Digestive Tract And Accessory Organs Flashcards

1
Q

The mouth is

A

A stratified squamous epithelial mucosa-lined cavity for ingestion

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2
Q

The lips & cheeks are

A

skeletal muscle covered by skin that help to keep food between teeth when we chew

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3
Q

The palate forms

A

The roof of the mouth

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4
Q

Palate that aids in manipulation of food

A

Hard palate

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5
Q

Palate that rises during swallowing to close the nasopharynx

A

Soft palate

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6
Q

The tongue

A
  • is made of skeletal muscle
  • Repositions and mixes food with saliva, initiates swallowing, & aids in speech production
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7
Q

Taste buds are housed in

A

The papillae on the tongue surface

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8
Q

Cells types that make up the minor and major salivary glands

A

◦ Serous cells – produce a watery secretion (enzymes, ions, mucin)
◦ Mucous cells – produce mucus

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9
Q

Along with water saliva contains

A

◦ Electrolytes
◦ Salivary amylase & lingual lipase, mucins, lysozyme
◦ Antibodies
◦ Small amount of metabolic waste

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10
Q

Mastication

A

begins the mechanical breakdown of food & mixes food with saliva

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11
Q

The 20 teeth that are lost to make way for the permanent dentition are

A

Primary dentition (deciduous or baby teeth)

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12
Q

The 32 teeth, including wisdom teeth (third molars)

A

Permanent dentition

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13
Q

Incisors are used for

A

Cutting

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14
Q

Canines (cuspids) are used to

A

tear or pierce

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15
Q

Premolars (bicuspids) & molars (tricuspids) are used for

A

grinding

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16
Q

3 regions of the tooth are

A

◦ Enamel-covered crown
◦ Neck surrounded by gingiva (gums)
◦ Root embedded in the jawbone

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17
Q

Cement is

A

The calcified connective tissue that anchors the root to the periodontal ligaments
◦ Holds tooth in the bony socket of the jaw

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18
Q

Dentin is

A

A bone-like material that underlies the enamel & surrounds the pulp cavity (which contains blood & nerve supply)

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19
Q

The Oropharynx & laryngopharynx provide a

A

common passageway for food, fluids, & air

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20
Q

Food is propelled into the esophagus by

A

Muscular contraction within the walls

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21
Q

The Esophagus provides a passageway for food & fluids from

A

the laryngopharynx to the stomach, where it joins at the cardiac orifice

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22
Q

The Esophagus provides a passageway for food & fluids from

A

The laryngopharynx to the stomach, where it joins at the cardiac orifice

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23
Q

Keeps the cardiac orifice closed when food is not being swallowed

A

Gastroesophageal (cardiac) sphincter

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24
Q

2 major phases of deglutition (swallowing):

A
  1. Buccal phase – voluntary
    ◦ Occurs in mouth – bolus of food is
    forced into oropharynx by tongue
  2. Pharyngeal-esophageal phase – involuntary
    ◦ Food is squeezed through pharynx &
    into esophagus
    ◦ Controlled by swallowing centre of
    medulla & pons
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25
Q

Bolus being churned is

A

Mechanical breakdown via extra oblique layer of smooth muscle in stomach

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26
Q

Hydrolysis of the churned food begins

A

Protein digestion (via pepsin) which turns food into chyme

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27
Q

Folds in the stomach that wall allow stomach to expand
◦ Empty stomach – volume of ~50 ml
◦ Full capacity – 4 L Major regions include:
◦ Cardia, fundus, body, & pylorus

A

Rugae

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28
Q

Stomach’s surface epithelium of mucosa is composed of

A

simple columnar epithelium
◦ Surface mucous cells – produce a protective coat of alkaline mucus

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29
Q

Columns of secretory cells that produce gastric juice are found in

A

Gastric pits which extend to gastric glands

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30
Q

Mucous neck cells secrete

A

Mucus

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31
Q

Parietal cells secrete

A
  • HCL to activate pepsin which denatures proteins
  • intrinsic factor of glycoprotein which is required for absorption of vitamin B12 in small intestine
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32
Q

Chief cells secrete

A

◦ Pepsinogen – the inactive form of pepsin (hydrolyzes proteins in positive feedback mechanism)
◦ Gastric lipase – hydrolyzes a small portion of lipids (~15%)

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33
Q

G cells secrete

A

enteroendocrine cells that secrete gastrin
◦ Stimulates gastric secretions &
promotes movement of food along the GI tract (facilitates digestion)

