Digestive System
What keeps food in the stomach until its ready to advance into intestine? Where is it located?
Pyloric Sphincter Location: junction of stomach and small intestine
Which area of the stomach is site for digestion?
Pyloric region
What is pyloric stenosis? What age is this most common? What happens when one has pyloric stenosis? How is it corrected?
Pyloric sphincter is too tight and doesn't allow for food to leave the stomach. Occurs in infants the most Result... projectile vomitting after eating Corrected by surgical loosening of the pyloric sphincter.
What can the liver do if part of it is removed?
Regenerate
What do accessory organs do?
Release enzymes into small intestine
What does the hormone gastrin stimulate the release of during the gastric phase? How?
Releases H+ Positive feedback
All salivary glands secrete _________ which contains __________ for digestion.
Saliva Enzymes
When chyme reaches small intestine it causes the release of which intestinal enzymes?
Secretin CCK (cholecystokinin)
What is the entire surface of the stomach lined with? What does it contain that is responsbile for secreting bicarbonate rich mucous?
Simple columnar epithelium Goblet cells
What is another medical term for the small intestine?
Small bowel
Where does absorption mostly occur?
Small intestine
What kind of muscle is the esophagus made up of?
Smooth and Skeletal muscle
Why should pepsinogen remain inactive until it reaches mucous? When location is pepsinogen typically in its active form?
So it doesnt destroy Stomach
What keeps food from getting into your nose? How?
Soft palate --- automatically rises to block off the nasopharynx
What is the gallbladder's main job?
Store bile produced by the liver
Which salivary gland is underneathe the tongue and produces the least amount of saliva?
Sublingual gland
Which salivary gland is inferior to the posterior mandible, and produces 60-70% of saliva (the most out of the 3 glands)?
Submandibular gland
What does propulsion refer to?
Swallowing + Peristalsis
What system slows down GI mobility?
Sympathetic Nervous System
What structures are considered accessory digestive organs?
Teeth-Tongue-Salivary glands-Gallbladder-Liver-Pancreas-Spleen
What occurs when nutrients travel to the liver via the hepatic portal vein? What type of blood is being delivered?
The liver regulates blood glucose levels, amino acids, remove any poisons, and store certain vitamins Oxygen-poor, nutrient rich blood
The celiac phase and gastric phase of gastric juices/acids have what in common? What's the main difference between them?
They both release the same things: gastrin, histamine resulting in H+ release Main difference: location, gastric phase relies on positive feedback of the celiac phase to produce H+
What is the function of surface mucous cells?
They make mucous
What is the main function of the accessory digestive organs?
To ASSIST in digestion
What is the function of the neck of the tooth?
To connect the root (in the bone) to the crown (above the gums)
The large intestine includes which structures? (8)
Transverse colon, Descending colon, Ascending colon, Cecum, Sigmoid colon, Rectum, Vermiform appendix, Anal canal
Once nutrients are absorbed from the small intestine where do they travel?
Travel to the liver via the hepatic portal, and then to the heart.
What is periodontics? Example?
Treatment of abnomal conditions of the tissues surrounding the teeth Ex: gingivitis
What are some pancreatic proteases? Name active and inactive form.
Trypsinogen (inactive) - Trypsin Chymotrypsinogen (inactive)- Chymotrypsin Procarboxypeptidase (inactive)- Carboxypeptidase
What is the difference between trypsinogen and trypsin?
Trypsinogen is the inactive precursor enzyme Trypsin is the active enzyme - becomes active once reaches the duodenum
Describe where the stomach is located.
Upper left quadrant of the abdominal cavity Left of the liver Infront of the spleen
Anatomically where is the liver located?
Upper right quadrant of the abdomen
Why is vit b-12 neccessary to be absorbed and used? What occurs without it?
Used for erythropoesis (production of RBCs) Pernicious anemia occurs without it
what are the microscopic and finger-like projections in the mucosa of the small intestine called? What is the name for this?
Villi, Microvilli Brush border
The serosa is the __________ layer of the ______________.
Visceral Peritoneum
What is the membrane that covers the surface of the internal organs?
Visceral peritoneal membrane/peritoneum
Which peritoneum sometimes folds over on itself forming mesenteries? Give an example.
