Digestive System Flashcards
What is the digestive tract (proper)
The tube from the mouth to the anus. Including the oral cavity pharynx esophagus, stomach, small intestine, and large intestine
What are accessory organs to the digestive tract?
tongue, teeth, salivary glands, liver, gallbladder, pancreas; includes glands that secrete substances into digestive tract.
What is ingestion?
Introduction of food into the oral cavity
What is mastication
Process of chewing to mechanically break foods down
What is propulsion?
Movement of food down the GI tract
What is swallowing (deglutition)?
Bolus moves from the oral cavity to the esophaghus
What is a bolus
A mass. In reference to the digestive tract it is often a mass of chewed food.
What is peristalsis?
The wave of circular muscle relaxation ahead and contraction behind the bolus that moves it to the digestive tract
What is chyme?
Food as soon as it enters the stomach
How does propulsion occur in the stomach?
By contraction that cause stomach acid “waves”
How does propulsion occur in the small intestine?
Segmental contraction
What is the function of secretions?
To lubricate liquefy and digest
What are the three major secretions in the digestive tract?
Mucus, Water, and Enzymes
What is digestion?
The mechanical and chemical processes that break down food
What is absorption?
Movement of molecules from food from the tract into the blood or lymph
What is elimination?
Poo
What are the Functions of the digestive system?
Ingestion and Mastication
Propulsion and Mixing
Secretion
Digestion
Absorption
Elimination
What is the order of the digestive tract?
Oral Cavity (mouth)
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
What are the four layers of the digestive tract?
Mucosa
Submucosa
Muscularis
Serosa
What is the mucosa layer of the digestive tract?
The innermost layer
Contains in order:
Mucous epithelium
Lamina Propria
Muscularis Mucosae
What layer contains the lamina propria?
The mucosa Layer
What is the Lamina Propria?
Connective tissue that holds epithelial cells together allows passage of blood vessels and nutrients
It also contains the intestinal glands/crypts
Where are the intestinal glands/crypts found?
In the Lamina Propria of the Mucosa layer
What is the second layer of the digestive tract?
The submucosa layer
What are the four parts of the Submucosa layer?
A thick CT layer that has nerves, blood vessels, lymphatics, and small glands
The submucosal plexus
A network of neurons and glial cells (enteric NS)
What organs lack the submucosal plexus?
The stomach and the esophagus
What is the third layer of the digestive tract?
The muscularis
What is the muscularis?
It is 2 or 3 layers of smooth muscle (both circular and longitudinal layers)
What lies between the layers of smooth muscle in the muscularis?
Myenteric Plexus acts to control the movement along the GI tract.
Interstitial pacemakers to promote rhythmic contraction.
What is the 4th, most superficial layer of the digestive tract?
The serosa (adventitia)
What is the serous membrane of the digestive tract called?
The peritoneum
What is the serosa made of
Connective tissue
How is the digestive system regulated?
Nervous regulation
Chemical Regulation
What is the local nervous regulation of the digestive system called?
The enteric nervous system
What does the enteric nervous system do?
Coordinates peristalsis and regulates local reflexes
What is the general nervous system regulation of the digestive system controlled by?
The Central Nervous System
What are the two types of nervous regulation of the digestive system?
Local (enteric)
General (systemic)
What would cause a reflex based on the sight, smell, or taste of food?
General nervous regulation of the digestive system
What are the two types of chemical regulation of the nervous system?
Neurotransmitters (ACh Stimulates, NE inhibits)
Hormones
What are the main hormones used in regulation of the digestive system
Gastrin
Secretin
Paracrine Factors (histamine)
What does serotonin’s role in regulation of the digestive system?
It stimulates digestive motility
What is digestive motility?
Digestive movement
How many sets of teeth do humans have?
2 (deciduous and permanent)
What are the 4 types of teeth found in humans?
Incisors, Canines, Premolars, and Molars
What are the three layers of teeth in order of outermost to innermost?
Enamel
Dentin
Pulp
What is the muscle that humans use to chew?
Masseter
Temporalis
(Medial and Lateral pterygoids)
What are the three salivary glands?
Parotid
Submandibular
Sublingual
What is found in saliva?
Other than mostly water
Salivary amylase (starch)
Lingual Lipase (lipid)
Lysozyme (antibacterial)
IgA
What are the three stages of swallowing?
Voluntary
Pharyngeal (reflex)
Esophageal (reflex)
What organs are involved in reflexive swallowing?
The pharynx and the esophagus
What are the sphincters in the esophagus called?
The upper (striated) and lower (smooth) sphincters
What is the voluntary phase of swallowing?
Pushing the bolus of food into the oropharynx which initiates the pharyngeal phase
What happens during the pharyngeal phase of swallowing?
Pharyngeal constrictor muscles contract in succession
Upper esophageal sphincter relaxes for food to be pushed in
What is special about the pharyngeal phase of swallowing?
The muscles involved are skeletal, but the phase is involuntary
What happens during the esophageal phase of swallowing?
Peristaltic waves and gravity push the bolus through the esophagus
The lower esophageal sphincter relaxes
Why is the lower esophageal sphincter tonically constricted?
To prevent gastric reflux
What are the Rugae in the stomach?
They are a series of ridges produced by the folding of the organ wall.
What is the significance of the rugae in the stomach?
It increases the surface area (area of absorption) by 20X