whats the volume rate of gastric secretions? - Between meals - Eating / food in stomach

- Slow rate (15-30 mls/hr) - Superimposed on basal rate (150 mls/hr)

Lecture 25 GI Physio Secretion Flashcards by kayla w

what are the Major EXOCRINE secretions?

Enzymes
Mucus
Electrolyte (serous) solution

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whats the Functions of exocrine secretion?

Digest food
Dilute food
Optimal pH
Protection and lubrication

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exocrine secretions

whats the volume of saliva, stomach, pancreas, liver, and SI? (from least to most)

Liver = 0.5 L / day
Pancreas, Saliva, SI = 1.5 L/day
Stomach = 3L/day

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~8L/day + oral intake

RE- absorption important

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production of saliva

whats the 3 pairs of salivary glands?

Parotid gland
sublingual gland
submandibular gland

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whats the volume and rate of saliva?

1.5 L day-1

Rate

Basal 0.3 ml/min
Stimulated - 1.5 ml/min

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whats the composition of saliva?

Mucus (lubrication)
Dilution solution of NaHCO3 / NaCl
Enzymes (a-amylase, lipase)

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why do you have Dilution solution of NaHCO3 / NaCl in saliva?

dilution

optimal pH

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what enzymes in saliva?

a-amylase

lipase

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whats the functions of saliva?

Not essential
Lubrication
Hygiene
Digestion

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why do you need lubrication from saliva?

chewing

swallowin

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why do you need hygiene from saliva?

irrigation

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whats digestion from saliva?

dissolves food allows tasting

a-amylase

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how do you regulate of salivary secretion?

Nervous

Autonomic nervous system

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what does the Nervous do for regulation of salivary secretion?

Thought, smell, sight of food

Presence of food in mouth, chewing

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what does the Autonomic nervous system do for regulation of salivary secretions?

Parasympathetic
- Acetylcholine - copious volumes

Sympathetic
- Adrenaline - small volume of viscous fluid

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regulation of salivary secretions

Autonomic nervous system
Parasympathetic

Acetylcholine -

copious volumes

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regulation of salivary secretions

Autonomic nervous system
Sympathetic

Adrenaline -

small volume of viscous fluid

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whats the volume of gastric secretions?

2 - 3 L per day

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whats the volume rate of gastric secretions?

Between meals
Eating / food in stomach

Slow rate (15-30 mls/hr)

- Superimposed on basal rate (150 mls/hr)

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whats the composition of gastric secretions between meals?

mainly mucus

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whats the composition of gastric secretions while eating / food in stomach?

NaCl / H2O
Acid 150 mM HCl, pH 1.0
Mucus
HCO3
Pepsinogen
Intrinsic factor

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for gastric secretions

whats the function of mucus?

Protection against Abrasion and Acid

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for gastric secretions

whats the function of intrinsic factor?

Absorption of Vitamin B12 in small intestine

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for gastric secretions whats the function of pepsin?

Secreted as pepsinogen Converted to active form pepsin by acid Starts digestion of proteins

for gastric secretions whats the function of Gastric acid?

``` Denatures protein Activates pepsinogen to pepsin Optimum pH for pepsin Protection Dilutes food ```

what do surface cells secrete?

mucus / HCO3

what do chief cells in the gland secrete?

pepsinogen

what do parietal cells in the gland secrete?

acid | intrinsic factor

regulation of gastric secretion whats it coordinated with?

eating and arrival of food

regulation of gastric secretion what are the 3 phases?

cephalic gastric intestinal

whats the cephalic phase?

head controls secretion ~20% of secretion associated with meal preparation stimuli - Higher centres (though, smell, sight) - chewing action / taste

whats the cephalic phase respond systems?

parasympathetic NS | modifies activity of ENS - stimulates motility and secretion

cephalic phase diagram

sight and of food, and stimulation of taste and smell receptors ⟶ cerebral cortex ⟶ hypothalamus and medulla oblongata ⟶ vagus nerve

whats the cephalic phase stimuli?

- Higher centres (though, smell, sight) | - chewing action / taste

whats the gastric phase?

stomach controls secretion ~70% of secretion associated with a meal ensures sufficient secretion to handle the ingested food

whats the gastric phase stimuli?

stretch / distension | products of digestion

what does the gastric phase responds to?

local reflex - ENS | external reflex - para NS

what does the local reflex (ENS) and external reflex (para NS) of the gastric phase stimulate?

motility and secretion

whats the intestinal phase?

intestine regulates secretion ~10% of secretion associated with the meal controls delivery to SI (-'ve feedback)

whats the intestinal phase stimuli?

distention of duodenum | arrival in duodenum of: Acid and products of digestion

what does the intestinal phase respond to?

Hormones - GIP, CCK and secretin Nerves - enterogastric reflex

what does Hormones - GIP, CCK and secretin, and Nerves - enterogastric reflex of the intestinal phase do?

Inhibit motility and secretion

what phase inhibits motility and secretion?

Intestinal phase

what phase stimulates motility and secretion?

cephalic - modifies activity of ENS Gastric - ENS (local reflex) and para NS (ext reflex)

what phase has the most secretion associated with a meal?

