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321 - Physiology > Lecture 32 - Carbohydrate Digestion & Absorption > Flashcards

Lecture 32 - Carbohydrate Digestion & Absorption Flashcards

1
Q

Enteroendocrine cells are derived from crypt cells and migrate up

A

The crypt-villus axis

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2
Q

Digestion:

A

Process of breaking dietary compounds into simple molecules that can be absorbed

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3
Q

Absorption:

A

Simple molecules generated from digestion are transferred into blood or lymph

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4
Q

From lumen to capillary blood, nutrient molecules need to cross

A

Apical membrane: between lumen and intracellular space and extracellular fluid
Basolateral membrane: between intracellular space and extracellular fluid

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5
Q

Cell membranes are composed of

A

A bilateral membrane of phospholipids: a hydrophilic head extending into the aqueous fluid on the outside and inside of the cell and hydrophobic tails between hydrophilic surfaces

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6
Q

Interspersed among the phospholipids are various types of proteins:

A

Transporters, pumps, and channels are important for material to cross the lipid bilayer

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7
Q

Lipid-soluble hydrophobic compounds can easily cross the

A

Lipid bilayer of cell membranes

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8
Q

Water hydrophilic materials cannot easily cross the

A

Lipid bilayer on their own

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9
Q

Particles will also move from one compartment of high concentration to another compartment of low concentration, if

A

The barrier between the two compartments is permeable to the substance

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10
Q

The chemical driving force is proportional to

A

The concentration gradient

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11
Q

If there is more than one molecule crossing a cell membrane, does each kind have its own concentration gradient or chemical gradient

A

Yes

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12
Q

In electrical driving force, same charges _______ & opposite charges _______

A

Repel, attract

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13
Q

In the resting cell, cations are attracted to the __________ of the cell and anions are attracted to the ___________ of the cell

A

Interior, exterior

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14
Q

The magnitude of the electrical force depends upon the

A

Size of the membrane potential and the charge of the ion

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15
Q

The greater the membrane potential or the charge of the ion the greater the

A

Electrical driving force

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16
Q

The more lipid soluble a substance is the greater the _____

A

Permeability to that substance in phospholipid bilayers

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17
Q

When going through a phospholipid bilayer, the membrane permeability is lesser if

A

The molecule is larger and more irregular in shape

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18
Q

Can fatty acids and triglycerides freely cross the lipid bilayer down their concentration gradient?

A

Yes, even though they are very large and can be charged, they are very lipid soluble

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19
Q

What is passive transport?

A

Molecules moving down their electro/chemical gradient to the other side of the membrane. No energy used

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20
Q

All epithelial cells lining the GI tract have an

A

Apical and basolateral membrane

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21
Q

Adjacent epithelial cells in the GI tract are linked to another on all sides by

A

Tight junctions

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22
Q

Tight junctions form a seal between cells that is relatively impermeable to

A

bacteria, viruses, and large molecules that have been ingested

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23
Q

The tight junctions also provide resistance to the passage of

A

Small ions and water, but can be overcome if electrochemical forces are great enough

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24
Q

Paracellular transport is

A

Movement of solute across the tight junctions between enterocytes

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25
Q

Accumulation of negatively-charged chloride anions creates an electric potential that attracts

A

Sodium, pulling it across tight junctions into the lumen. The net result is secretion of NaCl

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26
Q

Secretion of NaCl creates an osmotic gradient across the tight junction and

A

Water is drawn into the lumen

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27
Q

What is transcellular absorption?

A

Most of the nutrients of the body are too large to cross the tight junctions and must be moved across the absorptive enterocytes. Think endocytosis or exocytosis

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28
Q

The mechanism used to transport a solute across the apical membrane is often different from that used to transport the same solute across the….

A

Basolateral membrane

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29
Q

Exocytosis

A

Vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell

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30
Q

Endocytosis

A

Engulfing substance from outside the cell with the cell membrane, and bringing it into the cell

31
Q

LOOK AT SLIDE 33 TO GET DIAGRAM ABOUT TRANSCELLULAR / PARACELLULAR PROCESSES. Did u do it ???????

A

yes <3 i am gonna slay this midterm

32
Q

Paracellular transport is ________ driven and only functions when _______________

A

Concentration, when solute concentration in the lumen is very different than the concentration in the extracellular fluid

33
Q

The most important enzymatic reaction in digestion is

A

Hydrolysis - the breaking of a chemical bond by the addition of a water molecule

34
Q

The diet of any animal contains hundreds of if not thousands of of different molecules but the bulk of the ingested nutrients are in the form of huge macromolecules that cannot be absorbed into the blood without first being reduced to

A

Much simpler and smaller forms of the molecule

35
Q

Monosaccharides

A

Either 6 carbon sugars like glucose and galactose or 5 carbon like fructose

36
Q

_________ are the breakdown products of more complex carbohydrates and can be efficiently absorbed across the wall of the digestive tube and transported into the blood

A

Monosaccharides

37
Q

Disaccharides

A

Two monosaccharides linked together

38
Q

Most important disaccharides in nutrition and digestion are

A

Lactose and sucrose

39
Q

Oligosaccharides

A

Relatively short chains of monosaccharides

40
Q

What are intermediates in the breakdown of polysaccharides to monosaccharides

A

Oligosaccharides

41
Q

What are the most abundant dietary carbohydrates for all animals except very young ones?

