Non-endocrine gland endocrinology Flashcards by Leah Stevenart

What are the incretins?

Gastric-inhibitory peptide (GIP)
Glucagon like peptide (GLP-1)

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Where is gastrin produced from?

G cells in duodenum and stomach

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What is the stimuli that causes gastrin secretion?

Presence of peptides and AAs in gastric lumen
Stomach distension
Vagal stimulation
Hypercalcaemia

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What are the major effects of gastrin?

Stimulates release of gastric acid from parietal call - decreased pH
Stimulates release of pepsinogen from chief cells

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Why is gastric secretion inhibited at ~pH3

Further decrease in pH can cause gastric ulceration

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What is the clinical relevance of gastrin in cats and dogs

Gastrinomas - tumours in gastric secreting cells
Leads to excessive gastrin production => vomiting, inappetance, abdominal pain

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Where is secretin produced?

duodenum

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What stimuli causes secretin secretion?

H+ in SI/acid from stomach

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What is the major effect of secretin?

Stimulates release of bicarbonate-rich pancreatic and biliary fluid to buffer gastric acid

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Where is cholecystokinin (CKK) produced?

duodenum
Brain cells

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What is the stimuli for CCK (cholecystokinin) release?

fatty acids, monoglycerides and AAs in SI
Expansion of stomach after meal => CCK in brain

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Where is gastric inhibitory polypeptide (GIP) produced?

Proximal SI

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What is the stimuli that causes the secretion of GIP (gastric inhibitory polypeptide)?

Fat, glucose and AAs in SI

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What are the major effects of GIP (gastric inhibitory polypeptide)?

Inhibits gastric secretion and motility
Increases release of insulin in response to elevated blood glucose levels
Increases insulin sensitivity of adipocytes
Stimulation of lipoprotein lipase activity in adipocytes

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Where is GLP-1 (glucagon like peptide) produced?

L-cells of ileum and jejunum

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What stimulates GLP-1 (glucagon like peptide) secretion?

CHO, fat and protein in SI

What is the effect of GLP-1 (glucagon like peptide)

Promotes insulin secretion
Suppresses glucagon driven gluconeogenesis
Slows gastric emptying
Promotes satiety/fullness in hypothalamus

Where is Ghrelin produced?

Stomach

What stimulus causes ghrelin secretion?

starvation

What is the action of ghrelin?

strong stimulant for appetite and feeding

Which nuclei of the hypothalamus is responsible for appetite regulation?

arcuate nucleus

What hormones control appetite?

Leptin causes satiety (anorexigenic)
Ghrelin stimulates appetite (orexigenic)

What is the action of the satiety and appetite centres in the hypothalamus?

Satiety centre:
- respond to high glucose levels
- inhibits eating
Appetite centre:
- responds to low glucose levels
- stimulates eating

How do ghrelin and leptin regulate appetite?

Insulin and leptin interact with POMC in arcuate nucleus of hypothalamus to inhibit appetite
Ghrelin inhibits insulin and leptin

What are the effects of having no leptin production/response?

hyperphagic - always hungry => obesity Hypothermic Infertile

What is the effect of CCK

Released rapidly in response to a meal: - stimulates gallbladder contraction - secretion of pancreatic enzymes and bicarbonate - slows gastric emptying - inhibits gastric acid secretion - reduces food intake

What are the most relevant adipose hormones?

Leptin Adinopectin

What is action of adinopectin?

improves insulin sensitivity low in obesity and insulin resistant states

What are the renal hormones?

Erythropoietin Renin Calcitriol

What is the source, stimuli and function of erythropoietin

Produced by interstitial fibroblasts of kidney Response of hypoxia Promotes RBC production

What is the source, stimuli and action of renin?

Produced by juxtaglomerular cells of kidney Respond to decreased arterial pressure Initiate RAAs to improve/increase blood pressure and volume

Describe the renin-angiotensin aldosterone system

what are the heart hormones/natriuretic peptides

BNP ANP

What is the source of BNP?

ventricular cardiomyocytes

What is the stimuli for BNP secretion?

stretch of ventricles caused by increased blood volume

What is the action of BNP?

reduced vascular resistance (lower BP) Affects afferent and efferent glomerular arterioles to increase hydrostatic pressure and promote GFR Weakens medullary conc gradient (promote water loss) Promotes Na loss from kidney Reduces aldosterone production

what is Zollinger-ellison syndrome and what are the clinical consequences?

Excess gastrin Clinical consequences: - chronic gastric ulcers due to excess gastric acid - vomiting due to stomach acidity - diarrhoea - acid secretion irritates intestines - Weight loss - dehydration - abdominal pain - inappetance - Haematemsis (vomiting blood)