BIOL 204 > digestion > Flashcards

digestion Flashcards

don't make comments about my digestion (60 cards)

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1
Q

digestive tract

A

hollow tube that runs from one opening to another

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2
Q

cloaca

A

in many vertebrates, a common cavity at the end of the digestive tract for the release of both excretory and genital products

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3
Q

3 major regions of the digestive tract

A

buccal cavity, pharynx, alimentary canal

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4
Q

buccal cavity

A

space inside the mouth

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5
Q

pharynx

A

throat

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6
Q

alimentary canal

A

everything posterior to the buccal cavity and pharynx (contains an esophagus, stomach, and intestines in most vertebrate taxa)

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7
Q

name some accessory organs of the digestive system. are they actually part of the digestive tract?

A

pancreas, liver, gallbladder, salivary glands, etc. these are not part of the digestive tract

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8
Q

what type of muscle propels food through the digestive tract?

A

smooth muscle

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9
Q

describe the embryonic origin of the lining of the pharynx and alimentary canal

A

endoderm

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10
Q

describe the embryonic origin of the liver, gallbladder, and pancreas

A

endoderm

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11
Q

describe the embryonic origin of the lumen of the digestive tract

A

archenteron

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12
Q

describe the embryonic origin of the lining of the buccal cavity

A

epidermal ectoderm

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13
Q

describe the embryonic origin of salivary glands

A

most arise from endoderm, but some (eg. parotid gland) arise from ectoderm

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14
Q

for a substance to actually enter the body, what needs to happen?

A

a substance must be broken down into molecules small enough to be absorbed, then it must pass through an epithelial cell or between 2 epithelial cells

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15
Q

epithelial cells

A

line certain structures of the body (eg. the lumen of the digestive tract)

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16
Q

list 6 examples of vertebrate diets

A

omnivores, carnivores, herbivores, detritivores, nectarivores, hematophagy

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17
Q

when assessing the quality of food, what 2 factors are considered?

A
  • how much energy is released when the food is digested (caloric content)
  • how difficult it is to digest
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18
Q

why are chemoreceptors (eg. taste buds on the tongue) important?

A

they help assess the quality of food and decide whether or not something is safe to ingest

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19
Q

why is it important to have mucus in saliva?

A

it lubricates the food and makes it slippery to it passes through the esophagus more easily

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20
Q

pharyngeal jaws

A

found in some actinopterygii; allow mechanical digestion to begin in the pharynx

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21
Q

epiglottis

A

structure in mammals that prevents food from entering the larynx

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22
Q

esophagus

A

muscular tube that propels food from the pharynx into the stomach

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23
Q

crop

A

pouch in the esophagus of many birds that stores food to be digested later or regurgitated to feed their young

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24
Q

crop milk

A

nutritious substance formed from the lining of the crop that is regurgitated by birds to feed their chicks

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25
3 types of digestion
mechanical, chemical, microbial
26
mechanical digestion
physically breaking up food into smaller pieces
27
chemical digestion
breaking food down using enzymes
28
microbial digestion
microorganisms in the digestive tract secrete substances that digest food
29
rugae
folds in the stomach lining that allow the stomach to stretch as it fills with food
30
how many layers of smooth muscle does the stomach have? what is the function of this muscle?
the stomach has 3 layers of smooth muscle which mechanically churn and crush the food to break it down
31
how does mechanical digestion prepare food for chemical digestion?
mechanical digestion physically breaks food apart to increase surface area for chemical digestion
32
what are the sphincters at either end of the stomach?
anterior end - cardiac sphincter posterior end - pyloric sphincter
33
sphincters
rings of smooth muscle that constrict the 2 ends of the stomach and ensure that nothing leaks out while the stomach is churning food
34
gastric pits
indentations in the stomach lining that gastric glands secrete substances into
35
gastric glands
secrete substances (enzymes, mucus, acid) into the gastric pits that make up gastric juice
36
why is acid necessary in the stomach?
- destroys pathogens - activates pepsinogen into pepsin, which is responsible for protein digestion - denatures (unfolds) proteins, exposing more surface area for pepsin to degrade them
37
why is mucus necessary in the stomach?
mucus provides lubrication and a protective coating for the stomach lining to prevent it from digesting itself
38
gizzard and proventriculus
the 2 stomach chambers in some vertebrate taxa (eg. birds)
39
proventriculus
smaller, anterior stomach chamber in birds which produces acid and enzymes for chemical digestion
40
gizzard
larger, posterior stomach chamber in birds specialized for grinding
41
intestines
main site of chemical digestion of proteins, fats, and carbs
42
duodenum
most anterior region of the small intestine; contains glands which secrete bicarbonate
43
what 2 organs produce secretions that are important for digestion in the small intestine?
pancreas and liver
44
pancreas
produces bicarbonate and enzymes (amylase, trypsin, etc.) for chemical digestion
45
liver
produces bile, which acts as an emulsifier
46
emulsifier
breaks down globules of fats that are stuck together so lipases can break them down chemically
47
why is mucus important in the small intestine?
mucus forms a protective coating that protects living cells against digestive enzymes and infection by pathogens
48
list 6 features of the small intestine that make it specialized for nutrient absorption
- high surface area - long passage, which increases time for absorption - microvilli - thin epithelium - enzymes in the membranes of epithelial cells - highly vascularized lining of intestine
49
plicae
permanent circular folds in the lining of the small intestine
50
villi
tiny projections of the epithelium of the small intestine
51
how many cell layers thick is the epithelium of the small intestine?
one cell layer thick
52
microvilli
microscopic projections of the cell membrane of each individual enterocyte that greatly increase surface area for nutrient absorption
53
enterocytes
absorptive cells of the intestinal epithelium
54
approximately how much smaller is a microvillus compared to a villus?
~1000 times smaller
55
pyloric sphincter
controls the exit of food from the stomach
56
pyloric caeca
pouches in the junction of the stomach that are sites for chemical digestion and nutrient absorption
57
spiral valves
increase surface area of the intestinal epithelium for nutrient absorption and slows the passage of food through the digestive tract, allowing more time for digestion
58
what taxa have spiral valves? what do taxa without spiral valves have instead to increase nutrient absorption?
chondrichthyes, dipnomorpha, petromyzontida, and some non-teleost actinopterygii have spiral valves. tetrapods and most actinopterygii have a very long small intestine instead, which slows the passage of food and increases surface area for nutrient absorption.
59
are herbivorous diets generally higher or lower quality than carnivorous ones?
herbivorous diets are more difficult to digest (involves lots of breaking down cellulose), so they are lower quality
60
would the digestive tract of a herbivore or carnivore be longer?
herbivorous diets are lower quality (less calories per gram), so absorption needs to be maximized to get the most out of the food. therefore, the digestive tract of a herbivore would be longer to prolong digestion and increase surface area for absorption.
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