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HHP > Digestive System > Flashcards

Digestive System Flashcards

1
Q

Oral cavity is lined by mucosa of three different types?

A

Masticatory mucosa, lining mucosa, specialized mucosa

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2
Q

What is vermillion in lips?

A

Transitional zone between lining mucosa and skin

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3
Q

What is vermillion lined with?

A

Thin keratinized stratified squamous, has sensory innervations and capillaries, no hair follicles or glands

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4
Q

What is dorsal side of tongue lined with?

A

Stratified squamous with patches of keratin

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5
Q

What is ventral side of tongue lined with?

A

Stratified squamous non keratinized, lingual salivary glands

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6
Q

What is intrinsic muscle in tongue?

A

Striated muscle, with muscle at right angles of each other, provides flexibility of tongue

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7
Q

What is extrinsic muscle in tongue?

A

Skeletal muscle, one end attached to bone

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8
Q

What is sulcus terminalis in tongue?

A

Transitional line that separates tongue in 2/3 anterior and 1/3 posterior

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9
Q

What does anterior 2/3 of tongue contain?

A

Lingual papillae

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10
Q

What does posterior 1/3 of tongue contain?

A

Lymphoid follicles called lingual tonsils

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11
Q

What are 4 types of lingual papillae on tongue?

A

Filiform, Foliate, Fungiform, Circumvallate

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12
Q

Describe Filiform papillae

A

Located on dorsal surface, projections of CT, keratinized stratified squamous, no taste buds, mechanical function of keeping food on tongue

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13
Q

Describe Fungiform papillae

A

Mushroom like projections in between filiform papillae, taste buds on apical surface

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14
Q

Describe Foliate papillae

A

Leaf like on lateral surface of tongue, taste buds located on lateral walls, serous glands empty into clefts

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15
Q

Describe Circumvallate papillae

A

8-12 located infront of sulcus terminalis, contain most taste buds 250 each, taste buds located on lateral walls, Von Ebners Glands located beneath papillae

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16
Q

Describe Von Ebners Glands

A

Serous glands that secrete into moat of circumvallate papillae, washes out material stuck in moat, quick perception of taste sensation

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17
Q

Describe taste bud

A

Cells with taste receptors, taste pore is located at apex

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18
Q

Where can taste buds be found?

A

Lingual papillae, soft palate, posterior pharynx, posterior epiglottis, glossopalantine fold

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19
Q

What cells do taste buds have?

A

Supporting cells, sensory cells, basal cells

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20
Q

What are sensory cells in taste buds?

A

Chemoreceptor cells, most numerous, microvilli on apical surface, tight occluding junctions at apical region, basally synapse with afferent nerves, 10 day turnover

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21
Q

What are supporting cells in taste buds?

A

Sustentacular cells, microvilli on apical surface, tight occluding junctions at apical region with adjacent cells, 10 day turnover

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22
Q

What are basal cells in taste buds?

A

Stem cells that replenish sensory and supporting cells

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23
Q

What is soft palate lined with?

A

Stratified squamous non keratinized, mucus glands and skeletal muscles

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24
Q

What is hard palate line with?

A

Mucoperiosteum, stratified squamous keratinized and parakeratinized, rugae and palatine glands

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25
Q

How many teeth do humans have?

A

32

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26
Q

What are the 3 hard tissue types in teeth?

A

Enamel, denting, cementum with soft tissue pulp

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27
Q

What are the major salivary glands?

A

Parotid, submandibular, sublingual

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28
Q

What are the minor salivary glands?

A

Buccal, Lingual, Labial, Palatine

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29
Q

What is main structure of major salivary gland?

A

Salvion, composed of acinus, intercalated duct, striated duct, excretory duct

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30
Q

What is the acinus?

A

Function unit blind sac composed of secretory cells

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31
Q

What are the three types of acinus secretory cells?

A

Serous, Mucous, Mixed

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32
Q

What structure surrounds base of acinus cell?

A

Connective tissue with nerves and blood vessels

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33
Q

What are acinus cells joined together by?

A

Junctional complexes

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34
Q

What cell surrounds the acinus cell?

A

Myoepithelial cell

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35
Q

Where is myoepithelial cell located?

A

Between basal plasma membrane of acinus cells and basal lamina

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36
Q

What is function of myoepithelial cell?

A

Long cellular projections contract and squeeze the acinus cell, aids in removal of secretion of saliva that has accumulated in hollow center of acinus, moves it out of duct system

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37
Q

What is merocrine secretion?

