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Sem3: PHYS30240 GI and Renal Physiology > L5 Pancreatic Secretions and Spleen > Flashcards

L5 Pancreatic Secretions and Spleen Flashcards

1
Q

Which part of the Pancreas appears first?

A

Dorsal

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2
Q

Components of Dorsal Pancreas?

A

Body

Tail

Isthmus

Accessory pancreatic duct (Duct of Santorini)

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3
Q

Components of Ventral Pancreas?

A

Pancreatic head

Uncinate process

main pancreatic duct (Duct of Wirsung): becomes dominant after fusion

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4
Q

Condition in which the ductal systems of the dorsal and ventral buds do not fuse and the dorsal duct system remains well developed?

A

Pancreas Divisum

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5
Q

Endocrine cells of the pancreas that secrete insulin, glucagon other hormones into blood?

A

Islets of Langerhans

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6
Q

Exocrine cells of the pancreas that secrete Aqueous and Enzymatic components of pancreatic juice?

A

Pancreatic Acini / Duct cells

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7
Q

The Aqueous component of Pancreatic secretions comes from what cell?

A

Centro-Acinar Duct Cells

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8
Q

The Enzymatic component of Pancreatic Secretions come from what cell?

A

Acinar Cells

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9
Q

Role of Aqueous component of pancreatic secretions

A

High levels of Bicarbonate (HCO3-) neutralizes gastric acid in chyme

Release stimulated by hormone Secretin

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10
Q

What triggers the release of aqueous component of pancreatic secretions?

A

Release stimulated by hormone Secretin

S- cells perceive a change in pH as chyme enters the duodenum => Release secretin => Inhibits gastric motility and stimulates the secretion of Aqueous component from duct cells w/ bicarbonate to neutralize acid

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11
Q

What is required to facilitate the accumulation of CL- in the lumen of the pancreatic duct to allow normal pancreatic bicarbonate secretion?

A

Apical CFTR Cl Channel is required for secretion of Bicarbonate

In Cystic Fibrosis, CFTR-dependent chloride conductance is reduced leading to decreased pancreatic secretions

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12
Q

2 Sources of bicarbonate secreted by pancreatic centroacinar duct cells?

A

1) Intracellular Carbonic Anhydrase Activity
2) Basolateral import of bicarbonate via HCO3/Na Symporter

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13
Q

What is the ionic concentration of pancreatic juice dependent on?

A

When flow rate is LOW: Bicarbonate secretion concentration is LOW

When flow rate is HIGH: Bicarbonate secretion concentration is HIGH

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14
Q

Constituents of Enzymatic Component of Pancreatic Secretions?

A
  • Amylase
  • DNAase/RNAase
  • Elastase
  • 3 Lipases (Triacylglycerol hydrolase, Cholesterol Hydrolase, Phospholipase)
  • 3 Proteolytic Enzymes (Trypsinogen, Chymotrypsinogen,
    Procarboxypeptidase)
  • Trypsin inhibitor (keeps proteolytic enzymes inactive until in intestine)
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15
Q

3 Lipases within pancreatic secretions from acinar cells and their functions

_____=> 2 free fatty acids + monoglyceride

_____ => 1 free fatty acid + cholesterol

_____=> 1 free fatty acid + lysophosphatide

A

Triacylglycerol hydrolase => 2 free fatty acids + monoglyceride

Cholesterol ester hydrolase => 1 free fatty acid + cholesterol

Phospholipase => 1 free fatty acid + lysophosphatide

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16
Q

3 Proteolytic Enzymes in pancreatic secretions and their functions?

A
17
Q

What is Orlistat?

A

Orlistat is a lipase inhibitor used as a treatment for obesity. It prevents the hydrolyzation of triglycerides into fatty acids => dietary lipids cannot be absorbed in the gut

18
Q

What is Olestra?

A

Olestra is a synthetic “fat” composed 7-8 fatty acids attached to a sugar backbone. It is inaccessible to lipases and cannot be broken down into fatty acids => Passes through the GIT unabsorbed

19
Q

Controls of Intestinal Phase of Pancreatic Secretion?

Proportion of secretions?

A
  • Products of protein and fat digestion in duodenum => Secretion of CCK by I-Cells (Duodenum/Jejunum) => Enzyme-rich secretions by Pancreatic Acinar Cells and Vagal sensory Activation
  • Low pH in Duodenum => Secretion of Secretin by S-Cells => Secretion of Bicarbonate-rich fluid by Pancreatic Duct Cells
  • >70% of secretions
20
Q

Control of the Gastric Phase of Pancreatic Secretion?

Proportion of secretions?

A

Distention of stomach=> Vago-Vagal Reflex => Secretion of Gastrin by G-Cells and ACh from nerve endings => Enzyme-rich secretions by Pancreatic Acinar Cells

<10% of secretions

21
Q

Control of Cephalic Phase of pancreatic secretion?

Proportion of secretions?

A

Sight/Smell/Taste of food => Parasympathetic vagal activity => Secretion of ACh by nerve endings and Secretion of Gastrin by G-Cells=> Enzyme-rich secretions by Pancreatic Acinar Cells

<20% of Secretions

22
Q

Hormones that regulate pancreatic secretion?

A

Gastrin released from G- Cells due to distention of stomach/vagal stimulation => Enzyme-rich secretions by Pancreatic Acinar Cells

Secretin released by S-cells when acid is in the Duodenum => Secretion of Bicarbonate rich fluid by Duct Cells

CCK is released by I-Cells when fat/protein is in Duodenum/Jejunum => Enzyme-rich secretions by Pancreatic Acinar Cells / Bicarbonate rich fluid by Duct Cells

23
Q

What Causes Pancreatitis? Acute vs. Chronic?

A

Premature activation of Trypsin within the Pancreas

  • Acute: Gall Stones
  • Chronic: Alcohol/Infection
24
Q

Diagnosis of Pancreatitis?

A

Measurement of serum lipases is a more reliable indicator (High sensitivity, low false negative rate)

Raised enzyme levels could also be due to renal disease (reduced clearance) => Normalize enzyme values to creatinine to rule out

25
Q

What is the largest accumulation of lymphoid tissue in the body?

A

Spleen

26
Q

Functions/Histology of the Spleen?

A
  • Filters Blood
  • Protection against blood-borne antigens
  • Produces antibodies + activated lymphocytes
  • Iron homeostasis (Heme – metabolism to bilirubin)

White Pulp (20% ) - Lymphoid cells

Red Pulp (80%)- Splenic Sinusodis (RBC removal and iron recycling)

27
Q

What Triggers Pancreatic Enzyme Secretion?

A

Intestinal Fatty Acids and Amino Acids => CCK Secretion by I Cells of Duodenum/Jejunum

Sem3: PHYS30240 GI and Renal Physiology (24 decks)

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