Visceral peritoneum Small intestine
What does chemical digestion refer to?
Work of digestive enzymes
What replaces the serosa in the esophagus?
adventitia (made up of CT)
What is tested in liver tests?
albumin, ALT, AST, bilirubin
What names does the digistive tract also go by?
alimentary canal GI tract
What is common about all 5 cell types of the stomach?
all simple columnar epithelial cells make up the mucosa layer of the stomach all involved in chemical digestion and protection
What does saliva contain?
amylase, antibodies, lysozyme (enzyme that kills bacteria)
What procedure is typically required for apendicitis (inflammation of the appendix)?
apendectomy
What is the function of the falciform ligament?
attaches liver to anterior abdominal wall
What is the lingual frenulum? What if youre born with a short lingual frenulum? What is the lingual frenulum's main function?
attachment to floor of mouth "tongue tied" cant speak as well due to limitations Anchors the tongue down so we dont choke on it
What is most of your tooth made of? What is dentin? what % calcium phosphate crystal is it made of?
dentin a bone-like material 70% Ca
What takes place in the digestive tract?
digestion
What is added to chyme? Where does chyme travel to ?
digestive juices from the stomach are added to chyme travels to the duodenum
Where are most foods absorbed? Where are most fats absorbed?
duodenum + jejunum ileum
What covers dentin? What % Ca is this dentin covering made up of?
enamel 95%
Where does peristalsis occur?
esophagus, stomach, small intestine, large intestine
Which nerves are responsible for taste?
facial (7th cranial nerve) + glossopharyngeal (9th cranial nerve)
What are epiploic appendages?
fat-filled pouches of visceral peritoneum that hang from surface of the large intestine
Which areas of the stomach are designated for storage?
fundus, body
The quadrate lobe of the liver is located near the what?
gallbladder
What do enteroendocrine cells produce? What is another function? Why is the production of these cells important?
gastrin and ghrelin hormones aids in gastric motility (contraction) gastrin is important because it stimulates secretion of HCL (from parietal cells) + pepsinogen (from chief cells) ghrelin is important because it stimulates the hypothalmus to increase appetite.
What is the inferolateral surface of the stomach known as?
greater curvature of the stomach
Which mesenteries are most prominent? What do they accumulate between their folds?
greater omentum lesser omentum *accumulate: ADIPOSE TISSUE between their folds
What stops/blocks gastric secretion?
high-acidity (HCL)
Where does the common bile duct empty?
into the duodenum
What are organs in the abdomen that are completely covered with visceral peritoneum referred to as?
intraperitoneal organs
What is another name for the inhibitory phase of the intestinal phase? What is it's main function?
"enterogastric reflex" Slows empyting of the stomach so that duodenum doesnt get swamped with too much food at the same time
What is the greater omentum called? Why is this?
"fatty apron" It has high adipose tissue content
Once bolus is mechanically mixed in the stomach via the ____________ ____________, it becomes what?
- gastric muscles - chyme
What does CCK do once released?
-enters blood and stimulates gallbladder to release bile into the duodenum - stimulates pancreatic enzymes to release into the duodenum
What does secretin do once released?
-enters blood and targets the pancreas to release HCO3 which neutralizes acid from the stomach that goes to the duodenum. -stimulates bile synthesis via hepatocytes
The pancreas is what % exocrine, what % endocrine? What is the function of exocrine, function of endocrine?
1% endocrine - secretes insulin + glucagon into blood 99% exocrine - produce digestive enzymes
Explain the 3 steps of defecation reflex
1. Distension/stretch of the rectal walls due to mass movement of feces stimulates stretch receptors which inturn send signals along afferent fibers to the spinal cord neurons 2. Spinal reflex initiated..parasympathetic motor fibers (efferent) stimulate the rectal walls to contract and the interal anal sphincter to relax 3. When its convenient to defecate, voluntary motor neurons are inhibited and allow external anal sphincter to relax so that feces may pass through.
What are the 3 main parts of the small intestine? State in its anatomical order. State in its length order from biggest to smallest.
1. Duodenum 2. Jejunum 3. Ileum Length from big to small: Ileum, duodenum, jejunum
The digestive system is broken down into what 6 phases?