A

Acini mucous, serous, and seromucous secretions secrete products through this

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38
Q

Where are intercalated ducts located?

A

In between acinus and larger striated duct, prominent in watery serous secreting glands

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39
Q

What is function of intercalated ducts?

A

Secrete HCO3- ions into acinar products as well as absorb Cl- from acinar products

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40
Q

What is another name for intercalated ducts since they are found in the lobule?

A

Intralobular ducts

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41
Q

Where is striated duct location?

A

In between intercalated duct and excretory duct

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42
Q

What is striated duct lined with?

A

Transitions from simple cuboidal to simple columnar

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43
Q

Why is the striated duct appear striated?

A

Basal plasma membrane forms infoldings

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44
Q

What does striated duct have enclosed in the membrane infoldings?

A

Numerous longitudinally arranged mitochondria

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45
Q

What does mitochondria do for striated duct?

A

Typifies reabsorption of fluids and electrolytes

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46
Q

What is the function of striated duct?

A

Reabsorption of Na+, secretion of K+ and HCO3-

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47
Q

What is another name for striated duct since found in lobule?

A

Intralobular duct

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48
Q

What is the excretory duct?

A

Principle duct, opens in oral cavity

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49
Q

What is excretory duct lined with?

A

Transitions from simple columnar to pseudostratified columnar to stratified columnar

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50
Q

What is another name for excretory duct since found in lobule

A

Intralobular duct

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51
Q

Describe parotid gland

A

Serous gland, secretes proteins and watery secretions, secretions stored in zymogen granules located in apical cytoplasm, numerous rER and ribosomes giving basophilic base, plasma membrane shows basal surface infoldings and basolateral folds

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52
Q

What are two key features in parotid gland that helps with identification?

A

Facial nerve branches, and intraparotid adipose tissue can be found in adults

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53
Q

Describe submandibular gland

A

Mixed gland, serous and mucous acini, mucous acini are capped with serous demilunes

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54
Q

Describe sublingual gland

A

Predominately mucous acini, typically elongated tubules of mucous cells with serous demilunes, called mixed glands with no serous acini secretion, secretions are only mucous

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55
Q

Define mucosa

A

Epithelium, lamina propria, muscularis mucosae

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56
Q

What does lamina propria typically contain?

A

CT, vessels, diffused lymphatic tissue, GALT

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57
Q

What is muscularis mucosae?

A

Thick ring of smooth muscle, allows mucosa to move by itself

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58
Q

What is submucosa?

A

Thick CT layer that supports mucosa, contains vessels, lymphatics, nerves, contains Meissners plexus (postganglionic neurons of parasympathetic system)

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59
Q

What does submucosa control?

A

Intestinal gland secretion, movement of water and ions across epithelium

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60
Q

What are the two locations where submucosa contains glands?

A

Esophagus- Esophageal glands proper
Duodenum- Brunners glands

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61
Q

What is muscularis externa?

A

Two layers of smooth muscle; inner circular and outer longitudinal, contains parasympathetic nerve plexus Myenteric plexus

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62
Q

What is function of myenteric/auerbachs plexus?

A

Move perpendicularly to each other to produce PERISTALSIS

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63
Q

Where is serosa found?

A

Intraperitoneal organs- stomach, spleen, liver, parts of duodenum, small intestine, transverse colon

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64
Q

Where is adventitia found?

A

Retroperitoneal organs- esophagus, rectum, duodenum, ascending and descending colon

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65
Q

What is serosa?

A

Mesothelial lining with CT

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66
Q

What is adventitia?

A

CT with nerves and vessels

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67
Q

What are 4 types of mucosa found in junction zones of GI tract?

A

Protective, Secretory, Absorptive, Absorptive/Protective

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68
Q

What does absorptive mucosa contain?

A

Crypts and villi

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69
Q

What genes are responsible for maintaining balance in junctional zones?

A

Hox genes

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70
Q

What happens when hox genes fail to maintain balance in junctional zones?

A

Negative changes, malignancies

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71
Q

What are the 4 junctional zones?

A

Esophageal-gastric zone
Gastro-duodenal zone
Ileo-cecal zone
Recto-anal junction

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72
Q

What change takes place in esophageal-gastric zone?

A

Stratified squamous of esophagus transitions to simple columnar of stomach

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73
Q

What change takes place in gastro-duodenal zone?

