Digestive System Flashcards

1
Q

digestive tract

A
  • hollow passage from the mouth to the anus/cloacal opening
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2
Q

division of digestive tract (3)

A
  • buccal cavity
  • pharynx
  • alimentary canal
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3
Q

alimentary canal (4)

A
  • esophagus
  • stomach
  • small intestine
  • large intestine
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4
Q

how does food truly enter the body

A
  • it must be absorbed: pass through an epithelial cell or pass between two epithelial cells
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5
Q

digestive system: main functions

A
  • digestion

- absoprtion

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6
Q

digestion

A
  • breaking down of food into molecules that can be absorbed
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7
Q

absorption

A
  • uptake of molecules through the epithelium of the digestive tract into the blood or lymph
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8
Q

general process of the digestive system (8)

A
  • ingestion
  • food storage
  • mechanical digestion
  • chemical digestion
  • microbial digestion
  • absorption
  • water reabsorption
  • defecation
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9
Q

general diets (6)

A
  • other animals (carnivore)
  • plants (herbivore)
  • combination of everything (omnivore)
  • dead organic material
  • blood
  • nectar
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10
Q

quality of food

A
  • the relative difficulty of digesting the food and the amount of energy released when the food is digested
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11
Q

higher quality foods (2)

A
  • release of a relatively large amount of energy

- requirement of relatively little time or energy for digestion

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12
Q

rank the quality of these foods: whole fish, leaves, blood

A
  1. blood
  2. fish
  3. leaves
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13
Q

what are the characteristics of an organism that eats high quality food (2)

A
  • small or no stomach

- small intestine does not require much surface area

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14
Q

buccal cavity (4)

A

site of ingestion, feeding, and swallowing:

- tongue, chemoreceptors, salivary glands, saliva

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15
Q

buccal cavity: tongue

A
  • aids to propel food through the pharynx and into the alimentary canal during swallowing
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16
Q

buccal cavity: chemoreceptors (taste buds) (2)

A
  • signal to brain to start digestion

- detect quality of food

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17
Q

buccal cavity: salivary glands/saliva (3)

A
  • mucus (lubrication, protect/buffer lumen lining)
  • digestive enzymes
  • toxins
18
Q

pharynx (3)

A
  • posterior to the buccal cavity
  • many tetrapods lose slits during development, but are retained in fish
  • many tetrapods have structure to prevent foods from entering larynx (epiglottis)
19
Q

alimentary canal: esophagus

A
  • muscular tube that transports food from pharynx to the stomach
20
Q

aves: esophagus (2)

A
  • contains crop used to store large amounts of food to be digested at a later time or regurgitated to feed their young
  • lining of crop can produce nutritious substance (crop milk) that is regurgitated to feed young
21
Q

alimentary canal: stomach (3)

A
  • stores meal
  • mechanically churns food to physically break it down into smaller pieces
  • gastric glands secrete mucus, enzymes, and acid for chemical digestion
22
Q

stomach: why is mechanical digestion necessary?

A
  • increases SA to allow chemical digestion to be more efficient and accessible to enzymes
23
Q

rugae

A
  • folds in the stomach that can unfold to increase stomach volume for storage of food
24
Q

mono-gastric stomach (2)

A
  • single chamber stomach

- mechanical digestion generally due to muscular action

25
aves: stomach (3)
- two chambered stomach: gizzard and proventriculus - proventriculus: produces acid and enzymes for chemical digestion - gizzard: specialized grinding stomach, may contain sand or small stones
26
alimentary canal: small intestines (2)
- main site of chemical digestion of proteins, fats and carbohydrates - major site of nutrient absorption
27
alimentary canal: anterior of SI (3)
- duodenum - contains glands that produce alkaline secretions - liver and pancreas produce secretions (bile, enzymes) into the duodenum
28
bile
- acts as an emulsifier: breaks globules of fat into smaller droplets, increasing SA for enzymes to act
29
what to the glands within the SI produce (2)
- enzymes | - mucus
30
what general structural features of the SI help to increase the total amount of nutrients absorbed (4)
- large surface area - thin epithelium - vascularization - specializations that increase length of time spent in small intestine
31
how does the SI increase SA (2)
- plicae: circular folds in internal surface that are covered in microvilli; do not unfold (permanent) - microvilli: tiny projections of the cell membrane
32
how many layers thicks is the epithelium of the SI
- one cell thick
33
small intestine: pyloric caeca (3)
- located at junction of stomach and duodenum - sites of chemical digestion and nutrient absorption (not fermentation) - internal surface contain villi and microvilli, increasing SA for nutrient absorption
34
small intestine: spiral valve (2)
- chrondrichthyes and sarcopterygii - increases SA for digestion and absorption and slows passage of food through the intestine, increasing time available for digestion
35
how do vertebrates without spiral valves prolong digestion (2)
- small intestine length is greatly increased | - helps slow passage of food and increases SA
36
alimentary canal: microbial digestion (2)
- symbiotic microorganisms can digest some foods that vertebrate cannot produce enzymes for (cellulose; fermentation) - some microorganisms produce vitamins as well
37
intestines: colic caecum (3)
- present at the junction between small and large intestines - many aves have 2 colic caeca - blind-ending chamber specialized for fermentation: contains enlarged SA and many microorganisms that digest cellulose
38
how do vertebrates that digest cellulose using fermentation in the caecum obtain nutrients from digested cellulose?
- release fecal pellets and eat them again to absorb cellulose nutrients
39
alimentary canal: large intestine (2)
- consolidates undigested material into feces for defecation - water reabsorption from indigested material to avoid dehydration: from digestive glands, enzymes, mucus and other secretions
40
which large intestine would be larger: terrestrial tetrapods or freshwater tetrapods
- terrestrial tetrapods: conserving and retaining H2O is more important
41
coelom (2)
- created in space between splanchnic and somatic hypomere layers - gives rise to major body cavities of adult body
42
peritoneum (3)
- continuous sheet of tissue/serous membrane that secretes lubricating fluid - reduces friction to protect organs - lines the pleuroperitoneal cavity/peritoneal cavity