4th Exam histoo Flashcards
(512 cards)
1
Q
What transition of muscle is seen in the esophagus
A
From skeletal to smooth
2
Q
Nervous tissues that innercate the digestive tract wall
A
ANS ganglia and nerve fibers, enteric NS
3
Q
Mucosa of the GI wall
A
Simple columnar Epithelium, LCT (lamina propria), smooth muscle
4
Q
Function of the mucosa of GI wall
A
Protection, absorption, secrete/synthesize hormones and enzymes.
5
Q
Submucosa of GI wall
A
DICT, vessels, submucosa/meissner’s plexus
6
Q
Function of submucosa of GI wall
A
Blood supplies nutrients, nerves control fluid and gland secretion and muscle movement
7
Q
Muscularis externa of the GI wall
A
Contains myenteric/auerbachs plexus
8
Q
Function of muscularis externa
A
Nerves control smooth muscle to perform perstalsis, mixing, propulsion, segmentation
9
Q
Adventitia or serosa of GI wall
A
DICT/LCT. (Serosa is LCT and mesothelium)
10
Q
Function of adventitia/serosa of GI wall
A
Supply nutrients/protect outer surface
11
Q
What is the intrinsic NS of the GI tract
A
Enteric NS
12
Q
What is the ENS/INS capable of
A
Local autonomous functions such as motility, secretion, mixing and integration of local hormones released from cells.
13
Q
How do the ENS, CNS, and ANS interact
A
ENS is functionally coupled to the CNS and ANS adn it receives input and modification parasympathetic and sympathetic system.
14
Q
What gives extrinsic supply to the GI tract
A
ANS and it works cooperatively with the ENS to regulate mucosal secretion and peristalsis
15
Q
ANS and ENS provide __________ input to the GI tract
A
Visceral sensory
16
Q
What two ganglionic plexuses are formed by the ENS and ANS
A
Submucosal and myenteric plexuses
17
Q
Where are the neuron cell bodies of the plexuses formed by the ENS and ANS derived from
A
Neural crest
18
Q
The mucosa of the GI tract has variations in the epithelium. What areas vary and what epithelium do they contain
A
The mucosa of the esophagus contains SSNK as opposed to simple columnar. Also varies in the Pharynx and oral cavity.
19
Q
What is the key feature of the lamina propria in the GI tract
A
Glands throughout the layer
20
Q
What is the lamina propria composed of
A
Glands, LCT, blood and lymphatics capillaries/lacteals; lymphatic/WBC’s.
21
Q
What cells are located in the glands of the GI tract
A
Multipotent stem cells
22
Q
Glands in the lamina propria of the lower 1/3 of the esophagus
A
Esophageal cardiac glands
23
Q
Glands in the lamina propria of the stomach
A
Gastric glands that are named based on their location in the stomach (cardiac, fundic, pyloric)
24
Q
Glands in the lamina propria of the intestine (small and large)
A
Intestinal glands or crypts
25
What layer is unique to the GI tract
Muscularis mucosa
26
What is the composition and function of the muscularis mucosa
Composition: thin band of smooth muscles that marks the boundary between mucosa and submucosa
Function: provide local movement/mixing of contents and folding of mucosa
27
What digestion is done in the oral cavity
Mechanical by chewing and chemical digestions of carbs and fats.
28
Digestions of the stomach
Mechanical-peristaltic mixing and propulsion
Chemical-digestion of proteins, fats
Absorption
29
Digestion of small intestine
Mechanical-mixing and propulsion via segmentation
Chemical-digestion of carbs, fats, polypeptides, nuclei acids
Absorption
30
Digestion of large intestine
Mechanical-segmental mixing and propulsion
Absorption
31
Waht is the submucosa of the GI tract derived from
Mesoderm
32
Composition of the submucosa in the GI wall
DICT, large arterioles, venules and lymphatic vessels
33
What supplies innervation to the submucosa of the GI wall
Meissner’s plexus. contains ENS/ANS neurons and fibers.
34
What parts of the GI tract wall contains glands in teh submucosa
Th esophagus and the duodenum
35
Where is the muscularis externa derived from
Mesoderm
36
Composition of the muscularis externa in the GI tract wall
Contains two layers of smooth muscle; inner circular and outer longitudinal.
37
Auerbach’s plexus
Myenteric plexus of nerves that contains ENS and ANS neurons and fibers. It is located in the muscularis externa of the GI tract wall
38
What variation of muscularis externa is seen in the esophagus
Transition from skeletal to smooth and skeletal to just smooth in the lower 1/3
39
What variation of muscularis externa is seen in the stomach
Three layers of smooth muscle. Inner oblique, middle circular, outer longitudinal.
40
What variation of muscularis externa is seen in the large intestine
Teniae coli
41
What variation of muscularis externa is seen in the sphincters
Localized thickening’s of smooth muscle that act as valves in certain areas
42
What classification of neurons does each plexus contain
Enteric neuron cell bodies and fibers, Parasympathetic postganglionic (vagus), sympathetic nerve fibers (splanchnic), visceral afferent/sensory nerve fibers.
43
What is another name for serosa in the GI tract
Peritoneum
44
What are all intraperitoneal organs covered with
Serosa/serous membrane
45
What is the name of the epithelium that makes up serosa
Mesothelium
46
What organs do serosa cover
Organs with “free” surface—not attached to surrounding structures
47
Adventitia
LCT—>DICT. Located between two adjacent organs, or b/w an organ and body cavity retroperitoneal.
48
Where are all retroperitoneal organs anchored and what are they covered with
Anchored to the posterior wall posteriorly and covered with serosa anteriorly
49
Another name for
Serosa
Adventitia
Pariteal peritoneum
Peritoneal cavity
50
Function of the mucosa of the digestive tract
Function in protection, absorption, and secretion
51
What layer of the mucosa exhibits the most variation
Epithelium
52
Where is the protective mucosa located
Oral cavity, pharynx, esophagus, and anal canal
53
Histological appearance of protective mucosa
SSNK with a layer of CT called the lamina propria. Few glands in the LP. Will see glands in submucosa of esophagus that produce mucus.
54
Where is the secretory mucosa located
Stomach
55
What is the histological appearance of the secretory mucosa
Simple columnar epithelium; the cells of the epithelium, are secretory and invaginate into lamina propria to form gastric glands. Also see glandular epithelium, mucus cells, and other cell types.
56
Where is the absorptive mucosa. And what is the primary absorption occurring?
Small intestine and mainly nutrient absorption
57
Histological appearance of the absorptive mucosa
Mucosa folds appear as finger-like projections called villi. Some parts of epithelium invaginate into LP and form intestinal glands. Also see simple columnar epithelium w/microvilli
58
Enterocytes
Simple columnar epithelium with microvilli and involved in nutrient absorption
59
What kind of mucosa are present in the large intestine
Absorptive and protective
60
Histological appearance of mucosa(s) in the large intestine
Simple columnar epithelium w/microvilli (enterocytes that are structurally diff from cells in small intestine). Epithelial cells, and epithelium invaginates into the lamina propria to form glands and contains abundant goblet cells.
61
What kind of glands are formed by the epithelium in the LP throughout all regions of tubular gut
Exocrine glands
62
What are the key identifying features of the proximal 1/3 of the esophagus
SSNk, glands may be present in submucosa, muscularis mucosa becomes pronounced moving distally, only contains skeletal muscle.