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34
Q

H and Cl ions are secreted

A

Separately so they can later be assembled into HCL

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35
Q

Protons (H+) are secreted into stomach lumen by

A

proton pumps (H+-K+ ATPase powered by ATP)

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36
Q

Chloride ions (Cl-) move into parietal cells

A

via Cl-/HCO3- antiporters & diffuse into stomach lumen through Cl- channels
◦ Resulting increase in bicarbonate (HCO3-) in blood leaving the stomach – alkaline tide

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37
Q

In the stomach HCL secretion is stimulated by

A

◦ Acetylcholine (ACh) – released from parasympathetic neurons
◦ Gastrin – produced by G cells

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38
Q

Histamine, a paracrine released from mast cells in lamina propria enhances the effects of

A

ACh & gastrin

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39
Q

First cephalic (reflex) phase is triggered by

A

Aroma, taste, sight, or thought
◦preparatory phase
◦↑ saliva secretion & gastric gland acuity

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40
Q

The second Gastric phase is triggered by

A

Stretch & chemical stimuli
◦ Neural & hormonal mechanisms ↑gastric secretion & motility

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41
Q

The third Intestinal phase is

A

The distention of duodenum to inhibit gastric motility & emptying
◦ Neural & hormonal factors slow exit of chyme &
enhance digestion of food in small intestine

42
Q

The liver is

A

The largest gland in the body (~3 lbs) – our only internal organ that can regenerate

43
Q

The liver is composed of

A

Four lobes of lobules, made of plates hepatocytes (liver cells)

44
Q

hepatocytes (liver cells)

A

◦ Secrete bile
◦ Process blood-borne nutrients, store fat-soluble vitamins
◦ Play important roles in detoxification

45
Q

Hepatocytes surround a central vein that drain

A

hepatic sinusoids (highly permeable capillaries)

46
Q

The portal triad is composed of

A
  • the Branch of hepatic artery
  • the Branch of hepatic portal vein
  • the Bile duct
47
Q

Supplies hepatocytes with oxygen-rich blood
- O2 to the liver

A

The Branch of the hepatic artery

48
Q

Carries venous blood rich in nutrients from the intestines
• O2 deficient blood goes through liver
• Filters out glucose/nutrient to store

A

Branch of the hepatic portal vein

49
Q

Attached to bile canaliculi

A

The bile duct

50
Q

Function of the gallbladder

A

Stores & concentrates bile that is not needed immediately for digestion
- stored until lipid rich food is consumed

51
Q

Bile is both a

A

◦Digestive secretion which functions in emulsification & absorption
of lipids by bile salts
◦Excretory product – bilirubin (pigment; derived
from heme)

52
Q

These form when bile salts are insufficient or excessive cholesterol crystalizes

A

Gallstones

53
Q
  • small clusters of exocrine cells that produce pancreatic juice
  • compose 99% of the pancreas
A

Pancreatic acini

54
Q
  • endocrine tissue
  • compose 1% of the pancreas
A

Pancreatic islets

55
Q

Pancreatic juice contains:

A

◦ Mainly water & some salts
◦ Bicarbonate (HCO3-) – helps neutralize acidic chyme
◦ Several enzymes (inactive forms)

56
Q

Pancreatic proteases digest

A

proteins into peptides

57
Q

Enteropeptidase is the brush-border enzyme that
activates

A

trypsinogen into trypsin (which activates the other proteases)

58
Q

digests starch

A

Pancreatic amylase

59
Q

Primary triglyceride-digesting enzyme

A

Pancreatic lipase

60
Q

Digests nucleic acids to nucleotides
◦ Ribonuclease (RNA) & deoxyribonuclease (DNA)

A

Pancreatic nucleases

61
Q

Hormones from _______ stimulate secretion of pancreatic juice & bile in response to chyme

A

small intestine enteroendocrine cells

62
Q

Cholecystokinin (CCK) – secreted in response to

A

fats & proteins in chyme

63
Q

Secretin secreted in response to

A

acidic chyme

64
Q

NS that stimulates secretion when stomach is active

A

Parasympathetic

65
Q

Stimulate bile secretion

A

Reabsorbed bile salts returning to liver

66
Q

Small intestine is

A

The major site for digestion & absorption

67
Q

Blood from the intestine drains into the

A

hepatic portal system, where it is routed to the liver

68
Q

Duodenum is

A

The mixing bowl

69
Q

Jejunum is

A

Where most nutrient digestion & absorption takes place

70
Q

Ileum is

A

Where some absorption (e.g., B12, bile salts) takes place

71
Q

Allow more time & mixing for nutrient absorption in small intestine

A

Deep circular folds that force chyme to slowly spiral

72
Q

Increase SA of the small intestine

A

Mucosa with finger-like villi & microvilli (absorptive cell plasma membrane folds)