A

Simple columnar with PITS in stomach transitions to simple columnar with VILLI in duodenum

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74
Q

What change takes place in ileo-cecal zone?

A

Ileum with only VILLI, transitions to cecum with only CRYPTS

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75
Q

What change takes place in recto-anal zone?

A

Simple columnar of large intestine, transitions to stratified cuboidal of anus (then transitions to stratified squamous keratinized of anus)

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76
Q

What are pacemaker cells of enteric nervous system?

A

Interstitial cells of Cajal, ICC
Modulated by parasympathetic nervous system

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77
Q

What does submucosal Meissners plexus control?

A

Mucosal glands and muscularis mucosae

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78
Q

What does Myenteric/Auerbachs plexus control?

A

Muscularis externa, responsible for peristalsis movement

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79
Q

What is mucosa of esophagus lined with?

A

Stratified squamous non keratinized

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80
Q

What does submucosa of esophagus contain?

A

CT, cardiac glands that secrete neutral mucus, this protects mucosa from regurgitated gastric contents

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81
Q

What is special about muscularis mucosae in esophagus?

A

It runs longitudinally instead of the normal circularly, it is very thick in esophagus

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82
Q

What does submucosa of esophagus contain?

A

Dense irregular CT, vessels and lymphatics, Meissners plexus, esophageal glands proper that secrete acidic mucous that lubricates and protects mucosa

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83
Q

What does muscularis externa of esophagus contain?

A

Smooth muscle layer of inner circular and outer longitudinal, Myenteric plexus between the two layers

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84
Q

What is special about the smooth muscle in muscularis externa of esophagus?

A

Upper esophagus is striated, middle is striated and smooth, lower is smooth

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85
Q

Does esophagus have serosa or adventitia?

A

Adventitia until it reaches near intra-abdominal part, then becomes serosa

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86
Q

What is the Z line?

A

Squamo-columnar junction where esophagus epithelium changes abruptly to stomach epithelium of simple columnar

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87
Q

What happens when Z shifts proximally?

A

GERD, extreme case is Barrets esophagus, can cause adenocarcinoma

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88
Q

What causes Z line to shift?

A

Reflux of gastric contents cause damage to esophageal epithelium and cause z line to shift proximally.

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89
Q

What three regions does the stomach have?

A

Cardiac, Fundic, Pyloric

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90
Q

What does stomach contain that flatten when stomach is full?

A

Rugae, composed of mucosa and submucosa

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91
Q

What are gastric mucosa invaginations?

A

Gastric pits or foveolae

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92
Q

What opens at the base of gastric pits?

A

Gastric glands

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93
Q

What are gastric surface and pits lined with?

A

Simple columnar epithelium

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94
Q

Fundic glands in fundus extend from?

A

Bottom of gastric pit to muscularis mucosae

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95
Q

What do surface mucous cells secrete?

A

Alkaline mucous containing mucin

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96
Q

What do mucous neck cells secrete?

A

Acidic mucous containing mucin

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97
Q

What do parietal cells secrete?

A

Intrinsic factor and HCl

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98
Q

What do chief cells secrete?

A

Pepsinogen and gastric lipase

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99
Q

What do G cells secrete?

A

Gastrin straight into blood (enteroendocrine cell)

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100
Q

Describe gastrin-histamine complex in parietal cells?

A

G cells are stimulated, they secrete Gastrin, this activates DNES cells called enterochromaffin like cells ECL, when ECL cells are activated they secrete histamine, the histamine binds with histamine 2 receptors on parietal cells, this causes parietal cell to secrete HCl

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101
Q

What do parietal cells have extensively?

A

Intracellular canaliculi systems and tubulovesicular membrane systems that contains proton pumps

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102
Q

Explain process of an actively secreting parietal cell?

A

Intracellular canaliculi systems widen, tubulovesicular membrane system merges with canaliculi system, becomes larger and actively pump protons H+ into lumen;
H2O is split in parietal cell into H+ and hydroxide OH-, H+ is pumped out into the lumen via the H+/K+ pump, while OH- binds with CO2 to form bicarbonate HCO3-, an exchange occurs as HCO3 leaves the parietal cell and enters the capillary, Cl- leaves the capillary and enters parietal cell, then travels to the lumen to meet H+ and forms HCL in lumen

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103
Q

What are enteroendocrine cells also known as?

A

Neuroendocrine cells, called Diffuse Neuroendocrine System cell, DNES

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104
Q

What are some DNES cells functionally classified as?