1. Ingestion 2. Propulsion 3. Mechanical digestion 4. Chemical digestion 5. Absorption 6. Defecation
Histology of the alimentary canal contains 4 layers. Name these layers.
1. Mucosa 2. Submucosa 3. Muscularis (external muscle layer) 4. Serosa
What are the 3 main functions of the alimentary canal/ GI?
1. Take food into the body 2. Process food (breaks down+Absorbs) 3. Dispose of leftover waste
Stimulation of gastric juices (acids) happens in which 3 phrases?
1. celiac phase 2. gastric phase 3. intestinal phase (initial/excitatory, inhibitory)
What are the 2 functions of bile?
1. emulsifcation (break down large lipids in SI) 2. route of excretion of toxins from the liver to the SI
What are the 2 types of anal sphincters?
1. internal anal sphincter 2. external anal sphincter
What are the 4 macromolecules of blood?
1. lipids 2. carbs/sugar 3. protein 4. nucleic acid
What are the treatments for gallstones?
1. lithotripsy (makes stones smaller and easier to pass) 2. cholecystectomy 3. medications which dissolve them slowly
What are the 5 most important types of cells in the stomach?
1. surface mucous cells 2. mucous neck cells 3. chief cells (zymogenic cells) 4. Parietal cells 5. enteroendocrine cells (G cells)
What does the muscularis layer of the alimentary canal consist of?
2 layers of smooth muscle Myenteric nervous plexus
What is the teniae coli?
3 longitudinal bands of smooth muscle layers
Describe the peristalsis process of the stomach: What are the 3 steps of peristalsis in the stomach?
3 steps: propulsion, grinding, retropulsion Peristaltic waves make its way from fundus to the pylorous where most grinding happens near the pylorous, then the chyme is controlled into the duodenum by the pyloric valve..which also keeps substances IN the stomach.
How many lobes does the liver have? What are their names? Which ones are anterior/posterior.
4 (left, right, (anterior) caudate, quadrate (posterior))
How long after a meal for the stomach to completely empty?
4-6 hours depending on the fat content.
What is the volume of an empty stomach? What is the volume of a completely full stomach?
50ml 1 gallon/4liters
What % of lipids that are released into the duodenum are digested by pancreatic lipase?
90%
What is Mesocolon and what does it do?
A mesentery. Attaches parts of the large intestine to posterior abdominal wall
What is a hernia? Where is a common place for hernias to develop?
A protrusion of an organ through an opening, (opening usually caused by a site of weakness). Abdomen
What does the lesser omentum connect?
lesser curvature of stomach and duodenum to liver
What digestive enzymes do the exocrine glands of the pancreas produce?
lipase/amylase, trypsinogen, chymotrypsinogen, procarboxypeptidase, rnase, dnase
What are lipids, carbs/sugars, protein, and nucleic acid broken down into?
lipids-> triglycerides, carbs/sugars->glucose, protein->amino acids, nucleic acids->RNA?DNA
If any of these enzymes in the liver tests are found in the blood, what does that mean?
liver damage of some sort
What does the appendix contain?
lymphoid tissue
What makes Vit K? How is it absorbed?
Bacteria (mainly occurs in large intestine due to large amounts of bacteria). Absorbed through the large intestine wall
Where does the colon begin and end?
Begins: ileum (ileocecal valve) Ends: anus
Anatomically, where is the pancreas located?
Below the stomach tucked into the C shape of the duodenum.
Where is the myenteric plexus located?
Between the 2 layers of smooth muscle in the muscularis layer of the alimentary canal.
What is the mass of food and saliva mixed together and formed by the tongue called?
Bolus
When fatty food enters the duodenum, the g cells of the duodenal mucosa secrete what? What does the release of this hormone do?
CCK hormone (cholecystokinin) stimulates gallbladder contraction and release of bile when chyme is in the small intestine AND stimulates release of pancreatic enzymes.
What is the cecum? Where is it located? How is the appendix associated with the cecum?
Cecum is a sac right beneath the ileocecal valve. The appendix hangs from the cecum.
What is each root ensheathed with? What is it?
Cementum Bony tissues
What occurs during the initial/excitatory phase of the the intestinal phase?
