Lecture 16 week 9

Question 1

What are different types of carbohydrates?

Answer 1

Monosaccharides, disaccharides, polysaccharides

Question 2

What are some examples of monosaccharides ?

Answer 2

GLucose, fructose, galactose

Question 3

What are some examples of disaccharides and how are they formed?

Answer 3

Sucrose : glucose+fructose
Maltose : glucose +glucose
Lactose : glucose + galactose

Question 4

What are some examples of polysaccharides and give explanation

Answer 4

Starches: from plants
Fibers: indigestible from humans
Glycogen: Stored in muscle and liver of animals

Question 5

In lactose intolerance:

How are glucose and galactose absorbed?

Answer 5

Absorbed by active transport

Question 6

Lacotse intolerance:

How is fructose absorbed?

Answer 6

Absorbed by facilitated transport

Question 7

How does lactose intolerance occur?

Answer 7

Deficiency in lactase enzyme results in lactose intolerance.

Question 8

Peptide and amino transport:

What is step 1 of this process?

Answer 8

Proteins broken down into smaller peptides

Question 9

Peptide and amino transport:

What is step 2 of this process?

Answer 9

Epithelial cells secrete peptidases to break down larger peptides into individual amino acids

Question 10

Peptide and amino transport:

What is step 3 of this process?

Answer 10

Transported throughout body in bloodstream to
produce energy or protein synthesis

Question 11

Peptide and amino acid transport:

What happens in the stomach regarding protein digestion?

Answer 11

1. Protein chewed and swallowed into the stomach
2. HCL denatures proteins, unfolding their 3D structure, revelaing polypeptide chain
3. Enzymatic digestion by pepsin forms shorter polypeptides.

Question 12

Peptide and amino acid transport:

What happens in the small intestine?

Answer 12

1. In small intestine, trypsin, chymotrypsin and proteases continue enzymatic digestion, forming tripeptides, dipeptides and amino acids
2. In enterocytes, tripeptides and dipeptides are further broken down into amino acids which are absorbed into the blood

Question 13

Peptide and amino acid transport:

What happens after proteins broken down by small intestine

Answer 13

Enters bloodstream

Question 14

How are lipids broken down?

Answer 14

Mouth (lingual lipase) -> Stomach (gastric lipase) -> small intestine (pancreatic lipase)

Question 15

When can lipases act on lipids

Answer 15

Lipases can only act on lipids when broken down

Question 16

Where is bile produced and stored

Answer 16

Bile is produced in the liver and stored in the gallbladder

Question 17

What does bile do?

Answer 17

Aids digestion of lipids through emulsification (large lipid globules broken down and distributed in chyme)

Question 18

Are bile salts hydrophilic or lipophilic?

How and why is it like this?

Answer 18

Bile salts are amphipathic

Hydrophilic side interfaces with water and hydrophobic side interfaces with lipids

Question 19

How does lipid absorption and transport occur?

Answer 19

• Absorbed as fatty acids &
  monoglycerides
• Reassembled into triglycerides &
  packaged as chylomicrons (type
  of lipoprotein)
• Chylomicrons are too large to
  cross capillary wall – first
  absorbed into lymphatic system
• Will re-enter circulation through
  thoracic duct near heart

Question 20

The large intestinal phase of digestion and absorption

What is ileal chyme and what does it do?

Answer 20

comes in from ileum (via ileocecal valve)
* Any unabsorbed nutrients
* Hormones & chemical messengers
* Soluble fibre
* Insoluble fibre
* Microbes
* Cellular debris
* Excretion products from the liver

Question 21

The Large Intestine (cecum & colon):

What does the colonic epthelium do?

Answer 21

Absorbs water and simple ions (sodium, potassium, magnesium, calcium)

Question 22

The Large Intestine (cecum & colon):

What do resident microbes digest and absorb? What is produced as the end product?

Answer 22

Digest and absorb what chemicals they can in the process of fermentation. Short chain fatty acid produced as end products

Question 23

The Large Intestine (cecum & colon):

What do resident microbes produce? What is the end product?

Answer 23

Produces some vitamins as a by product of their metabolism (vitamin K, some B vitamins). Some end products can have hormone like activity.

Question 24

The Large Intestine (cecum & colon):

What do resident microbes produce during their digestion?

Answer 24

Produce gases during their digestion and consumption of ileal chyme (carbon dioxide, methane, hydrogen sulfide)

Question 25

The Large Intestine (cecum & colon): What do newly arriving, live microbes do?

Answer 25

Newly-arriving, live microbes (probiotic or other) seek to get a foothold in the microbial ecosystem & multiply

Question 26

What is hedonic hunger/eating?

Answer 26

The drive to eat to obtain pleasure in the absence of an energy deficit

Question 27

What is homeostatic hunger/eating?

Answer 27

Increased motivation to eat following depletion of energy stores