63
What are the key features of the middle 1/3 of the esophagus
SSNK, no glands in the LP and submucosa, muscularis externa consists of smooth and skeletal muscle. Smooth is inner circular layer and skeletal is outer longitudinal
64
Key features of the distal 1/3 of the esophagus
SSNK until the cardiac-esophageal sphincter, epithelium changes to simple columnar at junction, glands in the LP by the cardiac junction, muscularis externa is only smooth muscle, thickening of muscularis forms lower esophageal sphincter.
65
If you see a tube with SSNK what structure are you looking at
Esophagus
66
What germ layer is the esophagus derives from
Endoderm
67
What are the glands. In the cardiac esophageal junction called
Esophageal cardiac glands
68
What nerve stimulates the lower esophageal sphincter
Vagal nerve provides parasympathetic innervation to the LES
69
What happens to the LES if there is a loss of innervation
Food accumulation due to the loss of competency (ability to contract) of sphincter. This leads to gastric reflux
70
What are the regions of the stomach
Cardia, fundus, body, pylorus
71
What are rugae
Transient macroscopic folds of mucosa and submucosa in the stomach that allow for distention
72
Fovea/gastric pits
Small macroscopic depression in the stomach that represent the opening of the gastric glands to the luminal surface
73
What are the three histological regions of the stomach
Cardiac, fundic/body, pyloric
74
What is the principal function of the stomach mucosa
Secretion of fluid; mucus, HCL, electrolytes, hormones, Enzymes, production of chyme
75
What causes gastroesophageal reflux (GERD)
Hiatal hernias- cardiac part of stomach slides upward through diaphragm
Loss of patency of LES
These lead to contents of stomach pushing back into esophagus
76
What are some of the clinical findings of GERD
Heartburn, nocturnal asthma due to acid entering airway, acid erosion of enamel, bloating, sensation of fullness
77
What histological changes can occur with GERD
Columnar Metaplasia within the esophagus. SSNK—>simple columnar and may eventually see acid producing parietal cells usually seen in the stomach and intestinal goblet cells.
78
What is considered a premalignant condition for esophageal cancer
Barrett’s esophagus
79
Esophageal ulcers
Secretion of acids into the esophagus causes ulcerations to develop and lead to increased risk of bleeding or lead to scar tissue formation and narrowing of the esophagus.
80
Esophageal cancers
Due to continued Metaplasia in increased glandular intestinal cells leads to esophageal adenocarcinoma—typically effects lower 1/3 of esophagus
81
What does the stomach function to do
Secretion, mixing, and partial digestion. Limited absorption—absorbs lipid soluble water substances like water, aspirin, and alcohol
82
What substances will the stomach absorb
Lipid soluble substances like water, aspirin, and alcohol
83
What are the key macroscopic features of the stomach
Gastric rugae
84
What are the key microscopic features of the stomach
Gastric pits, gastric glands
85
What do gastric glands do
Responsible for the secretion of “gastric juice” into stomach lumen
86
Mucosa of the stomach
Where pits and glands are located.
Contains simple columnar epithelium made of mucous cells that secrete mucus (NO GOBLET CELLS)
Contains an LP with gastric glands and a muscularis mucosa
87
What are the three types of gastric glands
Cardiac glands, fundic glands, pyloric glands.
*galnds contain different types of epithelial cels that open into gastric lumen
88
Cardiac glands
Mucus secreting
89
Fundic glands
Acid-pepsin, hormones, mucus
*largest
90
Pyloric glands
Mucus secreting and hormones
91
Which glands of the stomach are brightly stained
Fundic glands
92
Stem cells of the gastric glands of the mucosa
Replace epithelium—Multipotent differentiation gives rise to all gastric epithelial cells, located near base of gland
93
Mucous cells of stomach and the two subtypes
Line the epithelial surface and pit/neck of the gland through the stomach.
Surface cells-secrete an alkaline mucus to protect against self digestion from HCL
Neck/pit cells-secrete acidic mucous to protect against pathogens
94
Parietal cells
Secretes HCL and IF
95
Staining pattern of a parietal cell
Stain very pink w/a bullseye nucleus
96
What does IF do
It is a co factor necessary for vit b12 absorption in the ileum
97
What happens when there is a loss of ability to absorb b12
It leads to faulty RBC synthesis
98
Chief cells
Synthesize pepsinogen which is the inactive form of pepsin
99
How does pepsinogen become activated
It is activated by HCL secreted from parietal cells
100
What is pepsin
A proteolytic enzyme activated in stomach by HCL NS it is necessary for protein digestion
101
Enteroendocrine cells and two examples of a hormone they release
Produces hormones released into Fenestrated capillaries of the LP.
They release histamine and gastrin
102
Histamine
Stimulates acid secretion by acting on parietal cells
103
Gastrin
(G cells) Stimulates gastric motility and indirectly stimulates HCL
104
What controls the real ease of acid and enzymes in the GI tract
Neural and hormonal control and physical input (food)
105
What will damage to the epithelium and glands in teh GI result in
Impact of secretion in glands and alter digestive function
106
Where are stem cells located in the GI tract and stomach
In the epithelium of mucosa throughout GI and in the mucosa of all gastric glands in the stomach
107
Where are parietal cells located
In the epithelium of mucosa layer- fundic glands of stomach
108
Where are chief cells located
In the epithelium of mucosa layer-fundic galnds of stomach
109
Where are enteroendocrine cells located
Epithelium of mucosa layer-gastric glands of stomach
110
Where are mucous cells (of stomach) located
Epithelium of mucosa layer-surface
Luminal surface of gastric epithelium
Gastric pits of stomach
111
What is the role of stem cells of the stomach
Regeneration of damaged epithelium in stomach and intestine
112
What is the role of parietal cells
Digestion, protection, absorption (IF), and they contain receptors for hormones produced by enteroendocrine cells and NT’s—>gastrin, Ach, histamine all cause HCL secretion
113
What is the role of chief cells
Start protein digestion in the stomach; cleaves vitamin B12 from animal products
Product is released into lumen of gastric glands
114
What is the role of enteroendocrine cells
They release product into LCT surrounding gland and enter capillaries—paracrine effect
Function histamine and gastrin both impact acid secretions of parietal cells (increase it)
115
Function of mucous cells
Protection/lubrication against acids. Thick viscous mucus secretion onto epithelial surface—protects mucosa form autodigestion
116
Submucosa of stomach
Transient longitudinal folds of DICT project into the mucosa called gastric rugae
117
Muscularis externa of stomach
Three layers of smooth muscle that appears thicker when compared to other regions of the GI Tract
Inner oblique
Middle circular
Outer longitudinal
118
What is the function of the small intestine
Digestion of food and absorption of nutrients; protein, carbs lipids.
119
What does the small intestine require for digestion
Pancreatic enzymes and bile
120
What does the small intestine absorb
Minerals, water soluble vitamin (B family and vit C, folate), fat and lipid soluble vitamins (A, E, D, and D that require emulsification by bile)
121
What is vitamin D needed for
Ca absorption
122
What is vitamin K needed for
Synthesis of plasma clotting factors
123
What are the three regions of the small intestine from proximal to distal
Duodenum, jejunum, ileum
124
Plicae circularis
Permanent folds in submucosa that increase surface area. They are absent in the proximal duodenum and distal ileum.
