Digestive Physiology Flashcards
What two important processes make up digestive physiology?
Absorption (Across enterocytes into bloodstream) and digestion (Food broken down into individual components)
What happens to products that are not absorbed or digested?
Excreted in the feces
What is the lumen of the gut lined by?
Enterocytes
What are enterocytes supported by?
Mucosa
What is contained in the mucosa?
Exocrine glands (Some glands lay outside the gut), with endocrine glands in mucosal invaginations
What is the muscularis comprised of?
Two layers of involuntarily controlled muscle, the inner circle contracts/constricts (Oriented perpendicular to the direction of the lumen) and the outer layer moves material forward (Oriented longitudinally)
How is the muscularis controlled?
Autonomic nervous system
Where is the serosa located and what is its function?
Located outside the muscularis and protects gut from surrounding organs
Where is the submucosal plexus and the myenteric plexus?
The submucosal plexus is wrapped around the outside of the mucosa, and the myenteric plexus is located between the two layers of muscularis
How is the gut able to contract spontaneously?
Controlled by the ANS but with no external connections, enteric nerves not coordinated with the rest of the body (Called myogenic contraction)
Is gut activity under sympathetic or parasympathetic control?
Parasympathetic (Rest and digest), will shut down with sympathetic stimulation
What is one of the biggest endocrine glands in the body?
The gut
What is the only portion of the gut that changes throughout the entire tract?
Mucosa
What is digestion and by what mechanisms can it occur?
Breaking down food into component molecules, can be achieved mechanically (Chewing to reduce fiber length and/or with muscle) or chemically (Inorganic: With water or acid, or enzymatically)
What is absorption?
Movement of molecules across enterocytes into the blood, requires energy
What four requirements are required for efficient food processing?
Proper sequential events (Need sensory fibers to detect presence of food in each stage), coordination (Sensory/motor pathways), nerve innervation (Extrinsically: Parasympathetic nerves, Intrinsically: Nerve plexuses), hormones (Trigger exocrine release when stimulated by food or food chemical)
How does the herbivore diet differ from the carnivore diet?
Herbivore: HIGH volume, LOW energy
Carnivore: LOW volume, HIGH energy
How can the horse stomach be so small even though it eats a high volume of food?
The food is continually being processed and moved throughout the system
How does the dog’s digestive activity relate to its stomach size?
Has a large stomach but low processing speed, so need to be able to contain material while it is processed
