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Human Structure and Function 2 > 3 (23) The Digestive System > Flashcards

3 (23) The Digestive System Flashcards

1
Q

What is digestion?

A

the process of breaking down larger food molecules into smaller food molecules

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2
Q

What is absorption?

A

the passage of the smaller molecules into blood and lymph

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3
Q

What is the alimentary canal? What structures are accessory organs?

A
  • (GI tract) tube that runs from mouth to anus; digests food and absorbs fragments (mouth, pharynx, esophagus, stomach, small intestine, large intestine)
  • accessory organs: teeth, tongue, salivary glands, liver, gallbladder
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4
Q

What is the splanchnic circulation?

A

all blood flow originating from the celiac, superior mesenteric, and inferior mesenteric arteries, which is widely distributed to all abdominal viscera
- receives about 25% of cardiac output when at rest

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5
Q

What is the “tube within a tube” model?

A
  • one for food to enter the body (mouth), one for wastes to leave the body (anus)
  • the tube-within-a-tube plan allows specialization of parts along the tube, such as a stomach, intestine, etc.
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6
Q

What are the four structural layers of the alimentary canal?

A

mucosa
submucosa
muscularis
serosa

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7
Q

The mucosa can be further divided into what three parts?

A

1 - EPITHELIUM => strat. squam. epithelium, simp. col. epithelium, and enteroendocrine glands
2 - LAMINA PROPRIA => areolar CT; blood, lymph vessels and nodules
3 - MUSCULARIS MUCOSAE => two layers of smooth muscle

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8
Q

In which of these parts would we find MALT?

A

lamina propria

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9
Q

How does the epithelium of the mucosa change throughout the alimentary canal?

A

mouth, esophagus, anal canal => strat. squam. epithelium

stomach and intestines => simp. col. epithelium

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10
Q

What are the three functions of the mucosa?

A

1 - SECRETION => mucus, digestive enzymes/hormones
2 - ABSORPTION => nutrients from digestion
3 - PROTECTION => from infectious diseases

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11
Q

Where would you find the submucosal plexus? The myenteric plexus?

A

SUBMUCOSAL PLEXUS => found in submucosa; autonomic nerve supply to muscularis mucosae, blood vessels, and secretory cells
MYENTERIC PLEXUS => found in muscularis mucosae;

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12
Q

How does the type of muscle found in the muscularis layer change along the alimentary canal?

A

mouth, pharynx, superior esophagus, external anal sphincter => voluntary (skeletal) muscle
the rest of GI tract => smooth muscle

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13
Q

In general, how do parasympathetic fibers and sympathetic fibers affect the alimentary canal?

A

PARASYMPATHETIC => stimulate digestive activities

SYMPATHETIC => inhibit digestive activities

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14
Q

What is another name for the serosa? What is its function?

A

serous membrane = visceral peritoneum

- lubricates

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15
Q

Where does adventitia replace the serosa?

A

esophagus

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16
Q

What is mastication?

A

chewing

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17
Q

What is the oral cavity?

A

buccal cavity; mouth
(cheeks, lips, tongue, hard/soft palates)
lies between teeth and gums

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18
Q

What is the vestibule?

A

the area between the teeth, lips and cheeks

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19
Q

What is the labial frenulum? The lingual frenulum?

A

LABIAL => the soft tissue that attaches the lip to the anterior surface of the maxillary gingiva
LINGUAL => a fold of mucous membrane connecting the ventral tongue to the floor of the mouth

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20
Q

What is ankyloglossia?

A

tongue-tie => an unusually short, thick or tight band of tissue (lingual frenulum) tethers the bottom of the tongue’s tip to the floor of the mouth

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21
Q

What type of muscle is found in the tongue? Where does this muscle attach?

A
  • skeletal muscle

- attaches at lingual frenulum at the floor of the mouth

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22
Q

What covers the surface of the tongue?

A

papillae cover the surface of the tongue: filiform, fungiform, circumvallate, foliate (foliate does not have taste buds)

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23
Q

What kind of epithelium lines the oral cavity? Why is this helpful?

