digestive system Flashcards
1
Q
muscosa
A
simple columnar epithelium
mucus
found in stomach
2
Q
mucous
A
secreted by goblet cells
protects digestive organs
eases food passage
3
Q
lamina propria
A
loose areolar CT
contains capillaries for nourishment and absorption
lymphoid follicles (MALT) that defend against microorganisms
4
Q
muscularis mucosae
A
SM
aids in local movements of mucosa
5
Q
submucosa
A
loose areolar CT
contains blood, lymphatic vessels, lymphoid follicles, submucosal nerve plexus
6
Q
serosa
A
part of visceral peritoneum
loose areolar CT covered w/ mesothelium in most digestive organs
replaced w/ fibrous adventitia in esophagus
7
Q
peristalsis
A
adjacent segments of the alimentary tract organs which alternately constrict and relax moving food along the tract distally
occurs in esophagus, stomach, small intestine, and large intestine
initiated by rise in hormone motilin in late intestinal phase
8
Q
segmentation
A
nonadjacent segments of alimentary tract organs which alternatively contract and relax moving food forward then backward;
food mixing and slow food propulsion
occurs in small intestine
parasympathetic NS increases while sympathetic decreases
9
Q
long ANS fibers
A
synapse w/ enteric plexus
control digestion by either sympathetic or parasympathetic stimulation
10
Q
sympathetic stimulation
A
inhibit digestive activities
decreases gastrin secretion
11
Q
parasympathetic stimulation
A
stimulate digestive activities
increases gastrin secretion
12
Q
short ANS fibers
A
synapse w/ submucosal nerve plexus and myenteric nerve plexus
13
Q
submucosal nerve plexus
A
regulate glands and SM in the mucosa
14
Q
myenteric nerve plexus
A
controls GI tract motility
15
Q
buccal cavity
A
oral mucosa (stratified squamous epithelium)
teeth
salivary glands
tongue
uvula
16
Q
salivary glands
A
produce saliva
parotid, submandibular, sublingual
17
Q
parotid gland
A
anterior to ear
external to masseter muscle
opens into oral vestibule next to the 2nd upper molar
serous
18
Q
submandibular gland
A
medial to body of mandible
opens at the base of the lingual frenulum
serous
18
Q
sublingual gland
A
anterior to submandibular gland under the tongue
opens via 10-12 ducts into the floor of the mouth
mucous
19
Q
saliva
A
97-99.5% of water
slightly acidic
consists of electrolytes, salivary amylase and lingual lipase, mucin, urea and uric acid, lysozyme, IgA, defensin
20
Q
crown
A
covered by enamel
21
Q
cement
A
calcified CT
covers root and attaches it to peridontal ligament
22
Q
peridontal ligament
A
forms gomphosis
23
Q
gingival sulcus
A
groove where the gums border the tooth
24
pulp cavity
surrounded by dentin
contains pulp embedded in root canal and extends to root
25
pulp
houses blood vessels and nerves
26
deciducus teeth
20
erupt 6-24 months of age
fall out b/w ages 6-12
27
permanent teeth
32
28
functions of saliva
moistening and lubricating
initiation of digestion
protection of oral tissues
buffering action
taste
oral hygiene
29
dentin
bone-like material under enamel
30
enamel
made up of hydroxyapatite
31
wisdom teeth
aka third molars
may erupt at ages 17-25, or may not erupt at all
32
functions of buccal cavity
mechanical digestion via chewing or mastication
initiation of digestion via amylase
taste
formation of bolus
initiation of swallowing
33
filiform
whitish
gives tongue roughness and provides friction
34
fungiform
reddish
scattered over tongue
contains taste buds
35
vallate
V-shaped row in the back of tongue
contains taste buds
36
foliate
on lateral aspects of posterior tongue
contains taste buds that are found primarily in infants and children
37
tongue
skeletal muscle
reposition and mix food while chewing
formation of bolus
initiation of swallowing, speech, and taste
38
hard palate
palatine bones and palatine processes of maxillae
slightly corrugated to help create friction against tongue
39
soft palate
formed mostly of skeletal muscle
closes off nasopharynx during swallowing
contain uvula
40
pharynx
stratified squamous epithelium and mucus producing glands
divided into oropharynx and laryngopharynx
allows the passage of food, fluids, and air
41
esophagus
stratified squamous epithelium and esophageal glands that secrete mucus
muscularis externa (skeletal-superior, mixed-middle, smooth-inferior)
adventita
42
deglutition
involves tongue, soft palate, pharynx, and esophagus
consists of buccal and pharyngeal-esophageal phase
43
buccal phase