A

Amine Precursor Uptake and Decarboxylation cells, APUD

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105
Q

Where do APUD cells originate from?

A

Neural crest cells

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106
Q

Where do enteroendocrine cells originate from?

A

Endoderm

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107
Q

What two secretions does enteroendocrine cells secrete?

A

Endocrine-into blood circulation, ex. CCK or gastrin
Paracrine- diffuse locally to target cell, ex. Somatostatin

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108
Q

What is an enteroendocrine open cell?

A

Chemoreceptor, microvilli detect chemical changes in lumen and in response secrete hormones into blood stream

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109
Q

What is an enteroendocrine closed cell?

A

Paracrine secreting cell, most abundant, not in reach of lumen, hormones secrete paracrine secretions

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110
Q

What is Zollinger Ellison Syndrome?

A

Also called Gastrinoma, when excessive gastrin secretion occurs and leads to excessive stimulation of parietal cell, excessive HCl secretion, this causes gastric or duodenal ulcers

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111
Q

Where are undifferentiated stem cells located in acinus?

A

Isthmus region

112
Q

What cells move upwards from undifferentiated cells?

A

Surface mucous cells, renewed every 3-5 days

113
Q

What cells move downwards from undifferentiated cells?

A

Parietal cells, renewed every 150-200 days
Enteroendocrine and Chief cells, renewed every 60-90 days

114
Q

Describe cardiac glands

A

Tubular, mucous secreting and occasional endocrine cells, short pits

115
Q

Describe pyloric glands

A

Coiled tubular, deep pits, glands empty into pits, composed of mucous secreting cells, G cells, and parietal cells

116
Q

What does lamina propria of stomach contain?

A

Reticular fibers, fibroblasts, smooth muscle, diffused lymphocytes, lymphatic nodules

117
Q

What does mucularis mucosae of stomach contain?

A

Inner circular and outer longitudinal smooth muscle

118
Q

What does submucosa of stomach contain?

A

Dense CT, blood vessels, Meissners plexus that innervated muscularis mucosae

119
Q

What does muscularis externa of stomach contain?

A

Inner oblique, middle circular, outer longitudinal smooth muscle, Myenteric plexus between layers

120
Q

What does serosa of stomach contain?

A

Mesothelium with CT

121
Q

Where does small intestine begin and end?

A

Gastro-duodenal junction and ends at ileo-cecal junction

122
Q

What are plicae circulares or valves of Kerckring?

A

Permanent folds, composed of mucosa and submucosa, increases absorptive surface area of small intestine

123
Q

What are villi in small intestine?

A

Projections of mucosa, which consists of epithelium, laminal propria and smooth muscle cells, increases absorptive surface area in small intestine

124
Q

What does microvilli do for small intestine?

A

Increase absorptive surface area

125
Q

Define Lacteal

A

A central lymphatic vessel in the lamina propria, crucial for absorption of lipids

126
Q

What are intestinal glands or Crypts of Lieberkuhn?

A

Tubular glands located in lamina propria, open into intestinal lumen at base of villi, composed of simple columnar continuous with surface cells

127
Q

What does lamina propria in small intestine contain?

A

Surrounds intestinal glands, fills core of villi, contains cells of immune system, contains GALT

128
Q

What are two types of GALT?

A

Diffuse lymphatic tissue
Nodules of lymphatic tissue

129
Q

What is diffused lymphatic tissue?

A

Scattered immune cells throughout lamina propria, ex. Lymphocytes, plasma cells, mast cells

130
Q

What are nodules of lymphatic tissue?

A

Cells aggregated into discrete isolated single nodules, nodules can aggregate together too, ex. Peyers Patch

131
Q

What do enterocytes function in?

A

Reabsorption of water and electrolytes, digested food, and secretions of enzymes

132
Q

What junctional complexes do enterocytes hold?

A

Adhering, desmosomal, and tight junctions at apical surface that form barrier between lumen and intercellular compartment

133
Q

What do lateral folds do for enterocytes?

A

Increase lateral surface of cell, enlarge intercellular space during active absorption

134
Q

What do microvilli do for enterocytes?

A

Increase surface area for absorption

135
Q

What do goblet cells provide?

A

Mucus that is water soluble

136
Q

Where are paneth cells located?

A

Base of crypts of leiberkun

137
Q

What gives paneth cells basophilia in cytoplasm?

A

High numbers of rER and ribosomes

138
Q

What gives eosinophilia to paneth cells in apical cytoplasm?

