Week 3 - are you what you eat?

Question 1

What is an enzyme?

Answer 1

• protein catalyst that increases the rate of a chemical reaction without being used up in the reaction
• highly specific

Question 2

What are accessory organs of the digestive system?

Answer 2

• primarily glands which secrete fluid into the digestive system
• liver, gall bladder, pancreas

Question 3

What are the 6 parts of the digestive system?

Answer 3

oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, anus

Question 4

What are the parts of the small intestine?

Answer 4

duedenum, ilium, jejunum

Question 5

What are the parts of the large intestine?

Answer 5

cecum, colon (ascending, transverse, descending), rectum, anal cavity

Question 6

List and explain the 6 functions of the digestive system (in order)

Answer 6

1. ingestion: food into digestive tract via stomach
2. mastication: chewing, large –> small surface area to facilitate chemical digestion
3. secretion: lubricate, liquify, digest
4. digestion: mechanical and chemical digestion of food into nutrients
5. absorption: nutrients from digestive tract into cells
6. elimination: waste products removed as faeces during defecation

Question 7

What are the layers of the digestive system?

Answer 7

• mucosa: innermost layer, secretes mucus
• submucosa: connective tissue layer containing blood vessels and nerves
• muscularis: 2/3 muscle layer, movement and secretion
• serosa/adventitia: outermost layer, connective tissue, stability

Question 8

What are mesenteries?

Answer 8

connects organs together; routes by which vessels and nerves pass from body wall to organs

• greater omentum: stomach to transverse colon
• lesser omentum: stomach to liver and diaphragm

Question 9

What is the palate?

Answer 9

• hard: anterior, hard bone

- soft: posterior, soft muscle

Question 10

How many teeth do adults have?

Answer 10

32

Question 11

What are the teeth types and their function?

Answer 11

incisors: biting
canines: tearing
premolars: grinding and crushing
molars: grinding and crushing

Question 12

What is the purpose of salivary glands?

Answer 12

produces and secretes saliva

Question 13

What is the function of saliva?

Answer 13

moistens and lubricates, protects oral cavity, contains salivary amylase (digests carbs) and lysozyme (antibacterial)

Question 14

What enzymes are found in saliva?

Answer 14

Salivary amylase: digests carbs

Lysozyme: antibacterial

Question 15

What is the function of the pharynx?

Answer 15

• throat

- connects oral cavity to the esophagus

Question 16

What is the purpose of the uvula?

Answer 16

-prevents food/drink from entering the pharynx

Question 17

What is the esophagus?

Answer 17

A tube that connects the pharynx to the stomach, 25cm long, is posterior to the trachae

Question 18

What is the epiglottis?

Answer 18

prevents food and drink from entering the trachea (flap)

Question 19

Describe the three phases of swallowing

Answer 19

1. voluntary phase: tongue pushes bolus to back of oral cavity towards oropharynx
2. pharyngeal phase: soft palate (uvula) closes off nasopharynx, bolus touches receptors on oropharynx and swallowing reflex is initiated, epiglottis covers trachea
3. esophageal phase: bolus moved down esophagus by peristalsis

Question 20

What is peristalsis?

Answer 20

the process by which food moves through the gut, waves of smooth muscle relaxations and contractions

Question 21

What is the process of peristalsis?

Answer 21

Wave of relaxation moves ahead of bolus, allowing bolus to pass downwards
Waves of contractions occur behind the bolus to propel bolus downwards into relaxed part of esophagus.

Question 22

What is contained in, and occurs in, the stomach?

Answer 22

Bolus moves into the stomach and is now called chyme (thick, soupy liquid)
The stomach produces mucus, HCL, and pepsin (digests protein)

Question 23

What are the sphincters of the stomach?

Answer 23

cardiac/gastroesophageal and pyloric

Question 24

What are the parts of the stomach?

Answer 24

cardiac, fundus, body and pyloric

Question 25

What are the layers of the stomach?

Answer 25

• visceral peritoneum
• muscularis –> outer longitudinal, middle circular, inner oblique
• submuscosa
• muscosa

Question 26

What are rugae?

Answer 26

Folds in the stomach that allow for stretching after eatting

Question 27

How often does the stomach empty?

Answer 27

every 4 hours, or 6-8 after a fatty meal

Question 28

What are the divisions and lengths of the small intestine?

Answer 28

small intestine = 6m
duodenum = 25cm
jejunum = 2.5m
ilium = 3.5m

Question 29

What three mechanisms increase the surface area of the small intestine?

Answer 29

• plicae ciruclaris - small circular folds in the wall
• villi - folds in mucosa, contains blood vessels and lacteals
• microvilli - small folds on epithelial cell surface

Question 30

What is the role of the liver?

Answer 30

makes roughly 100mL of bile a day, stores glucose as glycogen, detoxification

Question 31

What is the role of the gall bladder?

Answer 31

stores and concentrates bile and releases bile after fatty meals

Question 32

What is the role of the pancreas?

Answer 32

produces lipase, pancreatic amylase, trypsin

Question 33

What is the role of the large intestine?

Answer 33

water absorption and vit K and B synthesis by microbes

Question 34

What are the 6 classes of nutrients?

Answer 34

carbs, lipids, proteins, vitamins, minerals, water

Question 35

Why are chemicals taken into the body?

Answer 35

• produce energy

- provide building blocks for other materials

Question 36

What are the building blocks of carbs?

Answer 36

monosaccharides

Question 37

What are the building blocks of proteins?

Answer 37

amino acids

Question 38

What are the building blocks of lipids?

Answer 38

triglycerides (fatty acids and glycerol)

Question 39

What is the recommended amounts of carbs, proteins and lipids?

Answer 39

carbs: 45-65%
lipids: 20-35%
proteins: 10-35%

Question 40

What is an example of a monosaccharide, disaccharide and polysaccharide?

Answer 40

monosaccharide: glucose, fructose, galactose
disaccharide: sucrose, lactose, maltose
polysaccharide: glycogen, starch, cellulose

Question 41

What are uses of carbs in the body?

Answer 41

• ATP production
• storage in the liver and muscle cells
• DNA, RNA, ATP, glycoproteins, glycolipids

Question 42

What is the structure of an amino acid?

Answer 42

R group, amine group, carboxyl group

Question 43

What is the difference between essential and non-essential amino acids?

Answer 43

essential: can’t be produced in the body, 9

non-essential: can be synthesised by essential amino acids

Question 44

What is the difference between a complete and incomplete protein?

Answer 44

complete: food that contains all 9 essential amino acids, eg fish, meat, poultry, cheese, eggs
incomplete: food that doesn’t contain all 9 essential acids, eg leafy greens, grains, legumes, grains

Question 45

What is the difference between saturated, unsaturated and trans fat?

Answer 45

Saturated: all C bonds taken by H
Unsaturated: some C=C bonds, H can be added
Trans fat: unsat fats that have been artificially altered to be more saturated

Question 46

What are some uses of lipids in the body?

Answer 46

• ATP
• cholestrol used as a component of plasma membrane, bile salts
• phosopholids - forms cell membrane
• eicoanoids - involved in inflammation, blood clotting, tissue repair, smooth muscle contraction

Question 47

Vitamins

Answer 47

essential for normal metabolism, can’t be produced by the body, organic

Question 48

Minerals

Answer 48

inorganic, components of co-enzymes, vitamins, haemoglobin, organic molecules, membrane potential and action potential, mechanical strength to bones and teeth