The GI Tract Flashcards

1
Q

What is our main source of energy?

A

calories

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2
Q

What are carbohydrates?

A

our primary fuel source

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3
Q

What are the two things we can do with carbohydrates?

A
  1. burn in mitochondria for ATP
  2. store as fat for later
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4
Q

What are fats used for?

A

energy storage

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5
Q

Are fats more efficient than carbs and proteins? By how much?

A

yes, they are! they are 2x as efficient

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6
Q

What are the three overarching essential ingredients we need to function?

A
  1. protiens
  2. vitamins
  3. minerals
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7
Q

What are proteins used for?

A

to break down into amino acids

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8
Q

How many amino acids can your body make?

A

11/20, so the rest you have to eat

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9
Q

What are vitamins?

A

organic substances that CAN’T be made by the body

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10
Q

What are minerals?

A

inorganic substances that CAN’T be made by the body

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11
Q

What is the GI tract?

A

digestive system (mouth to anus)

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12
Q

What do accessory organs do in the GI tract?

A

they help secrete enzymes that aide digestion

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13
Q

What are some accessory organs?

A
  1. liver
  2. gallbladder
  3. salivary gland
  4. pancreas
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14
Q

What is the lumen?

A

the hole running through the GI tract

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15
Q

What is the mucosa?

A

inner layer of the GI tract that secretes mucus, protects other layers, and absorbs nutrients

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16
Q

What type of tissue is the mucosa?

A

epithelial

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17
Q

What is the submucosa?

A

2nd innermost layer, that has lymphatic, nerve, and blood vessels

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18
Q

What type of tissue is the submucosa?

A

connective

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19
Q

What is the muscularis layer?

A

the 3rd innermost layer that has circular and longitudinal muscles for pushing food down

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20
Q

What type of tissue is the muscularis layer?

A

smooth muscle tissue

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21
Q

What is the serosa?

A

outermost layer, protects tract from the outside

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22
Q

What type of tissue is the serosa?

A

epithelial

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23
Q

What is the beginning of digestion?

A

when salivary glands secrete enzymes

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24
Q

What if you have no teeth for food breakdown?

A

no problem, some birds swallow pebbles and do the mechanical breakdown in their gizzard

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25
Q

What is the salivary gland controlled by?

A

your brain

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26
Q

How does swallowing start and end?

A

it starts voluntary and ends involuntary

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27
Q

What does the esophagus do?

A

connects pharynx to stomach

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28
Q

What happens to the esophagus when you swallow?

A

your brain tells the esophagus to send one way waves to move food downwards

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29
Q

What is a sphincter?

A

openings that let food in and then close itself, so that food doesn’t travel backwards

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30
Q

What is the entrance to the stomach from the esophagus?

A

the esophageal sphincter

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31
Q

What happens in the stomach to the food?

A

gastric juices mix with food

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32
Q

What does HCl do in the stomach and where does it come from?

A

it creates the low pH environment in the stomach and it is secreted from the parietal cells

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33
Q

What other gastric molecule is in the stomach?

A

pepsinogen

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34
Q

Is pepsinogen active or inactive?

A

inactive, the stomach keeps it that way until the food arrives because you don’t want to digest your own stomach

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35
Q

How is pepsinogen turned active?

A

when our stomach becomes acidic by the HCl and pepsinogen turns into pepsin

36
Q

What cells does pepsinogen come from?

A

chief cells

37
Q

Does the stomach absorb nutrients from the food?

A

no, that happens in the small intestine

38
Q

What are the three parts of the small intestine?

A
  1. duodenum
  2. jejunum
  3. ileum
39
Q

What does the duodenum do?

A

fats are broken down here with accessory organs pancreas and gallbladder

40
Q

What does the jejunum do?

A

this is where absorption officially starts

41
Q

What does the ileum do?

A

absorbs more nutrients

42
Q

Is the small intestine small?

A

nope, it has a huge surface area and it’s about the size of a tennis court

43
Q

What do the villi and microvilli do?