A

Large secretory granules that contain lysozyme that digest cell walls of bacteria, a-defensins, and zinc

139
Q

How do paneth cells play a role in regulating normal enteric micro flora?

A

By phagocytizing bacterial types and protozoa

140
Q

What do enteroendocrine open cells secrete?

A

Hormones, ex. Mo cells secrete motilin, I cells secrete CCK

141
Q

What cells secrete CCK?

A

I cells

142
Q

What does MO cells secrete?

A

Motilin

143
Q

What do enteroendocrine closed cells secrete?

A

Paracrine hormones, ex. D cells

144
Q

What do D cells secrete?

A

Somatostatin

145
Q

Where are hormone containing granules located in enteroendocrine cell?

A

Basal part of cell

146
Q

What are M cells?

A

Epithelial cells that overly peyers patches and other lymphatic nodules

147
Q

Where are M cells located?

A

Apical surface and have microfolds instead of microvilli

148
Q

What is special feature of M cells?

A

Have deep pocket like recess connected to extracellular space

149
Q

What cells reside in M cell recess?

A

Dendritic cells, B and T lymphocytes, macrophages

150
Q

What does apical surface of M cell express?

A

GP2 receptors for specific macromolecules, like gram negative bacteria

151
Q

What happens to substances that bind to M cell GP2 receptors?

A

They are internalized in endocytic vesicles and transported to recess

152
Q

Why are M cells called Antigen Transporting Cells?

A

They transport antigens to recess, from apical surface in endocytic vesicles

153
Q

What do antigens activate in M cells?

A

GALT for immune response

154
Q

What are tuft cells?

A

Chemosensory cells, can detect pathogens too

155
Q

What are tuft cells characteristic for?

A

Short tuft of microvilli on apical surface

156
Q

Are tuft cells apart of immune response?

A

No

157
Q

Where are stem cells located?

A

At base of crypts

158
Q

What happens to cells that are being replaced by stem cell differentiation?

A

Cells destined to become goblet or epithelial cells migrate up towards villus, undergo apoptosis, and get sloughed off

159
Q

When do enterocytes and goblet cells get replenished?

A

4-6 days

160
Q

When do endocrine cells replenish?

A

Every 4 weeks, migrate in both directions

161
Q

When do paneth cells replenish?

A

Every 4 weeks, migrate downwards

162
Q

What are intraepithelial lymphocytes?

A

Lymphocytes that have migrated to intestinal epithelium and occupy epithelium

163
Q

What does submucosa of small intestine contain?

A

Dense CT and Brunners glands in duodenum

164
Q

What do Brunners Glands secrete?

A

Both serous and mucous secreting cells, neutralizes acid from stomach which protects small intestine and creates optimal pH for activation of pancreatic enzymes

165
Q

What does muscularis externa of small intestine contain?

A

Inner circular and outer longitudinal smooth muscle, Myenteric plexuses between layers

166
Q

What 2 types of movements does small intestine Myenteric plexus provide?

A

Segmentation and peristalsis

167
Q

What is segmentation contraction?

A

Circular layer only, circulates chyme locally and mixes with digestive juices and moves it to contact with mucosa for absorption

168
Q

What is peristalsis?

A

Coordinated movement of inner and outer layer, moves intestinal content distally

169
Q

What does serosa of small intestine contain?

A

Mesothelium and small amounts of loose CT

170
Q

What is function of large intestine?

A

Reabsorption of electrolytes, water, and elimination of waste

171
Q

What does mucosa of large intestine contain?

A

Invaginations to form tubular glands called crypts of leiberkuhn that extend through full thickness of mucosa, composed of goblet cells, no plicae circulares, no villi

172
Q

What are colonocytes?

A

Columnar absorptive cells that function in reabsorbing water and electrolytes, located on mucosal surface, numbers decrease distally

173
Q

Where are goblet cells found in large intestine?

A

Numerous in crypts, numbers increase towards rectum

174
Q

What is function of goblet cell in large intestine?

A

Secrete mucous and facilitate elimination of of semisolid to solid waste

175
Q

What are tuft cells in large intestine?

A

Chemosensory cells

176
Q

What do tuft cells secrete in worm infections in large intestine?

A

Interleukin 25

177
Q

When do tuft cells increase in large intestine?

A

During worm infections

178
Q

What do tuft cells play a role in, in large intestine?

A

Initiation of colorectal cancers

179
Q

What does lamina propria of large intestine contain?

