Gastrointestinal I Flashcards
How long is the GI tract in a cadaver?
30 feet
How long is the living GI tract?
around 15 feet
Divisions of the small intestine:
Duodenum
Jejunum
Ileum
Divisions of the Large Intestine:
Cecum Ascending Transverse Descending Sigmoid
4 functions of the GI tract:
Motility
Secretion
Digestion
Absorption
What are the constant low levels of contractions in the GI tract know as?
Tone
What is the purpose of tone?
Maintain steady pressure
What are the 3 types of motility?
Propulsive (peristalsis)
Segmentation (mixing)
Tonic contractions (sphincters/valves)
2 functions of Segmentation?
Mechanical digestion
Facilitate absorption
6 sphincters in the GI tract:
UES - Upper Espophageal Sphincter LES - Lower Esophageal Sphincter Pyloric Ileocecal Internal Anal External Anal
What regulates the movement of contents of the common bile duct into the duodenum?
Sphincter of Oddi
Where are the voluntary areas of control in the GI tract?
UES
External Anal Sphincter
*the ends
What do the voluntary control areas in the GI tract have in common?
Skeletal muscle
instead of smooth
How much saliva and gastric juice are produced daily?
- 5 L saliva
2. 5 L gastric juice
How much bile and pancreatic juice are produced daily?
- 5 L bile
1. 5 L pancreatic
How much intestinal secretion and mucus are produced daily?
- 0 L intestinal
2. 0 L mucus
Most chemical digestion takes place via…
Hydrolysis
Where are the brush border enzymes?
Plasma membrane of enterocytes
How much fluid enters into or is secreted into the lumen of the intestine every day?
How much ends up in the stool?
9.0 L
100 mL
Where to the 4 basic quadrants intersect?
Belly button
What are the 9 Abdominal-Pelvic regions?
Rt and Lt Hypochondirac Epigastric Rt and Lt Lumbar Umbilical Rt and Lt Inguinal Pubic
What layer covers the external surfaces of most digestive organs?
What is it continuous with?
Visceral peritoneum
Parietal peritoneum
What lies between the visceral and parietal peritoneum?
Peritoneal Cavity
*with peritoneal fluid
lubricates
What is inflammation of the peritoneum?
Peritonitis
What is the condition of accumulated peritoneal fluid called?
Ascites
What is a large fold of peritoneum in the abdominal cavity?
Greater Omentum
What is the greater omentum attached to?
Transverse colon
What anchors the small intestine to the posterior abdominal wall?
Mesentery
T/F
The contents within the lumen are technically outside the body
True
What condition penetrates the gastric mucosal barrier?
Peptic Ulcer Disease (PUD)
What is obstructed in Acute Pancreatitis?
Main pancreatic duct
(causing rupture)
*damages pancreas, duodenum
What can cause peritonitis via bacterial invasion?
Ruptured appendix
What are the 4 major layers of the GI tract wall?
Mucosa
Submucosa
Muscularis Externa
Serosa
What delineates the Mucosa and Submucosa?
Muscularis mucosae
What is the self-induced electrical activity in the digestive smooth muscle called?
(3 things)
Slow-wave potential
Basal Electrical rhythm (BER)
Pacemaker potential
What are 2 terms for the submucosal and myenteric plexuses in the gut?
Intrinsic Nerve Plexuses
Enteric Nervous System
*sensory, motor, exocrine, endocrine, etc.
What is the parasympathetic innervation for the esophagus, stomach, small intestine, and ascending colon?
(upper GI tract)
Vagus
The mixed vagus nerves innervating GI tract are what percentage afferent and efferent?
Afferent: 75%
Efferent: 25%
What 4 GI tract structures does the Vagus nerve innervate parasympathetically?
Esophagus
Stomach
Small Intestine
Ascending colon
What is the parasympathetic innervation for the lower GI tract?
(transverse, descending, sigmoid colons and anal canal)
From where are they derived?
Pelvic splanchnic nerves
S2, S3, S4
The majority of parasympathetic nerves to the GI are ____.
Some are _____.
Cholinergic
Peptidergic
Name 4 peptidergic molecules.
VIP
Enkephalins
Neuropeptide Y
Substance P
What are the 3 divisions of Adrenergic (sympathetic) ganglia that serve the GI tract?
Celiac
Superior mesenteric
Inferior mesenteric
What percentage of Adrenergic nerves to the GI tract are afferent and efferent?
