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human bio YEAR 11 > digestive system > Flashcards

digestive system Flashcards

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1
Q

what is digestion?

A

the process of breaking down large nutrient molecules into smaller molecules which can be absorbed into the blood and cells

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2
Q

what is mechanical digestion?

A

physical breakdown of food into smaller pieces to increase surface area
what is mechanical digestion?

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3
Q

what are the 3 location where mechanical digestion occurs?

A

mouth = teeth cut, tear and grind food

stomach = churning action breaks down food further

bile = emulsifies fates (breaking fat down into smaller droplets)

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4
Q

how does mechanical digestion help speed up absorption of nutrients?

A

increase surface area allows more effective chemical digestion as the chemicals can access more food

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5
Q

what is chemical digestion?

A

uses enzymes to break bonds of large complex molecules into smaller, simpler ones.

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6
Q

what digestive enzymes are involed in chemical digestion of nutrients?

A

amylase = breaks down starch into maltose. maltase breaks down maltose into glucose

pepsin = breaks down proteins into peptides and amino acids

lipase = breaks down lipids into fatty acids and glycerol

nucleic acids = are split into nucleotides

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7
Q

what is the alimentary canal?

A

continuous tube that runs from the mouth to the anus, including all digestive organs

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8
Q

how does food get chemically and physically digested in the mouth?

A

mechanical - teeth, chewing

chemical - as food is chewed it is mixed with saliva which contains amylase which begins chemical digestion of starch into maltose

tongue shapes food into a bolus. it moves up and back pushing bolus to the pharynx which leads to the oesophagus

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9
Q

what is peristalisis?

A

Involuntary waves of muscle contraction that keep food moving along in one direction

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10
Q

what is the structure of the oesophages?

A
  • tube that connects pharynx to stomach (23-25cm).

- wall has a double layer of muscle - circular and longitudinal muscle

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11
Q

describe the structure of the stomach

A

enlarged section of the alimentary canal.
food undergoes chemical and mechanical digestion

nutrients are not absorbed into the bloodstream through the stomach because the internal surface is covered by a thick layer of mucus.

folds unfold to accommodate what you’re eating.

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12
Q

describe mechanical digestion in the stomach

A

mechanical - waves of muscular contraction. has oblique, circular and longitudinal muscle so stomach can contract in many ways, churning the food and mixing it with gastric juice.

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13
Q

describe chemical digestion in the stomach

A

chemical - enzymes (pepsin/gastric protease) in the gastric juice. breaks the bonds between certain amino acids breaking proteins into shorter polypeptide chains.

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14
Q

what is the function of the thick mucus in the stomach?

A

protects stomach lining and prevents it from digesting itself

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15
Q

what is the pyloric sphincter?

A
  • between the stomach and duodenum.

- regulates flow of material from stomach into the duodenum

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16
Q

what is gastric juice?

A
  • contains HCl, mucus and digestive enzymes (pepsin)

- stomach lining is specialised for secretion of gastric juice

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17
Q

what is a bolus?

A

food after it has been chewed and mixed with saliva

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18
Q

what is chyme?

A

Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach.

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19
Q

what is the small intestine?

A
  • 6-7m long.

- receives material pushed through pyloric sphincter from the stomach.

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20
Q

what are the 3 regions of the small intestine?

A

duodenum, jejunum, ileum

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21
Q

what is the duodenum and its function?

A
  • first part of the small intestine.
  • receives acidic food from stomach and secretes alkaline juice.
  • most chemical digestion occurs here before chyme moves further
22
Q

what is the jejunum and its function?

A
  • middle section.

- its lining allow effective absorption of carbs and proteins - not fats

23
Q

what is the ileum and its function?

A
  • final part.

- B12, bile salts and any remaining productions of digestion are absorbed

24
Q

what is bile and how does it help in digestion?

A
  • enters duodenum through the common bile duct.
  • contains no digestive enzymes, but has bile salts which emulsify fats.
  • break the fat into tiny droplets
25
Q

how does pancreatic juice help with digestion?