73
Q

Mucosa of the small intestine is composed mostly of

A

absorptive cells (absorb & digest nutrients)

74
Q

Tubular glands in the small intestine that contain several types of secretory cells

A

Intestinal crypts

75
Q

Goblet cells of the small intestine

A

produce mucus

76
Q

Enteroendocrine cells of the small intestine

A

produce hormones (e.g., CCK & secretin)

77
Q

Paneth cells of the small intestine

A

produce antimicrobial compounds that can destroy invasive bacteria (secretes lysozyme and is capable of phagocytosis)

78
Q

Stem cells of the small intestine

A

replace the other cell types (villus epithelium is renewed every 2-4 days)

79
Q

Intestinal juice is secreted in response to

A

acidic chyme, containing mostly water & mucus

80
Q

Intestinal juice with pancreatic juice provides a

A

Liquid medium to help nutrient absorption

81
Q

Brush-border enzymes that are present in plasma membrane of the microvilli of absorptive cells

A

◦Carbohydrate digesting – e.g., sucrase, lactase,
maltase (disaccharides → monosaccharides)
◦Peptidases – peptides → di- & tripeptides, a.a.
◦Nucleotide digesting – nucleosidases &
phosphatases

82
Q

Following a meal chyme is mixed and propelled through the intestine via

A

Segmentation & some peristalsis working together

83
Q

Between meals the remnants are moved toward large intestine in waves via

A

migrating motor complex (type of peristalsis)

84
Q

The ileocecal valve is

A

A one-way valve from the small intestine to the large intestine that relaxes to allow chyme to enter the cecum

85
Q

The large intestine

A

Absorbs water & eliminates indigestible food residues as feces

86
Q

The first part of the large intestine is

A

The Cecum

87
Q

The appendix is

A

A mass of lymphoid tissue & bacterial storehouse capable of recolonizing the gut when necessary

88
Q

The segments of the colon in order are

A

ascending, transverse, descending & sigmoid colon

89
Q

The rectum has 3

A

valves that stop feces from being passed during flatulence

90
Q

The last segment of large intestine that opens to the body’s exterior at the anus

A

Anal canal

91
Q

A unique feature of the large instestine is the teniae coli which is

A

three bands of longitudinal smooth muscle in the muscularis layer

92
Q

A unique feature of the large instestine is the Haustra which are

A

Pocket-like sacs caused by partial contraction (tone) of teniae coli
Epiploic appendices – fat-filled pouches of visceral peritoneum (unknown function)

93
Q

A unique feature of the large intestine is Epiploic appendices which are

A

fat-filled pouches of visceral peritoneum (unknown function)

94
Q

Movements that aid mechanical digestion & propulsion in the large intestine are

A

Haustral contractions – slow segmenting movements triggered by stretch (aid water absorption)

Peristalsis – slow, 3-4 contractions/min

Mass peristalsis – slow, powerful waves that drive contents into rectum (activated by food in stomach)

95
Q

The thick mucosa of the large intestine contains

A
  • intestinal crypts (glands)
  • absorptive cells – water, ions, some vitamins
  • a large number goblet cells – mucus producing
96
Q

Functions of the complex community of bacteria & other microorganisms that live in the digestive tract

A

◦ Ferment some of the indigestible carbohydrates
◦ Synthesize B complex vitamins & vitamin K
◦ Influence behaviour of the immune system
◦ Also help to protect against ingested pathogens &
may affect some diseases

97
Q

Feces are forced into the rectum by

A

Mass peristalsis which stretches the rectal wall & initiates the defecation reflex

98
Q

In defecation contraction of the sigmoid colon & rectum while relaxing the internal anal sphincter is stimulated by

A

The Parasympathetic NS

99
Q

In defecation conscious control allows relaxation of the

A

External anal sphincter

100
Q

Intra-adominal pressure to assist in defecation is increased via

A

Valsalva’s manoeuvre