Biol121 Digestion Lecture 3 Chemical Digestion

Front 1

What are the (8) essential nutrients?

Back 1

1. Carbohydrates

2. Proteins

3. Lipids

4. Vitamins

5. Minerals

6. Electrolytes

7. Fibre

8. Water

Front 2

What are the (3) different types of carbohydrates, from biggest to smallest?

Back 2

BIGGEST: Polysaccharides

MIDDLE: Disaccharides

SMALL: Monosaccharides

Front 3

What is the only type of carbohydrate that can be absorbed?

Give (2) examples of these.

Back 3

Monosaccharides

Glucose, fructose

Front 4

What are (3) examples of disaccharides?

Back 4

Sucrose, lactose, maltose

Front 5

What are polysaccharides the storage of?

Give (2) examples.

Back 5

Glucose.

Starch, glycogen, (cellulose)

(cellulose can't be digested, is dietary fibre & gets secreted)

Front 6

What are proteins made of?

List (4) roles of this ^ .

Back 6

A chain of amino acids.

support, movement, transport, buffering

Front 7

What are the functions of lipids? (5)

Back 7

1. Large energy source (KJ wise)

2. Insulation (myelin)

3. Physical protection (adipose)

4. Chemical messenger

5. Structural component of cells

Front 8

What are fats broken down into?

What are 2 types of these that we do not make within the body?

Back 8

Fatty acids.

Omega 3 (Linoleic acid)

& omega 6 (Alpha-linolenic acid)

Front 9

What is the most important fatty acid in terms of digestion?

Back 9

Triglycerides (three amino acid chains bound by a glycerol)

Front 10

Where does carbohydrate digestion begin, stop, then start again? Talk me through it.

Back 10

Salivary amylase starts to break down carbohydrates in the mouth, ph7.

Denatured in the stomach with acidity being higher.

Begins again in small intestine.

Front 11

Where is lingual lipase released?

What pH can it work with?

Back 11

Glands under the tongue,

3-6, so it can continue digesting lipids in the stomach.

Front 12

What chemical digestion is taking place in the stomach, via what enzymes?

Back 12

Pepsi = protein digestion

Lipase = lipid digestion

(carbohydrate digestion has stopped)

Front 13

Describe the three steps of protein break down in the stomach (think cells, proenzymes, enzymes).

Back 13

1. Cheif cells in stomach wall secrete proteases (pepsinogen).

2. Inactive pepsinogen converted into pepsin by HCl

3. Pepsin breaks proteins into polypeptides

Hint 13

chief cells > pepsinogen > hcl > pepsin > polypeptides

Front 14

What is the pancreas's role in chemical digestion for carbs?

Describe the (5) steps.

Back 14

Secreted into the small intestine:

1. Alpha amylase into the S.I

2. Breaks down starches into

3. Oligosaccharides, then into

4. Polysaccharides, then into

5. Di & monosaccharides e.g. glucose

Front 15

What is the pancreas's role in chemical digestion for lipids?

Back 15

Released into the small intestine:

1. Pancreatic lipase breaks down complex lipids into fatty acids & glycerol

Front 16

What is the pancreas's role in chemical digestion for nucleic acids?

Back 16

Nucleases secreted by the pancreas break down nucleic acids into nucleotides

Front 17

What is the pancreas's role in chemical digestion for proteins?

Back 17

Proteolytic enzymes

- break protein complexes down into polypeptides (proteases)

- break down peptides into amino acids

Front 18

What (4) things is the pancreas good at breaking down?

List the thing and the primary ingredient for its breakdown.

Back 18

Proteins: proteolytic enzymes.

Lipids: pancreatic lipase.

Nucleic acids: nucleases

Carbohydrates: alpha amylase

Front 19

What organ produces bile?

Back 19

Liver.

Front 20

What do bile salts do to lipid droplets in the stomach/digestive tract?

What is the role of bile...

Back 20

Not water soluble, SO:

- emulsify them/break them apart

- increase the surface area to expose them to pancreatic lipase better

Front 21

What enzymes, released by the small intestine's brush boarder cells, break down carbs?

What exactly does each target, & what is the product?

Back 21

Maltase, sucrase, lactase.

Maltose, sucrose, lactose.

= monosaccharides.

Front 22

How are carbs digested in the S.I?

List the (2) steps.

Back 22

1. Pancreatic amylase made in pancreas & secreted to SI.

2. Break down polysaccharides not done by salivary amyl into trisaccharides & disaccharides.

Front 23

How are the disaccharides + trisaccharides left over from pancreatic amylase then turned into monosaccharides? Steps.

Back 23

1. Intestinal microvilli brush-boarder enzymes released (maltase, sucrase + lactase).

2. Maltase breaks down maltose, sucrase breaks down sucrose, lactase breaks down lactose INTO monosaccharides.

Front 24

Through what are monosaccharides absorbed?

