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Anatomy & Physiology 2 > Digestive System Chp. 23 (Test 4) > Flashcards

Digestive System Chp. 23 (Test 4) Flashcards

1
Q

What is the overall function of the digestive system?

A

takes in food, breaks it down into absorbable molecules, absorbs them into the blood stream, & rids body of indigestible remains.

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2
Q

What are the six essential steps in digestion?

A
  1. ingestion
  2. propulsion
  3. mechanical digestion
  4. chemical digestion
  5. absorption
  6. defecation
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3
Q

What is ingestion?

A

taking food into the digestive tract

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4
Q

what is propulsion?

A

moving food thru alimentary canal. includes swallowing & peristalsis. it’s the major means of moving food, involves alternating waves of contraction and relaxation of smooth muscles in tract.

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5
Q

What is mechanical digestion?

A

physical preparation of food for chemical digestion. includes chewing, mixing food with saliva, churning in stomach, and segmentation( rhythmic local construction of small intestine- designed to mix food with digestive juices.

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6
Q

What is chemical digestion?

A

series of catabolic steps where food is broken down into their simple building blocks. done by enzymes. starts in mouth and finishes in small intestines.

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7
Q

What is absorption?

A

passage of digested end products from lumen of GI tract into blood or lymph. happens in small intestines. once in blood or lymph, nutrients get delivered to liver via hepatic portal circulation. liver collects nutrients for metabolic processing of storage before releasing them back to the bloodstream for general cellular use.

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8
Q

What is defecation?

A

elimination of indigestible substances in form of feces.

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9
Q

What are the two major divisions of the digestive system?

A

the alimentary canal and the accessory digestive organs.

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10
Q

What is the alimentary canal?

A

also known as gastrointestinal tract. continuous digestive tube that’s open at both ends.

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11
Q

What is the accessory digestive organs?

A

assists with digestion. includes teeth, tongue, salivary glands, gallbladder, liver, and pancreas.

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12
Q

What is the histology of the alimentary canal?

A

from the esophagus to the anal canal, the walls of the alimentary canal have the same four basic layers: mucosa, submucosa, muscularis externa, and serosa.

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13
Q

What is the mucosa layer in the alimentary canal?

A

innermost layer. simple columnar epithelium & small layer of smooth muscle. major function: 1. secrete mucus, digestive enzymes, and hormones. 2. absorb end products of digestion. & 3. protect against infectious disease

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14
Q

What is the submucosa layer in the alimentary canal?

A

aerolar connective tissue with lots of blood vessels, lymphatic vessels, elastic fibers and nerves.

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15
Q

What is the muscularis externa in the alimentary canal?

A

typically two layers of smooth muscle- inner circular layer and outer longitudinal layer. responsible for the segmentation and peristalsis. in a few places the circular layer thickens to form a sphincter.

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16
Q

What is the serosa in the alimentary canal?

A

protective outer most layer- aerolar connective tissue. becomes part of the visceral peritoneum. the esophagus’s outer layer is called the adventitia- made of fibrous connective tissue. it actually binds the esophagus to surrounding structures.

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17
Q

What are the parts of the mouth that are involved with digestion?

A

mucus lined oral cavity. lips, tongue, palate, salivary glands, and teeth.

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18
Q

What is the function of saliva?

A
  1. clean mouth
  2. dissolve food so that it can be tasted
  3. moistens food making it easier to swallow
  4. begin chemical digestion of carbs-starchy foods
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19
Q

What is salivary amylase?

A

enzyme that begins chemical digestion of carbs- starchy foods

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20
Q

What is mastication?

A

chewing

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21
Q

What is the difference between deciduous teeth and permanent teeth? &how many?

A

deciduous teeth- milk teeth. are first set to erupt. “baby” teeth, erupt 6month to 24 months. total of 20.
permanent teeth- second set of teeth to erupt. starting around age 6. total of 32

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22
Q

What are the different types of teeth?

