Compendium 3

Question 1

Enzymes

Answer 1

• protein catalyst that increases the rate at which a chemical reaction proceeds, without the enzyme being permanently changed
• highly specific&raquo_space; active site on an enzyme can only bind to a specific reaction
• many different enzymes needed in the body for different chemical reactions
• LIPASE&raquo_space; enzyme that breaks down lipids
• PROTEASE&raquo_space; breaks down proteins

Question 2

Anatomy of Digestive System

Answer 2

Accessory organs: primarily glands, secrete fluids
Digestive tract: also called alimentary tract
» oral cavity (mouth)
salivary glands
esophagus
stomach
small intestine
==> duodenum, ileum, jejunum
==> AO: liver, gallbladder, pancreas

Question 3

Ingestion

Answer 3

the introduction of food into the stomach (via the mouth)

Question 4

Mastication

Answer 4

Chewing

Mechanical digestion creates more surface area for chemical digestion

Question 5

Secretion

Answer 5

lubricate, liquefy, digest

e.g. mucus, secrets along the digestive tract, lubricates food, coats and protects lining

Question 6

Digestion

Answer 6

Mechanical and chemical digestion of food into nutrients

Question 7

Absorption

Answer 7

Movement of nutrients out of digestive tract into cells

Question 8

Elimination

Answer 8

Waste products removed from body (faeces). Defecation

Question 9

Histology of Digestive Tract

Answer 9

One large tube from mouth to anus plus the accessory organ

1. MUCOSA: innermost layer, secretes mucus
2. SUBMUCOSA: connective tissue later, contains blood vessels, nerves etc.
3. MUSCULARIS: 2/3 muscle layer, movement and secretion
4. SEROSA/ADVENTITIA: outermost layer, connective tissue, stability

Question 10

Peritoneum

Answer 10

Walls and organs of the abdominal cavity are lined with serous membranes

Question 11

Oral Cavity

Answer 11

Digestion begins in mouth
- Hard palate > hard bone, anterior
- Soft Palate > soft muscle, posterior
- Tongue
- Teeth
     >> masticate (chew) food, turn into bolus

Question 12

Teeth

Answer 12

Two sets
  1. primary/milk (childhood)
  2. permanent/secondary (adult,32)
Types
- incisors, canines, premolars, molars

Question 13

Salivary Gland

Answer 13

Produce and secretes saliva into oral cavity

• SALIVA > protects oral cavity, moistens, lubricates and digests food
• AMYLASE > enzyme food in saliva that breaks down carbohydrates into smaller sugars
• LYSOZYME - antibacterial enzyme

Question 14

Pharynx and Esophagus

Answer 14

PHARYNX (THROAT) > connects oral cavity to the esophagus
- Uvula (soft palate) prevents food/drink from entering the nasopharynx
ESOPHAGUS > tube that connnects pharynx to stomach (25cm)
- epiglottis prevents food/drink from entering the trachea

Question 15

Swallowing

Answer 15

1. Voluntary Phase: tongue pushes bolus back of oral cavity towards pharynx
2. Pharyngeal Phase: soft palate (uvula) close off the nasopharynx. Bolus touches receptors on oropharynx and swallowing reflex moves bolus down pharynx and into esophagus. Epiglottis covers trachea
3. bolus is moved down esophagus towards stomach by peristalsis

Question 16

Peristalsis

Answer 16

Process by which food moves through the gut. Waves of small muscle relaxations and contractions

Question 17

Stomach

Answer 17

• food comes from esophagus and stomach churns it into chyme
• produces mucus, hydrochloric acid, protein digesting enzymes
• contains a thick muscle layer that lubricates and protects epithelial cells on stomach wall from acid pH 2-3

Question 18

Stomach Layers

Answer 18

Visceral peritoneum (serosa)
Muscularis: three layers
- outer longitudinal
- middle circular
- inner oblique
Submucosa
Mucosa

Question 19

Movement of Stomach

Answer 19

• 3 muscular layers enable churning of food. Make chyme
• combination of mixing waves (80%) and peristaltic waves (20%)
• both esophageas and phyloric sphincters and closed
• stomach empties every 4 hours (6-8 after a fatty meal)

