GI secretions Flashcards by Michael Gallagher

How does our food digest and enter cells.

we break them down into tiny pieces (digestion) absorb them across the gut epithelium transport them via blood

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list the functions of gastrointestinal secretions

-chemical digestion
-lubrication
-signalling
-protection
-activation of enzymes
-excretion of waste

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state the differences between exocrine and endocrine glands

exocrine glands-produce and secrete substances onto and epithelial surface by way of a duct

endocrine glands-secrete their products, hormones, directly into blood rather than a duct

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describe the gastrointestinal secretions of salivary glands

secretion of lubricating fluid containing, containing enzymes that breakdown carbohydrates

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describe the gastrointestinal secretion of the gastric

acid, pepsin and gastric lipase

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describe the gastrointestinal secretions of liver/gallbladder

secretion, storage and modification of bile

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describe the gastrointestinal secretions of pancreas

exocrine cells secrete buffers and digestive enzymes, endocrine cells secrete hormones

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describe gastrointestinal secretion of the small intestine

secreton of digestive enzymes

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describe the major salivary glands

-3 pairs of major salivary glands (partoid) (submandibular) (sublingal)
-exocrine glands ie secrete saliva via a duct

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describe the minor salivary gland

-600-1000 minor salivary gland
-mucousal lining of oral cavity, lips and cheek palate
-each is an individual exocrine gland with its own duct

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descibe the composition of saliva

-99.4% water (remaining 0.6% contain)
-mucins
-electrolytes (Na+, Cl-, HCO3-)
-antibodies
-enzymes-amalayse

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list the functions of saliva

-buffer-ions keep pH at 7
-keeps mucosa moist-protects against mechanical damage and essential for speech
-solvents-dissolve chemicals i food to aid detection by taste receptots

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what is xerostomia and the symptoms

sensation of dryness in the mouth often assoiciated with problems in saliva production.

-acid erosion of teeth
-dysphasia
-infection
-dysgeusi dysosmia
-cracked lips

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what controlls the production of sliva

the autonomic nervous system, activation of both parasympathetic and sympathetic divisions cause salivation

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what role does the parasympathetic nerves play in salivation

modulate volume of fluid secreted

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what role do the sympathetic nerves play

modulate the composition of saliva (amalayse,LgA)

what is the properties of gastric secretions and what is it composed of

-stomach produces endocrine and exocrine secretions
-gastric juice aids stomach

-water
-hydrochloric acid (HCl)
-pepsinogen
-intrinsic factor
-mucus

name the 2 gastric gland cells

-parietal cells
-chief cells

describe the properties of parietal cells

SECRETE INTRINSIC FACTOR
-needed for absorption of vitamin B12
SECRETE HCl
-ph 1.3
-kills microbes
-denatures proteins
-activates enzymes

describe the properties of chief cells

SECRETE PESINOGEN
-converted to pepsin-active form
-breaks certain peptide bonds
SECRETE GASTRIC LIPASE
-splits short chain triglycerides into fatty acids and monoglycerides

describe the mucous cells in the gastric gland

SECRETE MCOUS
-forms a protective barrier
-has alkaline properties
SUPERFICIAL EPITHELIA
MUCOUS NECK CELLS

what is the percentage of endocrine and exocrine secretions in the pancrease

(endocrine 2% of cells)
(exocrine 98% of cells)

what is released from exocrine glands in the pancreasv

1.2-1.5L of pancreatic juice/day
-WATER
-BICARBONATE (NaHCO3)-alkaline (pH 7.1-8.2)

what enzymes are do the exocrine glands realease in the pancreas

pancreatic amalayse-digetists starches
pancreatic lipase-digests fat
ribonucleoase-digest RNA
deoxyribonuclease

name and describe the enzymes in the pancreas

-amalayse, lipases, nucleases are secreted in active form but require ions and bile for ptimal activity -proteases secreted in inactive form and activated in duodenum --trypsiogen is activated to trypsin by brush border enzyme enteropeptidase --procarboxypeptidase and chymotrypsinogen are activated by trypsin

what cells are released from the endocrine glands in the pancreas when theres a fall in glucose levels

alpha cells- secrete GLUCAGON in response to a fall in blood pressure which stimulates and glycogenolysis and gluconeogenesis

what cells are released from the endocrine glands in the pancreas when theres a rise in blood glucose

beta cells- secrete insulin in response to a rise in blood glucose, inhibited by adrenaline in acute stress -allows cells to utilise glucose

when is somatostatin released from the endocrine gland in the pancrease

-stimulated by cholingeric innervation -inhibits gastrin release

draw and annotate the liver and gallbladder

refer to pic on GI powerpoint

what is the function of hepatocytes

-they have several functions, including bile production -hepatocytes--bile canaliculi--bile ductules--bile ducts

what type of tissue do hepatocytes belong too

epithelial cells

what are the properties of bile

-800-1000mL per day -pH 7.6-8.6 -digestive secretion -excretory product

what does bile contain

-bile salts -bilirubin -cholesterol, neuteral fats, phospholipids and electrolytes

what are the functions of bile

-lipid assimilation -elimination -neutralise gastric acid and provide optimum pH for pancreatic enzymes

describe the gallbladder

-thin walled, pear shaped, muscular sac on the ventral surface of liver -stores and concentrates bile by absorbing its water and ions -releases bile via cystic duct, which flows into bile duct

what are the 3 phases in secretion regulation

cephalic phase Gastric phase intestinal phase

describe the cephalic phase

-smell,sight,taste of food activates the CNS -facial, glossopharyngeal and vagus nerves are activated -salivary and gastric glands are activated -prepares mouth and stomach for food

describe the gastric phase

-food distends the stomach and stimulates stretch receports -chemoreceptors in stomach detects increase pH -peristalis and gastric juice secretion -chyme empties into duodenum - decrease pH and decrease distension -negative feedback loop

describe the intestinal phase

-begins when food enters small intestine -inhibits exit of chyme from stomach (inhibition of gastric motility. contraction of pyloric sphincter) -promotes digestion of food in SI -neural enterogastric reflex -hormonal elemnt (CCK and secretin)