125
What are the key microscopic features common to all parts of small intestinal mucosa
Villi, microvilli, crypts (intestinal glands)
126
Where are intestinal crypts located
In the lamina propria of small intestine
127
Peyers patches
MALT/GALT tissue that is very prominent in ileum. Amount of tissue increases distally from duodenum to ileum
128
Brunner’s glands
Alkaline mucous glands found only in submucosa of duodenum
129
What is the epithelium of the villi in the small intestine and what cell types
Simple columnar epithelium with enterocytes (w microvilli) and goblet cells
130
What cell transfers antigens from epithelial surface into the intestinal crypts and where are these cells
M cells in the lamina propria
131
Where are stem cells in the small intestine located and what do they do
In the mucosa at the base of the intestinal gland. Replace cells that are damaged
132
What do the enterocytes in the small intestine do
Produce and secrete enterokinase enzymes on the enterocytes that aid in digestion and absorption
133
Wha type of epithelium are enterocytes of the small intestine
Simple columnar w/microvilli
134
What do goblet cells in small intestine do and where are they most prevalent
They produce mucin and increase in number as you move distally toward anus
135
What do enteroendocrine cells of the small intestine do
Produce and secrete hormones into lamina propria as the food enters.
136
What two products do enteroendocrine cells of the small intestine release
Secretin-cause secretion of bicarbonate ions/fluid from duct cells of pancreas and liver—inhibits gastric motility
Cholecystokinin-CCK which acts on galbladder and pancreas for bile enzymes
137
What do Panethe cells do and where are they located
Secrete lysosome when exposed to bacteria and are ONLY found in the small intestine at the base of the intestinal glands.
138
What kind of tissue is prominent in the ileum
LCT w MALT to peyers patches
139
What structures reside in the Submucosa of the small intestine
Plicae circulares, brunners glands (duodenum only)
140
What gland is specific to the duodenum
Brunners glands
141
Muscularis externa of the small intestine
Contains and inner circular layer and outer longitudinal layer.
142
What is the pyloric sphincter and what layer is it in
B/w stomach and duodenum and is a thickened inner circular layer of muscular externa.
143
How can you best recognize the pyloric sphincter
A transition in the mucosa —-villi and crypts appear
144
Adventitia and serosa of small intestine
Adventitia is between the organ (duodenum) and posterior wall. Serosa covers the anterior surface of the organ
145
What do retroperitoneal structures in the small intestine exhibit
Both layers of an adventitia and serosa
146
What does the duodenum receive
Bile and pancreatic enzymes
147
What are key features of the duodenum
Submucosal brunners glands that contain mucus cells and appear pale in color when compared to intestinal glands of the LP. Can see pancreas because of anatomical position
148
What parts of the duodenum are brunners glands more numerous
1st and 2nd
149
Jejunum
Primary site of nutrient absorption
150
Key features of jejunum
Numerous long villi, large prominent plicae, increased in goblet cell number compared to duodenum, absence of Submucosal glands, NO MALT usually
151
Ileum
Site of vitamin B12 absorption
152
Key features of the ileum
Higher number of goblet cells, paneth cells in the base of the villi, *presence of peyers patches*, large lacteals, no Submucosal glands.
153
In what area of the small intestine are peyers patches most visible and a key indetifier of that area
Ileum
154
What is the function of the large intestine
No digestion. Conveys chyme to feces via fermentation by bacteria. Some absorption of vit K, B, and ions. Reabsorbs water and electrolytes to compact feces and eliminate wastes
155
What vitamins do the gut bacteria of the large intestine synthesize
Vit K, vit B1, B2, B6, biotin and B12
156
What is the heme breakdown product excreted in feces
Bilirubin
157
What area the regions associated with the large intestine
Cecum, appendix, colon (3 parts) , rectum and anal canal
158
Gross macroscopic features of lg intestine
Tenia coli, Haustra, plicae semilunar, epiploic appendices
159
Tenia coli
3 thickened bands of outer longitudinal muscle
160
Haustra
Outpocketing of wall and give colon its segmented appearance
161
Plicae semilunar
Transient folds of submucosa *not always present
162
Epiploic appendices
Serosa (peritoneum) filled with fat
163
What are key microscopic features of the large intestine
Intestinal glands **no villi*, MALT/peyers patches
164
Two layers of mucosa
Epithelium and LP
165
Epithelium of the mucosa of the large intestine
Absorptive simple columnar called enterocytes that contain microvilli, goblet cells (increase and move distally)
166
LP of mucosa in lg intestine
Intestinal glands—abundant glands that appear straight
167
What are the specific cell types of the intestinal glands in the colon
Absorptive columnar cells, goblet cells, enteroendocrine cells, stem cells, peyers patches
168
What channels do the absorptive columnar cells w/microvilli in the lg intestine contain
Ion channels, Na/K.
169
What does ATPase activity promote
Na+ absorption and H2O follows passively (in the lg intestine in absorptive columnar cells w/microvilli)
170
What cell lubricate mucosa for ease of passage and are abundant in the lg intestine
Goblet cells
171
What cells produce hormones in the lg intestine
Enteroendocrine cells and they affect motility and absorption
172
Stem cells are only located in the small intestine T/F?
FALSE. They are consistent throughout GI
173
Submucosa of lg intestine
Contain plicae semilunaris
174
Muscularis externa of lg intestine
Inner circular layer that mixes contents and an outer longitudinal muscle
175
What structures do the muscularis externa of the lg intestine contain
Tenia coli- 3 distinct regions of thickened bands of outer longitudinal muscle (shorter than length of colon)
Haustra-pouches between Tenia coli that independently segmented mixing of chyme
176
Adventitia and serosa of lg intestine
Adventitia between the organ and posterior wall
Serosa covers anterior surface of organ
177
All retroperitoneal structures of the lg intestine exhibit adventitia and serosa T/F
True
178
What structures of the large intestine are retroperitoneal
Ascending colon and descending colon
179
Is the transverse colon intraperitoneal or retroperitoneal
Intraperitoneal
180
What are the types of accessory glands
Salivary, pancreas, liver, gallbladder
181
Where do the excretory ducts of the liver, pancreas and gallbladder open into
The 2nd part of the duodenum via the duodenal papilla
182
What are the major salivary galnds
Parotid, submandibular, and sublingual
183
Where do salivary glands deliver their products
Into the lumen of the oral cavity
184
How do the salivary glands connect to the oral cavity
Exrectory ducts
185
Where does the parotid gland develop from
Ectoderm
186
Where do submandibular and sublingual galnds derived from
Endoderm
187
What are the key features of minor salivary glands
Non-encapsulated groups of excretory units, locates in submucosa/intraorally, short w multiple excretory ducts and few intralobular, epithelium or skeletal muscle may be seen
188
What are the key features of the major salivary glands
Encapsulated CT divided into lobules and lobes, extra-oral location bilaterally, numerous intra and interlobular ducts, long excretory ducts
189
What salivary gland produces more saliva during stimulation
Parotid
190
What type of secretion does the parotid have and what is the name of its main excretory duct
Pure serous and Stenson’s duct that opens to buccal 2nd max molar
191
What kind of secretion does the submandibular gland have and what is the name of its main duct
Mixed (60% serous, 40% mucus). Wharton’s duct on floor of mouth
192
What type of secretion does the sublingual gland have and what is the name of its main duct
Mixed (70% mucus, 30% serous). Ducts of rivinus joins bartholins in floor of mouth
193
Are major or minor salivary gland duct systems more extensive
Major
194
What are the parotid and submandibular galnds mainly controlled by
ANS
195
What controls the secretory activity of the sublingual gland
ANS and constitutive exocytosis
196
What are the structural components of salivary glands
Supportive tissue and glandular tissue
197
Supportive/stromal tissue
DICT
198
Glandular/parenchymal tissue
Myoepithelial cell, secretory acinar cells, duct cells
199
What are the histological features of structural components in stromal supportive tissue
CT in major glands forms a capsule that divides tissue into lobes and lobules. Conveys BV’s and nerves.
