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human bio 11 > chapter 9 - the digestive system > Flashcards

chapter 9 - the digestive system Flashcards

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Biology 101 flashcards
1
Q

what are the associated organs

A
  • pancreas, liver, gall bladder (accessory organs)
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2
Q

what is digestion

A
  • carbohydrates, proteins and fats are broken down into units small enough to be absorbed into the blood and cells
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3
Q

what are the functions of the digestive system

A
  • ingestion of food and water
  • mechanical digestion
  • chemical digestion
  • movement along the alimentary canal
  • absorption of food into the bloodstream
  • elimination of food / defection of materials not absorbed
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4
Q

what do cells need

A
  • vitamins, minerals, water, simple sugars, fatty acids, amino acids
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5
Q

what is the structure of the mouth

A
  • human dental formula 2:1:2:3 (x4)
  • 2 incisors: chisel shaped, cutting and biting
  • 1 canine: conical, tearing
  • 2:3 premolars and molars: broad crowns with cusps, crushing and grinding
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6
Q

mechanical digestion in the mouth

A
  • ingestion, food enters the mouth
  • teeth: breaks down food into smaller pieces
  • mucous: lubricates food and with aid of tongue forms a bolus, pushed into pharynx
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7
Q

chemical digestion in mouth

A
  • salivary glands: 3 pairs, secrete enzymes and mucous

- salivary amylase: breaks down starch into polysaccharides and disaccharides (pH 6.7)

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8
Q

structure of the oesophagus

A
  • circular and longitudinal muscles

- causes wavelike contractions to move the bolus

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9
Q

mechanical digestion of the oesophagus

A
  • the bolus moves down the oesophagus due to wavelike contractions (peristalsis)
  • movement is lubricated –> secretion of the mucous
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10
Q

structure of the stomach

A
  • longitudinal, circular and oblique muscles
  • mucosa lining: specialised cells which secrete gastric juices
  • holds food for 2-8 hours
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11
Q

mechanical digestion in the stomach

A
  • churning of the food, contracts in different ways / directions
  • provides chyme (soupy thick liquid)
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12
Q

chemical digestion in the stomach

A
  • mucosa lining secretes gastric juices (mucous, pepsinogen, HCl) into gastric pits
  • mucous: lubricates
  • HCl: maintains low pH of 1.5-1.8, activates pepsinogen (becomes pepsin)
  • pepsinogen: becomes pepsin –> breaks down proteins into peptides and polypeptides
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13
Q

absorption in the stomach

A
  • nutrients are not absorbed in the stomach

- alcohol and some drugs (aspirin) are absorbed

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14
Q

what is the function of the pyloric sphincter

A
  • allows for substances to enter the small intestine only once ready (after 2-8 hours)
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15
Q

structure of the small intestine

A
  • 6m long, thin, duodenum, jejunum, ileum
  • mucosa lining: folds internally (large SA)
  • villi: projections that extend from folded surface, allow for absorption
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16
Q

what is the alimentary canal

A
  • continuous tube that runs from the mouth to the anus (9m approx)
17
Q

what are the villi in the small intestine

A
  • 1mm long, single cell layer, contains lymph and blood capillaries
  • lymph: absorption of fatty acids and glycerol, fat soluble substances
    • -> carried to lymph nodes as fat -> lymphatic system -> blood drains into heart
  • blood: absorption of amino acids, simple sugars, water, water soluble substances
    • -> carried to liver via hepatic partial vein -> stored or continues to body cells
18
Q

mechanical digestion in the small intestine

A
  • movement: segmentation
  • bile: secreted in the liver and stored in the gall bladder
  • bile emulsifies fats (lipids -> fat droplets = easier to be broken down), this increases SA -> lipase can enter -> fatty acid and glycerol
19
Q

chemical digestion in the small intestine

A
  • pancreatic juices / enzymes (duodenum): produced in pancreas, digestion
    • -> pancreatic amylase, lipase, protease, ribonuclease and deoxyribonuclease
  • intestinal juices / enzymes (duodenum): produced in intestine, digestion
    • -> intestinal amylase, lipase, protease
20
Q

absorption in the small intestine

A
  • takes place in the jejunum and ileum
  • amino acids, simple sugars, fatty acids, glycerol, vitamins, minerals, water
  • movement of small intestine wall promotes absorption
21
Q

structure of the large intestine

A
  • 1.5m long, thick

- ascending, transverse and descending colon, rectum, anus

22
Q

mechanical digestion in the large intestine

A
  • very slow

- 18-24 hours

23
Q

absorption in the large intestine

A
  • most of the water, minerals and vitamins are absorbed
24
Q

what is the faeces made of

A
  • undigested food material (cellulose, bile pigments, bacteria)
  • bacteria breaks down in large intestine, sometimes converted into vitamins which are then absorbed

human bio 11 (23 decks)

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