What are monosaccharides?

Back 24

By the intestinal epithelium.

Smallest units of carbs.

Front 25

How are glucose & galactose absorbed in the SI?

Back 25

Via co-transport mechanisms

Via a sodium-glucose protein pump

Front 26

How is fructose absorbed in the SI?

Back 26

Via facilitated diffusion / co-transport mechanisms (fructose channel)

Front 27

Where do monosaccharides go after being absorbed into capillaries?

What does this organ do to glucose, fructose & galactose?

Back 27

Directly to the liver. (Hepatic portal)

Fructose + galactose = turned into glucose.

Glucose = stored as glycogen if excess.

Front 28

How does mechanical digestion get involved in chemical digestion in the stomach, relating to proteins?

Back 28

Mech digestion helps break weak bonds in secondary + tertiary structure of proteins, allowing pepsin access to turn it into polypeptide

Front 29

What (4) things are secreted by the pancreas into the S.I that before reaching the S.I are inactive? (Break down proteins)

Back 29

Trypsinogen

Chymotrypsinogen

Proelastase Procarboxypeptidase

Hint 29

TCPP

Front 30

Explain the conversion of trypsinogen into something else.. (2)

Back 30

1. Trypsinogen produced by pancrease (inactive)

2. Secreted into S.I. Enterpeptidase converts trypsinogen into trypsin.

Front 31

What does trypsinogen do in the S.I? (3 things)

Back 31

Converts:

Chymotrypsinogen into chymotrypsin

Proelastase into elastase Procarboxypeptidase into carboxypeptidase

Front 32

What targets amino acid/peptide chains in the S.I?

Back 32

Carboxypeptidase.

Front 33

What breaks down proteins into polypeptides in the S.I? (3)

Back 33

trypsin, chymotrypsin & elastase

Front 34

What substances does the small intestine secrete directly to break down proteins?

Back 34

Dipeptidases & peptidases

breakdown dipeptides + peptides into amino acids

Hint 34

Front 35

By what mechanisms are amino acids absorbed by the intestinal epithelium?

Where does it travel from here?

Back 35

Facilitated diffusion + co-transport.

"Sodium-dependent amino acid co-transporters"

To the liver.

Front 36

Give the name for carbs from big to small as they break down.

Back 36

Carbohydrates/starches > oligosaccharides > polysaccharides > di/monosaccharides

Front 37

Give the names for proteins from big to small as they break down.

Back 37

Proteins > oligopeptides > polypeptides > dipeptides > amino acids

Front 38

What do lingual + pancreatic lipases target, & what do they produce?

Back 38

Triglycerides

Fatty acids + monoglycerides.

Front 39

Describe lipid breakdown step by step. (5)

Back 39

1. Lingual lipase produced in mouth, begins lipid digestion

2. Lingual lipase continues in stomach.

3. Pancreatic lipase joins LL in S.I.

4. Bile salts from liver join in S.I.

5. Bile salts emulsify lipid droplets, allowing pancreatic lipase to go to work.

Front 40

How are monoglycerides + fatty acids absorbed by the S.I, being fatty?

Back 40

Bile salts surround fat cells to form "micelles" that can be absorbed.

Front 41

What happens to lipids after they are absorbed by the S.I, being fats?

Back 41

monoglycerides + fatty acids reform into triglycerides, join with cholesterol + fat soluable vitamins to become

chylomicrons

Front 42

1. What are chylomicrons coated in? Why?

2. What are they a type of?

Back 42

1. Protein shell. To allow them to be suspended in water/blood.

2. Lipoprotein.

Front 43

Describe the steps that take place to chylomicrons after they're absorbed. (5)

Back 43

BYPASS HEPATIC PORTAL.

1. Packaged into vesicles by golgi.

2. Taken up by lacteals (smallest lymph vessles).

3. Enter venus blood.

4. Broken into fatty acids + glycerol.

5. Pass through capillary into tissues for use.

Front 44

What do fat-soluable things avoid?

Back 44

The hepatic portal. They travel via lymph around the body, into the blood, before reaching the liver.

Front 45

How does the liver regulate lipids in circulation? (2)

Back 45

1. releases lipid reserves as blood levels decline

2. removes lipids for storage when levels are high

Front 46

1. What does "LDL" stand for?

2. Good/bad?

3. What are some good things it does? (2)

4. What can it result it?

Back 46

1. Low density lipoprotein.

2. Bad cholesterol!

3. helps in cell membrane structure, synthesising steroid hormones e.g. testosterone, oestrogen

4. Plaques. CVD.

Front 47

1. What does "HDL" stand for?

2. Good/bad?

3. What role does it do?

Back 47

1. High density lipoprotein.

2. Good cholesterol!

3. Reduced bad cholesterol/LDL