A

Collagen table, pericryptal fibroblast sheath, GALT, lymphatic vessels

180
Q

What is collagen table in large intestine lamina propria?

A

Thick layer of collagen and proteoglycan, between basal lamina and fenestrated capillaries, participates in water and electrolyte transport from intercellular compartments to vascular compartment

181
Q

What is pericryptal fibroblast sheath in large intestine?

A

Fibroblast population adjacent to stem cells, cross talk between the two regulates cell division

182
Q

What is GALT in large intestine?

A

Well developed lymphocytes and large nodules

183
Q

Are lymphatic vessels normally present in between crypts?

A

No, number of vessels increase with inflammation, ex. ulcerative colitis

184
Q

Why do adenoids and malignancies become very large in large intestine before they enter lymph system?

A

Lymphatic vessels are not common in large intestine, so the malignancy has to grow large enough to reach a nearby lymph vessel

185
Q

What does muscularis externa in large intestine contain/

A

Inner circular and outer longitudinal, condensed into 3 prominent bands called Teniae coli

186
Q

Does large intestine have serosa or adventitia?

A

Adventitia since it is retroperitoneal

187
Q

What does appendix structure consist of?

A

All four layers of GI present, few crypts, dominant lamina propria with large numbers of lymphatic nodules extending into submucosa, contains absorptive cells, M cells, and goblet cells, covered in serosa

188
Q

What does mucosa of rectum contain?

A

Transverse folds called rectal valves, simple columnar, no villi, deep simple tubular intestinal glands, large number of goblet cells

189
Q

What is anal canal divided into and where are parts derived from?

A

Upper 2/3 is derived from endoderm, lower 1/3 is derived from surface ectoderm

190
Q

What is the junction called between upper 2/3 and lower 1/3 of anal canal?

A

Pectinate or Dentate line

191
Q

What type of columns are present in mucosa above pectinate line?

A

Anal columns called Columns of Morgangi

192
Q

What is present at inferior ends of Columns of Morgangi in anal canal?

A

Anal valves, with anal sinuses slightly above them that contain mucous secreting glands

193
Q

What does submucosa of anal canal contain?

A

Deep branched tubular glands called anal glands, circumanal glands that are apocrine sweat glands, and venous plexuses

194
Q

What does muscularis externa of anal canal contain?

A

Inner circular and outer longitudinal, in the middle third of anal canal- the inner circular layer forms the internal anal sphincter (smooth muscle)

195
Q

What is external anal sphincter formed by?

A

Skeletal muscle

196
Q

What lines the upper 1/3 or colorectal zone?

A

Simple columnar, derived from hind gut endoderm

197
Q

What lines the middle 1/3 or anal transition zone?

A

Stratified cuboidal with no muscularis mucosae, derived from hind gut endoderm

198
Q

What lines the lower 1/3 or squamous zone?

A

Stratified squamous keratinized (after hiltons white line), derived from surface ectoderm

199
Q

What is junction called at squamous zone when stratified squamous becomes keratinized?

A

Hiltons white line

200
Q

What does Hiltons White line demarcate?

A

Junction of internal and external anal sphincter

201
Q

What does liver function in?

A

Glucose metabolism, protein metabolism, lipid metabolism, storage of vitamin A and D and iron, detoxification, removal of damaged RBC, bile production, eliminates waste products

202
Q

What does Hepatic portal vein bring to liver?

A

Nutrients and toxic material absorbed, blood cells and breakdown from spleen, endocrine secretions from pancreas, deoxygenated blood that empties into sinusoids

203
Q

What does Hepatic artery bring into liver?

A

Oxygenated blood that empties into sinusoids

204
Q

Why are liver sinusoids never fully exposed to oxygenated blood?

A

Because the hepatic portal vein brings in deoxygenated blood, hepatic artery brings in oxygenated blood, this forms a mixture of the two, never allowing sinusoids to be fully exposed to oxygenated blood only

205
Q

What are liver sinusoids remnants of?

A

Fetal vitelline veins

206
Q

What function do liver sinusoids hold?

A

Provide exchange of substances between blood and hepatocytes

207
Q

Where do liver sinusoids drain?

A

Drain into central vein

208
Q

What is order of draining?

A

Sinusoid-Central vein-Sublobular veins-Hepatic veins-IVC

209
Q

What does liver parenchyma consist of?

A

Plates of hepatocytes, separated by sinusoids

210
Q

What does connective tissue stroma of liver consist of?