A
  • produced by pancreas which contains many enzymes.
    = pancreatic amylase - helps break down starch

= pancreatic protease - breaks down proteins into small chains of amino acids

= ribonuclease and deoxyribonuclease - digest RNA and DNA

= pancreatic lipases - break down fats into fatty acids and glycerol

26
Q

how does intestinal juice help with digestion?

A

pancreatic protease - breaks down proteins into small chains of amino acids

ribonuclease and deoxyribonuclease - digest RNA and DNA

pancreatic lipases - break down fats into fatty acids and glycerol

27
Q

how does absoption occur in the small intestine?

A
  • products of digestion, vitamins, minerals and water are absorbed through the wall of the small intestine into the blood.
  • the lining has folds to maximise the absorption of nutrients
    how does absorption occur in the small intestine
28
Q

what are villi?

A

finger like projections that increase the SA for absorption

29
Q

how are amino acids and simple sugars absorbed in the small intestine?

A

absorbed by active transport into the blood capillaries to the liver

30
Q

what is the structure of the large intestine?

A
  • 1.5m long.
    includes caecum, colon, rectum, anus, appendix
  • no villi, no digestive juices secreted.
31
Q

what is the functin of the large intestine?

A

lining secretes lots of mucus

most of the remaining water is absorbed so the contents become more solid

32
Q

what is the colon?

A

longest part of large intestine. has an inverted u shape

33
Q

what is the caecum?

A
  • pouch
  • 6cm long
  • where small intestine joins large intestine
34
Q

what is the appendix?

A

small tube attached to the caecum

35
Q

what is the anus?

A

external opening at the end of the rectum

36
Q

what is the rectum?

A
  • last part of large intestine.

- material left in colon after water absorption is pushed into rectum by peristalsis.

37
Q

what does faeces contain?

A

water, undigested food, cellulose, bacteria, bile pigments.

- remains of cells that have broken away from the internal lining of canal

38
Q

what is the gall bladder?

A

pouch near liver that stores bile produced in the liver.

39
Q

what is bile?

A

contains bile salts which break up fats so lipases can act on a larger SA.

  • neutralises acidity of food coming from stomach, enabling lipase its optimal high pH.
  • contains no enzymes
40
Q

what is the pancreas?

A

produces pancreatic juices containing enzymes and neutralise acids from the stomach

41
Q

what are salivary glands?

A

secrete saliva containing amylase and mucus that lubricates, dissolves food and holds food in lump

42
Q

what is the role of the liver

A

produces bile

43
Q

what lifestyle choices have an effect of digestion?

A

activity level, drugs, diet

- cause conditions like constipation, diarrhoea, bowel cancer and coeliac disease

44
Q

what are the causes and symptoms of constipation?

A
  • caused by lack of cellulose and fibre in diet, lack of exercise, emotional problems.
  • leads to excess water reabsorbed as the food remains in large intestine too long
  • painful and infrequent defection
45
Q

what are the treatment options for constipation?

A
  • Drinking more fluids
  • eating more high-fibre foods
  • getting regular exercise
46
Q

what are the causes and symptoms of diarrhoea?

A
  • caused by bacteria, virus or parasite
  • results in quicker peristalsis so not enough water is absorbed and irritation of intestines
  • watery and frequent faeces
47
Q

what are the causes and symptoms of bowel cancer?

A
  • uncontrolled growth of cells in the walls of the large intestine
  • caused by diet high in processed meat and low in fibre, high alcohol consumption and smoking
  • pain in abdomen, blood in stool, change in bowel habits,
48
Q

what are causes of coeliac disease?

A

caused by abnormal immune reaction to gluten.

49
Q

what are the treament for coeliac disease?

A

strict gluten free diet

50
Q

what are the treament for coeliac disease?

A

strict gluten free diet

human bio YEAR 11 (28 decks)

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