200
What cells are seen in stromal tissue
Lymphocytes, macrophages, fibroblasts, plasma cells
201
What do the plasma cells in the CT of stromal tissue secrete
IgA
202
How is IgA transferred from CT
By transcytosis from CT to secretory Acinar salivary gland cells
203
What cells are in the parenchymal tissue of salivary glands
Serous acinar cells, mucous acinar cells, mixed seromucous acinar cells
204
Serous acinar cells
Synthesize glycoproteins and enzymes (protein adn enzyme rich). Watery electrolyte secretion aids in digestion and protects tooth with buffering capacity
205
Mucous acinar cells
Synthesize mucin and anti microbial proteins. Carb rich, viscous secretion aids in protection/bolus formation
206
Appearance of mucous acinar cells
Pale stained cytoplasm with flattened basal located nucleus
207
Mixed seromucous acinar cells
Found in submandibular and sublingual glands. Contain a serous cap called a serous demilune.
208
All parenchymal tissue (secretory and duct cells) in gland are NOT derived form the same germ layer T/F
FALSE! They are
209
where are myoepithelial cells found adn what do they do
B/w acinar cell or duct cell and basement membrane of salivary glands
Supportive; facilitate secretory discharge of secretory acinar cell (ANS control)
210
What are the two major classifications of ducts
Intralobular and interlobualr
211
What are teh two types of intralobular ducts
Intercalated and striated
212
Intercalated ducts
Receive primary saliva directly from acinar cells. Have low/flattened cuboidal epithelium
213
Primary saliva is ____________ relative to plasma
Isotonic
214
Striated duct
Receives primary saliva from intercalated duct. It modifies ion concentration and pH of primary saliva.
215
In modification of saliva by striated ducts what is reabsorbs vs what is secreted
Na+ and Cl- are reabsorbs and duct cells secrete HCO3- and K+ into the saliva BUT duct is impermeable to water. This causes saliva to be hypotonic relative to plasma and more alkaline pH.
216
What epithelium are in striated ducts
Simple cuboidal to simple columnar
217
Interlobular ducts
Excretory ducts found in CT between lobules and they contain simple columnar to stratified cuboidal epithelium.
218
What is the epithelium of the main excretory ducts of the major salivary glands
Stratified columnar to SSNK in oral cavity
219
Path of salivary flow
Acinar cell—>intercalated duct—>striated duct to interlobular duct—>main excretory ducts
220
What affects the amount of modifications in salivary ducts
Flow rate through the ducts
221
What is flow rate of the salivary ducts controlled by
ANS—cooperatively para and symp
222
Merocrine
How minor glands release their products and it is done through constitutive exocytosis
223
What is regulated exocytosis controlled by
The ANS both
symp-greater protein response
parasympathetic-greater volume response
224
Untimulated/resting flow of saliva
Higher amount of mucous b/c the role of saliva protection of tooth and mucosa via salivary pellicle. Saliva is more hypotonic relative to plasma
225
Stimulated flow
Higher amount of enzymes, volume, bicarbonate, adn electrolytes. The role of saliva is clearance, buffering, remineralization—higher pH due to faster flow rate. Saliva is less hypotonic
226
Unconditioned refelx
Tactile or gustatory input stimulates; present at birth
227
Pathway of unconditioned reflex
Afferent (GSA<,SVA) input form peripheral receptors, mechanoreceptor, chemo receptor, nociceptors
Salivatory centers in BS nuclei
ANS parasympathetic and sympathetic terminate on salivary gland acinar and duct cells
228
Examples of salivary reflexes
Gustatory- salivary reflex:stimulation of tase buds (sour highest)
Masticatory-SR:stimulation of chewing from PDL and mucosa
Olfactory-SR:smell stimulates submandibular and sublingual glands
229
Conditioned reflex
Acquired response due to stimulation through special senses; requires processing through higher brain centers and may stimulate or inhibit salivation
230
Conditioned reflex pathway
Stimuli from smell, nausea,s tress, fear
Cortex and higher CNS centers process input; may stimulate/inhibit salivatory centers
Salivatory centers in BS nuclei
ANS fibers terminate on acinar/duct cells
231
Unstimulated resting flow rate
Primary saliva—rich in proteins, electrolytes and water. Isotonic
232
How is saliva modified as it flows through the duct in unstimulated conditions
Removal of Na/Cl, secretion of HCO3-, no water absorbed in duct. NaCl absorption greater than HCO3-!
233
What does a slower flow rate in unstimulated conditions result in
A more hypotonic saliva due to more time for absorption
234
Stimulated conditions
Outcome of ANS stimulation saliva composition—>increased secretion and flow rate.
Parasympathetic: produces ting watery low viscous material
Sympathetic: produces viscous enzyme rich saliva with low fluid solution
235
How is primary saliva modified in the duct during stimulated conditions
Removal of NaCl (little), secretion of HCO3- (high rate), no water removed in duct.
236
What does primary saliva increase in during stimulated conditions
Increases in electrolytes and water; proteins
237
In stimulated conditions what does an increased flow rate result in
A less hypotonic (more isotonic) saliva due to less time to reabsorb
238
Is a stimulated pH higher or lower than resting levels
Higher
239
What does low flow rate due to pH
Lowers it (6.5-6.6); more hypotonic
240
What does high flow rate do to pH
Higher pH (6.7-7.6); less hypotonic
241
What are the biochemical components of primary saliva
Water, electrolytes, mucopolysaccharides(mucin), salivary proteins, enzymes, antibodies, small organic molecules
242
What three active components function in protection in saliva
Water, mucin, salivary proteins
243
What active components function in buffering capacity in saliva
PO4^-3, HCO3
244
Antimicrobial/anti-fungal active components of saliva
Mucin, IgA, lysozyme, lactoferrin, histatins
245
Active components of saliva that function in digestion/taste
Water, amylase, lipase
246
What active components of saliva function in tissue repair
GF’s, histatins
247
Where are the biochemical components of primary saliva secreted from
Acinar cell/intercalated duct
248
Cellular components of whole saliva
Desquamated epithelial cells, lymphocytes, bacteria
249
What are the components of whole saliva
Biochemical components (primary saliva), cellular components
250
Acquired pellicle
Protective layer of mucin and salivary proteins that coats the tooth surface
251
Plaque
Colonization/attachment of bacteria to pellicle- amount and type of bacteria influence plaque pH
252
Exocrine secretion of sublingual, submandibular, and parotid glands and pancreas and what types of ducts do they contain
SL-mixed, mainly mucus (acinar)
SM-mixed; mainly serous (acinar)
P-only serous
**all intercalated and striated intralobular ducts
Pancreas- serous only; intercalated intralobular ducts only
253
What type of epithelium is found in the three main salivary gland interlobular ducts
Stratified epithelium
254
What kind of gland is the pancreas gland
Endocrine and exocrine
255
Exocrine secretion of pancreas
digestive enzymes, fluid, bicarbonate
256
What synthesizes digestive enzymes of the pancreas
Serous acinar cells and release them into intercalated ducts
257
Endocrine function of the pancreas
Produces hormones that influence blood sugar and glucose metabolism
258
What hormone do enteroendocrine cells from the duodenum release to stimulate pancreatic acinar cells to secrete digestive enzymes
Cholecystokinin (CCK)
259
Islets of langerhans
Region of hormone secreting endocrine cells in pancreas
260
Pancreatic acinar units
Groups of serous cells, nuclei basally located and numerous in eosinphillic granules
