Lecture 2 - Histology 1 (Baekey) Flashcards
1
Q
what are the 3 different layers of lips within the oral cavity?
A
- mucosa
- submucosa
- core
2
Q
what cell type is found within the mucosa of the lips?
A
stratified squamous epithelium (keratinized in herbivores not carnivores)
3
Q
what type of tissue do you find within the core layer of the lips?
A
fibroelastic connective tissue and skeletal muscle
4
Q
what does the primary palate form from?
A
caudal growth of the medial palatal process
5
Q
what does the secondary palate form from?
A
lateral palatal processes that elevate and grow medially and use in the center with the primary palate and nasal septum
6
Q
in what species do you most commonly see a cleft palate? what is it caused by?
A
brachycephalic dogs, Abyssinian cats
can be caused by ingestion of lupine (wildflowers) by pregnant sheep or cattle
7
Q
what layers do you see within the hard palate
A
- mucosa - keratinized stratified squamous epithelium
2. lamina propria - extensive vascular beds for heat exchange
8
Q
what is the function of the soft palate?
A
divides oropharynx and nasopharynx
9
Q
what is on the dorsal and ventral surface of the soft palate?
A
dorsal surface: nasopharynx w/ respiratory epithelium
ventral (oral) surface: keratinized stratified squamous epithelium
10
Q
what are the layers of the soft palate?
A
- lamina propria
2. core: fibrous connective tissue and skeletal muscle
11
Q
what cell types do you find in the tongue?
A
stratified squamous epithelium covering a core of skeletal muscle
12
Q
what are the 5 different tyeps of papillae?
A
- filiform
- conical
- fungiform
- foliate
- vallate (circumvallate)
13
Q
what characteristics about filiform papillae are significant?
A
its keratinized (especially in cats) and in rows
14
Q
what characteristics about conical papillae are significant?
A
keratinized; located on dorsal surface of root
15
Q
what characteristics about fungiform papillae are significant?
A
gustatory (taste buds), scattered
16
Q
what characteristics about foliate papillae are significant?
A
taste buds, serous glands at base
17
Q
what characteristics about vallate (circumvallate) papillae are significant?
A
ringed by furrow; taste buds; serous glands at base
18
Q
what cell types do you find in taste buds?
A
gustatory cells
sustentacular cells
basal cells
nerve fibers
19
Q
location of tastes
A
sweet = tip of tongue
salt = tip
sour (acid) = sides
bitter = region of circumvallate papillae
20
Q
taste is mediated by what cranial nerves?
A
7, 9, and 10
21
Q
describe the development of teeth
A
- invagination of oral ectoderm forms dental lamina
- dental buds form at base of dental lamina
- dental buds differentiate into inverted cups called enamel organs, which produce deciduous teeth
22
Q
what is dental papilla derived from?
and what does it form?
A
dental papilla is derived from neural crest
forms from tooth dentin and pulp
23
Q
define eruption
A
occurs in each deciduous tooth as downward growth of root exerts pressure against alveolar bone, and the crown is forced upward to break through enamel organ and gingiva
24
Q
describe the development of permanent teeth
A
a second bud forms off of the dental lamina. the growing permanent tooth puts pressure on the root of the deciduous tooth, causing the root to be resorbed and the deciduous tooth to fall out
25
what is an example of ectopic teeth?
ear teeth in horses
26
what are the 3 cell types seen in teeth
1. ameloblasts
2. odontoblasts
3. cementoblasts
27
describe ameloblasts
apical processes (Tome's processes) secrete slightly mineralized rods; mineralization initiates in rods, forming enamel (the hardest substance in the body)
28
describe odontoblasts
neural crest origin
- deposit predentin at the dentinoenamel junction
- predentin is mineralized, forming dentin
- odontoblastic processes extend as odontoblasts retreat
29
describe cementoblasts
forms cementum which binds dentin to alveolar bone via peridontal ligaments
30
what are the two types of teeth?
1. brachydont
| 2. hypsodont
31
what are the four parts of a brachydont tooth?
1. crown
2. neck
3. root
4. pulp cavity
32
what is significant about the crown of a brachydont?
enamel covers dentin
| ameloblasts disintegrate at eruption
33
what is significant about the neck of a brachydont?
attachment to gum epithelium is weak, providing entry point for infection
34
what is significant about the root of a brachydont?
cementum covers dentin
| anchored to bone by fibrous bundles called periodontal ligaments
35
what is significant about the pulp cavity of a branchydont?
contains loose connective tissue, blood vessels, nerves
36
what animals have a hypsdont teeth
all horse teeth, ruminant cheek teeth, rodent incisors, pig canines
37
what are significant characteristics of a hypsdont teeth?
constantly erupting and growing
enamel organ breaks open before tooth erupts, cementum is then deposited on enamel and ameloblasts continue to make enamel
infundibulum provides additional enamel surface for chewing
38
what are the major salivary glands?
parotid, mandibular, sublingual, molar (cat), zygomatic (carnivores)
39
what is significant about adenomeres in salivary glands?
they are predominately serous
40
what is significant about myoepithelial cells in salivary glands?
they contract to express secretions
41
what cell types do you find within ducts of salivary glands
low cuboidal epithelum to stratified squamous epithelium
42
what is significant about striated ducts in salivary glands?
columnar epithelium
| striations are due to mitochondria and infoldings of basal membrane; these influence ionic and water content of saliva
43
what tunics lie within the esophagus?