A

incisors, canines, premolars, and molars.

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23
Q

What is the function of incisors and how many do you have?

A

chisel-shaped. used for cutting/biting into food. total of 8

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24
Q

What is the function of canines and how many do you have?

A

fanglike. used to tear or pierce food. total of 4.

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25
Q

What is the function of premolars and how many do you have?

A

broad surfaces with rounded cusps. good for grinding. total of 8

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26
Q

What is the function of molars and how many do you have?

A

4-5 cusps. best for grinding. total of 12. includes “wisdom teeth”

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27
Q

What is the basic structure of a tooth?

A

consists of 2 major regions: crown and root. the crown is covered by enamel. the bulk of the tooth is dentin. the tooth is held in place by cementum. also have a pulp cavity in the center of tooth- blood vessels and nerves.

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28
Q

What is enamel?

A

covering of the crown of the tooth. hardest substance in the body- not a real tissue. once cells make it, then they die off. if enamel decays or is broken- it needs to be artificially replaced.

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29
Q

What is dentin?

A

protein rich bone-like tissue. this is formed throughout life.

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30
Q

What is cementum?

A

tough connective tissue, attaches to the periodontal ligament. holds tooth in place.

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31
Q

What is dental caries?

A

cavities. results from gradual demineralization of enamel and underlying dentin by bacteria.

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32
Q

What is dental plaque?

A

a film of sugar, bacteria, and other mouth debris, that adhere to teeth. if the plaque is not removed, it calcifies, forming calculus- tartar. these hard deposits break seal between gingivae and teeth.

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33
Q

What is gingivitis?

A

anaerobic bacterial infection in the gingivae (gums). if not removed, have pockets of infection that neutrophils attack but also attack the tissues around infection.

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34
Q

What is periodontal disease?

A

when gingivitis causes the neutrophils to attack the tissues around the gingivae and the periodontal ligament gets destroyed. 95% of people over the age of 35 have this. and it accounts for 80-90% of tooth

35
Q

What is deglutition?

A

swallowing. complex process involves 22 separate muscle groups

36
Q

What are the two phases of deglutition?

A

buccal phase and pharyngeal-esophageal phase.

37
Q

What occurs during the buccal phase?

A

it’s a voluntary phase; tip of tongue moves up to hard palate, then contract tongue to force food back into oropharynx.

38
Q

What occurs during pharyngeal-esophageal phase?

A

it’s an involuntary phase, controlled by the swallowing center in the medulla. once food enters pharynx, respiration is momentarily inhibited. uvula closes off nasopharynx & epiglottis covers opening into respiratory passages. solid foods- 4-8 seconds. liquids- 1-2 seconds

39
Q

What is the function of the stomach?

A

temporary storage tank & site for chemical breakdown of proteins & food is converted to a creamy paste.

40
Q

What is the basic anatomy of the stomach?

A

cardia, fundus, body, pylorus, cardiac sphincter, pyloric sphincter.

41
Q

What is chyme?

A

creamy paste in which food is converted into in the stomach.

42
Q

What are the cells in the gastric pits?

A

parietal cells and chief cells

43
Q

What is the function of parietal cells?

A

secretes HCl, makes pH.

44
Q

What is the function of chief cells?

A

secretes pepsinogen (inactive protein-digesting enzyme). HCl is need to activate pepsinogen to pepsin

45
Q

What are ulcers and how are the treated?

A

crater-like erosions of the stomach wall. caused by acid-resistant helicobacter pylori bacteria that burrows thru the mucus and destroys protective mucosal layer. spicy foods, stress, alcohol, aspirin, ibuprofen, and smoking can be partially to blame as well. if H pylori is the cause, treatment is antibiotics to kill the bacteria and/or a blocker for histamine receptors which inhibits HCl secretion. if H pylori is not the cause, treatment is also histamine receptor blocking drugs- Tagamet or Zantac

46
Q

How is chyme moved into the small intestine?