261
What do pancreatic acinar cells do
Function to synthesize inactive enzymes that are stored in secretory granules in the apex of the cell
262
What do pancreatic enzymes do
Inactive enzymes (zymogens) are transported to small intestine and become activated by the enterokinases enzyme on enterocytes. Required for digestion of proteins, carbs, lipids in SI
263
What hormone do enteroendocrine cells produce in duodenum that acts on pancreatic acinar cells
Cholecystokinin (CCK)
264
What happens due to CCK release
Pancreatic enzymes released into intercalated ducts of pancreas delivered to duodenum
265
What nervous system contributes to pancreatic enzyme secretion
Parasympathetic
266
Path of flow in pancreas
Intercalated ducts—>intralobular ducts—>interlobular ducts—>main pancreatic duct
267
What is a key histological feature of intercalated ducts of the pancreas
Centroacinar cells that represents the first part of the intercalated duct
268
What epithelium is found in the ducts of the pancreas
Simple cuboidal to simple columnar. EXCEPT FOR MAIN DUCT which is stratified cuboidal
269
What do intercalated duct cells produce
Fluid and bicarbonate rich solution that neutralizes chyme and keeps digestive enzymes happy
270
What is the physiological mechanism that controls fluid secretion of excretory ducts of pancreas
Secretion hormone produced by enteroendocrine cells in duodenum and stimulate bicarbonate and fluid secretion from intercalated duct cells
271
What is the pancreas divided by
Divided into lobules by CT
272
What is found in the CT of the pancreas
Blood vessels and large interlobular ducts
273
What principle cell types of the pancreas produce what hormone
Alpha cells- glucagon
Beta Cells- insulin
274
What do islets cells look like and do
Light stained clusters of cells scattered among acini. Function to respond to glucose blood levels, amino acid levels, intestinal hormone
275
What are the minor cells of pancreas what do they produce
PP/F cells- pancreatic polypeptide
Delta cells-somatostatin
Minor cells hormones regulate stomach acid secretion, intestinal motility, pancreatic secretion
276
What kind of capillaries are in the pancreas
Fenestrated! They receive hormones
277
PSNS effect on pancreas
Increase insulin secretion and some glucagon
278
What system modulates hormones secretion of pancreas to maintain responsiveness
ANS
279
What gland increases blood glucose levels and what does it secrete to do so
Adrenal gland—epinephrine and cortisol
280
What does the inability to produce or respond to insulin cause
Diabetes Mellitus—excess glucose in urine and increase urine output
281
Type 1 diabetes
Autoimmune destruction of beta cells by T cells (CD+8). Individuals can’t synthesize insulin
282
Type II diabetes
Insulin resistant. Still make it but target cells can’t bind insulin so sugar remains in the blood stream
283
What is the impact of hyperglycemia on the body
Promotes chronic inflammation and increases risk for periodontal disease!
284
Exocrine function of liver
Bile production and excretion from liver cells into bile canaliculi that drain larger ducts into portal area
285
Endocrine function of the liver
Secretion/synthesis of plasma proteins and metabolites into sinusoids for delivery to body
286
Principal cell type of the liver
Hepatocytes—liver cell involves in metabolism, storage, detoxification, plasma protein production, bole synthesis
287
Kupffer cells
Phagocytic cells found in perisinusoidal space of Disse and they store vit A and other fat soluble vitamins. Act as stem cell and synthesize collagen during hepatocyte damage
288
Perisinusoidal space (of Disse)
Space located between the hepatocyte and sinusoid capillary and it functions to serve as a site of metabolic exchange
289
Central venule (liver)
Terminal hepatic venule located at the center of lobule/centrilobular area
290
Sinusoids of liver
Discontinuous capillaries and Fenestrated endothelial cells but no BM
291
What makes up the portal triad/area
Portal vein, hepatic artery, bile duct
292
What does a portal area do
Supplies each lobe of the liver
293
Interlobular branches of the liver
Branches of hepatic and portal vessels found between adjacent lobules
294
What make the sinusoids in the interlobular areas of the liver
Discontinuous capillaries —within the lobule receive MIXED blood from venule and arteriole
295
Where does the central vein receive blood form
Sinusoids
296
Direction of blood flow in the liver
Intraabdominal branches of liver—>inter-hepatic/intralobular—>drainage of lobule and liver in intra abdominal branches
297
Where does the hepatic vein drain
IVC
298
Hepatic liver lobule
Describes the secretion of proteins and metabolic by-products into the blood (PA to CV)
299
Portal lobules of liver
Describes the route of secretion of bile int bile ductules. Flow from centrilobar area to periportal
300
Hepatic acinus
Describes the removal of compounds from blood and the amount of oxygen and nutrients delivered along a gradient from the portal area to the central vein of the liver lobule. There are three zones
301
What zone is oxygen rich, highest in nutrients and first exposed to blood born Ag
Zone 1
302
What zone is O2 poor, high in detoxification enzymes and can create toxic by products
Zone 3
303
What is zone 2
Intermediate zone
304
Why does bilirubin need conjugated and where
To produce water-soluble excretable bilirubin glucuronide and the lives does this
305
Liver dysfunction and alterations in hepatocytes may manifest in the oral cavity as well as other regions of the body T/F
True
306
Functions of liver
Glycogen/triglyceride storage, gluconeogenesis, detoxification, secretion of bold acids, bilirubin conjugation, production of blood plasma proteins, vit storages
307
What happens if the live can’t metabolism lipids, carbs, proteins
Accumulation of fat in liver cells that can lead to malnourishment
308
What happens if the liver is unable to detoxify drugs, hormones, metabolites, or convert waste
Decreased drug clearance, accumulation of toxins in cells
309
What happens if the lives can no longer synthesize bile salts or breakdown RBC’s
Jaundice —decreased intestinal absorption of fats —>fatty stool
310
What happens if the liver cannot synthesize blood plasma proteins
Bleeding—increased clotting time. Edema of CT because loss of albumin. Impaired immune response
311
What happens if the liver can not longer store and activate vitamins
Decreased ability to clot. Anemia. Decreased Ca+ absorption that can lead to osteoporosis
312
What is bile composed of
Bile salts and bile pigments from RBC breakdown from spleen
313
Function of bile
Required for emulsification of fats adn fat soluble vitamins to allow for intestinal absorption
314
What role do hepatocytes play in bile production
Bile synthesis and sectretion
Bilirubin conjugation and excretion
315
Hepatocyte secretion of bile
Bile is constitutively secreted along with bicarbonate from hepatocytes into bile ducts and transferred form liver to gallbladder
316
Where is bile stored and concentrated
Gallbladder
317
What happens to bile salts after they have been used
90-95% of bile salts are reabsorbed form capillary beds in small intestines and recycled back into the liver
318
Without _______________ bile conjugation can’t occur
Glucuronyltransferase
319
Path of bile flow
Intra hepatic/intralobular excretory ducts—>Bile canaliculus—>canal of hering—>bile duct—>extrahepatic ducts—>common hepatic and cystic duct release bile into common bile duct that enters 2nd part of duodenum
320
An opening between adjacent hepatocytes that receive bile
Canaliculus—joined by tight junctions
321
Histological features of gallbladder
Mucosa—simp columnar w no microvilli. LP present.