1. mucosa - has 3 laminar sublayers
2. submucosa - has mixed glands and a submucosal nerve plexus
3. muscularis - inner circular, outer longitudinal and has a myenteric nerve plexus
44
what are the 3 layers within the mucosa of the esophagus?
1. lamina epithelialis - stratified squamous
2. lamina propria - contains many lymph nodes
3. lamina muscularis - increases in thickness caudally, exhibits longitudinal folds
45
what is the cell type of the muscularis tunic of the esophagus in various species?
dogs, ruminants = striated
pigs, horses, cats, humans - striated cranially, smooth caudally
birds - all smooth
46
where is the myenteric nerve plexus located within the muscularis tunic within the esophagus?
between the circular and longitudinal muscle layers
47
where are submucosal and myenteric plexuses found?
throughout the gut tube and constitute the enteric nervous system, derived from neural crest
48
what is the function of myenteric plexus?
gut motility
49
function of submucosal plexus
sensing the environment within the lumen, regulating gastrointestinal blood and lymph flow and controlling epithelial cell function
50
interstitial cells of Cajal
myoid cells of mesenchymal origin that are also found in these plexuses. they provide a pacemaker function to the peristaltic action of the enteric nervous system
51
how is healing in the esophagus?
poor; due to leakage, poor tissue strength and connective tissue support and segemented/marginal blood supply
52
what are the tunics of the glandular stomach
mucosa: gastric folds, gastric pits
epithelium
lamina propria: carnivores have stratum compactum and submucosal and myenteric nerve plexuses
53
name the 4 regions of the glandular stomach
1. esophageal = stratified squamous epithelium
2. cardiac = simple columnar, branched, coiled glands
3. fundic = simple columnar, longer tubular glands w/o branching
4. pyloric = similar to cardiac but with deeper gastric pits
54
where is the pyloric spincter located?
in tunica muscularis at gastroduodenal junction
55
mucosal lining cells
simple columnar surface epithelium expands and contracts depending upon degree of distension caused by fodo itnatek. these cells secrete a neutral mucus that lubricates and protects the stomach lining. the apical portion of these cells exhibits short microvilli.
56
what are the 4 epithelial cells of gastric glands
1. parietal cells - secretes HCl
2. mucous neck cells - located between the parietal cells; secrete acid mucous
3. chief (zymogen) cells - secrete gastric enzymes (pepsin)
4. enteroendocrine cells - secrete monoamine and peptide hormones into lamina propria and blood. upon stomach distension G cells secrete gastrin, which stimulates HCl release by parietal cells.
57
what is repair and replacement of the stomach like?
repair is excellent
gastric lining cells are replaced every 2 - 3 days
glandular cells are replaced every 5 - 7 days
58
name the parts of the compound forestomach
1. rumen
2. reticulum
3. omasum
4. abomasum
59
significance of reticulum
function: fermentation
- concial papillae (no smooth muscle)
core of tunica muscularis
60
significance of rumen
function: mechanical breakdown
has core of isolated smooth muscle made of laminal muscularis mucosa
- has secondary and tertiary papillae
61
significance of omasum
function: mechanical breakdown
- primary folds contain lamina muscularis
- secondary papillae present
62
significance of abomasum
same as glandular stomach
| - major chamber used at birth
63
what are some adaptations to increase absorptive and secretory surface
1. increased length
2. circular mucosal folds
3. glands
4. villi
5. microvilli
64
what are the regions of the small intestine (3)
1. duodenum: main site of submucosal glands
2. jejunum
3. ileum: peyer's patches are large lymph nodule aggregations
65
what are the 3 tunics located in the small intestine?
1. mucosa
2. submucosa
3. muscularis
66
what are the layers within the mucosa of the small intestine
1. lamina epithelium
2. lamina propria
3. lamina mucularis
67
what is located within the lamina propria located within the mucosa of the small intestine
- crypts of Lieberkuhn (mucosal glands)
- capillary network and lymph lacteals in villi
- stratum compactum in carnivore
68
what is significant about the lamina muscularis located within the mucosa of the small intestine
extends into villi and serves to pump lacteals and capillaries
69
what is contained within the submucosa of the small intestine
- submucosal glands in the duodenum secrete an alkaline fluid that neutralizes stomach acids
- submucosal nerve plexuses innervate the villi
70
what is located within the muscularis of the small intestine
inner circular and outer longitudinal layers
| - myenteric nerve plexus
71
what type of cells are found in both nerve plexuses (submucosal and myeneteric nerve plexus)
interstitial cells of Cajal - they are modified myoid cells of mesenchymal origin that interact with nerve terminals and serve as pacemakers for the contractile activity of the gut muscles
72
what is another name for submucosal nerve plexuses?