A
  • non-keratinized stratified squamous epithelium

- helpful bc it is stratified squamous, it is protective to the tissue behind it and regenerates quickly

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24
Q

Where would you find the lingual tonsils? The palatine tonsils? The pharyngeal tonsils (adenoids)?

A

LINGUAL => near back of tongue, underneath it
PALATINE => found near roof of mouth near soft palate
PHARYNGEAL => near opening of auditory tube and near base of nasal cavity

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25
Q

What bones make up the hard palate?

A

palatine bones, palatine processes of maxillae

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26
Q

What is the function of the soft palate and the uvula?

A

SOFT PALATE => closes off nasopharynx during swallowing

UVULA => projects downward from its free edge and aids the soft palate

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27
Q

How many sets of teeth do you get? How many teeth does a normal adult have?

A
  • two sets of teeth

- normal adult = 32 teeth (20 baby teeth)

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28
Q

What are the basic parts of a tooth?

A
  • crown
  • root
  • neck
  • dentin
  • enamel
  • pulp cavity
  • root canal
  • apical foramen
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29
Q

Where would you find dentin in a tooth? Enamel?

A

DENTIN => found under enamel and around pulp cavity

ENAMEL => the outer, protective covering of a tooth

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30
Q

What is in the pulp cavity?

A

contains blood vessels, nerves, and connective tissue

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31
Q

What are incisors good for? Cuspids? Molars?

A

INCISORS => chisel shaped for cutting
CUSPIDS => fanglike teeth that tear or pierce
MOLARS => best for grinding

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32
Q

What are the three sets of salivary glands? Where are they located? Where do they enter the mouth?

A

PAROTID => found close to ear (Stensen’s duct, drains saliva from the parotid gland into the mouth)
SUBMANDIBULAR => under jaw
SUBLINGUAL => found under the tongue

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33
Q

What are mumps?

A

inflammation of parotid glands

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34
Q

Do all the salivary glands produce the same type of saliva?

A

NO
there are two types of secretory cells from saliva:
- serous cells = parotid, submandibular
- mucous cells = sublingual

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35
Q

What digestive enzyme is found in saliva and what does it break down?

A

AMYLASE => digests starches

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36
Q

What else is found in saliva and what else is saliva good for?

A
  • mostly water
  • amylase
  • lingual lipase
  • mucin
  • metabolic wastes (urea)
  • lysoyzme, IgA, cyanide compound to protect from microorganisms
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37
Q

How is saliva production affected by input from the parasympathetic and the sympathetic nervous system?

A

PARASYMPATHETIC => increases saliva production

SYMPATHETIC => decreases saliva production

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38
Q

What are the three sections of the pharynx?

A
  • nasopharynx
  • oropharynx
  • laryngopharynx
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39
Q

What is deglutition? What are the three stages? Which are involuntary?

A

swallowing

  • voluntary stage
  • pharyngeal stage (involuntary)
  • esophageal stage (involuntary)
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40
Q

What 3 areas close off to be sure food goes in the right direction?

A

mouth
pharynx
epiglottis

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41
Q

What is the esophagus? Where is it located in relation to the trachea?

A
  • connects pharynx to stomach

- behind the trachea

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42
Q

What opening in the diaphragm does the esophagus pass through? What happens if this area becomes enlarged and the stomach becomes entrapped in the diaphragm?

A

esophageal hiatus => opening in diaphragm

- hiatal hernia = when the stomach comes up through the esophageal hiatus and is trapped in the diaphragm

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43
Q

The esophagus contains a lower sphincter. What is it called? When is it open and when is it closed?

A

lower sphincter => gastroesophageal (cardiac) sphincter
OPEN => when moving food into stomach
CLOSED => to prevent stomach acid from entering esophagus

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44
Q

How does food travel through the esophagus?

A

food is pushed through the esophagus and into the stomach by means of a series of contractions called PERISTALSIS

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45
Q

What are the divisions of the stomach?

A 
cardiac region
fudic region
body
pyloric region
pyloric canal
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46
Q

What sphincter is located between the stomach and the small intestines?

