digestive Flashcards
(126 cards)
1
Q
What layerof the GI tract is the serosa and what is its prupose?
A
outer tough connective tissue membrane for protection
2
Q
What does the muscularis extrena of the GI tract do?
A
longitudinal and circular muscle layers for contraction
3
Q
What is the submucosa?
A
Loose connective tissue, blood vessels and glands for secretion
4
Q
What are the three layers of the GI tract mucosa?
A
muscularis mucosa (interna), lamina propria made of loose connective tissue, epithelium lining
5
Q
What is the function of the mucosa layers?
A
function for digestion and absorption of nutrients
6
Q
What are the two nerve networks in the enteric nervous system?
A
myenteric plexus (Auerbach) and submucosal plexus (Meissner)
7
Q
Where is the myenteric plexus located?
A
neuron net between circular and longitiudinal muscle layers
8
Q
What is the function of the myenteric plexus?
A
contorls contraction of muscularis extrena & controls peristalsis, segmentation, haustration and mass movement
9
Q
Where is the submucosal plexus located?
A
scattered neurons in the submucosal layer
10
Q
What does the submucosal plexus do?
A
controls contractions of muscularis mucosa (interna) & controls glandular secretion of mucosa
11
Q
What controls GI secretions and contractions throughout the gut wall?
A
enteric nervous system reflexes
12
Q
What do the prevertebral sympathetic gangflia reflexes do?
A
transmit signals between GI sections such as gastrocolic, enterogastric and colonoileal
13
Q
What is the name of the reflexes that respond to pain and defecation?
A
spinal cord and brain stem reflexes
14
Q
What is the law of the gut?
A
peristalsis
15
Q
What is peristalsis?
A
The GI basic propulsive movement in which a contractile ring moves towards the anus with downstream receptive relaxation
16
Q
What is mixing?
A
Local intermittent constrictive waves of regular contractions for chopping and mixing the food.
17
Q
What is segmentation?
A
Concentric contractions that divide the small intestine into small segments
18
Q
What is haustration?
A
Concentric contractions that divide the large intestine into small haustral segments
19
Q
What is mass movement?
A
Propulsive contractions that move fecal matter along the large intestine.
20
Q
In splanchnic circulation; where do the arterial branches come from?
A
from the abdominal aorta
21
Q
What are the three branches of the celiac trunk and where do they go?
A
hepatic artery proper to the liver, left gastric artery to the stomach and splenic artery to the spleen
22
Q
Where does the superior mesenteric artery go?
A
small intestine, ascending colon, tansverse colon
23
Q
Where does the inferior mesenteric artery go?
A
descending colon, sigmoid colon and rectum
24
Q
What does the hepatic portal system consist of?
A
superior mesentric vein, gastic veins, inferior mesenteric vein and the splenic vein
25
What do the liver reticuloendothelial and hepatic cells do?
remove bacteria, detoxify chemicals and absorb nutrients from the venous blood
26
Where does the hepatic vein drain all the venous blood?
inferior vena cava
27
What does the oral cavity consist of?
Cheeks and lips, tongue, and hard and soft palate
28
What is the space between the cheeks and teeth called?
vestibule
29
What do the hard and soft palate do?
Allow breathing and cewing at the same time
30
What are the palatoglossal and palatopharyngeal arches?
names of the hard and soft palate
31
What 2 msucles elevate the teeth to crush food?
masseter and temporalis
32
What 2 muscles swing teeth in side-to-side grinding action of molars?
medial and lateril pterygoids
33
What 2 types of enzymes does saliva include?
salivary amylase and lingual lipase
34
What immunoglobulin inhibits bacterial growth in the saliva?
immunoglobulin A
35
What breaks starch down into disaccharides?
salivary amylase which is secreted by salivary glands
36
What is the only part of swallowing that is under concious control?
buccal phase
37
What does the pharyngeal pahse consist of?
soft palate closes nasopharynx & epiglottis closes larynx, food bolus pass from oropharynx into laryngopharynx
38
When can choking occur?
if foood bolus got stuck in the laryngopharynx
39
What occurs during the esophageal phase?
the upper esophageal sphincter open, peristalsis propels food bolus down the esophagus toward the sotamch, lower esophageal sphincter opens and food bolus enters stomach
40
In the stomach; what begins protein digestion?
pepsin
41
In th estomach; what begins fat digestion?
activated lingual lipase
42
What secretes the proctective mucous of the gastric glands?
mucous neck cells
43
What part of the gastric gland ssecrete HCl and IF?
parietal cells
44
What do the chief cells secrete?
pesinogen, gastric lipase and chymocin
45
What do entroendocrine cells secrete?
gastric hormones
46
What is the bottom most layer of the gastric glands?
where regenrative cells produce new cells
47
What does HCl do?
activates pepsin and lingual lipase, break connective tissue and plant cell walls, liquefies food to form chyme, convert ingested ferric ions to ferrous ions for absorption an duse in hemoglobin synthesis, destroys ingested bacteria and pathogens
48
What is intrinsic factor needed for?
