6.1 digestive system

Question 1

salivary glands

Answer 1

moistens food into a bolus. begins polysaccharide digestion. Secrete salivary amylase to start the digestion of starch.

Release saliva to moisten food and contains enzymes (e.g. amylase) to initiate starch breakdown. Salivary glands include the parotid gland, submandibular gland and sublingual gland.

Question 2

draw diagram of digestive system

Answer 2

see ipad (photos)

Question 3

liver

Answer 3

detoxifies certain molecules. stores vitamins, iron, glycogen. synthesizes bile.

Takes the raw materials absorbed by the small intestine and uses them to make key chemicals. Its role includes detoxification, storage, metabolism, bile production and haemoglobin breakdown.

Question 4

gall bladder

Answer 4

stores / concentrates bile

The gall bladder stores the bile produced by the liver (bile salts are used to emulsify fats). Bile stored in the gall bladder is released into the small intestine via the common bile duct.

Question 5

small intestine

Answer 5

absorbs nutrients.

A long, highly folded tube where usable food substances (nutrients) are absorbed. majority of digestion & absorption occurs here.

peristaltic muscle contractions slow to allow time for digestion/absorption
the wall of the small intestine contains villi to increase surface area for absorption.

Question 6

rectum / anus

Answer 6

stores and expels feces

Question 7

esophagus

Answer 7

transports food to stomach

A hollow tube connecting the oral cavity to the stomach. Food is mixed with saliva and then is moved in a bolus via the action of peristalsis.

Question 8

stomach

Answer 8

stores and churns food. begins protein digestion.

A temporary storage tank where food is mixed by churning and protein digestion begins. It is lined by gastric pits that release digestive juices, which create an acidic environment (pH ~2)

Question 9

pancreas

Answer 9

releases digestive enzymes. releases hormones (e.g. insulin). Also secretes certain hormones (insulin, glucagon), which regulate blood sugar concentrations.

Secretes digestive enzymes that include amylases, peptidases, lipases
Also secretes bicarbonate ions, a weak base, to neutralize stomach acid.
Also an organ of the endocrine system

Question 10

large intestine

Answer 10

absorbs water and ions.

The final section of the alimentary canal, where water and dissolved minerals (i.e. ions) are absorbed. Consists of the ascending / transverse / descending / sigmoidal colon, as well as the rectum.

Question 11

peristalsis

Answer 11

longitudinal and circular smooth muscles contract and relax to create a “peristaltic wave” that allows food to move along the digestive tract

Question 12

digestion

Answer 12

the breaking down of food into smaller particles. mechanical and chemical.

Question 13

mechanical digestion

Answer 13

includes chewing (mouth) and churning (stomach)

Question 14

chemical digestion

Answer 14

the breakdown of polymers into monomers in enzyme catalyzed reactions. digestive juices aid this process.

Question 15

alimentary canal

Answer 15

consists of organs through which food actually passes (oesophagus, stomach, small & large intestine)

Question 15

3 enzymes of the digestive system

Answer 15

amylases, proteases/endopeptidases, lipases

Question 16

accessory organs

Answer 16

aid in digestion but do not actually transfer food (salivary glands, pancreas, liver, gall bladder)

Question 17

mouth pH

Answer 17

7

Question 18

label a transverse cross section of the small intestine

Answer 18

see ipad (photos)

Question 19

label a longitudinal cross section of the small intestine

Question 20

carbohydrate digestion: how does Starch (amylose/amylopectin) → maltose → glucose → glucose monomers

Answer 20

starch → maltose
- mouth
- enzyme: salivary amylase, secreted from salivary glands
- optimal pH around 7

maltose → glucose
- small intestine
- enzyme: pancreatic amylase, secreted from pancreas
- optimal pH: 8

The epithelial lining of the small intestine also contains an enzyme called maltase, which further breaks down glucose into monomers.
Glucose then travels to the liver where it is metabolized into glycogen (if insulin levels are high).

Question 21

protein digestion

Answer 21

Proteins → peptide → amino acids

protein → peptide
- stomach
- enzyme: pepsin, secreted from stomach
- optimal pH: 2

peptide → amino acids
- small intestine
- enzyme: trypsin, secreted from pancreas
- optimal pH: 8

Question 22

pepsin

Answer 22

a type of protease enzyme

Question 23

lipid digestion

Answer 23

• (triglycerides) → fatty acids + glycerol
• small intestine
• enzyme: lipase, secreted from pancreas
• optimal pH: 8

Question 24

Explain the action of enzymes in the digestive system

Answer 24

Enzymes are proteins that speed up the rate of reactions
Each enzyme has an optimal pH level (max rate of reaction). Above/Below that pH, it is denatured.

Question 25

3 components of small intestine

Answer 25

• lumen
• mucosa
• smooth muscle

Question 26

structure of a villus (6)

Answer 26

• Single-layer of epithelial cells
• Large blood supply/capillary network
• Large number of villi
• Microvilli
• Lacteal
• Membrane Proteins

Question 27

label villi diagram

Answer 27

see ipad (photos)

Question 28

function of single-layer of epithelial cells in villi in small intestine

Answer 28

easy transport of nutrient, thin layer to cross

Question 29

function of Large blood supply/capillary network in villi of small intestine

Answer 29

more surface area for absorption

Question 30

function of having a large # of villi in small intestine

Answer 30

more surface area for absorption

Question 31

function of microvilli in small intestine

Answer 31

more surface area for absorption

Question 32

function of lacteal in villi of small intestine

Answer 32

transport of fatty acids

Question 33

function of membrane proteins in villi of small intestine

Answer 33

facilitated diffusion & active transport

Question 34

how is glucose transported across the epithelial cells of the small intestine?

Answer 34

• Secondary Active
• Co-transport w/ Na+ ions
• into Bloodstream

Question 35

how are monosaccharides (besides glucose) transported across the epithelial cells of the small intestine?

Answer 35

• Facilitated diffusion
• Hydrophilic Channel proteins
• into Bloodstream

Question 36

how are amino acids transported across the epithelial cells of the small intestine?

Answer 36

• Secondary Active
• Co-transport w/ Na+ ions
• into Bloodstream

Question 37

how are lipids transported across the epithelial cells of the small intestine?

Answer 37

• Simple diffusion
• simple diffusion into hydrophobic part of plasma membrae
• into Lacteal

Question 38

where are carbs, proteins, and lipids digested?

Answer 38

Carbohydrates are broken down in the mouth and small intestine, proteins in the stomach and small intestine, and lipids in the stomach and small intestine.