Physiology 2 - Adrenal cortex + medulla
Which part of the adrenal gland is innervated by the autonomic system?
Medulla
Role of hippocampus
Memory formation
Characteristics of Cushing's syndrome
Moon face, buffalo hump, obese trunk/head/neck, thin extremities, DM, osteoporosis
Location of GLUT3
Neuron
Which substance inhibits nicotinic ach receptors?
Nicotine
What kind of receptors are on the adrenal medulla?
Nicotinic acetylcholine receptors
Which enzymes are required for the synthesis of androgens/sex hormones from progesterone?
None
Which hormones are produced by the hypothalamus?
Oxytocin, TRH, CRH, GnRH, GHRH, ADH
What stimulates calcitriol?
PTH
Steps of synthesis of corticosterone from progesterone
Progesterone -> 11-desoxyxorticosterone -> corticosterone
Which hormone in the anterior pituitary is not affected if the portal circulation is blocked?
Prolactin
What causes iatrogenic Cushing's?
Prolonged glucocorticoid therapy
Which factors can activate the stress-axis?
Psychological stress Physical stress: extreme exercise, pain, hypoglycemia
Location of GLUT 1
Red blood cells and blood brain barrier
What is the inner layer of the adrenal cortex?
Reticular zone
Effect of increased corticsol on CNS
Sleepiness, depression
Which hypothalamic nuclei produce oxytocin and ADH?
Supraoptic and paraventricular nuclei
Which hormones are present in a bigger concentration in the portal circulation than in the peripheral circulation?
TRH
Which hormones are produced in the anterior pituitary?
TSH, ACTH, LH, FSH, GH, prolactin
Why does 11-beta-hydroxylase deficiency cause non-salt losing form of androgenital-syndrome?
The production of 11-desoxycorticosterone and corticosterone is not inhibited since 21-beta-hydroxylase is present. 11-desoxycorticosterone and corticosterone have a reduced but similar effect as aldosterone
How do glucocorticoids cause high blood pressure?
They increase the sensistivity of adrenergic receptors and increase water and salt retention
Difference between type one and two Addison's disease
Type one causes hyperpigmentation, not the secondary type
Effect of ADH on V1, V2, and V1-b receptors
V1: vasodilation V1-b: release of adrenocorticotrope hormone (ACTH) from the anterior pituitary V2: collecting tubules, water retention
Why do glucocorticoids cause decreased calcium content in bones?
Via inhibition of osteoblasts
How does GnRH reach the anterior pituitary gland?
Via portal vessels
Which vitamin is required for the production of steroid hormones from cholesterol?
Vitamin C
Other names for calcitriol
Vitamin D and 1,25 dihydroxycholecalciferol
Where is calcitonin produced?
parafollicular cells of the thyroid gland (c-cells)
What kind of cells are in the adrenal medulla?
chromaffin cells which produce catecholamines (adrenaline, noradrenaline and dopamine)
Effect of hyperparathyroidism on urine
decreased calcium concentration-increased phosphate concentration
What inhibits prolactin?
dopamine
What does the fasciculate zone secrete?
glucocorticoids (cortisol) and androgens
Effect of hyperparathyroidism on plasma
increased calcium concentration-decreased phosphate concentration
Function of aldosterone
increases Na+ reabsorption, K+ and H+ secretion
How does calcitriol increase blooc calcium?
increases calcium ansorption from the GI-increases calcium reabsorption in the kidneys
Effect of PTH
increases calcium reabsorption in the distal convoluted tubule-increases osteoclast activity-decreases concentration of plasma phosphate
Effect of calcitonin of blood calcium
lowers blood calcium
What is the adrenal medulla?
modified sympathetic ganglion
Location of GLUT4
muscle and adipose tissue
Location of GLUT5
small intestine
Effect of increased sensitivity of adrenergic receptors
- Beta-1 receptors in the heart: increased HR, SV, CO, BP - Alpha-1 receptors in the vessels: increased TPR and BP
Which factors activate adrenocorticotropic hormone?
- CRH (hypothalamus) - catecholamines (adrenaline, noradrenaline) - ADH/vasopressin (via V1-b receptors)
Organs involved in the stress axis and their corresponding products
- Hypothalamus: corticotropin releasing hormone (CRH) - Anterior pituitary: adrenocorticotropic hormone (ACTH) - Adrenal cortex: cortisol(glucocorticoid)
Which hormones does pro-opiomelanocortin (POMC) gene produce?
-Adrenocorticotrope hormone (ACTH) -Melanocyte stimulating hormone (MSH) -Lipoprotein hormone (LPH) -Beta-endorphin hormone
Functions of glucocorticoids (cortisol)
Increase of blood sugar via increasing gluconeogenesis Increasing glycogen synthesis decreased glucose uptake of cells increased proteolysis amino acid release from skeletal muscle lipolysis in limbs (central shift of adipose tissue) surfactant production by type II pneumocytes increased sensitivity of adrenergic receptors decreased calcium in bones increased sensitivity of mineralocorticoid receptors (water and salt retention) inmmunosuppressiv effect decreased WBC decreased interleukin levels decreased C-reactive protein levels
Effect of Cushing syndrome
Increased cortisol levels
Effect of acidosis on concentration of free calcium
Increased, plasma proteins bind H+
Effect of PTH on calcium levels on blood calcium
Increases blood calcium
Effect of calcitriol on blood calcium
Increases blood calcium
Effect of ACTH on CRH
Inhibition
Effect of cortisol on ACTH
Inhibition
Effect of cortisol on CRH
Inhibition
Effect of insulin on hormone sensitive lipase
Inhibition
Effect of insulin on lipolysis
Inhibition
How does PTH decrease plasma phosphate?
