Lecture 7: Upper GI Flashcards
single-cell organisms
- diffusion of water and ions
- phagocytosis/Endocytosis of large particles, digestion, and absorption in lysosomes
ex. amoeba
What is important in multicellular organisms?
Shape!
- if shape not hollow: greater ratio of volume to the exterior surface area than in a single cell
What is an example of simple multicelliular organisms
- cavity or lumen for optimal digestion and absorption
- organization into shapes that maximize surface area for exchange
What is GI function?
Take relatively large, solids or gels, and digest them into smaller molecules that can be absorbed as nutrients, while still serving as a secondary nervous system (ENS) and a barrier to toxins, bacteria, parasites, etc
What is unique about the gut?
Most of your immune system/cells are in the gut. The Brain/Gut connection, microbiome, and gut dysbiosis research is a rapidly emerging field
What is the functional anatomy of the GI?
GI: functional anatomy
Ingestion, Digestion, Absorption, Elimination
What are the phases of digestion?
- Cephalic
- Gastric
- Early Intestinal
- Late Intestinal
What is the cephalic response?
The intensity of response varies with food type (sweet, sour, salty, bitter) to influence our preference, digestion, and possibly energy balance
- can predict even how much we eat
Explain the pathway of cephalic phase with stimuli and effect response
What is the two-stage model of saliva secretion?
Primary vs Secondary
- Primary: ptyalin, mucous, extracellular fluid, Amylase containing; nearly isotonic; levels of Na, K, cl, and HCO3 similar to plasma (acinar cells)
- Secondary: K and HCO3, Modification of ionic content (ductal cells)
Saliva fxn?
neutralize acidity
What is Salivary Secretion: Acinar Cell Mechanisms
- Secretion of K+ and HCO3-
- Acinar cells also secrete enzymes including alpha-amylase, lingual lipase, and kallikrein and immunoglobulin A (IgA)
What do salivary ductal cells do?
Ductal cells modify initial saliva to produce final saliva
- absorb Na+ and Cl-, decreasing concentrations in saliva
- secrete K+ and HCO3-, increasing concentrations in saliva
- salivary HCO3- neutralizes oral bacterial acids
What are the major organic compents of saliva? List region, gland and function
What does chewing do? What is involved?
What are our 5 types of taste qualities?
- Bitter (toxins)
- Salt
- Sweet
- Sour
- Umami (savoriness –e.g. MSG)
What is swallowing coordinated by?
The swallowing reflex is coordinated by the medulla oblongata, which transmits the contraction of skeletal muscle, sphincters, and smooth muscle groups.
Somatic CN (conscious) to chew then ANS takes over (involuntary)
What is dysphagia?
difficulty/discomfort swallowing (eg. MS, ALS, injury)
What are the three integrated phases for normal swallowing (deglutition) ? List muscle, neural control and voluntary control
Explain how food moves.
- Peristalsis of bolus to the stomach
- Opening of LES
- Receptive relaxation in the stomach
What is necessary to deliver food to stomach?
The coordinated sequence of contraction and relaxation in the upper esophageal sphincter, the esophagus, and the lower esophageal sphincter
What are the inn of swallowing center + muscles involved in various areas
What are the pressures of UES, LES and intraespophageal?
- UES: 100 mm Hg
- Intraesophageal Pressure: -5 mm Hg
- LES: 20 mm Hg
What does sphincters prevent?
prevent influx of air into the stomach, as well as reflux of gastric contents into the esophagus.
What are the states that the GI sphincter can be in ?
- Resting State: Tone/Closed
- Relaxation/Open
- Constriction/Tightly Closed
What is happening in the resting state?
tone/closed
- Pressure in Sphincter > Adjacent Segments
- Inhibits movement through the sphincter
What happens in the relaxation/open phase of GI sphincters?
- Pressure in Sphincter = Adjacent Segments
- Allows movements through sphincter
What is happening in the constriction/tightly closed state of the GI sphincters?
- Pressure in Sphincter»_space; Adjacent Segments
- Important to prevent the flow
For lower esophagus, what two things are going on?
Distension in the esophagus can initiate what?
peristalsis through both local and vago-vagal reflexes (Note: Ach (contraction) and nitric oxide (relaxation) are major mediators)
what can occur to clear any remnants of food bolus?
secondary peristaltic waves
Dysphagia can result from?
- Can result from abnormalities that alter the mechanics of swallowing (e.g. GERD, Achalasia, Cancer)
- Can also arise secondary to neurological problems (e.g. patients with a stroke or ALS)
What are the espohageal stimuli with the receptor and response?
ingestion of cold substances can cause what?
What are common factors that alter LES pressure?
What is the GERD therapy?
What is happens to the stomach during swallowing?
receptive relaxation: Decreased SM Tone & Increased Stomach Compliance
- Also: Increased Acid Secretion
slide 32
What are the basal electrical rhythm phases?
How is BER in different small intestine segments?
Emesis important function in what?
neural control
What is happening with emesis?
What does parietal cell and chief cells do?
_ is essential for production of H+ ions
carbonic anhydrase
important for bicarb too!
Explain the rapid transition from resting to secreting
What 3 stimuli work together in synergistic manner?
POTENTIATION!
How does the vagal nerve play a role in cells
_ and _ secretion are tightly connected.
pepsinogen and acid secretion
Acid in the antrum stimulates what? What is the effect?
Explain how different cells play a part in breakdown
Vagovgal reflex and endocrine releast of gastrin stimulates what?
Pharmacological ways to limit
stomach acid?
How does acid secretion change before, during and after meals?
What is released into lumen with mucus? what is the ph at the cell surface?
What is Gastrinoma (Zollinger-Ellison Syndrome) and tx?
