Digestive System Flashcards
1
Q
Define Digestion, alimentary and gastrointestinal track
A
- Mechanical & physical breakdown of food, followed by its absorption.
- Alimentary = GI tract = all of the organs in the tube mouth to anus, about 30 feet
2
Q
Briefly describe the overall 5 steps of the digestion process
A
-Ingestion, movement, digestion, absorption, defecation
3
Q
List the organs of the GI track
A
- Oral cavity
- pharynx
- esophagus
- stomach
- small intestine
- large intestine
4
Q
List the digestive accessory organs
A
- Salivary glands
- teeth
- tongue
- pancreas
- liver
- gall bladder
5
Q
Describe the 4 layers of the GI track microstructure (in lumen)
A
- Mucosa- villi (surface area)
- Submucosa- very vascular
- Muscularis - mixes and mores food
- Serosa- visceral peritoneum-Surface connective tissue (watery)
6
Q
Define parietal and visceral peritoneum and peritoneal cavity.
A
- Parietal Peritoneum- (Shiny) lines abdominal wall
- visceral peritoneum- covers organs
- peritoneal cavity- space in between
7
Q
List and describe the location of the 5 peritoneal folds
A
Binds organs together, anchors them to body wall and suspends blood/lymph
- Mesentery proper- small intestine to posterior body wall
- mesocolon- large intestine to posterior body wall
- Falciform ligament - liver to anterior body wall
- lesser omentum (apron)- lesser curvature of stomach, duodenum to liver
- greater omentum- greater curve of stomach to posterior body wall
8
Q
Describe the boundaries of the oral cavity
A
- hard palate ( palatine process of maxilla/ palatine)
- Soft Palate (uvula)
- tongue
- cheeks
9
Q
Describe the labial frenulum, lingual frenulum, bolus, and papillae.
A
- Labial frenulum from inner lips to gums
- lingual frenulum from lower tongue to floor of mouth
- bolus is ball of food ready to swallow
- papillae are bumps on tongue including taste buds
10
Q
Describe the tissue that comprises the tongue
A
-Skeletal muscle and mucos membrane
11
Q
-Describe the location of the 4 main taste zones
A
- sweet- tip
- salt- behind sweet
- bitter- back
- sour-side
12
Q
Name the 3 pairs of salivary glands
A
- Parotid
- submandibular
- sublingual
13
Q
Describe the function, composition, and secretion control of the saliva
A
- Lubricate & moisten food
- kill bacteria,
- mostly water plus lysozyme, amylase & mucins
- PNS & food & mouth irritation increase salivation
- SNS & fear & dehydration decrease salivation ( dentist will give a shot of atropine to stop digestive juices)
14
Q
Define gingiva
A
- gum of the root of the aveoli
15
Q
Describe the general structure of the tooth
A
- cementum- bone like covering root of tooth
- enamel-covers dentin on crown (hardest substance in body
- pulp cavity- BV, Nerve, Lymp in cavity in dentin
- dentin- bone like substance (bulk of tooth)
- crown-above
- root- below
- neck-at gum
- apical foramen- end of root canal for nerve and bv to enter/exit
- periodontal ligament- anchors tooth to socket
16
Q
Name the hardest substance of the tooth
A
-enamel
17
Q
Define the directional terms labial buccal lingual palatal occlusal
A
- labial- lips
- buccal- cheek
- lingual- tongue
- palatal- closest to palate
- occlusal- chewing surface
18
Q
How many temporary and how many adult teeth in a normal person
A
temp-20
adult- 32
19
Q
Describe ingestion, mastication, and deglutition
A
- Ingestion is eating
- mastication is chewing
- deglutition is swallowing
20
Q
Define Phayunx, esophageal hiatus, peristalsis, and esophageal sphincters
A
- Pharynx is throat
- esophageal hiatus is hole in diaphragm for esophagus to pass into abdominal cavity
- peristalsis is wavelike rippling contraction (do not rely on gravity for swallowing)
- esophagus has circular muscles at superior & inferior ends.