50/50
T/F
Autonomic nerves influence GI tract altering nerve activity, altering hormone secretion, and innervating smooth muscle and glands
True
What secretes hormones in the GI tract?
Endocrine cells
What condition is marked by no salivary production and increased caries?
Xerostomia
What autoimmune disease strikes salivary glands?
Sjogren’s Syndrome
- most common cause of xerostomia
- *mostly women
Name 4 diseases that can cause xerostomia.
Sjogren’s
HIV
Diabetes
Parkinsons
What receptors mediate normal salivary function?
M3
muscarinic
What 3 components make up a salivary gland?
Acinus
Intercalated duct
Striated duct
What surrounds each acinus in the salivary gland?
Function?
Myoepithelial cells
Contraction and release of saliva
What are the 3 categories of salivary acinii?
Serous
Mucous
Mixed
What percentage of total saliva doe each gland produce?
Submandibular - 71%
Parotid - 25%
Sublingual - 3-4%
What type of secretions do each of the salivary glands produce?
Parotid - serous
Submandibular - mixed
Sublingual - mucous
What do the salivary glands look like under a microscope?
Parotid - mostly dark (lack of mucous)
Submandibular - mixed dark and light
Sublingual - mostly white
What ducts drain the salivary glands?
Parotid - Stenson’s
Submandibular - Wharton’s
Sublingual - Ducts of Rivinus
What are the 3 most important salivary proteins?
Alpha-amylase
Lingual Lipase
Mucins
What does salivary alpha-amylase cleave?
What deactivates?
Internal Alpha1,4
(no terminals or Alpha 1,6)
Gastric Acid
What are 3 antibacterial components of Saliva?
Lysozyme (targets walls)
Lactoferrin (chelates iron)
IgA
How many species of bacteria are in the oral cavity?
700
Name 4 oral bacteria and 1 anaerobe.
Streptococci
Lactobacilli
Staphylococci
Corynebacteria
Bacteroides
Three benefits of normal oral cavity flora.
Prevent colonization
Inhibition of non-indigenous species
Stimulates cross reactive antibodies
(antibody immune response)
T/F
Saliva contains buffering agents and minerals
true
At what pH can enamel be dissolved?
below 5.5
Where is the salivary center?
Medulla
Describe what the sympathetic response does for Salivary Output.
Scant
Protein rich
High K+ and HCO3-
T/F
Sympathetic and parasympathetic stimulation increase salivary secretion.
True
*but very different in character
What agents reduce salivary secretion?
Atropines
Cholinergic blockers
How many different chemicals can taste buds detect?
4-10k
Name 3 types of papillae.
Fungiform
Foliate
Circumvallate
What papilla is scattered over the entire tongue and responds to sweet and salty (and sour)?
Fungiform
What papilla responds mainly to sour?
Foliate
What are fungiform papillae taste buds innervated by?
Circumvallate?
CN VII - chorda tympani branch
CN IX - glossopharyngeal
What papillae responds best to bitter substances?
Circumvallate
Taste buds in the epiglottis are innervated by…
X - vagus
Taste buds in the palate are innervated by…
VII - facial nerve
T/F
Taste receptor cells are neurons
False
but synapse onto VII, IX, and X
What is at the taste pore?
Microvilli
What taste depolarizes membrane through influx of Calcium and sodium and inhibiting K+ efflux via cAMP?
Bitter
What taste goes through cascade ultimately releasing calcium into the cell?
Alkaloid
??
What taste relies on influx on Na+?
Salty
What taste relies on H+ to block channel and impede K+ from exiting the cell?
Sour
What taste acts through cAMP and PKA to inhibit K+ from exiting cell thus depolarizing the membrane?
Sweet
Where do gustatory cranial nerves terminate?
Solitary nucleus in the medulla
Rostral 1/2
Where does output of the Nucleus of the Solitary Tract lead?
2 places
Ventroposterior medial nucleus of the Thalamus
(VPM)
Insular Cortex
*this is why bad taste in mouth after seizure
T/F
Lower 3rd molar extraction causes gustatory loss by impacting the Lingual Nerve
False
only temporary, and not detectable by pt
The lingual nerve is a branch of…
Trigeminal (mandibular division)
*sensory innervation to the tongue
4 muscles of mastication.
Temporalis
Lateral Pterygoid
Medial Pterygoid
Masseter
What innervates the muscles of mastication?