Chyme reaches intestines and triggers G cells to release the hormone: intestinal gastrin Tells stomach to continue producing H+
The large intestine is also called the _________.
Colon
When the cystic duct and hepatic duct connect, what is this called?
Common bile duct
What is the function of the Jejunum?
Connects the duodenum to the ileum
What does the greater omentum do?
Covers most of the abdominal organs
How is bile drained from the gallbladder?
Cystic duct
What is the lower esophageal spincter made up of? Where is it located? What is another name for this sphincter?
make up: rounded smooth muscle located: junction of the esophagus and stomach AKA: cardiac sphincter
What is another term for chewing?
mastication
Where does mechanical digestion occur?
mouth (chewing), stomach (churning), small intestine (segmentation)
What is posterior to the nasal cavity?
nasopharynx
What are the 3 layers of the muscularis externa?
oblique, circular, longitudinal
What is the cavity name of the mouth?
oral/buccal cavity
What is posterior to the oral cavity?
oropharynx
Where are accessory organs located?
outside the GI tract
What are the 3 different salivary glands?
parotid, sublingual, submandibular
What is the function of the uvula?
prevents food from entering the nasal cavity
What are the main functions of the liver?
produce bile, filter/process nutrients absorbed from GI.
What is chirrosis? Why is this a problem? What are the main causes of chirrosis?
scarring of the liver blocks flow of blood through the liver excessive alcohol consumption, hepatitis
Where are diverticula most common?
sigmoid colon
What is the soft palate made of?
skeletal muscle
What are the 3 unique features of the large intestine?
teniae coli, haustra, epiploic appendages
Where does 90% of food absorption take place in the small intestine?
the lumen of the small intestine into the vessels with the villi
What is infection of the parotid gland caused by?
the mumps
What do mesenteries allow?
they allow for passage of blood vessels, lymphatics and nerves to supply the intestines
What are the accessory organs of the digestive system?
tongue, teeth, salivary glands, liver, gallbladder, pancreas
What is left from food absorption after going through ileum? What does this create?
water, cellulose, indigestible material, lots of bacteria All of this creates what we know as "feces"
What is peristalsis?
wave-like muscle contractions that push food through to the stomach
How are gallstones formed?
when large amounts of cholesterol accumulate in the gallbladder and water absorption leads to precipitation
What is orthodontics? (ortho meaning straight)
Deals with prevention and correction of abnormally aligned teeth.
What are the 2 completely different SETS of teeth each individual has in their lifetime? How many teeth for each set?
Deciduous (milk teeth) - 20 Permanent - 32
What does the submucosa layer consist of?
Dense irregular CT Blood vessels Lymphatic vessels Lymphoid follicles Nerve fibers
__________ and __________ are both ________ than bone.
Dentin Enamel Harder
Why do we not need to eat constantly?
Digestion in the stomach slowly occurs so its still using the food
What are the 2 main organ groups of the digestive system?
Digestive tract Accessory digestive organs
What is the funcition of active trypsin?
Digests polypeptides to shorter amino acid chains
When diverticula becomes inflamed what is it called?
Diverticulitis
What is each pouch of the lining of the colon called? What are multiple pouches called? What is the condition of having diverticula called? When does diverticulosis become common?
Diverticulum Diverticula Diverticulosis As you age, it becomes more common
In most places mesentery are ______ and attach to ___________ ___________ __________.
Dorsal Posterior abdominal wall
The common bile duct enters which part of the small intestine? Connected to the stomach via __________ _________.
Duodenum Pyloric valve
Which cells make the hormone secretin? What does the hormone secretin do?
Duodenum cells Stimulates bile production by the liver hepatocytes
The small intestine includes which structures? (3)
Duodenum, Jejunum, Ileum
Nerve fibers found in the submucosa layer of the alimentary canal are apart of which nervous system?
Enteric Nervous System
What does the mucosa layer consist of?
Epithelial tissue lamina propria (areolar CT) 2 thin layers of smooth muscle (muscularis mucosae)
What does the serosa layer of the alimentary canal consist of?
Epithelium (mesothelium) areolar CT
Explain a gastric ulcer.
Erosion of mucosa of the stomach, ulcer forms due to over-secretion of HCL/ undersecretion of mucous
Decribe microvilli
Extensions of the plasma membrane of the columnar epithelial cells which line the small intestine
What separates the large right lobe of the liver from the small left lobe of the liver?