A

pyloric sphincter

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47
Q

What additional muscle layer do we find in the stomach?

A

inner oblique of muscularis externa

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48
Q

What is the function of the stomach?

A

chemical digestion

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49
Q

What are rugae?

A

folds in the empty stomach

50
Q

What are gastric pits?

A

pores in the stomach that release gastric juices produced by the gastric glands

51
Q

How often is the surface epithelium of the stomach replaced?

A

every 3-6 days

52
Q

What do goblet cells produce?

A

mucus

53
Q

What do the chief cells produce?

A
  • pepsinogen (an inactive enzyme activated to pepsin by HCl and pepsin itself)
  • gastric lipase
54
Q

What do the parietal cells make?

A
  • hydrochloric acid (HCl)

- intrinsic factor (for the absorption of vitamin B12 important for DNA synthesis)

55
Q

What is intrinsic factor, and what does it do?

A
  • a substance secreted by the stomach which enables the body to absorb vitamin B12
  • it is a glycoprotein
56
Q

Why don’t we digest our own stomach?

A

we have a fluid (mucosal) layer of bicarbonate rich ions mucus that neutralizes any acid to protect our stomach from digesting itself

57
Q

What is the primary type of biological molecule broken down in the stomach? What enzyme does this?

A
  • proteins are the primary type of biological molecule broken down in the stomach
  • performed by the enzyme PEPSIN
58
Q

What is rennin?

A

(in infants) digests milk proteins

59
Q

What do the enteroendocrine cells or G cells of the stomach make?

A

gastrin
histamine
serotonin
somatostatin

60
Q

What do you get when you mix food and gastric juice?

A

food + gastric juice = CHYME

61
Q

What happens to gastric motility and secretion during the cephalic phase? What is the stimulus for this phase?

A

stimulation of TASTE AND SMELL receptors cause an INCREASE in stomach secretory activity

62
Q

What is the gastric phase and what affects it?

A
  • stomach distension activates stretch receptors

- affected by food chemicals

63
Q

What is the intestinal phase and what affects it?

A
  • as more food enter the small intestine, it inhibits the stomach
  • cholesystokinin (CCK) and intestinal somatostatin
64
Q

What hormones are involved in the cephalic, gastric, and intestinal phases?

A

CEPHALIC => cephalic phase induces ECL cells in the gastric glands to secrete histamine and increase HCl in the stomach
GASTRIC => gastrin? who knows…
INTESTINAL => cholesystokinin (CCK) and intestinal somatostatin

65
Q

How do Tagamet and Zantac block the production of stomach acid?

A

H2-blockers inhibit the action of histamine on the cells, thus reducing the production of acid by the stomach

66
Q

What substances are absorbed from the stomach?

A

water
ions
lipid soluble drugs
alcohol

67
Q

Which types of food cause the stomach to empty the fastest? The slowest?

A

FASTEST => carbohydrates

SLOWEST => fats

68
Q

What is the enterogastric reflex?

A

THREE reflexes:
1 - inhibit vagal nuclei in medulla oblongata
2 - inhibit local reflexes
3 - increases sympathetic fibers (decreases PS fibers)
[protects the small intestine from receiving too much acid from the stomach]

69
Q

How and why does vomiting occur?

A

HOW => deep breath, salivation, raise soft palate, close epiglottis, relax lower esophageal sphincter, contract diaphragm and abdominal wall
WHY => unpleasant smells, sounds, sights, stress, irritation, distension, unpleasant stimuli in small intestine

70
Q

Where is your pancreas?

A

pancreas is retroperitoneal - behind parietal peritoneum

71
Q

What other duct does the pancreatic duct join? Where does it empty?

A
  • pancreatic duct joins common bile duct to form hepatopancreatic ampulla
  • pancreatic duct empties into duodenal pilla (duodenum)
72
Q

What does pancreatic juice contain?

A

watery, alkaline solution containing water, salts, electrolytes, enzymes (proteases, amylase, lipases, nucleases) [digests proteins, carbs, nucleic acids, lipids]

73
Q

Why is trypsin important?