Meissner's nerve plexus
73
what is another name for myenteric nerve plexuses?
Auerback's nerve plexus
74
what cell types do you find wtihin the surface mucosa of the small intestine?
1. lining cells (enterocytes)
2. goblet cells
3. enteroendocrine cells
4. lymphocytes
75
what is the function of lining cells aka enterocytes? what do they look like?
terminal digestion of carbs and proteins and absorption
- they are columnar with apical microvilli densely packed into a brush border
76
what is the function of goblet cells
in surface mucosa they = secrete protective mucus
in intenstinal crypts of Lieberkuhn they - produce a glycoprotein mucus that lubricates and protects the surface of the epithelium
77
what do enteroendocrine cells secrete?
locally-acting hormones such as serotonin, glucagon, secretin, cholecystokinin
78
what do lymphocytes do within the surface mucosa of the small intestine?
migrate thru epithelium; more numerous caudally
79
what cell types do you find within the intestinal crpts of Lieberkuhn (straight tubular glands) within the small intestine
1. lining cells
2. goblet cells
3. enteroendocrine cells
4. paneth cells
5. basal stem cells
80
function of paneth cells
secrete enzymes; regulate microbial environment through secreted products
81
function of basal stem cells
retain mitotic activity and replace other cells
82
what is repair and replacement of the small intestine like?
good; stem cells in crypts replace other cells approx every 3 days
83
what are the functions of the large intestine
1. microbial activity; including fermentation in nonruminant herbivores
2. absorption of water, vitamins and electrolytes
3. secretion of lubricating mucus
84
histological features of large intestine
1. larger lumen than small intestine
2. villi not prominent
3. longitudinal folds instead of plicae circulares
4. diffuse and nodular lymphatic tissue
5. submucosal and myenteric nerve plexus
85
4 regions of the large intestine
1. cecum
2. colon
3. rectum
4. anus
86
features of cecum
have longitudinal folds called taeniae ceci (in pigs and horses)
87
features of colon
contain taeniae coli (pigs and horses)
- have longitudinal bands of smooth muscle
- have crypts of Lieberkuhn
88
features of rectum
thicker tunica muscularis than colon
| - tunica adventitia present
89
features of anus
columnar epithelium of rectum gives way to stratified squamous eptihelium of anus
- glands are prominent on anal side of recto-anal junction.
- at ano-cutaneous junction epithelium becomes keratinized in some species
90
repair and replacement of large intestine
replacement similar to small intestine
| - repair is less successful because of foreign material, bacteria and inadequate blood supply, leakage is common
91
what are the functions of hepatocytes
1. synthesize sugars, plasma proteins, clotting factors, lipids, urea, etc.
2. secrete bile salts, bile acids
3. excrete bile pigments
4. store lipids, vitamines, glycogen
5. transofrm toxins, drugs, hormones
6. metabolize lipids, proteins, carbs
7. hematopoesis occurs during fetal development
92
hepatic lobule
plates of parenchyma delimited by interlobular connective tissue
- sinusoids
- has central vein in center
93
sinusoids
- sandwiched between plates
- fenestrated
- hae no basal lamina
- endothelium is surrounded by hepatocyte microvilli
94
biliary system of flow is:
1. bile canaliculi
2. biliary ductules
3. interlobular bile duct
4. intrahepatic duct
5. hepatic duct
95
what is the flow from the hepatic duct to the gall bladder?
hepatic duct --> cystic duct --> gall bladder
96
what is the flow from the hepatic duct tot he duodenum?
hepatic duct --> bile duct --> duodenum
97
what makes of the portal triad in interlobular connective tissue?
1. interlobular bile duct
2. hepatic artery
3. hepatic portal vein
98
what makes up hepatic vasculature
1. hepatic artery
2. hepatic portal vein
3. von kupffer cells
4. central vein
99
what is the space of Disse?
it separates hepatocytes from endothelial cells and drains to portal lymphatic vessels
100
what are von kupffer cells
they line sinusoids within the liver along the endothelial cells. they are macrophage-like and phagocytose erythrocytes
101
what does the central vein do?
drain sinsuoids
102
which animals lack a gall bladder?
horse and rat
103
what are the tunics within the gall bladder
mucosa - simple columnar epithelium, folds when empty
| muscularis - smooth muscle
104
cell types in exocrine pancreas
1. serous acinar cells - secrete zyogmen granules containing enzymes
2. centroacinar cells - line acinus
3. cuboidal epithelium lines intralobular and interlobular secretory ducts
4. larger ducts may contain goblet cells or mucous glands
105
cell type of the avian esophagus and crop
made up of keratinized stratified squamous epithelium
106
what is the function of the crop
an esophageal diverticulum that serves as a storage organ. the lamina epithelialis produces crop milk which moistens food and is diagnostically useful
107
layers of the proventreniculus (glandular stomach)
mucosa - grooves (sulci); mucosal (rugosal) glands open into bases of the sulci
submucosa - glands open into excretory duct leading to papilla
108
layers of the ventriculus (gizzard)
mucosa - koilin, cornified secretory product
| muscularis - smooth muscle and dense white fibrous connective tissue