Falciform ligament
Describe the tongue as a structure. Why is this needed?
Flexible, Made up of interlacing bundles of skeletal muscle fibers of different planes Has to be flexible for speech. The different muscle fibers help tongue change shape.
What is ascites?
Fluid in peritoneal cavity.
What is chrones disease? What does it most commonly affect? What are some symptoms caused by chrones? What is a treatment of this?
Form of inflammatory bowel disease Most commonly affects the intestines abdominal pain, weight loss, diharrea, vomitting anti-inflammatory drugs
where are mucous neck cells found? What do they produce?
Found on the upper part of the gastric gland Produce acidic mucous
What is another name for enteroendocrine cells?
G cells
if the cardiac sphincter does not shut completely...
GERD occurs
Which structure is tucked under the liver and is small and green in color?
Gallbladder
What hormones are produced during the inhibitory phase of the intestinal phase? What are their function?
Gastrin Secretin GIP (gastric inhibatory peptide) Produced for the function of reducing stomach acid secretion
What allows for the bolus to move into the stomach from the esophagus? What occurs when this sphincter is too relaxed?
Gastroesophageal sphincter GERD (gastroesophageal reflux disease)
What does defecation refer to?
Getting rid of indgestible materials in the form of feces
What do parietal cells produce? What is the function of these produced substances?
HCl and intrinsic factor HCL is important for changing pepsinogen to pepsin and making stomach acid strong to kill bacteria Intrinsic factor is important for the absorption of vit b-12 from small intestines.
What most commonly causes gastric ulcers? Explain it.
Helicobacter pylori - a bacteria that lies underneath mucous layer and attaches to stomach epithelium
What is responsbile for draining the bile made from the liver? Where does the hepatic duct travel to?
Hepatic duct duodenum
Which veins carry venous blood from the intestine to the liver?
Hepatic portal veins
Once liver removes nutrients from the delivered venous blood, where does it drain?
Hepatic vein
Which nerves innervate the tongue?
Hypoglossal (12th cranial nerve)
The ileum joins the large intestine at the _______ _______.
Ileocecal Valve
Each jaw has how many incisors, canines, pre-molars, molars, and wisdom?
Incisors: 4 , Canines:2, Pre-molars:4, Molars:4, Wisdom: 2
The caudate lobe of the liver is located near the what?
Inferior vena cava
Where does the hepatic vein empty?
Inferior vena cava
What is the difference between the internal and external anal sphincter?
Internal anal sphincter is involuntary and made of smooth muscle cells External sphincter is voluntary and made up of skeletal muscles
Both parasympathetic and sympathetic are ______________.
Involuntary
What is a hiatal hernia?
It is when a portion of the stomach herniates through the diaphragm, into the thorax.
Describe plicae circulares fold of the small intestine. What is its function?
Largest and most visible by the naked eye Circular folds that look like ridges Its a fold of both mucosa and submucosa layers Forces contents to spiral down the lumen and slow passage down
Describe Villi
Layer of mucosa epithelial cells + underlying loose CT
What is the name for the superomedial surface of the stomach?
Lesser curvature of the stomach
What are the structures known as intraperitoneal organs? (9)
Liver-Spleen-Stomach-Jejunum-Ileum-Transverse colon-Sigmoid colon-Superior rectum- 1st part of duodenum
In the large intestine there is no villi, but the ___________ ____________ ___________ ______________ have ______________.
Luminal epithelial absorptive cells, microvilli
What does the small intestine contain thats mostly in the ileum and is in both the mucosa and submucosa?
Lymphoid tissues- Peyer's patches
What is endodontics?
Manages prevention, diagnosis and treatment of the dental pulp and the periradicular tissues that surround the root of the tooth
What are mesenteries? Example location.
Mesenteries are the double fold of the peritoneum...they attach many organs to the posterior wall ---(where peritoneum folds over on itself) ex. stomach,small intestine, pancreas, and spleen
The digestive tract is basically a tube from the ________ to the _______.
Mouth Anus
What structures are included in the digestive tract?
Mouth- Pharynx-Esophagus-Stomach-Small + Large intestines - Anus
What is the histology of the large intestine?