B12 absorption by small intestine & is necessary for RBCs production and maturation
49
What does gastric lipase produced by cheif cells do?
digest fat- specifically butter fat of milk in infants
50
Chymosin
curdles milk by coagulation proteins
51
What is pepsin secreted as? What converts it to active pepsin?
secreted as inactive pepsinogen zymogens
| HCl converts it to active pepsin
52
What nerve stimulates gastric secretion even before food is swallowed?
the vagus nerve
53
Food stetches the stomach and activates ____ and _____ reflexes
myenteric and vagovagal
54
What is the small intestine covered with?
lined with villi, covered with a simple columnaer mucous membrane
55
What is the single lymph capillary in the small intestine called?
a lacteal which absorbs most fat
56
What are the 3 function fo the small intestine?
mechanical digestion, chemical digestiona dn absorption of most substances
57
What are the 6 gastrointestinal hormones?
- gastrin- stimulates gastric acid secretion and mucousal growth
- cholecystokinin- stimulates pancreatic enymes and bicarb secretions, stim gallbladder contractions and gastric emptying
- secretin- stim pepsin and bicard secretion, inhibits gastric emptying
- gastric inhibitory peptide- stim insulin secretion, inhib gastric acid secretion
- motilin- stim gastric and intestinal motility
58
What cells are the 6 gastrointestinal hormones secreted from?
```
gastrin- G cells
cholecystokinin- I cells
secretin- S cells
gastric inhibitory peptide- K cells
motilin- M cells
```
59
What are acinar cells?
exocrine cells that secrete digestive enzymes into ducts
60
What cells secrete bicarbonates and what do the bicarbonates do?
duct cells
| bicarb buffers the acidic chyme from stomach and raise its pH from 2-3 to 7-8
61
Where is cholecystokinin (CCK) released from and in response to what?
released from duodenum in response to arrival of acid and fat
62
What does cholecystokinin do?
causes contraction of gallbladder, secretion of the acinar cells pancreatic enzymes and relaxtion of the hepatopancreatic sphincter (sphincter of Oddi)
63
Where is secretin released from?
released from duodenum in presonse to the presence of acidic chyme
64
What does secretin stimulate?
stimulates all ductal cells to secrete more bicarbonate
65
Where is gastrin released from?
stomach and duodenum
66
What does gastrin do?
weakly stimulates gallbladder contraction and pancreatic enzyme secretion
67
What are enzymes secreted as?
inactive zymogens
68
trypsinogen activated to trypsin by ____ enzyme from duodenum epithelium cells.
entrokinase
69
chemotrypsinogen activated to ____ by the _____ enzyme
chemotrypsin
| trypsin
70
procarboxypeptidase activated by the _____ enzyme to _______
trypsin
| carboxypeptidase
71
What are remaining starch digested into after protein digestion and how?
remaining starch is digested in intestine by pancreatic amylase into disaccharides
72
What are triglycerides digested by?
digested in the small intestine by pancreatic lipase
73
What does the digestion of a triglyceride yield?
a monoglyceride molecule and two fatty acid molecules
74
What is required from the gallbladder for lipase to digest fat more efficiently?
Bile
75
What is biles pathway?
hepatocytes secrete bile
bile flows from the liver through hepatic ducts into the gallbladder
bile flows from gallbladder down the bile duct into duodenum to mix with and emulsify the fat
76
What stores and concentrates bile?
gallbladder
77
What forms the common bile duct?
common hepatic duct and cystic duct from gallbladder unite
78
Before bile and pancreatic juices can enter the duodenum; what occurs?
common bile ducts unites with pancreatic duct
79
What are the functions of the liver?
(1) Carbohydrate, lipid and protein metabolism
(2) Removal of waste products & detoxification
(3) Storage of glycogen, vitamins and iron
(4) Phagocytosis by Kupffer cells
(5) Activation of vitamin D to Calcidiol
(6) Bile synthesis and secretion
(7) Plasma proteins synthesis
80
Where are brush border enzymes located?
on microvilli of intestinal absorptive cells
81
What do peptidases digest?
peptides to amino acids
82
What do intestinal lipases digest?
fats to glycerol & fatty acids
83
What do disaccharidases digest?
digest disaccharides to monosaccharides
84
What disaccharidase and resulting monosacchrides of sucrose?
sucrase
| results in glucose and fructose
85
What disaccharidase and resulting monosacchrides of maltose?
maltase
| results in glucose and glucose
86
What disaccharidase and resulting monosacchrides of lactose?
lactase
| results in glucose and galactose
87
How are DNA and RNA absorbed in the small intestine?
hydrolyzed by nucleases to nucleotides
nucleosidases and phosphatases of brush border split them into phosphate ions, ribose or deoxyribose sugar and nitogenous bases then absorbed
88
How are vitamins absorbed in the small intestine?
unchanged
A, D, E and K with other lipids
B complex and C by simple diffusion and B12 bound to intrinsic factor
89
How are mineral absorbed in the small intestine?
absorbed all along the small intestine
- sodium co-transported w sugars and amino acids
- Cl- exchanged for bicarb
- iron and calcium absorbed as needed
90
What type of epithelia cells line the large intestine?
simple columnar mucosa
91
What are 4 function of large intestine?
