a saturated and unsaturated fat?

A saturated fat has hydrogen attached to nearly every carbon; an unsaturated fat does not. Unsaturated fats are considered healthier.

7. What is a polypeptide?

A chain of amino acids linked together.

8. Name a disorder caused by a vitamin deficiency and its cause.

Vitamin D deficiency → rickets; Vitamin C deficiency → scurvy; Vitamin B1 (thiamine) deficiency → beriberi.

9. What are the building blocks of carbohydrates?

Monosaccharides.

10. What are the building blocks of proteins?

Amino acids.

11. What are the building blocks of lipids?

Fatty acids and glycerol.

12. What is the main function of carbohydrates in the body?

Energy source for cells; also form part of DNA/RNA and cell membranes (glycolipids, glycoproteins).

13. What is the main function of proteins in the body?

Regulate body functions (hormones, antibodies, membrane/structural proteins) and make up muscle tissue.

14. What is the main function of lipids in the body?

Myelin sheath formation, heat insulation, physiological regulation, cell membrane component, energy source.

15. Give dietary sources of carbohydrates.

Grains, breads, fruit, vegetables.

16. Give dietary sources of protein.

Meat, fish, dairy, nuts, beans, pulses and legumes.

17. Give dietary sources of lipids.

Dairy products, meat, fish, nuts.

18. What recommended % of daily kilojoule intake should come from carbohydrates?

45–65%.

19. What recommended % of daily kilojoule intake should come from protein?

10–35%.

20. What recommended % of daily kilojoule intake should come from lipids?

20–35%.

21. How much energy (kJ/g) does fat/lipid provide?

37 kJ/g — the most energy-dense macromolecule.

22. How much energy (kJ/g) does carbohydrate provide?

16 kJ/g.

23. How much energy (kJ/g) does protein provide?

17 kJ/g.

24. Which macromolecule does the body usually break down first for energy, and why?

Carbohydrates — because it's quicker and easier than breaking down fat or protein.

25. Why is it wrong to say kilojoules from fat, carbs and protein are 'equal' for health?

Each macromolecule has distinct structural/functional roles; relying on only one (e.g. all kJ from chocolate) causes malnutrition even if total kJ intake is 'normal'.

1. What is Basal Metabolic Rate (BMR)?

The minimum energy expenditure required to support metabolism in an awake, rested person after a good night's sleep and 12 hrs fasting at 22–23°C.

2. What % of total daily metabolic rate does BMR contribute?

65–70%.

3. What % of daily energy expenditure is used digesting food?

About 10%.

4. What % of daily energy expenditure can physical activity contribute?

Up to 30%.

5. What factors affect an individual's nutritional/energy needs?

Age, sex, height, physical activity level, pregnancy (+1254 kJ/day), lactation status (+2090 kJ/day).

6. What determines whether someone gains or loses body weight?

The balance between energy input (food/drink) and energy output (activity/exercise/BMR).

7. What is catabolism?

The biochemical reaction in cells that breaks down absorbed nutrient molecules to release usable energy (ATP).

1. What are the 4 main processes of the digestive system, in order?

1) Ingestion 2) Digestion 3) Absorption 4) Cellular respiration.

2. What is ingestion?

The intake of complex foods into the body.

3. What is the difference between digestion and absorption?

Digestion breaks down large food molecules into small particles (e.g. polysaccharides → monosaccharides). Absorption is when those molecules move from the digestive tract into the body

4. What is cellular respiration in the context of digestion?

Cells break down absorbed molecular building blocks to release energy, stored as ATP.

5. What is chyme?

The semi-liquid, acidic mixture of food and gastric juice that leaves the stomach and enters the small intestine

1. What is the main function of the mouth in digestion?

Chews food into a bolus (mechanical digestion) and salivary amylase begins chemical digestion of carbohydrates.

2. What is the main function of the oesophagus in digestion?

Transports the bolus from the pharynx to the stomach via peristalsis.