Question 20

Small Intestine

Answer 20

(6m)
Duodenum (25cm)
Jejunum (2.5m)
Ileum (3.5m)

Question 21

Duodenum

Answer 21

Chyme mixes with various digestive enzymes
Liver/gall bladder
- bile enters via the common bile duct, emulsifies fats
Pancreas
- enzymes enter via the pancreatic duct

Question 22

Liver

Answer 22

Makes bile (100ml/day). Stores glucose (as glycogen) and lipids for energy. Detoxification

Question 23

Gall Bladder

Answer 23

stores concentrated bile

Question 24

Pancreas

Answer 24

produces digestive enzymes. Produce insulin and glycogon for blood sugar homeostasis

Question 25

Large Intestine

Answer 25

- absorption of water | - cecum, colon, rectum, canal canal

Question 26

Digestive Process

Answer 26

Digestion (mouth, stomach, small intestine) - breakdown of food molecules for absorption into circulation - mechanical: breaks large food molecules into smaller - chemical: digestive amylase Absorption (nutrients from small intestine, water from the large intestine) - molecules are moved out of digestive tract and into circulation for distribution throughout body

Question 27

Nutrients

Answer 27

``` Chemicals taken into body to: - produce energy - provide building blocks to build other molecules 6 classes: - carbohydrates - proteins - lipids - vitamins - minerals - water ```

Question 28

Essential Nurtients

Answer 28

Chemicals that must be taken into the body, because we can't make them ourselves

Question 29

Recommended Amounts

Answer 29

Carbohydrates (45-65%) Lipids (20-35%) Proteins (10-35%)

Question 30

Carbohydrates

Answer 30

``` Most from plants Contains Carbon, Hydrogen, oxygen Large molecules made up of small building blocks - monosaccharides - disaccharides - polysaccharides ```

Question 31

Carbohydrate Absorption

Answer 31

- POLYSACCHARIDE CHAIN: digested by saliva (oral cavity) and pancreatic amylase (duodenum) - DISACCHARIDES CHAIN: digested by sucrase in intestines - MONOSACCHARIDE CHAINS: glucose absorbed into blood via villi/microvilli in intestine transported to liver via hepatic portal vein

Question 32

Carbohydrates (uses in body)

Answer 32

Glucose >> produce ATP Excess glucose >> glycogen and stored in muscles and liver cells Excess beyond storage is converted to fat Sugars also become part of DNA, RNA and ATP, glycoproteins, glycolipids

Question 33

Proteins

Answer 33

amino acids = basic building blocks amino acids aren't stored in the body functions of proteins >> regulate body functions

Question 34

Protein Absorption

Answer 34

- protein digested by pepsin in the stomach - polypeptides digested by trypsin in duodenum - peptides and individual amino acids are absorbed into blood via villi/mircovilli in intestine

Question 35

Lipids

Answer 35

Composed mostly of carbon, hydrogen, oxygen | Lipids/fats are broken down to release energy

Question 36

Tryglycerides

Answer 36

glycerol + 3 fatty acids

Question 37

Lipid Absorption

Answer 37

- bile from the gall bladder emulsifies lipids - lipase from the pancreas causes further breakdown - short chain fatty acids (monoglycerides) are absorbed into the lymphatic system via lacteals - lipids are stored in the adipose tissues and liver until needed

Question 38

Lipids (uses in body)

Answer 38

TRIGLYCERIDES: produce ATP CHOLESTEROL: found in liver and egg yolk. Components of plasma membranes, modified to form bile salts PHOSPHOLIPIDS: components of plasma membranes, myelin sheath, part of bile EICOSPHOLIPIDS: derived from fatty acids. Involved in inflammation, blood clotting, tissue repair, smooth muscle contractions

Question 39

Water Absoprtion

Answer 39

approx 9L | 99% absorbed

Question 40

Vitamins

Answer 40

Organic molecules in small quantities | Essential for normal metabolism

Question 41

Minerals

Answer 41

Components of co-enzymes,, some vitamins, haemoglobin, organic molecules Functions - membrane and action potential - add mechanical strength to bones and teech