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Biology > The Digestive System > Flashcards

The Digestive System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Digestion

A

The breakdown of large food molecules into smaller components. Once digested, nutrients can be absorbed. Vitamins, minerals, water can be absorbed without being digested.

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2
Q

Mechanical Digestion (physical)

A

The physical breakdown of food into smaller pieces (e.g. teeth)

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3
Q

Chemical Digestion

A

The breakdown of macromolecules by enzymes (e.g. enzymes in saliva, amylase)

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4
Q

Monosaccharides

A

•simple sugar (1 unit)
E.g. glucose, fructose, galactose

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5
Q

Disaccharides

A

•sugars (2 units)
E.g. sucrose, lactose, maltose

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6
Q

Polysaccharides

A

•many sugars
E.g. starch, cellulous
(Most common)

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7
Q

Parts of the Digestive System

A

Accessory Organs and The Digestive Tract

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8
Q

Accessory Organs

A

structures that aid digestion but food doesn’t go through

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9
Q

The Digestive Tract

A

organs that contain food

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10
Q

Mouth (teeth)

A

•humans get two sets of teeth
•20 deciduous (“baby” teeth)
•32 permanent that are covered in enamel, beneath is dentin with sensory cells, root attached tooth to the bone

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11
Q

Incisors teeth

A

•8 of them
•used for cutting

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12
Q

Canine teeth

A

•4 of them
•used for tearing/ripping

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13
Q

Premolar teeth

A

•8 of them
•used for grinding

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14
Q

Molar teeth

A

•12 of them
•used for grinding

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15
Q

Mouth (tongue)

A

•strong muscle containing taste buds (sweet, sour, salty, bitter)
•helps mold and smooth out food into a soft mass called a bolus, which is then pushed to the back of your mouth (pharynx) towards the esophagus

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16
Q

Bolus

A

Ball of chewed food

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17
Q

Salivary glands

A

produce saliva the begin chemical digestion of food (3 salivary glands)

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18
Q

Saliva contains:

A

•the enzyme amylase which starts to breakdown starch into simpler sugars
•mucus for lubrication, making it easier to swallow
•dissolves water-soluble food particles
•stimulates the taste buds

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19
Q

Mouth - Esophagus

A

•muscular tube between mouth and stomach (25cm long)

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20
Q

Swallowing

A

•during swallowing the soft palate moves up to close off the nasal cavity, epiglottis close off the trachea (or windpipe), muscles above the bolus push it through the esophagus by a series of rhythmic contractions peristalsis, the esophagus is unrivalled by cells that secrete mucins (triglycerides)

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21
Q

Esophagus - Stomach

A

•the entrance to the stomach is controlled by a ring of muscle called the esophageal sphincter
•usually closed to prevent acidic stomach contents from rising into the esophagus
•relaxes to allow food to enter stomach

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22
Q

Stomach

A

•muscular, J-shaped organ where food is temporarily stored while further chemical and mechanical digestion takes place
•walls are folded (called rugae) like an accordion, which allows the stomach to expand after a meal

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23
Q

Stomach (gastric juice)

A

•lined with millions of gastric glands that secrete gastric juice when simulated by presence of food
•approximately 400 to 800ml of gastric juice are released per meal

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24
Q

Gastric juice

A

•used for chemical digestion of food
•gastric juice is made up of HCl acid, enzymes, salts, water and mucus

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25
Q

Gastric Cells: Parietal

A

•secrete hydrochloric acid (HCl)(pH=1-2)
•the acid kills some bacteria, denatures bacteria, breaks down tissue, and activates the enzyme pepsin

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26
Q

Gastric Cells: Chief

A

•secrete pepsinogen
•HCl chemically removed part of this molecule, leaving the active enzyme pepsin

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27
Q

Gastric Cells: Mucus-secreting

A

•secrete mucus
•coats the inner lining of the stomach with a protective layer

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28
Q

Pepsin

A

•digests proteins into smaller polypeptide chains (breaks down protein)

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29
Q

Stomachs 3 methods of protecting itself from being digested

A
  1. Little gastric juice is secreted until food is present
  2. Some stomach cells secrete mucus which coats the walls and prevents the juice from harming the lining
  3. The production of pepsin- remains inactive until HCl is present
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30
Q

Stomachs 3 layers

A

•3 layers of muscle fibers that contract and relax to mechanically break up food and mix it with the gastric juice
•the result is a thick liquid called chyme
•the pyloric sphincter keeps food in stomach when closed