3. What is the main function of the stomach in digestion?

Mechanical digestion (churning) and chemical digestion of protein by pepsin; produces chyme.

4. What is the main function of the small intestine in digestion?

Chemical digestion of carbs, proteins and lipids by pancreatic enzymes; absorption of small molecules into the body across the GI wall.

5. What is the main function of the large intestine in digestion?

Absorption of water; synthesis of vitamin B and K by bacteria; formation of faeces.

6. Name the three accessory organs of the digestive system.

Liver, gallbladder and pancreas.

7. What is the liver's role in digestion?

Produces and secretes bile (important for fat digestion) and processes nutrients absorbed from the small intestine, since that blood passes through the liver first.

8. What is the function of bile in digestion?

Bile emulsifies fat, breaking large lipid droplets into smaller ones so enzymes can access them better, promoting lipid digestion and absorption.

9. What is the gallbladder's role in digestion?

Stores bile produced by the liver and delivers it to the duodenum.

10. What does pancreatic juice contain, and where is it delivered?

Digestive enzymes (for carbs, protein, fat) and bicarbonate ions; delivered to the duodenum via two main ducts

11. What is the function of pancreatic bicarbonate?

It decreases the acidity of chyme entering the duodenum.

12. Why must the liver and pancreas be located close to the duodenum?

Because both organs secrete their digestive substances directly into the duodenum.

1. What are the two surfaces of the liver?

A smooth surface that sits against the diaphragm, and the visceral surface (has ducts, vessels and the gallbladder attached).

2. Name the four lobes of the liver.

Right lobe, left lobe, quadrate lobe, and caudate lobe.

3. Where is bile produced and where is it stored?

Produced by the liver, stored/concentrated in the gallbladder, then delivered to the duodenum.

4. What happens to bile if the gallbladder is removed (e.g. due to gallstones)?

Bile becomes more dilute and can't be released 'on demand' after a fatty meal, so dietary fat is broken down less efficiently — the person should reduce dietary fat intake

5. What are gallstones?

Insoluble deposits inside the gallbladder from an accumulation of bile salts; can cause painful obstruction, sometimes requiring gallbladder removal.

1. Name the four muscles of mastication.

Temporalis, masseter, lateral pterygoid, medial pterygoid.

2. How does mastication contribute to digestion?

It mechanically breaks food into small pieces, increasing surface area for digestive enzymes to act on.

3. What is the difference between intrinsic and extrinsic tongue muscles?

Intrinsic muscles originate inside the jaw; extrinsic muscles originate outside the jaw (per compendium terminology).

4. What is the lingual frenulum?

The thin fold of tissue attaching the tongue to the floor of the mouth.

5. What is the role of the tongue once food is in the mouth?

Pushes the bolus against the hard palate, then directs it to the pharynx and oesophagus.

6. How many incisors does an adult have, and what is their role?

8 (4 upper, 4 lower); role: cutting.

7. How many canines does an adult have, and what is their role?

4 (2 upper, 2 lower); role: tearing.

8. How many premolars does an adult have, and what is their role?

8 (4 upper, 4 lower); role: grinding/shredding.

9. How many molars does an adult have, and what is their role?

12 (6 upper, 6 lower); role: grinding/shredding.

10. What forms the roof of the oral cavity, and what are its two parts?

The palate; anterior bony hard palate and posterior non-bony soft palate.

11. What is the role of the uvula during swallowing?

It closes off the nasopharynx so food is directed into the oesophagus rather than the nose.

12. How does saliva contribute to digestion?

It lubricates food for chewing/swallowing (serous + mucous components) and contains salivary amylase, which begins carbohydrate digestion in the mouth.

13. How many pairs of salivary glands are there?

Three pairs.

1. Name the three subdivisions of the pharynx.

Nasopharynx (back of nose), oropharynx (back of mouth), laryngopharynx (near the larynx).

2. What path does swallowed food take through the pharynx?

Mouth → oropharynx → laryngopharynx → oesophagus.