A

gastric contractile activity: at the pylorus, muscularis externa is thicker, so more powerful contractions occur. each peristaltic wave squirts 3 mL or less of chyme into the small intestine. the contraction closes the phyloric valve so chyme is pushed back into the stomach- further mixes. stomach usually empties within 4 hrs of a meal.

47
Q

What is emesis?

A

vomiting. reverse peristalsis + contraction of abdominal muscles and diaphragm. factors: extreme stretching of stomach or small intestines or presence of irritants such as bacterial toxins, excessive alcohol, spicy foods, certain drugs. these irritants activate emetic center in medulla, which induce vomiting. excessive vomiting can lead to dehydration and/or electrolyte imbalances.

48
Q

What are the different parts of the small intestine?

A
  1. duodenum: 10”, contains openings for bile and pancreatic juices
  2. jejunum: 8 feet
  3. ileum: 12”
49
Q

What is the function of the small intestine?

A

digestion is completed here and virtually all absorption occurs here. called small as the diameter is only 1-1.5” wide, but nearly 20’ long.

50
Q

What are the modifications of small intestine that makes it suitable for absorption?

A

circular folds, villi, and microvilli (brush border)

51
Q

What are circular folds?

A

deep permanent folds of mucosa and submucosa- they force chyme to spiral thru lumen, slowing it’s movement- more time for absorption.

52
Q

What are villi?

A

fingerlike projections of mucosa (like nap of a soft towel). inside each villus is capillary and lacteal for absorption.

53
Q

What are microvilli?

A

oh the villi wall cells- looks like brush border in that there are brush border enzymes in these cells that complete digestion (maltase, lactase, sucrase, aminopeptidase, carboxypeptidase, etc.)

54
Q

What are intestinal crypts?

A

pits in-between the villi. here find cells that make and secrete intestinal juice- watery mixture containing mucus that serves as a carrier fluid for absorbing nutrients from the chyme

55
Q

How does chyme move through the small intestine?

A

chyme moves through the small intestine by segmentation nearly exclusively. chyme is moved back and forth in the lumen a few centimeters at a time by alternating contraction and relaxation rings of smooth muscle. peristalsis does occur in the small intestine, but mostly after most nutrients have been absorbed.

56
Q

What is the function of the large intestines?

A

to absorb most of the water from indigestible food residues, store them temporarily, then eliminate them as feces. much lager diameter- 2.75”, but not as long 5’

57
Q

What are the major parts of the large intestine?

A

cecum, ascending color, transverse colon, descending colon, sigmoid colon, rectum, anus, and appendix.

58
Q

What is the function of the bacterial flora that exist in the large intestine?

A

they breakdown some of the indigestible carbohydrates (cellulose) and release irritating acids and mixture of gases. the gases synthesize B complex vitamins and vitamin K, that are both needed by the liver to make important clotting proteins.

59
Q

How does the contents move through the large intestine?

A

particles spend 12-24 hrs in the large intestine. mass peristalsis are long, slow-moving contractile waves across the color 3-4 times a day. force contents toward rectum. fiber helps increase the strength of these colon contractions and softens stool.

60
Q

What is defecation reflex?

A

signals travel to spinal cord which then causes the sigmoid colon and rectum to contract and internal anal sphincter to relax. signals also go up to cerebral cortex concerning appropriateness, if it’s a go- external anal sphincter relaxes and opens. if delayed, the reflex contractions end in a few seconds and rectal walls relax.

61
Q

What is diarrhea?

A

watery stools. anytime residue is rushed through large intestine, there is not enough time to absorb H2O. typically from bacterial infection in colon or from prolonged physical jostling of digestive tract during long running.

62
Q

What is constipation?

A

residue stays in large intestine too long –> too much H2O is removed. stool becomes hard and difficult to pass. lack of fiber in diet, laxative abuse, lack of exercise, or even emotional upset may cause this.