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31
Q

Intestines

A

•between stomach and anus
•has cells the secrete mucus to help lubricate food
•contains smooth muscle tissue to help move the food along
•has a lot of blood vessels interlaced through it- allows nutrients to be absorbed into the blood

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32
Q

Lumen (intestine)

A

the central space of the tract

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33
Q

Mucosa (intestine)

A

(epithelial lining) consisted of mucus-secreting, enzyme- secreting, absorptive and endocrine cells

34
Q

Submucosa (intestine)

A

layer of connective tissue that supports the blood vessels, lymphatic vessels and nerves

35
Q

Circular smooth muscle (intestine)

A

ring, contracts when contracts (squeezes)

36
Q

Longitudinal smooth muscle (intestine)

A

shortens when contracts (stretches)

37
Q

Serosa (intestine)

A

a layer of connective tissue holding everything in place

38
Q

Small Intestine

A

•long, thin muscular tube (6-7m long)
•most absorption of food nutrients occurs here- lined by villi that increase surface area
•Duodenum, jejunum, and ileum

39
Q

Duodenum

A

•0.5m long
•receives chyme from stomach
•receives secretions from pancreas and liver
•also receives: bile, digestive enzymes, and sodium bicarbonate
•where most of the absorption occurs

40
Q

Jejunum

A

•where the absorption of nutrients begins

41
Q

Ileum

A

•absorption of nutrients is completed here (leftover)

42
Q

Bile

A

•produced in the liver, stored in the gall bladder
•bile: salts, pigments, cholesterol (not an enzyme)(like soap)
•emulsifies fats- physically breaks down large fat droplets into smaller fat droplets
•increased surface area for lipase to act on

43
Q

Digestive Enzymes- “ase”

A

•produced in the pancreas and in the intestinal wall
•Lipase-lipids
•Protases- proteins
•Carbohydrase- carbohydrates (such as amylase- breaks down amylose)

44
Q

Sodium Bicarbonate

A

•from pancreas
•neutralizes acid, raises pH 8, protects intestines
•activated intestinal enzymes

45
Q

Jejunum and Ileum

A

•secrete more digestive enzymes from intestinal glands
•also is the major site for nutrient absorption (most in jejunum)
•especially adapted for this function because of its length and its increased surface area
•the intestinal wall is accordioned to create a series of circular folds

46
Q

Absorption in the Intestines

A

•mucosa has villi and microvilli
•nutrients cross the villi into the capillaries inside the villi
•these nutrients are carried along the portal vein to the liver, where they are processed
•the exception to this is the absorption of glycerol and fatty acids
•these enter the lacteal, where they are carried through the lymphatic system and enter the blood beyond the liver

47
Q

Villi

A

finger-like projections out from the wall, with many blood vessels through them

48
Q

Microvilli

A

each outer villus cell is lined with extensions of its cell membrane

49
Q

Large Intestine

A

•extends small intestine to anus
•wider and 1.5m long
•primary function is to absorb water from indigestible food
•remaining solid matter excreted as feces

50
Q

Large Intestine (2)

A

•material flows from the small intestine through the ileocecal sphincter into the cecum (a sac collecting at the bottom of the ascending colon)
•waste and water is pushed through the colon by peristalsis
•water and some remaining nutrients are absorbed into the body
•this concentrates the waste (feces), which is stored in the rectum

51
Q

Rectum

A

•storage sac, guarded by a complex set of sphincters
•defecation occurs when the anus is relaxed, eliminating the feces (egestion)

52
Q

Enzymes

A

•activation energy is the energy required to start a chemical reaction
•enzymes are proteins that are used to catalyze biological reactions by lowering the activation energy
•without enzymes, reaction in our bodies would require an excess amount of heat to occur, or not occur at all

53
Q

Enzymes (2)

A

•enzymes don’t get used up, they are ready to catalyze
•they are substrate specific
•they are pH and temperature specific, so much better in the correct environment to function (or they will denature=breakdown)
•some enzymes require coenzymes or cofactors (“helpers”) to function coenzymes are usually vitamins and cofactors are usually metals(e.g. Mg)

54
Q

Liver (2nd largest organ in the body)

A

•two lobes approximately 3lbs
•produced bile (stored in the gall bladder) that is needed to digest fats, secreted into the duodenum

55
Q

Fat Digestion

A

•bile: salts, pigments, cholesterol
•emulsifies fats- physically breaks down large fat droplets into smaller fat droplets

56
Q

Amino Acid Metabolism/Synthesis

A

•synthesizes amino acid (a.a.)
•removes nitrogen groups from a.a.

