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HL Bio > 6.1 digestion and absorption > Flashcards

6.1 digestion and absorption Flashcards

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Biology 101 flashcards
1
Q

why do we need to eat?

A

to provide our bodies with chemical energy, which can be converted to ATP to power processes in the body

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2
Q

what are essential nutrients and why do we need them?

A

they are nutrients not made by the animal and thus must be obtained from dietary sources

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3
Q

in digestion, assimilation is the….

A

synthesis of molecules in the body from the absorbed small molecular nutrients

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4
Q

label a diagram of the digestive system

A

-

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5
Q

the alimentary canal consists of organs in which food ____________ ________.

A

passes through

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6
Q

accessory organs are…

A

organs that aid in digestion but do not actually transfer food

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7
Q

what is the function of the mouth?

A
  • ingestion and chewing to break down food to smaller pieces -> incr SA:VR
  • salivary amylase secreted for the digestion of starch to maltose
  • alkaline medium of saliva for enzymatic activity
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8
Q

what organs have peristalsis in the alimentary canal?

A

esophagus, stomach, small intestine, large intestine

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9
Q

which part of the esophagus prevents acid and food reflux?

A

the sphincter muscle

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10
Q

what is the function of the esophagus?

A
  • transports food from mouth to stomach by peristalsis
  • prevents food and acid reflux through the contraction of sphincter muscle
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11
Q

which organ produces and secretes bile into the gall bladder?

A

the liver

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12
Q

the gall bladder stores ______ which functions to aid digestion by…

A
  • bile
  • helping to emulsify fats for incr SA:VR for more efficient digestion by pancreatic lipase
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13
Q

what is the function of the stomach? (3)

A
  • secretes HCl and pepsinogen
  • acidic medium kills pathogens in food
  • pepsinogen converted to pepsin due to HCl and digests proteins into amino acids
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14
Q

what does the pancreas do to aid digestion? (2)

A
  • secretes digestive enzymes for proteins, fats and carbohydrates
  • alkaline medium due to HCO3 ions for enzymatic activity
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15
Q

what happens in the small intestine? (2)

A
  • further digestion of food into monomers
  • absorption of monomers facilitated by intestinal folds to incr SA
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16
Q

what is the function of the small intestine? (3)

A
  • digests food into monomers
  • absorbs monomers across a 1-cell epithelium for quick movement into capillaries and lacteals
  • intestinal folds e.g. villi, microvilli incr SA for absorption
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17
Q

the three sections of the small intestine are…
1. duodenum
2. jejunum
3. ???

A

ileum

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18
Q

what is the function of the large intestine? (3)

A
  • absorption of water, vitamins and mineral ions
  • house beneficial bacteria
  • fermentation of undigested waste
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19
Q

the part of the body involved in egestion of undigested food is…

A

the anus

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20
Q

what part of the body stores undigested food?

A

the rectum

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21
Q

why are enzymes needed in digestion?

A

they are biological catalysts, meaning they speed up the rate of reaction at body temperature by lowering the activation energy of the catabolic reactions

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22
Q

intestinal enzymes are _______ ________ while pancreatic enzymes are _______________________ (ref to movement)

A

membrane-bound, carried along w food

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23
Q

what is peristalsis?

A

the rhythmic contraction of antagonistic circular and longitudinal muscles

24
Q

how does peristalsis aid digestion

A
  • it mixes chyme (semi-digested food) with enzymes
  • it moves it along the gut
25
Q

how is food moved along the gut? (3)

A
  • through peristalsis; the alternate contraction of the longitudinal and circular muscles
  • behind the food, the C muscle contracts and L muscle relaxes
    • gut wall constricts to become narrow and longer
    • prevents food from being pushed back while pushing food forward
  • at the food, the C muscle relaxes and L muscles contract
    • gut wall becomes wider and shorter
    • relaxation of C dilates gut wall and enables food to be pushed forward
    • contraction of L muscles shorten the distance to be travelled
26
Q

what takes place at the duodenum, jejunum and ileum respectively?

