Secretions from Salivary Glands and Stomach

What are the three phases of secretion?

cephalic - food anticipation

gastric, - mechanical stim

intestinal - stomach emptying into SI

The cephalic phase of saliva secretion is used to ____ and is triggered by what?

Prepare the GI tract

Triggered by food.

The sight or smell of food will activate what? What does this do?

PNS to increase secretion of saliva gastric acid gastrin and pancreatic enzymes

What are the 4 salivary glands?

parotid, submandibular, sublingual, buccal

What is saliva composed of?

water,

electrolytes,

proteins,

bicarbonate,

Urea

What is the function of saliva?

Stim taste buds

Lubrication

Clean mouth

Buffer, lysosymes and antitoxic proteins (protect)

How will saliva be produced?

Acinar glands will secrete fluid which will be modified by intercalated striated ducts

What enzyme will start to digest starch (hydrolysis starch to maltose) in the saliva?

a-amylase (works best at 6.0-7.0 pH)

What is mucin?

A lubricant that protects ducal surfaces.

Acinar cells will release what w/ exocytosis?

Secrete Cl, Bicarb and K+,

Na+ and H20 follow paracellularly

The duct cells will do what to modify saliva?

Create a hypotonic saliva by facilitating the reabsorption of Na/Cl in exchange for H+ and HCO3

H+ is recycled for ____ in saliva production. _____ cannot pass due to low permeability?

K+

H20

Saliva osmolarity will be determined by ____?

Flow rate

At a ____ flow rate saliva will be hypotonic. At a ____ flow rate the electrolyte concentration will increase?

Low

High

___ increases when secretion rates of saliva increase?

pH

____ is not affected by flow rates?

Protein concentrations.

Serous saliva will have more ____ and is produced by ____ gland?

Proteins

Parotid

Mucous saliva will have more ____ and is produced by?

Glycoproteins

Sublingual and submandibular

Where is lingual lipase found? What does it do?

Young animals on milk diet

Hydrolysis triglycerides

What will lysozymes do in the saliva?

Break down peptidoglycan protein (b-1,4glycocide bond)

What do antitoxic proteins do?

Protect against tannin a compound in plants that have a bitter taste and can negatively affect digestion

What problems can Tannin cause?

Reduction of food intake (taste)

Ruminal protein degradation

Inhibition of digestion enzymes (make complexes)

Neg affect on nutrient absorption in SI

What gland is going to neutralize Tannin and what animals typically have a better time doing it?

Parotid

Browsers

What is the buffer function of saliva?

Microbes produce volitial fatty acids and bicarb from saliva will buffer the acidic environment

What will HCl do?

A gastric secretion that

reduces pH

Activates pepsinogen

aids protein digestion

Kills bacteria

What is pepsinogen?

An inactive form of pepsin that will digest proteins by cleaving aromatic links

What are the intrinsic factors of Gastric secretions necessary for?

Allow vitamins B12 absorption in ileum

Dogs and cats have a ____ stomach

Horses will have a ______ and ____ stomach?

Glandular

Glandular and nongranular

Chief cells produce?

Pepsinogen (will become pepsin for protein digestion)

Parietal cells produce?

HCl

Surface mucosal cells produce?

Thick tenacious mucus for protection

How do parietal cells produce HCl?

-H+ pumped out in exchange for K+

-Cl will follow con gradient and be secreted

The alkaline tide and formation of HCl is dependent on what enzyme?

CA

What is the alkaline tide?

The exchange of Cl and bicarb on the basolateral side of the parietal cell allowing large amounts of bicarb to go into the blood

What neural stimulus going to activate HCl secretion?

PNS and ENS activate M3 receptors increasing Ca+ via g-protein

What endocrine stimuli will activate HCl secretion?

G-Cells -> Gastrin binds to CCK-B -> increase Ca2+ via Protein

Gastrin -> Histamine -> H2 Receptors increasing cAMP

Ca+ and cAMP will both stimulate what?

Proton pump

What will induce gastrin release?

AA and peptides

Stomach distention

Vagal stimulation

What will reduce parietal cell activation?

Stomach pH less than 2 will trigger neg feedback on Gcells resulting in less HCl production

Somastatin and prostaglandin downreg HCl production

Prostaglandin will be produced by ____ cells and inhibits ____ and ____ cells?

Epithelial cells, inhibits ECL cells and G cells

Somatostatin will inhibit what?

cAMP production

What will stimulate pepsinogen?

PNS on chief cells

Gastrin on chief cells

Secretin from duodenum on chief cells

Pepsinogen is produced by ____ cells and is an ___ form that is stored in ____?

Chief cells,

inactive form

Zymogen granules

Why is pepsinogen a proenzymes?

To prevent auto digestion of the stomach wall

What is going to activate pepsinogen to pepsin?

HCl