Digestion Physiology - Movement and Control Flashcards
What is prehension?
How the animal access the food
What is mastication and what is its purpose?
Chewing which breaks down, moistens and lubricates food by mixing it with saliva
What happens during swallowing to prevent food from going down the wrong way?
The epiglottis closes the trachea and the soft palate rises to block the nasal passage
What is in saliva?
Water, proteins, electrolytes and glycoproteins
What are 7 purposes of saliva?
- Moistens and lubricates food
- Breaking down food for taste
- Enzymatic digestion in some species
- Oral hygiene and immunological defence
- Thermoregulation
- Buffer
- Urea nitrogen salvaging in ruminants
How many of litres of saliva produced per day by humans?
1-2L
How many of litres of saliva produced per day by horses?
15-40+L
How many of litres of saliva produced per day by cows?
90-200L
What are the two muscle layers of the GIT?
- Circular
- Longitudinal
What happens when circular muscle contract in the GIT?
The tube constricts
What happens when longitudinal muscle contract in the GIT?
The tube dialtes
What are slow waves of membrane potential in GIT?
Slow waves are partial depolarisations in smooth muscle, meaning the membrane potential fluctuates but doesn’t reach a full action potential threshold
What impact does the parasympathetic nervous system have on the slow wave?
Raises the slow wave baseline and amplitude
What impact does the sympathetic nervous system have on the slow wave?
Decreases the slow wave baseline and amplitude
What is peristalsis?
Unidirectional wave like progression of a circular constriction of teh gut away from the mouth
What is antiperistalsis?
Action conveying food proximally towards the oral cavity
What is segmentation type of movement in the gut?
Non propulsive movement moving food back and forth mixing and absorbing
What is the purpose of the proximal stomach region?
Food storage area with little mixing but salivary amylase at work
What is the purpose of the distal stomach region?
Grinds and sifts food before entering the small intestine
What are enterogastric reflexes?
A feedback mechanism from duodenum to stomach to allow for different digestion and absorption rates
How does low pH in the duodenum influence enterogastric reflexes?
Inhibit stomach emptying
How does high pH in the duodenum influence enterogastric reflexes?
Inhibitory influences on stomach emptying removed
What are the two phases of small intestine motility?
- Digestive phase after food intake
- Interdigestive phase when little food in the gut
What controls the GIT?
Local neural and hormonal controls more important than central control
What is the anatomy of the enteric nervous system?
- Myenteric plexus - controls gut motility
- Submucosal plexus - regulates secretion and blood flow
What impact does the parasympathetic nervous system have on GIT?
- Relaxation of smooth muscle sphincters
- Increased motility and tone gut wall smooth muscle
- Increased blood flow
- Increased secretion
What impact does the sympathetic nervous system have on GIT?
= Increased tone sphincters making it difficult to move
- Relaxation of gut wall smooth muscle
- Decreased blood flow
- Decreased secretion
