pathophys quiz 2 GI Flashcards
Ingestion
it is important to know that we reabsorb H2O bc we secrete so much H2O into our digestive system
where do you absorb most of the H2O
small intestine (absorption is constant)
where else is water absorbed
large intestine, but it varies (this is why you become constipated)
Two ways food is digested
mechanically and chemically
where do chemical and mechanical digestion begin?
the mouth
Mechanical digestion
mastication and peristalsis
Chemical digestion
salivary amylase that breaks down carbs
-parasympathetic (rest and digestion) system releases salivary amylase
Compartmentalization
One region can excel at digesting one type of nutrient, another can excel at digesting something else
where do carbohydrates begin digestion?
the mouth
where do proteins get digested?
stomach
where do lipids get digested
small intestine
Absorption for most nutrients occurs where?
small intestine
where is water absorbed
SI and LI
where are drugs absorbed?
Mouth, stomach, SI, LI (depends on the drug)
Digestion disassembly process
Ingestion-digestion-absorption-secretion-elimination
elimination
involves parasympathetic and local reflexes
what are the 2 parts of the digestive system that involve any voluntary control?
ingestion (no eating)
elimination (holding yo shit)
GI regulation control mechanisms are mostly (voluntary or involuntary)
involuntary
GI regulation is governed by what?
Volume, position, composition the luminal contents (not by the nutritional state of the body)
what is the purpose of the mucosa?
enhance surface area in mucosal epithelium
High surface area is needed in digestion for…
more surface area for secretion, chemical reactions of digestion (many happen on surfaces of lumen cells), and absorption
what two types of cells does the epithelium have and what do they do?
Exocrine- make digestive chemicals or enzymes
Endocrine- communicate with other parts of the GI tract
What does the submucosa contain?
- Blood flow (fantastic) - feature portal system - direct oath for nutrients from the GI tract to the liver
- Nerve Plexus
Nerve plexus
-innervated by the autonomic (parasympathetic, via vagus nerve) nervous system, which can have a significant effect on the actions of your GI tract
Muscularis
- Circular muscle inside (concentric, like the sections of an earthworm you can see), and long muscle outside. it is how the digestive tract does the two types of movement it does- concentric contractions and peristalsis
- It also houses local and autonomic nerve but theres no voluntary control
Serosa (adventitia)
outer covering that comes between the GI tract and the peritoneal cavity
GI tract wall layers
Mucosa-Submucosa-Muscularis-Serosa
Digestion route
Mouth- pharynx-esophagus-peristalsis-stomach
Functions of Mouth and pharynx
- Mechanical digestion of all food
- Chemical digestion of carbs (salivary amylase)
- Voluntary + reflexive control of swallowing - a complex process
- Soft palate keeps food from going up into the nose
- Epiglottis keeps food from going down the trachea
Esophagus layers
-Mucosa- stratified squamous, so its durable. Not a ton of surface area bc theres no absorption here
-Submucosa- Nerves, vessels, and connective tissue
-Muscularis- longitudinal and circular smooth muscle; responsible for peristalsis
-Adventitia (serosa)- holds esophagus to the structures around it
(we use these layers to stage cancer)
Sphincter
muscular ‘doorway’ that opens to allow passage, closes to prevent it
what are the 2 types of sphincters and where are they located?
upper and lower esophageal sphincter (UES and LES)
Upper= at pharynx
Lower= near diaphragm
GERD
LES is leaky
Hiatal hernia
stomach herniated up in the thoracic region
Barrett’s
- can lead to cancer
- damage of stratified squamous by acid by LES
Peristalsis
- happens throughout the digestive tract
- the higher in the tract the more rapidly peristalsis happens
- involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward.
What is the stomachs pH?
2
How does the stomach mechanically digest food?
chyme
The stomach is a food reservoir, how big can it stretch:?
40-1000 ml
what is the only thing the stomach can chemically digest?
proteins
stomach facts:
- nutrient pacer (releases a bit at a time to the duodenum)
- minimal absorber
- look up the F,B,A,P of the stomach
Stomach wall
Mucosa
submucosa
muscularis
serosa
stomach mucosa
columnar epithelium (easily damaged): this is often what you see in a tissue with many glands. replaces itself every 3 days bc of wear and tear of acid. full of glands that produce HCl and pepsinogen (exocrine), gastrin (endocrine) -gastric gland
gastric gland
- mucous cells = mucous
- parietal cells=HCl
- Chief cells= Pepsinogen
- Enteroendocrine cells (G cells) = gastrin (it is endocrine to talk to pancreas and small intestine)
stomach submucosa
rich blood supply + nerve plexusendocrine
stomach muscular is
even an extra layer of muscle so churning can be vigorous, distention can be undone, and peristalsis can happen.
-nerve plexus is also there
stomach serosa
entry point for vessels and nerves
