Chapter 26: Digestive System Flashcards
What are the two components of the digestive system and their general functions?
1.Gastrointestinal (GI) tract: continuous tube from oral cavity to anus
2. Accessory digestive organs: assist breakdown of food through the liver, pancreas, and gallbladder
List the four tissue layers of the GI tract deep to superficial.
- Mucosa
- Submucosa
- Muscularis
- Serosa
Name the tissue layer and tissue type of the mucosa.
- Epithelium
- simple columnar with microvilli - Lamina propia
- areolar CT and capillaries (immune cells) - Muscularis mucosa
- thin layer of smooth muscle
Name the layers and tissue type of the submucosa.
Layers
1. Submucosal gland
2. Blood vessel
3. Submucosal nerve plexus
Tissue type: areolar or dense irregular CT
Name the tissue layers of the muscularis.
- Inner circular layer (smooth muscle)
- Myenteric nerve plexus
- Outer longitudinal layer (smooth muscle)
What are the primary types of motility of the GI tract.
- Mixing
- Propulsion
Name this most superficial layer and the tissue type.
Serosa
- areolar CT, collagen, elastic fibers
What are the two oral cavity functions and what type of CT is present?
- Ingestion
- Digestion
- mechanical (teeth and tongue)
- chemical (saliva)
Tissue type: nonkeratinized stratified squamous epithelium
List the 5 functions of saliva from salivary glands.
- moistens food = becomes bolus
- begin chemical digestion of starch
- food molecules dissolved for taste
- cleanses oral cavity
- help inhibits bacterial growth
What are the three salivary glands?
- Parotid
- Submandibular
- Sublingual
Identify this salivary gland and the amount of saliva it secretes.
Parotid salivary gland
- largest
- secretes 30% of saliva from parotid duct
Identify these salivary glands and the amount of saliva they secrete.
Submandibular salivary gland (inferior to mandible)
- 65% of saliva from submandibular duct
Sublingual salivary gland (bottom of tongue)
- 5% of saliva from multiple submandibular ducts
Describe the 3 phases of swallowing.
- Chewing (voluntary)
- bolus of food is pushed by tongue against hard palate
- moves towards oropharynx - Pharyngeal (involuntary)
- medulla oblongata controls swallowing reflex
- epiglottis closes over laryngeal opening - Esophageal (involuntary)
- muscles push bolus towards stomach
The esophagus tube connects which structure to which organ?
Connects the laryngopharynx to stomach
Is there digestion or absorption occurring in the esophagus?
no, propulsion only
Which type tissue is located in the esophagus?
Non-keratinized stratified squamous
(Exception is the muscularis)
List the 4 functions of the stomach.
- temporary storage
- bolus is chemically and mechanically digested
- protein digestion
- gastric folds (expansion)
The liquid form of bolus in the stomach is called….
Chyme
What are the 3 muscularis layers that churn food in the stomach?
- inner oblique layer
- middle circular layer
- outer longitudinal layer
Explain the process of gastric mixing.
- Contractions of smooth muscle in stomach wall mix bolus with gastric secretions to form chyme
- Peristaltic waves move stomach contents toward pyloric region
Explain the process of gastric emptying.
- The pressure gradient from the peristaltic waves causes sphincter to open
- Chyme enters duodenum
- Pyloric sphincter closes and retropulsion occurs
What are the two functions of the small intestine?
- Absorb 90% of water and nutrients
- Finish chemical digest (chyme)
- Peristalsis
What is the tissue type of the small intestine?
Simple columnar epithelium with microvilli
What is the shortest portion of the small intestine? What constitutes it as being the anatomic blender?
Duodenum
- chyme from stomach
- bile from liver/gallbladder
- pancreatic juices
Where does the most absorption and secretion occur in the small intestine?
Jejunum
Which part of the small intestine completes absorption and connects to the ileocecal valve?
Ileum
Identify this structure of the small intestine.
Circular folds
Identify these structures of the small intestine.
- Circular folds
- Intestinal villi
In intestinal villi, which two cells are present and what are their function?
- Microvilli: absorbs nutrients
- Goblet cells: produces mucin
Why does the small intestine contain circular folds?
To increase surface area
List the 3 functions of the large intestine.
- Absorption of water from remaining chyme
- Peristalsis
- Defecation = feces
What are the accessory digestive organs?
- liver
- gallbladder
- pancreas
Identify this accessory digestive organ.
Liver
What are the main functions of the liver?
- Produce and secrete bile
- bile emulsify fats
- left and right hepatic duct - Detox
- packed with smooth ER in cells
Identify this accessory digestive organ.
Gallbladder
What is the primary function of the gallbladder?
Concentrates and releases bile that is produced from the liver
Describe the endocrine and exocrine functions of the pancreas.
Endocrine: produce and secrete insulin and glucagon
Exocrine: produce pancreatic juices (mucin, bicarbonate, and digestive enzymes)
Describe how all the accessory organs work together.
Identify the following structures of the stomach.