63
Q

What is the digestive function of the liver?

A

make and secrete bile

64
Q

What is the digestive function of the gallbladder?

A

where bile is stored, also gallbladder absorbs some of H2O from bile.

65
Q

How does bile work?

A

bile emulsify (break up) fatty food into smaller globules, so that fat-digesting enzymes have more surface area to work on. bile is also a major vehicle for cholesterol excretion from the body.

66
Q

What are gallstones?

A

they are when too much cholesterol or two few bile salts are present which leads to cholesterol crystallization of bile.

67
Q

What is the treatment for gallstones?

A

dissolve crystals w/drugs or with ultrasound (lithostripsy), or vaporize with lasers or may have to surgically remove gallbladder.

68
Q

What is the digestive function of the pancreas?

A

pancreatic juices- provides environment for enzymes to finish chemical digestion.

69
Q

What is pancreatic juice?

A

they drain from pancreas via main pancreatic duct into the duodenum. it is water, enzymes, and electrolytes (especially HCO3-)

70
Q

What is malabsorption?

A

impaired nutrient absorption

71
Q

What are the common causes of malabsorption?

A
  1. something interferes with the delivery of bile or pancreatic juice to small intestine.
  2. factors that damage the intestinal mucosa (severe bacterial infections or excessive antibiotic therapy)
  3. something that reduces the absorptive surface area.
72
Q

What is celiac disease?

A

an autoimmune disorder where the immune system reacts to gluten. gluten breakdown products react with T cells to attack the intestinal lining. instestinal villi are damaged and surface area for absorption is reduced. symptoms: bloating, diarrhea, malnutrition. treatment: remove gluten from diet.

73
Q

What is chemical digestion?

A

the catabolic process where food is broken down to monomers (chemical building blocks) so that they can be absorbed.

74
Q

What are the organic classes of chemical digestion?

A

carbohydrate digestion, protein digestion, lipid (fat) digestion, and nucleic acid digestion.

75
Q

What occurs during carbohydrate digestion?

A

starch and disaccharides are broken down by salivary amylase (in mouth) and pancreatic amylase (in pancreas). into oligosaccharides and disaccharides. brush border enzymes (in small intestine) break them down even further. lactose into galactose and glucose, maltose into glucose, and sucrose into glucose and fructose.

76
Q

What occurs during protein digestion?

A

proteins are broken down by pepsin (in stomach glands) into large polypeptides. then broken down by pancreatic enzymes (in pancreas) into small polypeptides and small peptides. the broken down once again by brush border enzymes (in small intestine) into amino acids.

77
Q

What occurs during fat digestion?

A

emulsified triglycerides are broken down by lingual lipase (in mouth), gastric lipase (in stomach), emulsification by the detergent action of bile salts ducted in from the liver, and pancreatic lipases (in pancreas), into monoglycerides and fatty acids.

78
Q

What occurs during nucleic acid digestion?

A

nucleic acids are broken down by pancreatic ribonuclease and deoxyribonuclease (both in pancreas) and brush border enzymes (in small intestine) into pentose sugars, N-containing bases, and phosphate ions.

79
Q

Where does chemical digestion take place?

A

carb digestion- mouth and small intestine.
protein digestion- stomach and small intestine.
lipid digestion- mouth, stomach, and small intestine.
nucleic acid digestion- small intestine

80
Q

What are the major enzymes involved in carbohydrate digestion?

A

salivary amylase, pancreatic amylase, and brush border enzymes.

81
Q

What are the major enzymes involved in protein digestion?

A

pepsin, pancreatic enzymes, and brush border enzymes.

82
Q

What are the major enzymes involved in lipid digestion?

A

lingual lipase, gastric lipase, and pancreatic lipases.

83
Q

What are the major enzymes involved in nucleic acid digestion?

A

pancreatic ribonuclease, deoxyribonuclease, and brush border enzymes.

Anatomy & Physiology 2 (9 decks)

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