A

active form of trypsinogen and also activates other enzymes

74
Q

What neutralizes the stomach acid?

A

a watery alkaline solution at pH of 8 neutralizes stomach acid (found in pancreatic juice)

75
Q

Locate your liver. Name the four lobes.

A

right lobe, left lobe, caudate lobe, quadrate lobe

76
Q

How are the cells of the liver organized?

A

hexagonally

77
Q

What is the portal triad?

A

1 - a branch of hepatic portal vein
2 - a branch of hepatic artery
3 - bile duct

78
Q

What are Kupffer’s cells and what do they do?

A

fixed macrophages

  • stellate reticuloendothelial cells
  • remove debris such as bacteria and worn out cells
79
Q

The liver receives two kinds of blood from two sources. What are they?

A

hepatic artery

hepatic portal vein

80
Q

What happens to the remaining liver when a piece of it is surgically removed?

A

1 - liver hepatocytes secrete vascular endothelial growth factor (VEGF)
2 - endothelial cells proliferate and release hepatocyte growth factor (HGF) and interleukin 6, which cause hepatocytes to proliferate
3 - this process can replace the entire liver if up to 80% is remove

81
Q

The hepatic portal system is different from the hepatic vein. Know the difference and why the hepatic portal system is there!!

A

this is in blue, probably not on the test

82
Q

How does the liver function in carbohydrate metabolism?

A

gluconeogenesis

83
Q

How does the liver function in lipid metabolism?

A

it just does it

84
Q

How does the liver function in protein metabolism?

A

makes plasma proteins and clotting factors, removes amino groups

85
Q

How does the liver function in storage of vitamins and minerals?

A

stores glycogen, fat soluble vitamins, iron

86
Q

How does the liver function in phagocytosis?

A

removal of drugs

87
Q

How does the liver function in the removal of drugs?

A

some drugs are eliminated by the liver in the bile and excreted in feces

88
Q

What is the liver’s only role in digestion?

A

synthesis of bile, excretion of bilirubin

89
Q

What structures move bile from the liver to the gallbladder?

A

Bile canaliculi => bile ducts => right and left hepatic duct => common hepatic duct => joins cystic duct => forms common bile duct

90
Q

Where is the gallbladder located?

A

underneath the liver

91
Q

What does bile contain? What do bile salts do in digestion?

A

water, bile salts, cholesterol, lecithin, bile pigments, electrolytes
bile salts functions: aid digestive enzymes, enhance absorption of fatty acids, reduce surface tension (emulsification), increase the surface area, forms complexes with fatty acids and cholesterol called micelles

92
Q

What is enterohepatic circulation?

A

bile salts are reabsorbed by ileum and brought back to liver through hepatic portal system and can be re-secreted into the bile

93
Q

What affects bile secretion?

A

stimulated by secretin => it simulates biliary duct cells to secrete bicarbonate and water, which expands the volume of bile and increases its flow out into the intestine

94
Q

What does the gallbladder actually do? How does CCK affect it? What happens when it is removed?

A
  • gallbladder stores and concentrates bile
  • CCK causes it to contract
  • removal of gallbladder causes bile duct to enlarge and act as a storage organ
95
Q

What sphincters are found at the beginning and end of the small intestine? (Note: this should help you remember the order of the three sections.)

A

pyloric sphincter

ileocecal sphincter

96
Q

What are the three sections of the small intestine (in order)?

A

duodenum
jejunum
ileum

97
Q

What three structures are used by the small intestine to increase its surface area?

A

plicae circulares (circular folds)
villi
microvilli

98
Q

What are the crypts of Lieberkuhn? What types of cells are found here, and what do they make?

A
  • intestinal glands
  • enteroendocrine cells (CCK, secretin, GI peptide)
  • paneth cells (defensins, lysozyme; phagocytosis)
99
Q

Where are the digestive enzymes of the small intestine?

A
  • there are no enzymes secreted in intestinal juice

- enzymes are embedded in the brush border and can digest all food groups

100
Q

Why are intraepithelial lymphocytes (IELs) important and what is unusual about them?