``` gastric = 70 cephalic = 20 intestinal = 10 ```

whats the volume of pancreatic secretions?

1-1.5 L/day

whats the composition of pancreatic secretions?

enzymes = acinar cells Alkaline fluid (HCO3) = made by ducts

what do acinar cells do?

act on all classes of food

what are some acinar cells enzymes? ``` for: Lipolytic Amylytic Proteolytic Nucleolytic ```

``` lipo = lipase, phospholipase amy = amylase proteolytic = trypsin, chymo, carboxypeptidase nucleolytic = ribonuclease, deoxyribonuclease ```

whats the function of acinar cells?

Chemically digest food material Pancreas most important source of digestive enzymes

what is enzyme (of acinar cells) secretion stimulated by?

CHOLECYSTOKININ | CCK

what are proteolytic secreted as?

inactive precursor

proteolytic secreted inactive precursor whats it for Trypsin Chymotrypin Carboxypeptidase

Trypsinogen chymotrypsinogen procarboxypeptidase

what does trypsin do in SI?

activates other enzymes

in SI | how is trypsinogen converted to trypsin?

by enterokinase (enteropetidase) bound to the duodenal membrane

whats Alkaline fluid (HCO3) - ducts?

Neutralises chyme (acidic – from stomach) Creates optimum pH (6.7 – 9) for pancreatic and intestinal enzymes. made by duct cells stimulates secretin

whats secretin?

stimulates HCO3 secretion

what produces isosmotic HCO3 rich solution?

duct cells

Regulation of pancreatic secretion Slow basal rate during fasting. what type of regulation occurs during a meal?

Hormonal

Regulation of pancreatic secretion. what hormones are secreted for Hormonal regulation during meal?

CCK (Cholecystokinin) | Secretin

whats CCK (Cholecystokinin)?

Produced by duodenal endocrine cells in response to digestive products in lumen - amino acids, fats, carbohydrates Stimulates enzyme secretion by acinar cells

wheres CCK produced?

by duodenal endocrine cells in response to digestive products in lumen - amino acids, fats, carbohydrates

what does CCK do?

Stimulates enzyme secretion by acinar cells

whats Secretin?

Produced by duodenal endocrine cells in response to increased [H+] in lumen Stimulates HCO3 secretion by duct cells

wheres secretin produced?

by duodenal endocrine cells in response to increased [H+] in lumen

what does secretin do>

Stimulates HCO3 secretion by duct cells

whats the volume of biliary secretion?

0.5 L/day | produced in liver

what are the Products associated with digestion in liver / biliary secretion?

Bile salts & lecithin HCO3 rich fluid - secreted by duct cells

what are the Excretory products in liver / biliary secretion?

Bile pigments - waste products | Cholesterol - excreted by liver

whats the function of bile?

Bile salts and lecithin - Fat digestion and absorption HCO3 rich fluid - Neutralizes acid chyme Bile pigments - Excretion

whats the function of Bile salts and lecithin?

Fat digestion and absorption

whats the function of HCO3 rich fluid?

Neutralizes acid chyme

whats the function of Bile pigments?

Excretion

where is bile delivered and what control is it under?

to duodenum when food is present. Hormonal control

delivery of bile is under hormonal control. what hormone and how?

CCK (cholecystokinin) products of digestion in duodenum contraction of gall bladder Relaxation of duodenal papilla (sphincter of Oddi)

what is the volume of the SI secretion?

1.5 L/day

what does the SI secrete and why?

Mucus - Lubrication NaHCO3 solution (+ NaCl) - Neutralise acid - Dilute food

what does the LI secrete and why>

Mucus | - lubrication

GI secretion what are the Major EXOCRINE secretions?

Enzymes Mucus Electrolyte (serous) solution

GI secretion whats the Functions of exocrine secretion?

Digest food Dilute food Optimal pH Protection and lubrication

Lecture 25 GI Physio Secretion Flashcards

(81 cards)