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Biology AP > The Digestive System > Flashcards

The Digestive System Flashcards

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1
Q

what is the digestive system?

A

the human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion.

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2
Q

why do we eat?

A

energy, nutrients, and building molecules

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3
Q

what are the 4 processes that take place in the digestive system?

A
  1. ingestion
  2. digestion
  3. absorption
  4. egestion/ elimination
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4
Q

what is ingestion?

A

ingestion is when you eat the food

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5
Q

what happens when you put the food in your mouth?

A

you moisten up the food with your saliva. then you start to mechanically digest the food with your teeth, tongue, and hard palate. then chemical digestion happens. you taste from the chemoreceptors. the food is then rolled into a bolus, and goes down the esophagus.

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6
Q

what is saliva made of?

A

98% water, contains salivary amylase, electrolytes, immunoglobins, and nitrogenous products such as proteins, enzymes, and mucins.

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7
Q

why does food need to be moistened?

A

food needs to be moistened because otherwise it would have no taste, and would be very hard to swallow.

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8
Q

why is it important to mechanically digest food in the mouth?

A

chewing mechanically breaks down large pieces of food into smaller ones, therefore the food has an increasing surface area allowing larger areas of food to be exposed to saliva.

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9
Q

what is an example of chemical digestion?

A

salivary amylase, hydrolyzes amylose to maltose.

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10
Q

where does chemical digestion begin?

A

begins within the saliva

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11
Q

how does taste come from chemoreceptors?

A

every food and drink that you put in your mouth has particular chemical components, these chemicals are detected by special receptors called chemoreceptors. these chemoreceptors are contained within taste buds on the surface of the tongue.

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12
Q

what is a bolus?

A

a ball-like mixture of food and saliva that forms in the mouth during the process of chewing.

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13
Q

how does the bolus go down the esophagus?

A

the bolus goes down through peristalsis movement. the epiglottis closes, and the bolus goes through the alimentary canal reaching the stomach.

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14
Q

what is peristalsis?

A

peristalsis is a series wave-like muscle contractions that moves food to different processing stations in the digestive tract?

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15
Q

what is the alimentary canal?

A

the whole passage along which food passes through the body from the mouth to anus.

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16
Q

what are the circular and longitudinal muscles?

A

muscles behind the bolus contract, forcing it down, which the muscles in front contract.

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17
Q

what is the epiglottis?

A

flap of cartilage located in the throat behind the tongue and in front the larynx. the epiglottis is usually upright at rest allowing air to pass into the larynx and lungs

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18
Q

why does the epiglottis close when the bolus goes down the esophagus?

A

it closes to prevent the bolus from entering the trachea, therefore, preventing choking.

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19
Q

what is the trachea?

A

windpipe.

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20
Q

how does the bolus then enter the stomach?

A

the bolus enters the stomach from the esophageal/ cardiac sphincter.

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21
Q

what happens when the bolus enters the stomach?

A

the bolus goes in through the cardiac/ esophageal sphincter. the stomach absorbs some substances (very limited) - chemical digestion. the stomach mainly does mechanical digestion by having the same type of peristalsis movement as the esophagus. this churns the bolus with the gastric juice. the chyme then exists the stomach through the pyloric sphincter.

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22
Q

what is gastric juice made of? what is it called?

A

gastric juice is made of HCl, water, pepsin, and mucus

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23
Q

why is the stomach very folded?

A

the stomach is folded so it can expand when it is full.

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24
Q

what happens when the stomach expands when it is full?

A

stretch receptors signal when you are full. when food enters the stomach, the stomach stretches and activated stretch receptors. the stretch receptors can send a message to the medulla and then back to the stomach via the vagus nerve. the stomach accommodates to anything that is put in it.

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25
Q

what is the pylorus?

A

the part of the stomach that connects to the small intestine.

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26
Q

what type of substances does the stomach absorb?

A

the stomach absorbs non-polar substances such as ethanol (alcohol), aspirin, and anti-inflammatory drugs.

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27
Q

what is the pH of the stomach?

A

pH of 2 - very acidic environment

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28
Q

why does having an acidic environment help?

A

it grants immunity because the acid in the stomach is strong enough to kill anything that doesn’t belong there.

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29
Q

what is the esophageal cardiac/ sphincter?

A

surrounds the part of the esophagus at the junction between the esophagus and the stomach. also called cardiac sphincter. named from the adjacent part of the stomach, the cardia.

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30
Q

what is the pyloric sphincter?

A

a band of smooth muscle at the junction between the pylorus of the stomach and duodenum of the small intestine.

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31
Q

how many layers does the stomach have? what are they?

A

3 layers . the outer longitudinal, middle circular, and inner oblique.

32
Q

why is water necessary in chyme?

A

to mix the food and break it down.

33
Q

how does chyme get released?

A

even thinking of/ smelling food can cause the release of gastric juice.

34
Q

what is a parietal cell?

A

acid-secreting cell of the stomach wall.

35
Q

what creates the HCl acid in the stomach?

