Flashcards in Hormones Deck (52):
What is the function of the hormone secretin?
Stimulates release of bicarbonate by binding to secretin receptors on pancreatic centroacinar cells
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
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.
What is the function of the hormone gastrin?
Simulates parietal and chief cells
Stimulates muscle contraction (stiring and ejection)
What is the function of pepsin?
It is a protease enzyme, which works optimally at pH 1.5-2
What is the function of the hormone somatostatin?
Inhibits gastrin/ secretin secretion
Inhibits parietal cells
(Neuronally turned off during digestion)
Where is the hormone secretin produced?
S-cells of the duodenum
(released when low pH in duodenum)
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
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)
Which cells secrete the hormone somatostatin?
Delta cells in pancreas
D-cells in stomach antrum
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)
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
Where is the hormone motilin produced?
Endocrine M-cells (in duodenum and jejunum)
Where is the hormone gastrin produced?
G- cells (most abundant in gastric pits of pyloric antrum)
Where is the enzyme pepsin produced?
Produced from pepsinogen which is secreted by chief cells
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
What effect does serotonin have on the GI system?
Causes contraction of intestinal muscle around the food
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+)
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)
Where is calcitonin produced?
Parafollicular cells (C-Cells) of the thyroid
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?)
From Zona Glomerulosa (outermost layer)
What stimulates the release of adrenaline from the adrenal glands (and which layer of the adrenal gland?)
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?
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?
(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?
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)
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)
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+