Secretions Flashcards
Where does most of microbial digestion take place
In the large intestine
What kind of environment is needed for most digestion to take place
Need a warm moist environment
True or false microbial digestion is enzymatic digestion
True: it is because microbes also use enzymes to break down nutrients
What are the end products of digestion in the large intestine
Volatile fatty acids
What are the 3 common volatile fatty acid products of large intestine digestion
- Propinate
- Acetate
- Butyrate
What are short chain (volatile fatty acids) for animals (what do they act as)
They act as an energy source after absorption
What is the general ideal pH for digestion
Close to a neutral pH
How does the gut maintain a generally neutral environment, why does it have to do this
It constantly removes volatile fatty acids since they are acidic and the Ideal pH for digestion is close to a neutral pH
What is the retention time like in the large intestine compared to the small intestine
The large intestine has a longer retention time than the small intestine
Large (1 day) Small (~2-3hrs)
At what pH do short chain fatty acids form (what is their pka)
They form at a neutral pH
Pka = 4.5
What is the purpose of adding a hydrogen to charged SCFA’s
To make them non-polar so that they can cross the membrane via diffusion
What are the 2 ways that SCFA’s are absorbed, describe them
Non-ionic diffusion: the use of transporters in the small and large intestine for SCFA’s to diffuse across the membrane
Apical: the use of bicarbonate exchange to move SCFA’s across the membrane
Why is it so important that calves get immune transfer from the milk
Because calves do not get immunoglobulin transfer through the uterine wall
What is the majority of calf death due to
Failure of immune transfer
How does passive transfer of immunity through colostrum occur, describe this process
By nonspecific pinocytosis
The use of vesicles to transport materials across the membrane
What is the challenge with pinocytosis and immune transfer
The rate of pinocytosis after birth drops very quickly
Which decreases the rate of immunoglobular absorption also decreases quickly
What is the preferred energy source for cells in the rumen and gut lining
What does it do for… gut development and pinocytosis
Butyrate
Accelerates gut development
Decreases pinocytosis
What are the four key aspects (things) about passive transfer (immunity)
- Timing is important
- Pinocytosis capacity is limited (amount of IgG abs)
- Many factors affect colostrum quality
- Pinocytosis is not selective
What does the presence of celiac do to the microvilli in peoples guts that have celiac disease
It damages their microvilli in their gut
What is the formula for gut secretion
HCO3- + H+ (—) H2CO3 (—) H2O + CO2
Where does the H come from and where does the HCO3 come from in the chemistry of gut secretion equation
H comes from gastric secretions
HCO3 comes from pancreatic secretions
Where does the H come from and where does the HCO3 come from in the chemistry of gut secretion equation
H comes from gastric secretions
HCO3 comes from pancreatic secretions
What enzyme catalyzes the equation for the chemistry of gut secretion
Carbonic anhydrase
What is the purpose of salivary secretions in the chemistry of gut secretion
They neutralize acidic substances
What are the salivary glands and ducts associated with
It is associated with the mandible
What species do not have amylase secretions
Ruminants and carnivores
What is the composition of a salivary secretion
- HCO3 (bicarbonate) and H2PO4 (buffers)
- Sodium and Chloride
- Amylase (except in ruminants and carnivores)
What is the function of salivary secretions
To moisten food and facilitate mastication and deglutition
Also neutralize stomach contents (what is going in and coming out) back up
What is deglutition and what is mastication
Deglutition: swallowing
Mastication: chewing
What type of cell produce enzymes in salivary secretions
Acinar cells