A

the parietal cells on the stomach wall.

36
Q

what hormone is released to increase gastric juice?

A

gastrin

37
Q

where is HCl released?

A

HCl is released into the lumen of the stomach

38
Q

what is the lumen of the stomach?

A

the lumen of the stomach is the hollow region.

39
Q

what substance does HCl convert?

A

pepsinogen to pepsin.

40
Q

what is pepsinogen? what does it convert to? explain.

A

pepsinogen is a substance made by stomach cells. when it comes in contact with HCl acid, it turns into pepsin, which is an enzyme that helps hydrolyze peptide bonds.

41
Q

how does the HCl not burn through/ touch the stomach wall?

A

there is a mucus covering . this acts as a protective barrier, so the HCl doesn’t touch the stomach lining.

42
Q

what are gastric ulcers?

A

gastric ulcers occur when acid in the digestive tract eats away at the inner surface of the stomach or small intestine. the acid can create a painful open sore that may bleed.

43
Q

what are the parts of the small intestine? how long is each?

A

the first part is the duodenum, which is the first 30 cm long (connected to the pyloric sphincter). the second part is the jejunum, which is the next 2.5 m, and the last part is the ileum, which is 3.5 m long (connected to the colon)

44
Q

where does most of the digestion and absorption happen? why?

A

most of the digestion and absorption occurs in the small intestine because there are millions of villi and microvilli which increase surface area for absorption.

45
Q

where does the small intestine receive secretions from?

A

the liver, gall bladder, and pancreas.

46
Q

where does the chyme enter the small intestine from?

A

the pyloric sphincter.

47
Q

what does the chyme entering the small intestine trigger? why?

A

this stimulates the bicarbonate ions (CO3-2) secretions from the pancreas. this is so it can be neutralized, so the enzymes can work. this shuts down the pepsin.

48
Q

what does the pancreas produce?

A

produces bicarbonate ions, and digestive enzymes.

49
Q

what are the types of digestive enzymes does the pancreas produce?

A

it produces protease, lipase, carbohydrases, and nucleases.

50
Q

what is protease? what are examples of protease?

A

protease breaks down proteins. there is pepsin, trypsin, and chymotrypsin.

51
Q

what is lipase?

A

lipase breaks down lipids.

52
Q

what are carbohydrases? what are some examples?

A

breaks down carbohydrates. include lactase,maltase, sucrose, and amylase

53
Q

what do nucleases break down?

A

they break down nucleic acids

54
Q

what does the liver produce?

A

the liver produces bile.

55
Q

what is bile?

A

bile emulsifies lipids.

56
Q

where is bile stored? when is it released?

A

bile is stored in the gall bladder. it is released when you eat fatty foods. it gets released into the bile duct, which goes into the small intestine.

57
Q

what does emulsify mean?

A

break down oil into smaller sources to increase surface area.

58
Q

what does the wall of the small intestine do?

A

the wall secretes various enzymes.

59
Q

how does the chyme in the small intestine move?

A

moves through peristalsis.

60
Q

where do monosaccharides and amino acids move to?

A

they move to capillaries.

61
Q

what are capillaries?

A

very tiny blood vessels that connect arteries and veins to facilitate the exchange of certain elements between your blood and tissues.

62
Q

how do monosaccharides and amino acids move to capillaries?

A

through diffusion (high to low concentration). this is a type of passive transport, which is beneficial because less energy is used.

63
Q

where do lipids go in the small intestine?

A

lipids go to lacteals ( a lymphatic capillary), which is a part of the lymphatic system. this absorbs all the dietary fats in the villi of the small intestine and then goes into the bloodstream.

64
Q

where do nutrients go after broken up? what’s an example?

A

nutrients (now are monomers) end up in the blood and the blood then goes to the liver so the nutrients can be processed and stored. an example is that it stores glucose and glycogen, and deanimates amino acids

65
Q

why are the broken nutrients so small?

A

they are small so they can fit through the villi by diffusion.

66
Q

how long is the large intestine?

A

1.5 m long.

67
Q

what is the long intestine often called?

A

also called colon

68
Q

what type of foods enter the long intestine?

A

only foods that weren’t digested previously enters the large intestine. this includes some water and cellulose.

69
Q

how does water get absorbed in the large intestine?

A

through osmosis, then it enters the blood stream

70
Q

what does the bacteria in the large intestine do?

A

they make vitamins. these vitamins are needed because they are cofactors for enzymes.

71
Q

what happens if you absorb too much water?

A

constipation

72
Q

what happens if you absorb too less of water?

A

diarrhea

73
Q

why do you need energy from eating?

A

you must supply enough for basal metabolic rate (BMR)

74
Q

why do you need nutrients from what you eat?

A

you need essential nutrients, including minerals, essential amino acids, and essential fatty acids. these must all be in your diet.

75
Q

what is the difference between malnutrition and under nutrition.

A

malnutrition is an unbalanced diet (including excessive eating), while under nutritioned is deficiency of nutrients.

Biology AP (13 decks)

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