21
Q
describe the function of the esophagus
A
- transport food
22
Q
Describe the 4 areas and 2 curves of the stomach (J shaped)
A
- Cardiac region is where esophagus enters into stomach
- Fundus is storage pouch to the left of cardia
- body is majority of stomach,
- pylorus is inferior end of stomach
- Convex border is greater curvature
- concave border is lesser curvature
23
Q
Describe the location of the pyloric sphincter
A
-connects to duodenum (s. Intestine)
24
Q
Name the substances that comprise gastric juices; name the cells that produce them
A
- zymogenic cells make pepsinogen ( so we don’t break down our own stomach)
- activates pepsin and breaks down protein
- parietal cells make HCL (alkaline tide following a meal, only stomach can deal with such strong acid)
- protein breakdown, anti-microbial
- Mucus cells make mucus (protects stomach wall)
25
Name the hormone made by gastric cells
- gastrin
- increases secretions
- caffeine increases gastrin
- increases motility
26
Define chyme
-liquified food
27
Describe the mechanism of gastric motility
- Pacemaker cells cause waves of peristalsis from cardia to pylorus.
- If sphincter is closed, the chyme is pushed back towards the cardia and the process starts again.
28
Describe the stimulation controls of gastric motility
- Presence of food (eating, thinking about) stimulates motility.
- Gastrin, made by pylorus, stimulates motility.
- Certain foods can stimulate motility more than others. Caffeine stimulates gastrin release.
29
Describe the inhibitory controls of gastric motility
- Enterogastric reflex inhibits motility.
- A distended duodenum causes the release of
- GIP, cholecystokinin & secretin which inhibit gastric motility.
30
Describe the function of gastric mucus, hydrochloric acid and pepsinogen
- Mucus is so important because it protects the stomach lining from the powerful acid.
- HCl serves to inhibit microorganism growth & breakdown proteins.
- Pepsinogen is converted to an active pepsin in the acid environment which breaks down proteins.
31
Describe the stimulation mechanisms of gastric secretions
- Presence of food (eating, thinking about) stimulates gastric secretions.
- Gastrin, made by pylorus, stimulates motility.
- Certain foods can stimulate motility more than others. Caffeine stimulates gastrin release.
32
Describe inhibitory controls of gastric secretions
- -Enterogastric reflex inhibits gastric secretions.
- A distended duodenum causes the release of
- GIP, cholecystokinin & secretin which inhibit gastric motility.
33
Describe any absorption that occurs from the stomach
- very little
34
Describe the function of gastrin, secretin, cholecystokinin, and gastric inhibitory peptide
- Gastrin stimulates gastric motility & secretions & is released by stomach (pylorus) cells in response to distention.
- Secretin, cholecystokinin and gastric inhibitory peptide are released by the duodenum in response to distention & inhibit gastric motility & secretions.
35
Describe the location of the pancreas and pancreatic duct
-Pancreas is inferior to stomach and the duct travels from pancreas to the beginning of the duodenum
36
Describe the substances made by the pancreatic islet cells
- islets are the hormonal part of the pancreas
| - substances include insulin & glucagon
37
name the cell that makes pancreatic juice
-Acinar cells
38
Describe the composition of pancreatic juice
- Water
- Bicarbonate
- Amylase
- Lipase
- Proteases (carboxypolypeptidase, trypsin, chymotrypsin)
39
describe the function of trypin, chymotrypsin, carboxypeptidase, pancretic amylase, and pancreatic lipase
- Trypsin, chymotrypsin, and carboxypeptidase are proteins
- amylase breaks down carbohydrates (starch)
- lipase breaks down fat
40
Describe the neural and hormonal controls of pancreatic secretions
- Vagus nerve
- (PNS) stimulates secretions
- SNS inhibits it.
- Secretin, Cholecystokinin stimulates pancreatic secretions.
41
Define hepatocyte
-Liver cell
42
Describe the course of the common bile duct
-Liver has hepatic duct & gall bladder has cystic duct that join together forming the common bile duct which dumps into the beginning of the duodenum
43
Name the cells that make bile
-Hepatocyte
44
Describe the function of the gall bladder
-Stores bile
45
Describe the composition of bile
-Water, bile salts, bilirubin
46
Describe the purpose of bile salts and explain what is meant by enterohepatic circulation
- Bile salts Emulsify fat into smaller pieces so that they can be worked on by the lipases.