voluntary contraction of tongue
44
pharyngeal-esophageal phase
involuntary stimulation due to the vagus nerve
control center in medulla and lower pons
45
stomach
4 tunics
greater and lesser curvature
greater and lesser omentum
muscularis externa (3 layers of SM and inner oblique layer)
mucosa composed of simple columnar epithelium with goblet cells
gastric pits that contain gastric glands (produce gastric juice)
mucosal barrier made up of bicarbonate-rich mucus and tight junctions
46
parietal glands
secrete HCl and IF
47
chief cells
secrete pepsinogen and lipases
48
enteroendocrine glands
secrete serotonin (inhibitory), histamine, somatostatin (inhibitory), and gastrin
49
functions of stomach
mechanical digestion
secretion of gastric juices
regulation of gastric emptying
50
inner oblique layer
allows stomach to churn, mix, move, and physically break down food
51
pepsinogen
digests proteins
inactive enzyme
activated to pepsin by HCl or pepsin itself
52
lipases
digests ~15% of lipids
53
cephalic phase
conditioned reflex triggered aroma, taste, sight, thought
54
gastric phase
lasts 3-4 hrs
2/3 gastric juice released
stimulated by low acidity, distension, peptides, gastrin
Ach, histamine, gastrin necessary for max HCl secretion
55
enteroendocrine G cells
stimulated by caffeine, peptides, increased pH
56
intestinal phase
when partially digested food enters SI, it triggered gastrin release
release inhibited via chyme, fats, peptides, and irritating substances
57
enterogastric reflex
inhibits vagal nuclei in medulla
inhibits local reflexes
activates symp fibers
inhibits gastrin secretion
58
enterogastrones
secretes secretin, CCK, VIP
inhibits gastrin secretion
59
emesis
caused by extreme stretching and intestinal irritants such as bacterial toxins, alcohol, spicy foods, drugs
chemical/sensory impulses stimulate the emetic center of the medulla
60
liver
4 lobes (right, left, caudate, quadrate)
falciform and round ligament
common, hepatic, cystic bile duct
lobules hexagonal in structure and composed of hepatocytes
central vein in longitundinal axis
portal triad at each corner of a lobule (hepatic artery, portal vein, bile duct)
liver sinusoids
stellate macrophages
61
falciform ligament
separates larger right lobes from smaller left lobes
suspends liver from diaphragm and anterior abdominal wall
62
common hepatic duct
leaves liver
63
cystic duct
connects to gallbladder
64
bile duct
formed by the union of common hepatic and cystic duct
65
hepatocytes
increased rough and smooth ER, golgi, peroxisomes, and mitochondria
filter and process nutrient-rich blood
produce bile
perform detoxification
store fat-soluble vitamins
66
stellate macrophages
kupffer cells
remove debris and old RBCs
67
liver sinusoids
leaky capillaries b/w hepatic plates
68
functions of liver
detoxification
production of bile
regulation of cholesterol levels
69
bile
composed of bile salts, bilirubin, cholesterol, triglycerides, phospholipid, electrolytes
stored in gallbladder
released into SI following food ingestion, hormonal stimulation (CCK, secretin, gastrin)
70
function of bile
emulsification of fats
facilitation of fat digestion and absorption
71
gallbladder
stores, concentrates (absorbs water and ion), and releases bile
72
circular folds
force chyme to slowly spiral through lumen of SI
increases nutrient absorption
73
villi
extensions of mucosa w/ capillary beds and lacteals for absorption in SI
74
microvilli
brush border
contains enzymes for carbs and protein digestion
75
intestinal crypts
house secretory cells that produce intestinal juice (enteroendocrine and paneth cells)
76
enteroendocrine cells
secrete enteroendogastrones
77
paneth cells
secrete defensins and lysozyme
78
duodenum
curves around head of pancreas
shortest part
79
jejunum
extends from the duodenum to the ileum
2.5 m long
80
ileum
joins the large intestine at the ileocecal valve
3.6 m long
81
functions of SI
absorption
nutrient transport
regulation of pH and digestive enzymes
immune functions
secretion of hormones
82
bile acid sequestrants
cholestryramine, colesevelam, colestipol
decreases cholesterol by binding to bile acids in the intestines, preventing reabsorption
increases excretion of bile acids and production of new bile
83
4 tunics of digestive organs
mucosa
submucosa
muscularis externa
serosa or adventitia
84
amylase
digest carbs
85
lacteals
found in villi of SI
nutrient absorption of dietary lipids
86