A

Glissons capsule, blood vessels, nerves, lymphatics, bile ducts transverse in CT

211
Q

What are sinusoids?

A

Vascular channels

212
Q

What is Space of Disse?

A

Space between hepatocytes and sinusoidal endothelium

213
Q

What is classic lobule?

A

Hexagonal mass of tissue, with central vein in middle and 6 adjacent portal triads

214
Q

What is Space of Mall?

A

Space between hepatocytes and portal triad, site where lymph originates in liver

215
Q

Where does lymph originate in liver?

A

Space of Mall

216
Q

What is portal lobule?

A

Parenchyma is divided into interlocking triangles, consists of portal triad in the center and central veins at each end of 3 corners

217
Q

Explain flow of bile

A

Bile produced by hepatocytes enters membrane bound bile canaliculi between them and flows within hepatocyte plate towards bile duct in portal triad, moves opposite of blood flow

218
Q

What is liver acinus?

A

Diamond shaped, contains 2 central veins as long axis, and 2 portal triads as short axis

219
Q

What is the line connecting the two portal triads in liver acinus?
What does it provide?

A

Along this line runs the hepatic artery and portal vein that deliver blood into sinusoids
Best correlation between blood perfusion, metabolic activity, and liver pathology

220
Q

Describe Zone 1 of liver acinus

A

Closest to vessels, higher metabolic rate, large glycogen storage, last to die and first to regenerate. However, toxins in blood and bile stasis would effect zone 1 first

221
Q

Describe Zone 3 of liver acinus

A

Closer to central vein, last to receive oxygen or nutrition, cells get damaged without adequate nutrition, first to show ischemic necrosis during reduced perfusion, first to show fat accumulation, first to be effected in heart failure with inadequate blood to liver. However, last to respond to blood toxins or bile stasis

222
Q

Purpose of central lobule?

A

Drains blood from hepatic artery and portal vein to the central vein

223
Q

Purpose of portal lobule?

A

Drains bile from hepatocytes to the bile duct

224
Q

Purpose of Liver acinus?

A

Supplies oxygenated blood to hepatocytes

225
Q

What does portal vein provide?

A

Venous blood to sinusoids

226
Q

What does hepatic artery provide?

A

Arterial blood to sinusoids

227
Q

What does central vein receive?

A

Blood from hepatic sinusoids

228
Q

Sinusoids are lined with what?

A

Endothelial cells and Kupffer cells

229
Q

Endothelial cells have wide open fenestrate, and?

A

No diaphragm, discontinuous with large gaps between cells

230
Q

What are endothelial cells supported by?

A

Discontinuous basal lamina

231
Q

What is space of Disse?

A

Space between hepatocytes and endothelial cells, and kupffer cells

232
Q

What is important about space of disse?

A

Site of exchange of materials between blood and hepatocytes

233
Q

What does space of disse hold in adults?

A

Plasma

234
Q

What does space of disse hold in fetus?

A

Islands of blood forming cells

235
Q

What project into space of hepatocytes?

A

Small microvilli

236
Q

Where is Stellate cell/ Ito cell found?

A

In space of disse

237
Q

What is function of Ito cell?

A

Storage of vitamin A as retinyl esters in cytoplasmic lipid droplets

238
Q

What happens to Ito cells in liver cirrhosis and chronic inflammation?

A

Loose Vitamin A storage and differentiate into myofibroblasts, they then deposit type I and III collagen in perisinusoidal space which causes liver fibrosis

239
Q

What happens during recovery of liver injury?

A

Stellate/ Ito cells remodel extracellular matrix

240
Q

Describe how Ito cells cause portal hypertension?

A

Stellate/ Ito cells secrete GAGs and type I and III collagen, this leads to loss of sinusoidal fenestrations and may even turn into capillaries. Multiplied Ito cells contract and increase vascular resistance within sinusoid, causing portal hypertension

241
Q

What are Kupffer cells?

A

Derived from monocytes, form part of sinusoidal lining but do not form junctions with endothelial cells, involved in breakdown of RBCs, increase in number after splenectomy

242
Q

Why do Kupffer cells show yellow pigmentation?

A

They show hemosiderin, resulting from destruction of RBC

243
Q

What are pit cells?

A

Liver specific natural killer cells, belong to group of sinusoidal cells

244
Q

Why are pit cells known as large granular lymphocytes?

A

They are lymphoid cells containing specific granules

245
Q

Where do majority of hepatocyte cells live?