(1) Feces formation
(2) Limited digestion of undigested food by bacteria
(3) Formation of vitamin K and some B vitamins by bacteria
(4) Absorption of some water, electrolytes, vitamins and bile salts
92
How much water does the digestive tract receive a day? How much water is absorbed in the small intestine and the large intestine?
9 L/day
small intestine: 8 L/day
large intestine: 0.8 L/day
93
How is water absorbed?
by osmosis following the absorption of salts and organic nutrients
94
When does diarrhea occur?
when too little water is absorbed
- feces pass thru too quickly if GI is irritated
- feces contain high conc. of an unabsorbed solute such as lactose or chloride
95
What is constipation caused by?
poor motility causes greater absorption and hardens feces in transverse colon
96
What does feces consist of?
water, bacteria, undigested fiber, mucus, fat and sloughed epithelial cells
97
What are haustral contractions stimulated by?
distention
98
When does mass movement occur and what triggers it?
1 to 3 times a day
| triggered by gastrocolic and duodenocolic reflexes from stomach and duodenum filling
99
Is made of smooth muscle fibers, relaxed by parasympathetic pelvic nerve stimulation, constricted by sympathetic hypogastric nerve stimulate.. what am I?
internal anal sphincter
100
Is made of skeletal muscle fibers, innervated by the pudendal nerve, and under voluntary conscious control... what am I?
external anal sphincter
101
What does an intrinsic reflex do?
activates mass movement that fill the rectum and stimulate rectal stretch receptors
102
What does a spinal cord reflex do?
cause contraction of the rectum and relaxtion of the internal anal sphincter via parasympathetic pelvic nerve signals
103
What does a pudendal nerve reflex do?
causes concious voluntary relaxtion of the external sphincter and defecation
104
What is esophagitis?
inflammation of esophageal mucosa
105
What is dysphagia?
difficulty swalling caused by any esophageal obstructions or paralysis
106
What is paralysis of the swallowing mechanism caused by?
muscle dystrophy, myasthenia gravis or diseases that damage the swallowing center
107
What is achalasia?
failure of relaxation of the lower esophageal sphincter during swallowing due to myenteric plexus damage
108
In achalasia, food accumulation occurs above the sphincter, what is this called?
megaesophagus
109
What is gastritis?
inflammation of the gastric mucosa due to gastric barrier damage
110
What is achlorhydria?
complete failure of hydrochloric acid secretion by the gastric glands
111
What is pernicious anemia?
intrinsic factor deficiency due to chronic gastritis
112
What is a peptic ulcer?
excoriated areas of GI mucosa caused by the digestive action of gastric secretions
113
What is the small intestine abnormal digestion disorder caused by?
can be caused by failure of secretion of pancreatic enzymes due to pancreatitis or pancreatic duct block
114
What is the small intestine disorder tropical sprue?
malabsorption due to bacterial inflammation of the intestinal mucosa
115
What is the small intestine disorder nontropical sprue?
malabsorption caused by the toxic effect of gluten as in celiac disease and gluten--sensitive enteropathy
116
What is Hirschsprung's disease? (large intestine)
lack of ganglion cells int he myenteric plexus causes absence of the defecation reflexes and fecal accumulation in the sigmoid colon forming a megacolon
117
What is infectious diarrhea in the large intestine?
caused by viral or bacterial enteritis infections int he large intestine
118
What is psychogenic diarrhea in the large intestine?
caused by excessive stimulation of the parasympathetic nervous ssytem during periods of high nervous tension
119
What is ulcerative colitis in the large intestine?
extensive ulceration of the large intestine mucosa caused by allergic or immune destruction leading to severe diarrhea
120
What is paralysis of defecation?
can be caused by destruction of the conus medullaris nucleus in spinal cord injuries
121
What is nausea?
subconscious excitation of the vomiting center by irritative impulses fromt he GI tract, lower brain or cerebral cortex
122
What is vomiting used for?
the means by which the upper GI tract gets rid of its content
can be initiated by irritative impulses to the vomiting center or the chemoreceptor trigger zone
123
What is ascites?
accumulation of fluid and protein in the abdominal cavity due to decreased pplasma proteins or high protal capillary pressure
124
What can be causes for obstructions in the GI tract?
due to cancer, fibrotic adhesions or paralysis
125
What is flatus?
gases accumulation in the GI tract from swallowed nitrogen in the air or bacterial action in the large intestine generaitng hydrogen, methane, hydrogen sulfide, indole and skatole
126
What are 5 causes of ulcers in the stomach?
- high acid and peptic content
- irritation
- poor blood supply
- poor secretion of mucus
- infection, H. pylori