Muscularis externa —random orientation of smooth muscle
Excretory ducts—cystic duct
322
What causes gallstones (cholelithiasis)
High amounts of cholesterol or low amounts of bile salts
323
Cholecysititis/inflammation of gallbladder
Caused by blockage of cystic ducts due to gallstones
324
Obstructive hepatic jaundice
Caused by blockage of bile in common bile ducts due to gallstones
325
What causes the galbladder to release bile
CCK from duodenum via enteroendocrine cells
326
What does CCK act on
Smooth muscle to cause contraction
327
What causes bile release from the liver
Secretin released form the duodenum
328
After fats are emulsified and absorbed by enterocytes of small intestine where do they go
Enter lacteals as chylomicrons
329
Waht are majority of bile salts absorbed by
Intestinal epithelium—enterocytes
330
Where are all hematopoietic cells derived from
Mesoderm
331
Site of hematopoiesis in fetus
Shifts sites from liver—>spleen—>bone marrow long bones by 5th month in utero
332
Newborn hematopoiesis
Occurins in marrow cavity of all bones (red marrow)
333
Adult hematopoiesis
Marrow cavity of flat bones of skull and axial skeleton. Seen in red marrow of areas with high amounts of trabeculae
334
Megakaryocyte
Remain in bone marrow cause they are too big to leave and they release platelets/thrombocytes that remain in circulation.
Polyploidy-multiple nuclei
335
Erythrocytes
Anucleated RBC’s. Remain in circulation within a BV (peripheral blood)
336
Cells of myeloid lineage
Erythrocytes, granulocyte (neut, eos, baso), mast cells, megakaryocytes, monocytes
Eat
Good
Make
More
Money
337
Cells of Lymphoid lineage
Lymphocytes (b cells), thymocytes (T cells), T helper, T cytotoxic, T memory
338
What cells circulate in peripheral blood
Erythrocytes, granulocytes (neut, eos, baso), platelets
339
Peripheral blood
Specialized CT composed of cellular fragments suspended in a protein fluid called plasma
340
What cells from whole blood
Erythrocytes, leukocytes (granulocytes and agranulocytes), thrombocytes.
341
Function of erythrocytes
Transport gases and maintain pH
342
Polymorphic leukocyte
A granulocyte; neutrophils, eosinophils, basophils
Non-specific or innate immune response. Local and fast (min to hours) destruction of pathogens. No memory
343
Mononuclear leukocytes
Agranulocytes; monocytes, natural killer cells, B and T lymphocytes
Specific (adaptive) immune response. Specific recognition of pathogen. Have memory
344
Thrombocytes
Hemostasis and clotting
345
Plasma
PH 7.4. Aqueous ECM solution with no ECM fibers. Comprised of water, plasma, proteins*, electrolytes and inorganic acids.
346
Function of plasma
Transport nutrients, cells, proteins, hormones, waste, blood gasses, maintain pH, body temp, blood pressure and volume, and osmotic pressure between blood vessels and tissues
347
Albumin
Most abundant plasma proteins adn made by hepatocytes. Primarily maintains osmotic pressure of blood and is a carrier protein for hormones, drugs, and fatty acids
348
What activates fibrinogen
Prothrombin
349
Fibrinogen and prothrombin
Plasma proteins made by hepatocytes both help in blood clotting
350
Complement proteins
Important in inflammation and destruction of microorganisms. Synthesized by liver
351
Globulins
Made by hepatocytes functions as enzymes and proteins that transport compounds in the body
352
Y-globulins or antibodies
Synthesized and secreted by PLASMA cells in many locations
353
Whole blood
Plasma and cells
354
Plasma composition
Blood fluid only no cells. Includes clotting factors and proteins synthesized by liver
355
Serum composition
Plasma minus clotting factors
356
Whole blood transfusion
Patient receives plasma and cells
357
Blood component therapy
Patient receives specific components; RBC’s, platelets, plasma, and WBC’s
358
Complete blood count
Used for routine checkups, diagnosis of disease such as anemia, infection, malignancy, clothing problems and monitoring treatments
359
CBC
Calculates the cellular formed elements found in volume of blood—frequently expressed as a percentage indicating ratio between to vol of specific cells/vol of total blood
360
Differential count
Refers to percentage of each type of leukocyte in the Buffy count gives the number of specific type of WBC’s
361
Hematocrit
The % of RBC’s in a volume of blood. The measurements depends on the number size of red blood cells
362
Anemia
Low RBC/low hemoglobin count. Many types of anemia and may be cause by other diseases
363
Polycythemia
High RBC count. Increased RBC’s causes increases viscosity of plasma due to high cell #. Increased risk for blood clots
364
Leuokopenia
Low WBC count. Type depends on WBC afffected—signs of infection causing symptoms of high fever and sweating
365
Leukemia
High WBC count. Increased WBC due to uncontrolled proliferation of WBC in bone marrow
366
Lymphocytosis
High lymphocyte
367
Thrombocythemia
High platelet. Increased risk of blood blots within vessels
368
Lymphopenia
Low lymphocytes
369
Thrombocytopenia
Low platelet count. Prolonged clotting time, excessive bleeding and bruising
370
What blood cells increase during an allergic reaction
Eosinophils and basophils
371
Reticulocyte
Immature RBC, no nucleus, will have some granules and is larger than mature RBC. Make up 1-2% of RBC in peripheral blood and increase in number during some types of anemia
372
Lifespan of a RBC
120 days
373
Histological feature of erythrocyte
Anucleated, small size, biconcave shape. Flexible so they can pass in capillaries and increase surface area for max binding of O2
374
Waht is the oxygen binding protein on a RBC
Hemoglobin—iron containing groups
375
Cell surface receptors on RBC palms membrane
Refers to different types of proteins and complex carbohydrates bound to the surface of RBC. Surface receptors are called antigens and serve as basis of blood typing
376
Blood types and their antigens
A- only A antigen
B- Only B antigen
AB-both A and B antigen
O-no antigen
377
What blood type is the universal donor
Type O
378
What blood type is the universal recipient
Type AB
379
Histological features of platelets
Anucleated cell fragment with intracellular granules
380
What do the different types of granules in platelets function to do
Activation and release facilitates blood coagulation
Facilitate clot retraction and wound healing
381
Four steps of clot formation
1) vasoconstriction
2)platelet plug formation
3)activation of circulating plasma clotting proteins
4) fibrous clot—fibrin strands strengthen plug
382
Hemostasis
Stopping blood flow and clot formation
383
Thrombosis
Clot forms within intact vessel
384
Thromboembolism
Clot breaks fee
385
Bruising and prolonged bleeding
Increased with low platelet numbers
386
Primary and secondary hemostasis
Primary is platelet plug formation and secondary is fibrous clot formation
387
What do neutrophils function to do
Non specific immune response and acute inflammation, phagocytosis, elevated numbers during a bacterial infection. 1st to the scene to fight infection
388
Histological appearance of neutrophil
Segmented multi lobed nuclei with pink staining granules
389
Basophil
Immediate hypersensitivity allergic reactions. Segmented bi-lobed nucleus with basophilic stained (purple) granules
390
What receptors are located on a basophil surface
IgE receptors
391
What secondary granules are contained in a basophil
Histamine and heparin granules. Histamine causes vasodilation of blood vessels and heparin is an anticoagulant
392
Immediate allergic reaction
Pollen, food proteins, bee stings
393
Primary and secondary exposure of basophil
Primary- In response to allergen exposure the IgE antibody is produced and bind to the IgE receptor on basophil
Secondary- allergen specific for IgE antibody which is bound to IgE receptor on the basophil will bind and trigger granule release
394
What exposure causes a reaction in allergies
Second
395
Eosinophil
Anti-parasitic, chronic inflammation involving chronic allergies. Stains acidophillic and has a segmented bi-lobed nucleus
396
What do the granules of an eosinophils contain
Proteins that are anti parasitic and cytokines that respond to allergens
397
What receptors are found on an eosinophil
IgE that bind IgE antibodies
398
When will eosinophil cell count be high
During a parasitic reaction and during chronic inflammatory conditions such as asthma and hay fever (allergic reaction)
399
Monocyte
Acute inflammation and acts and an antigen present in cell that is needed for specific immunity. Kidney shaped nucleus with no granules and abundance cytoplasm.