57
Q

Detoxify Blood

A

•receives blood through portal vein (from GI tract) and filters blood to remove pathogens and toxins such as alcohol, nicotine, and drugs of harmful substances

58
Q

Breaks down old (senesecent) RBC

A

Kupffer cells (immune cell, macrophage), RBC lifespan 120 days, recycles hemoglobin, results in brown colour feces

59
Q

Produces Clotting factors

A

Liver

60
Q

Vitamin Absorption

A

Vitamins A and D are fat-soluble vitamins and depend on bile salts for absorption

61
Q

Liver + Pancreas: Blood sugar control

A

Low Blood Glucose and High Blood Glucose

62
Q

Low Blood Glucose

A

•pancreas releases glucagon, glucagon promotes the breakdown of liver glycogen - glucose which is released in the blood

63
Q

High Blood Glucose

A

•pancreas releases insulin, insulin stimulates liver to store glucose - glycogen and tells body to use glucose for energy or store it

64
Q

Hormones: CCK- Cholecystokinin

A

•once fat-rich chyme reaches the duodenum
•endocrine cells triggered and release hormone cholecystokinin (CCK)
•CCK is released - bloodstream- gall bladder- caused bile to be released
•bile then able to emulsify fats

65
Q

Hormones: Secretin

A

•presence of chyme in s.i. causes hormone secretin to be released from duodenum wall
•secretin travels- bloodstream- pancreas
•signalling pancreas to release enzymes & bicarbonate into a duct
•send enzymes & bicarbonate into duodenum

66
Q

Gall bladder

A

•stores and releases bile, which aids in the breakdown of fats

67
Q

Pancreas

A

•releases enzymes into duodenum, along with bicarbonate which alters the pH of chyme to pH 8 (more basic) so enzymes can function
•blood glucose regulation with liver

68
Q

Appendix

A

•where the small and large intestine join
•studies suggest is contains helpful bacteria that the large intestine uses to help absorb vitamins
•once thought to be a vestigial structure (changed in 2000’s)
•if inflamed- can be dangerous (leads to appendicitis)

69
Q

Diarrhea and Vomiting

A

•two ways the digestive system gets rid of disease-causing agents and foreign substances

70
Q

Nausea

A

•is the feeling or urge to vomit
•nausea & vomiting are symptoms of underlying conditions
•e.g. motion sickness, flu, food poisoning, concussion, etc
•vomiting signal comes from the brain

71
Q

Vomiting can cause

A

•risk or concerns: dehydration, choking, tears in the lining of esophagus, and strained abdominal muscles

72
Q

Diarrhea

A

•another way the body flushes out the system
•when water is inadequately absorbed in colon
•feces egested is watery
•most cases caused by infections: bacteria, viruses, or parasites (e.g. contaminated food or water)(walkerton, Ontario, 2000)
•risks also include dehydration, diarrhea and vomiting are also ways the disease- causing organisms can spread to others

73
Q

Constipation/Diarrhea

A

•the movement of waste through the colon is regulated to allow for the absorption of water while keeping feces soft and malleable enough to be eliminated
•if too much water or to little water is reabsorbed, the feces may be too dry (constipation) or too wet (diarrhea)

74
Q

Heartburn

A

•acid reflux pushes acids through the lower esophageal sphincter
•creates a burning sensation the the esophagus, which sits atop the heart

75
Q

GERD

A

Gastroesophageal reflux disease
•chronic upper gastrointestinal disease
•stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/or complications

76
Q

Peptic Ulcer

A

•ulcer- open sore
•sore in inner lining of lower esophagus, stomach, or duodenum

77
Q

Gastric Ulcer

A

•in stomach
•mucus lining of the stomach weakens
•acids eat away at the stomach lining
•causes: bacterial infection, excess alcohol, regular use of NSAIDS, smoking/tabacco, stress, etc.
•treatment (depending on source): antibiotics, anti-acids, etc

78
Q

Gallstones

A

•mineral salts used as a component of bile may calcify
•forms insoluble crystals that may block the bile duct
•treatment: surgery (if severe), medication to dissolve

79
Q

Appendicitis

A

•infection of the appendix
•inflammation may worsen until it bursts, spilling bacteria into the abdominal cavity

80
Q

Colon Cancer

A

•small lumps of calls called polyps grow on the inside of the colon
•polyps if left untreated can grow into colon cancer
•easily removed if caught early

81
Q

Lactose Intolerance

A

•people with lactose intolerance do not have enough of the enzyme lactase to breakdown lactose
•undigested lactose moves to the large intestine without being absorbed in the small intestine which bacteria then ferments, producing gas, which causes bloating, cramps, and discomfort

Biology (7 decks)

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