A

Quiescent in G0 phase

246
Q

Liver has good capacity for regeneration because?

A

They undergo mitosis when stimulated, ex. after partial hepatectomy, hepatocytes reenter cell cycle by going from G0 phase to G1 phase

247
Q

What do hepatocytes have numerous of?

A

Mitochondria, small golgi, rER and ribosomes, peroxisomes and lysosomes

248
Q

Cell surface specializations of hepatocytes include?

A

Sinusoidal- that are covered in microvilli
Basolateral- that have tight junctions, desmosomes, and gap junctions
Bile canaliculi- small tubules between adjacent cells through which bile flows

249
Q

What is function of peroxisomes?

A

Breakdown of hydrogen peroxide produced in many general cytoplasmic activities using the enzyme CATALASE

250
Q

What is role of alcohol dehydrogenase?

A

1/2 of alcohol ingested is converted to acetaldehyde

251
Q

What are lysosomes involved in?

A

Degradation of foreign material and unwanted cytoplasmic organelles, by autophagy

252
Q

What is biliary tree?

A

System of conduits of increasing diameter, carry bile from hepatocytes to gallbladder and then to intestine

253
Q

What does biliary tree start with?

A

Bile canaliculi, small passages formed by apposed grooves on lateral surface of neighboring hepatocytes that contain short microvilli, sealed from the rest of intercellular compartment by junctional complexes

254
Q

What does the gallbladder function in?

A

Concentration and storage of bile

255
Q

What does gallbladder release bile in response to?

A

CCK Cholecystokinin

256
Q

What does mucosa contain in gallbladder?

A

Epithelium and lamina propria, folds when gallbladder is empty

257
Q

What does epithelium of gallbladder contain?

A

Lined with simple columnar called cholangiocytes, well developed microvilli, apical junctional complexes, apical and basal concentrations of mitochondria, lateral folds

258
Q

What are Cholangiocytes?

A

Simple columnar cells found in gallbladder, specialized for water reabsorption

259
Q

What do epithelial cells of gallbladder actively transport?

A

Na+ and Cl- from cytoplasm to intercellular space, lateral movement of NaCl forces water to move from cytoplasm to intercellular space, intercellular space widens and water moves from intercellular space to the underlying fenestrated capillaries of lamina propria

260
Q

What does lamina propria in gallbladder contain?

A

Fenestrated capillaries, many lymphocytes and plasma cells

261
Q

What pockets does mucosa form in gallbladder?

A

Deep diverticula, called Rokitansky-Aschoff sinuses

262
Q

How are Rokitansky-Aschoff sinuses formed?

A

Growth and herniation of epithelium, may extend through muscularis externa

263
Q

What is negative factor of Rokitansky-Aschoff sinuses?

A

Bacteria can accumulate and cause risk factor for gallstones

264
Q

What does muscularis of gallbladder contain?

A

Bundles of smooth muscle

265
Q

What induces muscle contraction of muscularis in gallbladder?

A

CCK cholecystokinin, released by enteroendocrine cells of small intestine, release of CCK is stimulated by the presence of ingested fat in small intestine

266
Q

What is pancreas gland and what does it produce?

A

Mixed exocrine-endocrine glands, produces both digestive enzymes and hormones

267
Q

What does exocrine of pancreas do?

A

Serous gland, synthesizes and secretes into duodenum enzymes needed for digestion, ex. proteases, lipase, amylase, bicarbonate

268
Q

What does exocrine gland surround in pancreas?

A

Islets of Langerhans

269
Q

What does endocrine of pancreas do?

A

Synthesizes and secretes into blood, insulin, glucagon, and somatostatin, regulates glucose metabolism

270
Q

What do exocrine serous cells of pancreas exhibit?

A

Zymogen granules

271
Q

What are exocrine acinus drained by?

A

Intercalated ducts, no striated ducts, secrete 1.5L a day

272
Q

What are intercalated ducts of pancreas?

A

Initial cells of duct extend into lumen of acinus, these cells are called CENTROACINAR cells, unique to pancreas

273
Q

What are CENTROACINAR cells?

A

Cells of pancreas duct that extend into lumen of acinus, lack zymogen granules, stain lightly with eosin

274
Q

What do CENTROACINAR cells secrete?

A

Fluid rich in Na and bicarbonate, neutralizes chyme which creates optimal pH for enzymes

275
Q

What do intercalated ducts merge to form?

A

Larger interlobular ducts, these join with each other to form main pancreatic duct

HHP (17 decks)

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