V Mandibular Division
Action and innervation Masseter:
Elevate mandible
Masseteric branch Mandibular V
Temporalis Action and innervation:
Elevates mandible
Deep temporal branch Mandibular V
Lateral Pterygoid action and innervation:
Protrudes mandible
Lateral pterygoid branch Mandibular V
Medial Pterygoid action and innervation:
Elevates mandible
Medial pterygoid branch Mandibular V
Depression, elevation, lateral, and anterior-posterior movement creates what in the jaw?
Looping pattern
Three phases of mastication:
Opening
Closing
Occlusal (longest component)
What depresses the mandible?
3 muscles, 1 force
Gravity
Digastric
Geniohyoid
Mylohyoid
How long is the esophagus?
Thick?
18-26 cm
2 cm (ant/post)
3cm (lateral)
What vertebral level does the esophagus begin?
traverse diaphragm?
cardi of orifice?
C5-6
T10
T11
What type of epithelium is the esophagus lined with?
non-keratinized stratified squamous
What provides mucus for the esophagus?
Esophageal Glands
3 layers of esophageal wall?
Mucosa
Submucosa
Muscularis
What anatomical difference is there in the esophagus compared to the rest of the GI tract?
No Serosal outer layer
thin connective tissue instead
T/F
The esophagus has small veins
False
especially large gastric veins
What can cause bumps in the esophagus?
What is this called?
Submucosal venous spaces fail to drain
Esophageal Varices
What causes esophageal varices?
portal hypertension
*cirrhosis
3 phases of Deglutition (swallowing):
Oral/voluntary
Pharyngeal
Esophageal
What relaxes in the Involuntary pharyngeal phase?
Upper Esophageal Sphincter
What accounts for the inhibition of respiration and stimulation of glottic closure during deglutition?
Reflex Response
Peristalsis in the esophagus terminates at:
Lower Esophageal Sphincter
What condition entails the Lower Esophageal Sphincter’s inability to relax?
Achalasia
- doesn’t open
- entire meals back up this way
What common condition leads to heartburn and esophagitis (and ulceration and scarring)?
GERD - gastroesophageal reflux disease
What causes GERD?
What really bad thing is associated with it?
decrease in LES pressure
(doesn’t close)
esophageal adenocarcinoma
T/F
Steroidal based oral contraceptives decrease closing strength of the LES
True
along with caffeine, peppermint, spicy, citrus, smoking
What is a complication from persistent GERD?
Barrett’s esophagus and strictures
What causes strictures from persisted GERD?
Scar tissue, spasm, and edema
What do strictures in the esophagus cause?
Difficulty swallowing (dysphagia)
What is the term for painful swallowing?
Odynophagia
What indicated Barrett’s esophagus when looking down esophagus?
Red lining
with “tongues” indicating erosion
What replaces squamous mucosa in Barrett’s esophagus?
Columnar epithelium (resembling stomach/intestine)
What are the 4 main regions of the stomach?
Cardia
Fundus
Body
Pylorus
What are the 2 sphincters in the stomach?
LES - Lower Esophageal Sphincter
Pyloric
What defines the border of the Fundus to the Body?
Cardial notch
Where does the Greater Omentum hang from?
Greater curvature of the stomach
What are the 3 layers of muscularis musosa in the stomach?
Longitudinal (outer)
Circular (middle)
Oblique (inner)
What acts as the protective barrier in the gastric lining?
Alkaline mucus
with a lot of Bicarb
What enhances mucous production in the stomach?
Prostaglandins
What is the turnover rate of the lining of the stomach?
2-3 days
What type of epithelium is in the stomach?
Simple columnar
What are the deep channels in the simple columnar epithelium of the stomach?
Gastric pits
What are the 4 main gastric glands?
Mucous neck cells
Parietal Cells
Chief cells
Endocrine cells
What type of cells secrete the alkaline mucous?
Mucous neck cells
What to Parietal cells secrete?
HCL and IF
What do Chief cells secrete?
Pepsinogen
Gastric Lipase
What cells secrete gastrin and histamine?
Specifically?
Endocrine cells
G cells - gastrin
ECL (enterochromaffinlike) - Histamine
How much gastric juice is secreted daily?
2500 mL
Where are most Parietal cells located in the stomach?
Where are most Chief cells located?
G cells?
High body toward fundus
Body
Antrum
What does Gastrin stimulate?