A

hair like structures in the small intestine that increases absorption and it is called the “brush border”

44
Q

What are proteins and carbs broken down by?

A

the brush border enzymes

45
Q

Where do the broken down proteins and carbs go?

A

they are transported into cells and then into the blood stream

46
Q

What emulsifies fats in the small intestine?

A

bile salts

47
Q

What enzymes break down the fats into fatty acids?

A

lipase enzymes

48
Q

What happens to the fats after breakdown?

A

it diffuses across the membrane and is packed into transport proteins

49
Q

What are chylomicrons?

A

transport proteins that fatty acids are packed into

50
Q

Where does the fatty acid enter?

A

the lymph system first and then the circulatory system

51
Q

What does the pancreas do for the small intestine?

A

secretes enzymes “pancreatic juice” into the duodenum via the pancreatic duct

52
Q

What are some enzymes that the pancreas secretes?

A

bicarbonate, trypsin, amylase, and lipase

53
Q

What does bicarbonate do?

A

neutralizes stomach acids (after the food enters the small intestine)

54
Q

What does trypsin do?

A

aids with digestion

55
Q

Is trypsin stored actively or inactively?

A

inactively

56
Q

What kind of environment is amylase and lipase activated by?

A

basic (alkaline) environment

57
Q

Before the nutrients get distributed throughout the body, what must they pass through first?

A

the liver

58
Q

What is the main function of the liver?

A

detoxification

59
Q

What does the liver regulate?

A

glucose levels

60
Q

If there’s too much glucose, what does the liver do?

A

make glycogen

61
Q

If there’s too little glucose, what does the liver do?

A

break down glycogen

62
Q

What else does the liver do?

A

makes plasma proteins and filters dead bile pigments

63
Q

What is the large intestine also called?

A

the colon

64
Q

How large is the large intestine compared to the small one?

A

shorter but wider than the small intestine

65
Q

What does the colon do?

A

absorbs the last of the water, electrolytes, and vitamin k & compacts feces

66
Q

What is attached to the colon?

A

cecum and appendix

67
Q

Do we have a cecum?

A

no

68
Q

What does the cecum do?

A

helps digest cellulose

69
Q

What 2 sphincter muscles control the rectum?

A

a voluntary and involuntary muscle

70
Q

What is feces composed of?

A

water, mucus, bacteria. and bile pigments

71
Q

What do herbivores have in order to digest cellulose?

A

longer digestive tracts and a longer cecum

72
Q

What do ruminants have to help digest cellulose?

A

4 chambered stomachs

73
Q

What doe carnivores have because they don’t really eat plants?

A

shorter intestinal tracts (also because they chan tear and chew food)

74
Q

What is coprophagy?

A

when animals eat feces to absorb more nutrients

75
Q

What does ghrelin do?

A

stimulates hunger and feeding and it is released from the stomach to the brain

76
Q

What does leptin do?

A

tells CNS to limit food intake (high body fat=high levels of leptin)

77
Q

What is BMR?

A

calories needed by your body to perform basic functions

78
Q

What is the difference between Calorie and calorie?

A

Calorie = kcal
calorie = cal

79
Q

When does transition between voluntary to involuntary digestion occur?

A

when the food goes from the oral cavity to the pharynx

80
Q

How does swallowing affect breathing?

A

you momentarily hold your breath, when swallow, to close the airway so that food doesn’t go to your lungs

81
Q

What is peristalsis?

A

the motion of moving food down your esophagus

82
Q

Where are the bile salts made and stored?

A

made in the liver but stored in the gallbladder

83
Q

What is gastrin?

A

hormone that stimulates the secretion of gastric juices into the stomach

84
Q

What cells does gastrin target?

A

it targets chief and parietal cells because they’re the ones that secrete HCl and pepsin

85
Q

What is CKK and what does it do?

A

it is a hormone that stimulates the release of pancreatic juices

86
Q

What does GIP do?

A

it’s a hormone that responds to ingestion of glucose (it increases intake and absorption of nutrients)

87
Q

What is secretin and what does it do?

A

regulates and secretes bicarbonate into the duodenum