A

duodenum, jejunum: digestion
ileum: absorption

27
Q

identify the small intestine tissue layers

A

-

28
Q

what is one feature of the serosa

A

it is a membrane coated with mucus to reduce friction with other organs

29
Q

in the small intestine, the large blood and lymph vessels and nerves are contained in the…

A

submucosa

30
Q

how does villi enhance the rate of absorption in the small intestine?

A

microvilli and villi increases the SA of the epithelium with numerous folds

31
Q

what are 6 features of villi (mnemonic: MRS LIM)

A
  • microvilli
    • numerous folds increases SA
  • rich blood supply
    • rich supply of capillaries maintain conc gradient for diffusion
  • single layer epithelium
    • minimises diffusion dist btw lumen + blood
  • lacteals
    • absorbs lipids into lymphatic system
  • intestinal glands
    • exocrine pits release digestive juices
  • membrane proteins
    • facilitates transport of digested materials into epithelial cells
32
Q

why does the villus epithelium have a lot of mitochondria?

A

to provide ATP for AT

33
Q

fill in the list of membrane transport mechanisms:
1. ????
2. facilitated diffusion
3. ???
4. simple diffusion

A
  1. secondary active transport (co-transport)
  2. osmosis
34
Q

what monomers undergoes secondary AT?

A

glucose and amino acids

35
Q

how does glucose and amino acids enter the epithelial cell by secondary AT?

A

glucose and amino acids are co-transported across the epithelial membrane by the active translocation of Na+

36
Q

where do amino acids and glucose go and by what vessel after being absorbed into the bloodstream?

A

to the liver by the hepatic portal vein

37
Q

which monosaccharides enter by AT?

A

glucose and galatose

38
Q

which molecules enter by simple diffusion?

A

fatty acids, monoglycerides

39
Q

fructose enters by…

A

facilitated diffusion

40
Q

how are peptides absorbed?

A

co-transport by active translocation of H+

41
Q

fats enter the lacteal as…

A

chlyomicrons

42
Q

how does facilitated diffusion work?

A
  • through channel proteins
  • channel proteins help hydrophilic food molecules pass through hydrophobic part of plasma membrane
43
Q

what enters the epithelial cell by facilitated diffusion?

A

fructose, vitamins and some minerals

44
Q

what molecules enter the epithelial cells by osmosis and what is this in response to?

A

water molecules, in response to the movement of ions and hydrophilic monomers

45
Q

what type of materials can enter epithelial cells by simple diffusion?

A

hydrophobic materials

46
Q

lipids enter the epithelial cell by _______

A

simple diffusion

47
Q

what is linear-chain starch called?

A

amylose

48
Q

what is branched starch called?

A

amylopectin

49
Q

where is starch digested?

A

mouth and small intestines

50
Q

what enzyme breaks down amylose and amylopectin?

A

amylase

51
Q

what is the products of digestion of amylose and amylopectin?

A
  • amylose: maltose
  • amylopectin: limit dextrin
52
Q

where is maltose and limit dextrin digested?

A

at the membrane of microvilli

53
Q

what enzymes digest maltose and limit dextrin?

A

maltase and dextrinase

54
Q

maltase and dextrinase are ____________ (ref to position and mobility)

A

membrane-bound

55
Q

the hydrolysis of maltose and dextrin produce…

A

glucose monomers

56
Q

how is glucose absorbed? (6)

A
  • glucose is co-transported across the epithelial membrane by secondary AT
  • uses energy from the movement of Na+ ions down their electrochemical gradient at the apical side of the epithelial cell to transport gluc against its concentration gradient
  • glucose is transported out of epithelial cell from basolateral side by facilitated diffusion to the blood in villus capillaries
  • blood from villus capillaries then drain into venules in submucosa layer
  • glucose in venules will be brought to liver via hepatic portal vein
  • excess is converted to glycogen for storage

HL Bio (52 decks)

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