A

they release cytokines that kill infected cells

101
Q

What are the two movements of the small intestine, and what do they do? What triggers these movements?

A

SEGMENTATION => mixes and moves contents toward ileocecal valve; triggered by intrinsic pacemaker cells; rubs food substance against brush borders of small intestine to use some enzymes to break down even further
PERISTALSIS => moves meal remnants, bacteria, and debris to large intestine; triggered by rise in hormone motilin in late intestinal phase

102
Q

What are carbohydrates, proteins, lipids and nucleic acids broken down to (what are the monomers)?

A

carbs => monosaccharides
proteins => amino acids
lipids => fatty acids, monoglycerides
nucleic acids => pentoses, phosphates, nitrogenous bases

103
Q

How are the monomers absorbed?

A

monosaccharides => facilitated diffusion
amino acids => active transport
fatty acids, monoglycerides => simple diffusion

104
Q

Where do fats go when they are absorbed?

A

into the blood

105
Q

What is the peritoneum?

A

largest serous membrane of the body that holds the organs of the abdominal cavity together

106
Q

Which organs are retroperitoneal?

A

pancreas
duodenum
kidneys

107
Q

What are the mesentery and the mesocolon?

A

MESENTERY => surrounds and suspends small intestines

MESOCOLON => double fold of peritoneum that surrounds and suspends the colon (large intestine)

108
Q

What does the greater omentum look like, and what does it do?

A 
"lace apron"
fold of peritoneum that hangs from the greater curvature
- fat deposition
- immune contribution
- infection and wound isolation
109
Q

What is peritonitis?

A

inflammation of the peritoneum where the peritoneal covering stick together, localizing infection (causes piercing abdominal wound, perforated ulcer, ruptured appendix)

110
Q

What is ascites?

A

accumulation of fluid in the peritoneal cavity

111
Q

Where is the falciform ligament?

A

anchors the liver to the anterior part of the abdominal cavity

112
Q

Where is the lesser omentum?

A

suspends stomach from liver

113
Q

Which is longer, the small intestine or the large intestine?

A

smaller

114
Q

What three features are unique to the large intestine?

A

taenia coli => 3 bands of longitudinal muscle
haustra => pouches
epiploic appendages => small bags of lipid

115
Q

What does the mucosa of the colon look like?

A

thick simple columnar epithelium tissue except in the anal canal, which is stratified squamous epithelium

  • no circular folds, villi, digestive secretions
  • abundant deep crypts of goblet cells
116
Q

What are the sections of the large intestine?

A

cecum > colon > rectum > anal canal

117
Q

What is the appendix, and where is it located?

A
  • masses of lymphoid tissue
  • part of MALT immune system
  • bottom of cecum
118
Q

What happens in the large intestine? What does the digestion here? What benefit do we get from this?

A
  • no food breakdown except by enteric bacteria (only digestion done here)
  • manufacturing of certain vitamins (bacteria)
  • completion of absorption (especially water, vitamins, electrolytes)
  • formation and expulsion of feces
119
Q

What movements occur in the colon?

A
  • rhythmic ascending (antiperistaltic) waves of contraction originating at the anal end of the large bowel
  • rhythmic longitudinal contractions in the rectum and colon
  • irregular contractions
120
Q

What is the gastroileal reflex?

A
  • stimulated by the presence of food in the stomach and gastric peristalsis
  • causes peristalsis in the ileum and the opening of the ileocecal valve (which allows the emptying of the ileal contents into the large intestine, or colon)
121
Q

What is the gastrocolic reflex?

A

a physiological reflex that controls the motility of the lower gastrointestinal tract following a meal

122
Q

How does defecation take place?

A
  • mass movements force feces toward rectum
  • distention initiates spinal defecation reflex
  • parasympathetic signals stimulate contraction of the sigmoid colon and rectum, relaxes internal anal sphincter
  • conscious control allows relaxation of external anal sphincter
  • muscles of rectum contract to expel feces, assisted by Valsalva’s maneuver

Human Structure and Function 2 (13 decks)

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