400
Receptors on monocyte and macrophages
Receptors non specifically bind bacteria and antibody bound to foreign antigen. MHC class II receptors
401
What receptor is found on anucleated cells
MHC I
402
What receptor is found on all antigen presenting cells
MHC II
403
When do monocytes differentiate into macrophages
After they circulate for 1-3 day and then when they move into CT they differentiate
404
A macrophage may not act as an APC T/F
FALSE. They can act as an APC neeed to activate T cells
405
Lymphocytes
Antibody production—specific humoral immune response
They usually reside in lymphoid organs after maturation in bone marrow
406
B cells
Naive and haven’t encountered an antigen yet but they are immunocompetent
407
Plasma B cell
Makes antibody (immunoglobulins) that gets rid of antigen
408
Memory B cell s
Involved in secondary response
409
What receptors are found on B cells surface
IgD and IgM receptors and they also have MHC class II receptors
410
What does the type of Ab produced depend on
Antigen, time of exposure, first response vs secondary response and location of infection
411
After an antigen encounter what do b-lymphocytes differentiate into
Antibody secreting plasma cells and memory B cells
412
IgM
First Ab produced in response to antigen. Primary response
413
IgD
Bound to B cell also IgR
414
IgG
Majority of Ab in circulation after IgM initially produced so a secondary response; CROSSES PLACENTA.
415
IgA
Ab secreted into bodily fluids like saliva, GI fluid, respiratory fluid etc
416
IgE
Ab produced during an allergic reaction and is secondary Ab
417
Thymocytes (T cells) and the two types
Specific immune response—cell mediated and humoral immunity
T cytotoxic (CD8+)
T helper (CD4+)
418
Cell mediated immunity
T cell cause direct lysis of infected cells
419
Humoral antibody response
T helper cells activate B cells to have antibody production by plasma cells
420
T memory cells
Involved in second exposure to antigen
421
T regulatory cells
Regulatory T cells aid in preventing auto immunity
422
Histological feature of T cells
Large round nuclei and eccentric position. No specific granules
423
CD8+ involvement in T cell mediated immune response
Destroy intracellular pathogen
424
CD4+ cells involved in T cell helper response
Activates B cells and causes plasma cells to produce antibodies in response to extracellular pathogens
425
2x4=1x8
MHC 2 with CD4 and MHC 1 with CD8
426
Natural killer cells
Recognize and kill cells that lack MHC on surface—cell meditated immunity. Large round nuclei with secondary granules taht containe cytotoxic proteins.
427
Cell mediated/cytotoxic killing
NK cell cause direct cell lysis of virally infected cells, tumor cells, or stressed cells
428
Specific receptor is on surface of NK cells los for ________
MHC I
429
Innate immune response
Innate immunity constitutes the firs line of defense. Involved inflammation and occurs as site of infection. Mediated by cutaneous and mucous membranes, innate immune cells, complement proteins. No memory of encounter
430
Adaptive immune response
Occurs after an innate response occurred but did not resolve. Mediated by T and B lymphocytes. Requires and APC to present an antigen bound to MHC to a T cell
431
Primary adaptive immune response
Weak and slow. This response primes cells for second encounter
432
Secondary adaptive immune response
Second response to same antigen—fast, strong and involves memory
433
Primary lymphoid organs
Site of lymphocyte formation and maturation. No immune reaction
Bone marrow and thymus
434
Secondary lymphatic tissues
Sites of specific immune reaction due to LOCAL antigen exposure MALT, diffuse lymphatic tissue, lymphatic nodules
435
Secondary lymphatic organs
Site of a specific immune reaction for SYSTEMIC antigen exposures Lymph node—lymph born
Spleen—blood born
436
A specific immune reaction involves….
The activation of B cells and T cells through interactions with an antigen presenting cell and a specific antigen
437
Function of bone marrow
Site of hematopoietic cell differentiation and maturation.
Erythropoiesis
Granulopoiesis
Lymphopoiesis
438
Histological features of marrow cavity
Vascular sinusoids (discontinous capillary), stroma, developing hematopoietic cells.
439
Route of lymphocytes from bone marrow
Exit BM via blood vessel—>natural killer and b lymphocytes enter blood as immunocompetent—>T cells migrate first to THYMUS—>mature T cells released from thymus into peripheral blood as immunocompetent—>lymphatic secondary organs
440
Outcome of maturation of lymphocytes
Immunological tolerance and immunocompetence—learn to distinguish between self and non self and not react to self antigen with immune response. Ability to react specifically to no self antigens and adapt a response is immunocompetence
441
Autoimmunity
Immune response against self proteins. Self is seen as foreign because failure of B and T cells to establish tolerance during maturation
442
Thymus
Responsible for T cell education and maturation.
443
CT capsule
DICT surrounds two lobes of thymus and cat ties blood vessels and efferent lymphatic vessels
444
Thymic lobules
Cortex-outer region
Medulla-central region
Cortex is a darker stained than medulla
445
Epithelial reticular cells
In thymus. Supportive cells that facilitate T cell maturation (teachers). Endoderm derived.