Mucosa, Submucosa, Muscularis, Serosa
What does the colon mucosa secrete? What is the function of this secretion?
Mucous Functions to lubricate the passageway of fecal matter
Does digestion take place in the esophagus?
No
What is the gastric phase? (when does it occur, function, what is released in this phase)?
Occurs when food stretches the stomach walls. Stretching stimulates nerves to trigger release of gastric juice and gastrin hormone.
What is the celiac phase? (when does it occur, function)?
Occurs when it sees, smells, thinks, or tastes bolus - happens before bolus comes to stomach Makes alot of gastric juice so it can digest food when it arrives
What are the structures known as retroperitoneal organs?
Pancreas-Duodenum-parts of the colon posterior to the peritoneum
Where are the digestive enzymes of the pancreas emptied through? To go where?
Pancreatic duct Duodenum
The exocrine glands produce enzymes that make up what in the pancreas? What is its function?
Pancreatic juice Breaks down all 3 complex foods
What system speeds up GI mobility? How?
Parasympathetic Nervous System
What are the 2 serous membranes (serous peritoneum) of the abdominal cavity?
Parietal Peritoneum/ Peritoneal membrane Visceral Peritoneum/ Peritoneal membrane
What is the serous membrane that lines the wall of the abodominal cavity?
Pariteal peritoneal membrane/peritoneum
Which salivary gland is located anterior and inferior to the ears, and produces 25-30% saliva?
Parotid glands
What does pepsinogen (inactive)/ pepsin(active) do? What activates it?
Pepsin (active form) digests proteins HCL exposure changes pepsinogen to pepsin (the active form)
What do the chief cells/ zymogenic cells produce? What do they also produce in infants?
Pepsinogen (inactive form of pepsin) rennin in infants
Nerves of the parasympathetic nervous system activates what?
Peristalsis
What ensures that food gets to the stomach regardless of gravity/position of the body at that time?
Peristalsis of the esophagus
The cavity inbetween the serous peritoneum is called what?
Peritoneal cavity
What does mechanical digestion refer to?
Physical breaking up of food into smaller pieces
What does ingestion refer to?
Placing food in the mouth
Name the three types of folds in the small intestine.
Plicae circulares, villi, microvilli
What is haustra? What does haustra do?
Pouches in the wall of the intestine caused by puckering of the teniae coli. Haustra causes increased surface area of the colon
What is the function of the mucous layer of the stomach? What clinically occurs when the mucous layer breaks even a little bit?
Protects against acids Gastritis, Ulcers
What in the liver tests measures liver damage?
ALT and AST
What does absorption refer to?
Absorbing food into blood or lymph through the GI tract
What absorption occurs in the large intestine? What elimination occurs?
Absorption- water (9/10l absorbed from small intestine), electrolytes and fat soluble vitamins (vit K) Elimination- undigested food and SOME water
What is the epithelium of the mucosa layer of the large intestine made up of?
Absorptive (water, vitamins, electrolytes) goblet cells (produce mucous)
Digestion doesn't take place with in the ___________ ___________ ______________.
Accessory digestive organs
What is the function of the mesentery proper? What is its general shape?
Achors Jejunum and ileum (most of the small INTESTINE) to posterior abdominal wall Shape: Fan-shaped
What does splanchnic blood circulation refer to?
All arteries and veins that feed the digestive system
What does rennin do for infants?
Allows them to digest casein (milk protein)
What is the last inch of the colon that surrounds the anus? Often called what instead?
Anal canal Rectum
Once digested, food has to be absorbed into the ________.
blood
What is a nickname for the enteric nervous system?
brain of the gut
What is the function of canine teeth? Molars/Pre-molars? Incisors?
canine teeth: peircing/tearing molars/pre-molars: grinding/crushing Incisors: cutting/nipping
The pancreas digests which 3 complex foods?
carbs, fat, protein
What are the 4 main areas of the stomach? (list in order of superior stomach/esophagus entrance)
cardia(cardiac region), fundus, body, pylorus
What does the dentin surround? What does this part of the tooth that dentin surrounds contain?
central pulp cavity Contains: blood vessels, nerve fibers, CT
What are gallstones?
crystallized cholesterol