carb digestion
starch and disaccharides via salivary and pancreatic amylase in mouth (salivary glands) and pancreas
further broken down into monosaccharides via brush border enzymes in SI
glucose and galactose are absorbed via co-transport w/ Na+ ions
87
protein digestion
proteins broken down to large polypeptides via pepsin in stomach
large polypeptides broken down to small polypeptides and peptides via pancreatic enzymes in pancreas
further broken down to AA's via brush border enzymes in SI
AA are absorbed in intestinal cells via co-transport w/ Na+ ions
some dipeptides and tripeptides are absorbed via cotransport w/ H+ and hydrolyzed to AA within cells
infrequently, transcytosis of small peptides occurs
88
lipid digestion
unemulsified triglycerides broken down into monoglycerides via lingual lipase in the mouth (tongue), gastric lipase in the stomach, pancreatic lipase in the pancreas, and bile in the liver
fatty acids and monoglycerides enter the intestinal cells via diffusion
89
nucleic acid digestion
pancreatic ribonuclease and deoxyribose->nucleotide monomers in SI
brush border enzyme nucleosidases and phosphatases-> free bases, pentose sugars, phosphate ions in SI
units enter intestinal cells by AT via membrane carriers
90
nutrient absorption
all absorbed into capillary blood in the villi of SI and transported to the liver via the hepatic portal vein
absorbed via FD for carbs and proteins.
91
pancreas
endocrine cells consist of pancreatic islets that secrete insulin and glucagon
exocrine cells consist of acini that secrete pancreatic juice
secretes pancreatic amylase, lipase, and nuclease
92
pancreatic juice
watery, alkaline solution
neutralized chyme
pH of 8
consists of electrolytes and enzymes (amylase, lipase, protease)
93
protease
secreted in inactive form
activated in duodenum w many other enzymes such as trypsinogen, procarboxypeptidase, and chymotrypsinogen
94
CCK
induces the secretion of enzyme-rich pancreatic juice via acini
relaxes hepatopancreatic sphincter
95
secretin
causes the secretion of bi-carbonate rich pancreatic juice via duct cells
96
large intestine
simple columnar epithelium
abundant crypts w/ goblet cells
teniae coli
haustra
cecum
appendix
ascending, descending, transverse, sigmoid colon
rectum
anal canal
internal and external anal spincters
97
anal canal
stratified squamous epithelium (withstands abrasion)
98
functions of large intestine
absorption of water and electrolytes
formation and storage of feces
synthesis of vitamins (vitamin K)
immune functions (MALT)
peristalsis
fermentation of indigestible carbs
release of gases and fecal matter
99
feces
composed of undigested material (fiber and cellulose), water, bacteria, dead cells, mucus, stercobilin
formed by the gradual accumulation and processing of waste material in the large intestine
stored in rectum until defecation occurs
100
defecation
1. distention of rectum initials spinal defecation reflex
2. parasympathetic NS is activated and stimulates the contraction of the sigmoid colon and rectum, as well as relaxes the internal anal sphincter
3. concious control allows relaxation of the external anal sphincter
4. feces is expelled from anus
101
trypsinogen
activated to trypsin via enteropeptidase
102
trypsin
activates procarboxypeptidase and chymotrypsinogen
103
illeocecal sphincter
relaxes and admits chyme into large intestine when gastroileal reflex enhances force of segmentation in ileum and gastrin increases motility of ileum
104
internal anal sphincter
smooth muscle
105
external anal sphincter
skeletal muscle
106
gastrocolic reflex
initiates mass movement in the LI
107
osmosis
used to absorb water from the intestine
108
hepatopancreatic sphincter
regulates flow of bile from the liver and pancreatic juice from the pancreas into the duodenum of the SI
109
gastroileal reflex
movement of food from the stomach to the SI
110
emulsification
bile salts in bile interact with the fat molecules, breaking them down into smaller droplets
increases the SA of the fat, making it easier for digestive enzymes called lipases to access and break down the fats into fatty acids and glycerol, which can then be absorbed by the small intestine
111
micelles
composed of bile salts, phospholipids, cholesterol, fatty acids
formed in SI during lipid digestion and absorption (dietary fats and fat-soluble vitamins)
transport lipids across intestinal epithelial cells for absorption