A

Polysaccharides

42
Q

Name 3 large polymers of glucose

A

Starch, cellulose, glycogen

43
Q

Starch

A

A major plant storage form of glucose. Glucose molecules are linked by alpha (1-4) glycosidic bonds

44
Q

Cellulose

A

The other major plant carbohydrate. It’s the major constituent of plant cell walls

45
Q

Cellulose - glucose molecules are linked by

A

Beta (1-4) glycosidic bonds.

46
Q

Can vertebrates enzymatically digest beta (1-4) glycosidic bonds

A

No

47
Q

Glycogen

A

Major animal storage form of carbohydrate. It is multi-branched

48
Q

Glycogen - what links glucose molecules

A

Alpha (1,4) glycosidic bonds.

49
Q

Where does fructose come from

A

Fructose is a naturally occurring sugar found primarily in fruits (such as apples, dates, figs, pears, and prunes)
Vegetables (such as sugar beets, sugar cane, artichokes, asparagus, mushrooms, onions, and red peppers
Honey

50
Q

What begins the digestion of starch and glycogen and reduces them to disaccharides or oligosaccharides

A

Salivary and pancreatic amylase

51
Q

Do stomach acids and proteolytic enzymes have any effects on starches

A

Nope

52
Q

If u have 1M of glucose monomers and 1M of maltose (a disaccharide), do they have the same osmolarity?

A

Yes, as it depends on osmolarity

53
Q

What is the brush border

A

The microvillus border of intestinal epithelial cells

54
Q

What are brush border enzymes

A

Enzymes present on the apical membrane of absorptive cells lining the small intestines, complete digestion to monosaccharides

55
Q

Transporter proteins located near brush border enzymes facilitate

A

Absorption of monomers

56
Q

Example of development changes according to food intake

A

Lactase, which digests milk lactose, is found on the enterocyte brush border of all mammalian neonates. It often disappears after the animal is weaned.

OR

Sucrase, which digests sucrose, is often lacking in neonates and is expressed only after the animal is several weeks old

57
Q

Carbohydrate intolerance is the

A

Inability to digest certain carbohydrates due to a lack of one or more intestinal enzymes

58
Q

CHO intolerance - undigested disaccharides cause an osmotic load that attracts water and electrolytes into the bowel, causing

A

Water diarrhea. Bacterial fermentation of CHO in the colon produces gases (hydrogen, CO2, and methane), resulting in excessive flatulence, bloating and distension, and abdominal pain

59
Q

Treatment of CHO intolerance

A

Removal of the causative disaccharides from the diet

60
Q

Lactose intolerance (shoutout steph) is a digestive disorder caused by the

A

The inability to digest lactose, the main CHO in dairy products

61
Q

Lactose intolerance can cause

A

Various symptoms, including bloating, diarrhea, and stomach cramps

62
Q

People with lactose intolerance (steph its ur moment to shine) dont make enough of

A

The enzyme lactase

63
Q

Does lactose intolerance happen in dogs

A

Yes & it can cause diarrhea, vomiting, lack of appetite, bloating, flatulence

64
Q

Absorption of monosaccharides entails transport from

A

The intestinal lumen, across the epithelium and into the blood

65
Q

Monosaccharides liberated by the brush border enzymes are too large to cross the

A

Apical membrane easily

66
Q

Monosaccharides concentration over the apical membrane rises following a meal so there is a concentration gradient that can help them cross into

A

The cytoplasm, which the help of transporters (both active and passive)

67
Q

Once inside cytosol, the sugars exit the cells across the basolateral membrane by

A

Facilitated diffusion

68
Q

Why doesn’t the intestine digest all dietary starch and disaccharides to monosaccharides in the lumen?

A

The reason digestion is completed at the brush border is to prevent the osmolarity of the lumen contents from rising too high and drawing excessive amounts of water into the lumen. By liberating monomers in the brush border they can be absorbed almost as soon as they are liberated, preventing a rise in the osmolarity of the lumen contents

69
Q

Excess glucose gets stored in the

A

Liver and skeletal muscles as glycogen or, with the help of insulin, converted into fatty acids, circulated to other parts of the body and stored as fat in adipose tissue.

70
Q

Glucose can be converted to fatty acids and cholesterol through

A

De novo lipid biosynthesis pathways

71
Q

Diabetes is more common in __________ but can also occur in younger or pregnant pets

A

Older pets

72
Q

Diabetes is more manageable if

A

It’s detected early and managed with the help of a veterinarian

73
Q

Can diabetic pets have long and happy lives

A

Yes! With proper monitoring, treatment, diet, and exercise

321 - Physiology (52 decks)

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