Chapter 24: The Digestive System Flashcards
What are the 6 essential functions of the digestive system?
- Ingestion
- Secretion
- Mixing and propulsion
- Digestion (mechanical & chemical)
- Absorption
- Defecation
What are the 4 layers throughout the digestive tract walls?
- Mucosa (innermost; lining lumen)
- Submucosa
- Muscularis
- Serosa (outermost)
Mesentery
Connects the small intestine to the posterior body wall
Falciform ligament
Attaches the liver to the anterior body wall and diaphragm
Mesocolon
Connects the large intestine to the posterior body wall
Which organ lacks a serosa layer? What is the layer called instead?
The esophagus
The layer is called adventitia
(i.e. mucosa, submucosa, muscularis, adventitia)
What are the 2 layers of the muscular portion of the digestive tract calls? What organ has a 3rd layer and what is it called?
- Inner circular muscle
- Outer longitudinal muscle
The stomach has a 3rd layer called the oblique smooth muscle layer which comes before the other 2.
What is the difference between an omentums and mesenteries?
Omentums bind organs to eachother.
Mesenteries bind organs to the abdominal wall.
What are the 2 control mechanisms involved in regulating the digestive functions of muscle motility and secretions ?
- Endocrine control - involves various hormones (gastrin, secretin, CCK)
- Neural control - uses chemoreceptors and stretch receptors to send sensory input to the enteric NS and autonomic NS (both systems will control gut motility and GIT secretions)
What is the myenteric plexus?
Part of the enteric NS located in the gut wall between the circular and longitudinal muscle layers.
It controls gut motility
What is the submucosal plexus?
Part of the enteric NS located within the submucosa layer.
Controls GIT secretions
Which nervous system increases GIT activity and which one decreases it?
Parasympathetic - increases GIT activity
Sympathetic - decreases GIT activity
What secretion is made in the mouth and what does it do?
Salivary glands near the mouth will secrete salivary amylase into the mouth to begin carbohydrate digestion to turn starch into sugar.
What are the steps of swallowing?
- Tongue pushed food against hard palate and stimulates receptors for swallow initiation in pons/medulla
- The soft palate and uvula rise to close nasopharynx and allow food to pass through
- Epiglottis covers glottis and food passes through upper esophagus
- Peristalsis propels food (bolus) down
What is the main action of the esophagus?
Peristalsis
Occurs by circular muscle layer contracting to squeeze bolus downwards, and longitudinal muscle layer contracting to expand and receive the bolus.
What are the 4 regions of the stomach?
- Cardiac
- Fundic
- Body
- Pyloric
Parietal cells of the stomach
Produce HCL to maintain an acidic pH environment within the stomach.