- The bile salts are recycled by being reabsorbed from the ileum, and returned to the liver to make more bile
47
describe some mechanisms to stimulate the rate of bile secretion
- Enterohepatic circulation stimulates bile secretion
- vagus nerve
- secretin & cholecystokinin
48
Breifly, list some function of the liver
- Make bile
- detoxify
- store nutrients, vitamins & poisons
- metabolic hub
- get rid of old blood cells
- makes blood proteins and clotting factors
49
name the 3 segments of the small intestine
-Duodenum, jejunum, ileum
50
Define Villi, microvilli and duodenal gland
- Villi are finger-like extensions of the intestinal mucosa which increase surface area available for absorption.
- Microvilli are small ones.
- Brunner's gland secrete mucus.
51
Define lacteal
- Intestinal lymph vessel to absorb large particles that cannot fit into blood capillaries,
- fats & proteins.
52
Describe segmentation and peristalsis
- Segmentation is the sedentary mixing of food in the small intestine
- Peristalsis is the ripple like movement of the small intestine
53
Define absorbtion, where does 90% of the absorbtion occure
- Broken-down food passes from intestinal lumen into lymph or blood vessels.
- Most occurs in small intestine.
54
Describe the absorbtion of carbohydrates in the intestine
-Carbohydrates are broken down from saliva & again in duodenum from pancreatic amylase. It absorbs by active transport into blood capillaries.
55
Define micelle and chylomicron
- Micelle- fat and bile salts
| - Chylomicron- break down with in epithelial cells
56
Describe the various anatomical regions of the large intestine
- Cecum & with appendix are closest to ileum. They are lower right abdomen.
- Then the colon ascends, transverses, descends and has a sigmoid (S shaped) turn before entering...
- the pelvic cavity at which point it becomes the rectum.
- The rectum opens at the anus which is a series of two sphincters.
57
Define haustra and taeniae coili
- Haustra are the pouches- that divide feces
| - Taeniae coli is the the muscle that runs along the large colon that forms the haustra
58
Describe the gastroileal reflex, haustral churning, mass peristalsis, and the defecation reflex.
- gastroileal reflex when the stomach is full of food, the ileum releases its contents into the LI.
- This causes mass peristalsis of the LI. A couple of times per day, a huge peristalsis occurs in LI forcing contents into rectum.
- stretching the wall of the rectum leading to the defecation reflex in which case the internal anal sphincter relaxes and the person has the urge to defecate.
- Haustral churning is contraction of the colon resulting in mixing & more importantly dividing the contents into smaller pieces in the haustra.
59
Explain why defecation can be voluntarily controlled
-External anal sphincter is voluntary skeletal muscle
60
Define Feces
-Solid waste
61
Describe the basic functions of the large intestine
- Form & store feces.
- Lubricate feces due to numerous goblet cell secretions.
- A speck of water absorption
- Vit B/K synthesis
62
Describe the products of goblet cells
-Mucus
63
Describe the breakdown of protein
-Proteins are broken down in stomach
-(HCl & Pepsin)
-pancreatic proteases(enzymes) in S. Intestine
-Trypsin & Chymotrypsin & Carboxypeptidase
Amino acids are absorbed into blood vessels.
64
Describe the breakdown of Lipids
- Lipids are
- emulsified by bile salts
- broken down by lipases forming a micelle. -Micelle passes through intestinal wall & further broken down & bile salts released for recycling forming a chylomicron which is absorbed into lacteal.
65
Describe the breakdown of Vitamines
-Vitamins ADEK are absorbed with lipids & Bs and C are absorbed with the water.
66
Describe the breakdown of water and electrolytes
-A tremendous amount of water is absorbed (9l/day) and electrolytes are absorbed too. Calcium ions require vitamin D for absorption. An electrolyte is a chemical that ionizes when in solution.
67
What are the hormones of digestion
- Gastrin
- made by the pylorus cells
- Increases gastric motility
- Increases gastric secretions
- Secretin
- Made by distended duodenal cells
- Decreases gastric motility and secretions
- Increases pancreatic juices release
- Increase bile secretion
- Cholecystokinin-
- Made by distended duodenal cells
- Decreases gastric motility and secretions
- Increases pancreatic juices release
- Increase bile secretion
- Increases gall bladder contractions
- GIP (Gastric inhibitory peptide)
- Made by distended duodenal cells
- decreases gastric motility and secretions
- promotes insulin release
68
Describe the breakdown of carbohydrates
- Salivary amylase (mouth)
- Pancreatic amylase (s Intestine)
- enzymes-lactoase, maltase... (S intestine)