Parietal cells (IF and HCL)
What 2 hormones are secreted by the stomach?
Gastrin
Histamine
What is chyme?
Mixed food
combined with gastric juice
What causes the Alkaline Tide?
HCl production in Parietal cells from Bicarb
HCO3- released into blood and causes temporary alkalinity
T/F
The vagus nerve stimulates gastric secretion while food is still in the mouth (cephalic phase).
True
Describe the positive feedback loop in the stomach.
*What phase does this take place?
Gastrin (via vagal or distention stimuli)
stimulates gastrin secretion
(which stimulates more Gastrin, etc)
*Gastric Phase
What increases HCL secretion from parietal cells?
Histamine
How does Pepsin break apart AA’s?
Partially
can only cut certain linkages
What 3 hormones in the duodenum act to decrease gastric juice secretion?
CCK
Secretin
GIP (gastric inhibitory peptide)
What hormone released by the duodenum inhibits gastric motility?
GIP
What 3 signals stimulate H+ secretion in the stomach?
Histamine
Gastrin
Vagal (via Ach)
What inhibits the vagus nerve activity that stimulates the stomach?
Enterogastric Reflex
CCK, secretin, and GIP all _____ gastric motility and emptying
inhibit
What can cause acute gastritis?
Bacterial endotoxins, alcohol, aspirin, etc
What can cause chronic gastritis?
Helicobacter pylori
What does H. pylori produce that allows it to live in the stomach?
Urease
NH3 neutralizes stomach acid
What condition entails the prolapse of the stomach through the diaphragmatic/esophageal hiatus?
Hiatal Hernia
T/F
Hiatal hernias are more common in men
False
pregnancy pushing
T/F
Abdominal ascites is associated with hiatal hernia
True
Where is B12 absorbed?
Terminal ileum
T/F
Pernicous anemia is characterized by megaloblasts that lack biconcavity and live for days
False
Live for weeks rather than months
What are 2 oral manifestations of Pernicious Anemia?
Erythma/atrophy of tongue Megaloblastic anemia (red lesions in mucosa)
4 consequences of Emesis.
Acid-base disorders
volume/electrolyte depletion
Malnutrition
Aspiration Pneumonia
What phase of emesis is the antrum contracting and the cardia relaxing?
Retching
How does the diaphragm contract during emesis?
Downward
*facilitates opening of esophagus and LES
What two muscles are simultaneously contracted in emesis?
Diaphragm downward
Abdominals
What controls vomiting in brain?
Bilateral Vomiting Centers
What is located on the floor of the 4th ventricle in the brain?
Chemoreceptor Trigger Zone
*can initiate vomiting
What salivary flow rate is used to diagnose Sjogrens?
Less than 0.1 mL/min
What 2 classes of drugs cause Xerostomia?
Anti-Muscarinics
Beta-2 Agonists
Example of a LABA (Long Acting Beta-2 Agonist) used to prevent asthma.
Salmeterol
Muscarinic Antagonist used as a bronchodilator.
Ipratropium
Muscarinic Antagonist used for Incontinence (also increases heart rate)
Oxybutynin
What anti-histamine decreases salivary production?
Benadryl
Diuretic that decreases salivary secretion due to overall body fluid loss.
Hydrochlorothiazide
Nasal decongestant and vasoconstrictor that decreases salivary action.
Phenylephrine
Muscarinic Antagonist
Benztropine
How does Pilocarpine (Salagen) increase salivation?
Stimulates Muscarinics
How does Cevimeline (Evoxac) stimulate salivation?
Muscarinic Agonist (Ach mimicker)
What lubricant rinse helps with Xerostomia?
Biotene Oral Balance
T/F
Steroids (like Fluticasone) causes dry mouth
True
What is a very common side effect of corticosteroids?
Thrush (Candida albicans)
What is the best treatment for Oral Thrush?
Fluconazol
Why do non-specific Cox inhibitors cause stomach pain?
Decreases Prostaglandin activity and depletes stomach lining
What is the physiological prostaglandin?
Inflammatory?
Cox 1
Cox 2
What two antibiotics are prescribed for Peptic Ulcer Disease?
Clarithromycin
Amoxicilin
What drug acts as a PPI (Proton Pump Inhibitor)?
Esomeprazole
What drug acts as a Histamine-2 Receptor Blocker?
and partially inhibits H+ gastric secretion
Ranitidine