446
Thymocytes undergo maturation into three types
CD4+ T cells—t helper that recognize MHC II and foreign Ag
CD8+ T cells—t cytocoxic recognize MHC I and foreign Ag
T regulatory cells—prevent autoimmune response; inhibit auto reactive T cell which escape thymus
447
Macrophage function in phagocytosis
Eliminate self reactive or incompetent T cells. “House cleaning”
448
The thymus atrophies with age T/F
TRUE
449
Where do T cells undergo their final maturation
Medulla of the thymus and then exits thymus via postcapillary venules and efferent lymphatics
450
Thymic cortical cells
Immature thymocytes (T lymphocytes) that migrate from bone marrow and enter via blood vessels at corticomedullary junction then migrate to cortex
451
What do epithelial reticular cells of the thymus do
Produce hormones to stimulate maturation of thymocytes, thmhyic education, contribute to selective blood thymus barrier
452
What do macrophages in the thymus do
Phagocytose self reactive thymocytes
453
Blood thymus barrier
Protects thymus from blood born foreign antigens during T cells maturation by providing a selective barrier to circulating molecules
454
Layers of the blood thymus barrier
Endothelial cells of continuous capillary
Basement membrane
Epithelial reticular cells
455
What is a key functional event in the cortex of the thymus
Before cortical thymocytes can enter the medulla they must be:
T cell must have a functionally unique antigen receptor on surface so T cell can bind antigen
T cell must be able to recognize self MHC I or MHC II
456
How many T cells are positively selected to survive and move to the medulla
Only 10%
457
Where do T cells forms become immunocompetent
In Thymic cortex by expressing TCR
458
Cell types in the Thymic medulla
T helper cells—cell mediated and humoral immune response
T cytotoxic cells—cell mediated immune response
459
What is a key feature of the thymus
Hassall’s corpuscle or Thymic corpuscle which are old epithelial reticular cells that form groups of worn out cells. Appear as flattened epithelial cells concentrically arranged with keratinized center
460
What determines a cells survival in the thymus
The affinity of maturing CD4 or CD8 T cells to bind self proteins. Goal is to recognize but not react
461
Where do T cells migrate after becoming immunocompetent and self tolerant in thymus
To secondary lymphoid organs and tissues
462
What is MALT
High number of mature immune cells located in the LCT just below epithelium. Associated with mucosal layer of respiratory, urinary, digestive system and oral cavity (name based on location)
463
What are the two regions of MALT
Diffuse lymphatic tissue (scattered)
Nodular/follicular lymphatic tissue (spherical aggregate)
**the difference in regions correlates with type of adaptive immune response that occurs
464
Function of MALT
Common site of antigen entry across epithelium, site of local antigen recognition by lymphocytes, site of local adaptive immune reaction both cell mediated and humoral
465
MALT has a CT capsule T/F
FALSE! Not CT capsule only epithelium covers lymphatic tissue
466
What immune cells are found in MALT
B cells, plasma cells, t helper and cytotoxic cells, APC’s—macrophages, dendritic cells. Cells distributed throughout MALT based on adaptive immune response
467
What allows MALT to drain to nodes
Lymph capillaries and collecting lymphatic vessels
468
Where do lacteals drain
Into collecting/efferent lymphatic vessels that will transmit the collect lymph fluid to lymph nodes.
Lacteals only found in ileum CT!!
469
What is a unique feature of MALT
Contains High Endothelial Venules—specialized postcapillary blood venules with cuboidal endothelial cells vs simple squamous
470
What allows naive immunocompetent lymphocytes to endure CT from circulation
High endothelial venules
471
What is the function of diffuse lymphoid tissue
Site of antigen presentation and T cell mediated response
472
Cells in diffuse lymphoid tissue
Scattered t lymphocytes, APC’s,plasma cells, granulocytes, mast cells
473
Nodular lymphatic tissue function
Site of B cells and humoral antibody mediated immune response
474
Cells in Nodular lymphatic tissue
Spherical aggregation of B lymphocytes, plasma cells, APC. All held together by reticular tissue fibers
475
Layers of lymphatic nodule
Mantle/corona—outer dark stained layer
Germinal center —central light stained layer
476
Mantle/corona
Contains a high number of tightly packed smaller inactive B cells
477
Germinal center
Large pale stained cells that represent mature active by lymphocytes differentiating into plasma cells and memory B cells.
478
Mechanism stimulating an IR in MALT
Antigen perforates epithelia lining or is transported by an epithelial cell into LCT
Presence of Ag activate B cells and or T cells
479
Where is the site of cell mediated response by t cytotoxic cells in MALT
In the diffuse lymphatic tissue
480
Where is the site of antibody-mediated immune response in MALT
Lymph nodule
481
Definition of secondary lymphoid organ
DICT forms a capsule around the organ; each contains aggregations of lymphoid nodules
482
Function of secondary lymphoid organs
Site of adaptive immune response. Ag may be brought in by lymph or blood—route depends of lymphatic organ
483
Both lymph nodes and spleen can only mount a T cell-mediated immune response T/F
FALSE. Both can mount cell mediated and a humoral response
484
What are key features of a lymph node
Found along lymphatic vessels, receives lymph drainage via afferent lymphatics, contains outer cortex, paracortex and medulla
485
Hilum of lymph node
Concave surface where blood vessels enter/exit and efferent lymph vessels EXIT
486
Where do afferent lymphatic vessels enter lymph node
On the convex surface
487
What is the lymph node comprised of
Reticular CT comprised of reticular fibers (type III collagen) and reticular cells
488
What is the function of a lymph node
Lymph filtration and phagocytosis of foreign material from lymph
Facilitate the interaction of the APC and circulating lymphocytes
Regional activation of T and B cells and specific immune response
489
Cortex of lymph node
Contains lymphatic nodules often with germinal centers if B cells are activated. B cells predominate in cortex and it is where they are activated and site of humoral immune response
490
Paracortex of lymph node
Refers to region of cells located btwn Cortes and medulla. Predominant cell type I T cells. This is the sire of antigen presentation to t helper and cytotoxic cells. Site of cell mediated immune response
491
Medullary cords of lymph node
Organized as cluster of cells and CT. Predominate cell is antibody secreting plasma cells and memory B cells, macrophages,activated T cells. Antibodies enter blood and lymph from plasma cells. T and B cells enter medullary sinuses and exit efferent lymph vessel
492
Path of lymph drainage through node
Afferent lymph vessel—>subcapsular sinus—>cortical sinus—>medullary sinus—>efferent lymph vessels
493
What brings in new lymphocytes to lymph nodes
Post-capillary venule (HEV)
494
Where are HEV’s located in the lymph nodes
Paracortex
495
Functions of spleen
Filters blood to remove cellular waste, debris, antigen. Adaptive immune response to blood born antigen.
496
Function regions of the spleen
White pulp—lymphatic nodules scattered randomly
Red pulp—site of senescent RBC break down and recycling of iron for RBC synthesis in bone marrow
497
Surface appearance of spleen
Convex surface covere with visceral peritoneum and underlying CT
Concave surface called Hilum where vessels enter and exit
Capsule of DICT extends into underlying tissue
Stroma which is LCT made of reticular fibers
498
What comprises the bulk of the spleen
Red pulp
499
Marginal zone of spleen
Boundary b/w white and red pulp. Contains BV’s/sinus and aggregation of lymphocytes, macrophages, dendritic cells
500
Trabeculae of spleen
CT invaginating from capsule into organ; conveys BV’s
501
Type of cells in white pulp
Macrophages, t helper, B, plasma
502
Key feature of white pulp
A central arteriole
503
What cells predominate in lymphatic nodules in white pulp of spleen
B cells
504
Where is the primary site of IgM production in the body
White pulp of spleen
505
Where is the site of antigen presentation to T and B cells in the spleen
Marginal zone.
506
Marginal zone is the site of …
Antigen presentation of T cell to B cell, site of cell mediated response, site of naive and memory cell lymphocyte entry
507
Principle function of red pulp
Blood filtration
508
Two regions of red pulp
Splenic cords and splenic sinuses
509
Splenic cords
Clusters of cells organized as cords surrounded by vascular sinusoids. Traps damaged erythrocytes and platelets. Macrophages phagocytose worn out cells
510
Splenic sinuses
Linden with discontinuous BM and Fenestrated endothelial cells. Site of platelet and RBC breakdown by the macrophages
511
Hb breakdown
Done in splenic sinuses and broken down into;
Iron—retrieved stored as ferritin transported to liver
Heme—broken down to bilirubin, transported to live, conjugated and excreted as bile
512
Path of antigen in blood flow of spleen
Splenic artery—> trabecular artery—>central arteriole—>penicillar arteriole—>sheathed capillary with two routes to empty;
Open circulation—empties to sinusoid surrounding splenic artery
Closed circulation —sheathed empties directly into venous sinusoids
