Hormones Flashcards by James Adams

What is the function of the hormone secretin?

Stimulates release of bicarbonate by binding to secretin receptors on pancreatic centroacinar cells

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What is the function of the hormone CCK?

Inhibits gastric emptying and decreases acid secretion
Stimulates the acinar cells of the pancreas to release digestive enzymes and stimulates the secretion of a juice rich in pancreatic digestive enzymes

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What is the function of the hormone motilin?

Increases the migrating myoelectric complex component of gastrointestinal motility
(Increased peristalsis and encourages intestine emptying)
Stimulate the production of pepsin.

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What is the function of the hormone gastrin?

Simulates parietal and chief cells

Stimulates muscle contraction (stiring and ejection)

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What is the function of pepsin?

It is a protease enzyme, which works optimally at pH 1.5-2

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What is the function of the hormone somatostatin?

Inhibits gastrin/ secretin secretion
Inhibits parietal cells
(Neuronally turned off during digestion)

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Where is the hormone secretin produced?

S-cells of the duodenum

released when low pH in duodenum

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What is the function of the hormone VIP (vasoactive intestinal peptide)?

Smooth muscle relaxation and water secretion in intestines, stimulates bicarb/ pepsinogen secretion and inhibits gastrin
OVERALL IMPROVES MOTILITY

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What is the function of the hormone GIP (gastric inhibitory polypeptide)?

Stim’s release of insulin for pancreatic Beta cells

Also stim’s FA metabolism

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Which cells secrete the hormone somatostatin?

Delta cells in pancreas

D-cells in stomach antrum

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What is the systhesis pathway for active Vit D?

Vit D carried in blood stream to liver and converted into the pro-hormone calcidol
Calcidol is converted to calcitrol (Active vitD in the kidney)

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Where is the hormone CCK produced?

I cells located in the mucosal epithelium of the small intestine (mostly in the duodenum and jejunum)
- Stimulated by fatty acids/ some AA’s in chyme

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Where is the hormone motilin produced?

Endocrine M-cells (in duodenum and jejunum)

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Where is the hormone gastrin produced?

G- cells (most abundant in gastric pits of pyloric antrum)

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Where is the enzyme pepsin produced?

Produced from pepsinogen which is secreted by chief cells

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What is the function of the hormone calcitrol?

(Active form of vitD- release stim’d by PTH)
Raises blood calcium levels by increasing Ca2+ absorbtion in GI tract/ increasing renal reabsorbtion and releasing Ca2+ from bone

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What effect does serotonin have on the GI system?

Causes contraction of intestinal muscle around the food

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What is the function of the hormone calcitonin?

Decreases blood calcium levels
(Stimulates osteoblasts and inhibits osteoclasts)
(Inhibits GI absorbtion and renal reabsorbtion of Ca2+)

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What is the function of parathyroid hormone?

Increases blood calcium levels
(Stimulates osteoclasts to break down bone, inhibits osteoblasts)
(Activates vitamin D to increase GI Ca2+ absorbtion and promotes Ca2+ reabsorbtion in the kidney)

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Where is calcitonin produced?

Parafollicular cells (C-Cells) of the thyroid

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What stimulates the release of cortisol from the adrenal glands (and which layer of the adrenal gland?)

ACTH (from ant pituitary)

Released from Zona Fasiculata

What stimulates the release of sex steroids from the adrenal glands (and which layer of the adrenal gland?)

ACTH (from ant pituitary)

Released from Zona Reticularis

What stimulates the release of aldosterone from the adrenal glands (and which layer of the adrenal gland?)

Angiotensin II

From Zona Glomerulosa (outermost layer)

What stimulates the release of adrenaline from the adrenal glands (and which layer of the adrenal gland?)

Sympathetic stimulation

From adrenal medulla (central part)

What is the rate limiting step in cortisol synthesis?

Cholesterol - Pregnenolone | step is regulated by ACTH

What is the pre-cursor for all steroid hormones?

Cholesterol

What is the difference between peptide and steroid hormones in relation to their storage?

Peptide tend to be stored in a cell and released when stimulated by a trigger Steroid hormones are not stored

What effect does cortisol have on blood glucose?

Raises blood glucose

What type of hormone is aldosterone and how does it act?

Steroid hormone- Acts in kidney to preserve Na (therefore H2O) and raise blood pressure Also stimulated re-absorption of Na exchanged for K+ in the gut, saliva and sweat

What happens to aldosterone levels in hyperkalaemia?

Raised | All aldosterone causes excretion of K+

When is the best time to measure cortisol levels (in what form) and why?

Midnight in blood/ saliva | As normally low then so if raised very likely to be cushings syndrome

What is the action of ADH? Where is it released from? | aka vasopressin

Synth in hypothalamus, stored in post pituitary Inserts more Aquaporin(2) channels in kidney Causes SM vasoconstriction in BV's Acts to raise BP and concentrate urine

What is a short synacthen test?

Give ACTH and then measure cortisol 30min later | This should stim cortisol production

A patient on lifelong hydrocortisone to treat addisions disease is likely taking what doses and when?

10mg each morning | 5mg at lunchtime

The majority of hormonal feedback is what? | positive or negative

Negative

What is a low dose dextamethosone suppression test?

Give 1mg Dext at 12am | By 9am cortisol should be suppressed (measure levels at 9am)

Which cells produce GIP (gastric inhibitory polypeptide)? What is it secreted in response to?

K cells in duodenum | in response to glucose detected in duodenum

Where is GLP-1 secreted from? What stimulates it's secretion?

L cells of ileum | Nutrients (carbs, proteins, lipids) passing through Ileum

What is a secreteagouge?

An agent which causes or stimulates secretion

What is an incretin?

A metabolic hormone which stimulates release of insulin (from pancreatic B cells) This lowers blood glucose levels

What is the half life of GLP-1 and why is this?

Half-life of less than 2 minutes | Due to rapid degradation by the enzyme dipeptidyl peptidase-4

What is GLP-1 and what are it's functions?

Glucagon-like peptide 1 (An incretin) - Increases insulin secretion (+ increase B cell mass) - Decreases glucagon secretion - Decreased stomach emptying/ acid secretion - Increase satiety in brain (so don't take in more glucose)

What is glucagon and where is it produced?

Glucagon is a peptide hormone which raises blood glucose | It's secreted by alpha cells of the pancreas

What stimulates glucagon secretion?

Low blood glucose levels

What effects does glucagon have?

Glycogenolysis (in liver) Gluconeogenesis Induces lipolysis if there is insulin supression (DMT1)

What effect does glucagon have on the liver?

Stimulates glycogenolysis by binding with glucagon receptors on hepatocytes

Where is serotonin produced in the GI tract?

The gut is surrounded by enterochromaffin cells, which release serotonin in response to food in the lumen.

Where is the hormone calcitrol released from?

Proximal tubule in the kidney | Release is stimulated by PTH

Where is PTH secreted?

Chief cells of parathyroid

What is the Henderson-Hasselbalch Equation used for?

Calculating pH (especially of buffer systems)

What two things will stimulate aldosterone?

Increased angiotensin II | Increased serum K+

The peptide hormone secretin is released in response to?

Acidification of the duodenum