It inhibits the Na+/PO4 2- cotransportes in the proximal convoluted tubule
Effect of pheochromocytoma (adrenal medulla tumor)
-increased BP -hyperglycemia -mydriasis (pupil dilation) -piloerection -increased HR, BP, SV, CO, TPR -decreased blood flow to GI, urogenital tract, and skin -increased blood flow to skeletal muscle and coronary aa -decreased gastric motility and secretion of gastric juice -sphincter contriction -uterus and urinary bladder relaxation
Acute stress reactions
-increased blood glucose via B2-receptors on the liver -increased FFA via B3 receptors in adipose tissue -pupil dilation via A1 receptors on dilator pupil m. -piloerection via A1 receptors on erector pili -increased HR, SV, CO, BP via B1-receptors in the heart -increased TPR via A1-receptors on vessels (vasoconstriction) -decreased blood flow to GI, urogenital tract, skin via A1-receptors -increased blood flow to skeletal muscle and coronary aa via B2-receptors -decreased gastric motility and gastric juice production -sphincter constriction via A receptors -uterus and urinary bladder relaxation via B2-receptors
Extracellular concentration of free calcium ions
1,1-1,4 mmol/l
Enzyme required for synthesis of aldosterone from corticosterone
11-beta hydroxylase
Which enzymes are present in the zona fasicularis and reticularis?
17-alpha-hydroxylase
Which enzyme in the glomerular zone of the adrenal cortex is responsible for the production of aldosterone?
18-aldehyde oxygenase enzyme
Total concentration of extracellular calcium
2,2-2,8 mmol/l
Enzyme required for synthesis of corticosterone from progesterone
21-beta-hydroxylase
Which enzymes are required for the synthesis of glucocorticoids (cortisol) from progesterone?
21-beta-hydroxylase and 11-beta-hydroxylase
Causes of androgenital syndrome/virilism (androgen overproduction)?
21-beta-hydroxylase deficiency, 11-beta-hydroxylase deficiency, androgen producing tumor, hyperactivation of reticular zone
Enzymes required for the synthesis of aldosterone from progesterone
21-beta-hydroxylase, 11-beta-hydroxylase
Which hormones are secreted by the posterior pituitary?
ADH and oxytocin
Causes of primary Addison's disease
Adrenal cortex failure
Which molecules can be synthesized from cholesterol?
Aldosterone/mineralocorticoids, cortisol/glucocorticoids, and androgens/sex steriods
Effect of 21-beta-hydroxylase enzyme deficiency on the synthesis of mineralocorticoids (aldosterone) and glucocorticoids (cortisol)
Androgenital syndrom (virilism), salt-losing form
Effect of 11-beta-hydroxylase enzyme deficiency
Androgenital syndrome, non-salt-losing form
Which molecules are synthesized in the case of 21-beta-hydroxylase deficiency?
Androgens/sex steroids
What stimulates the production of aldosterone?
Angiotensin II, hyperkalemia, hyponatremia, ACTH (adrenocorticotroph hormone)
Why does 21-beta hydroxylase deficiency result in salt-losing form of virilism?
Because no aldosterone is produced and therefore less Na+ is reabsorbed
Location of GLUT2
Beta cells of pancreas, liver, kidneys, and small intestine
Effect of decreased corticsol on CNS
Brain malfunctions
How are catecholamines metabolized?
By MAO-A (monoamino oxydase), MAO-B, and COMPT (cathecolamine ortho-methyl transferase)
Causes of secondary Addison's disease
CRH deficiency -> low ACTH -> low cortisol-ACTH deficiency -> low cortisol
Reasons for secondary Cushing syndrome
CRH overproduction -> increased ATCH -> high cortisol-ACTH overproduction -> high cortisol
Where is PTH produced?
Chief cells of parathyroid gland
How is aldosterone synthesized from cholesterol?
Cholesterol -> pregonolon -> progesterone -> 11-desoxy-corticosterone -> corticosterone -> aldosterone
Why does adrenal cortex cause hyperpigmentation?
Corticsol inhibits ACTH, without it the levels of ACTH will increase. This causes increased transcription of propriomelanocortin gene which stimulates MSH, causing hyperpigmentation
Which hormone is affected by addison's disease and in what way?
Cortisol levels are decreased
Reasons for primary Cushing syndrome
Cortisol overproduction
Effect of increased amino acid release from skeletal muscle as a result of glucocorticoid exposure
Decreased muscle mass and increased gluconeogenesis
Effect of alkalosis on concentration of free calcium
Decreased, plasma proteins release H+ and bind calcium
Why does adrenal cortex cause low BP?
Due to unresponsiveness of catecholamines, water and electrolyte imbalance
Which organs produce calcitriol?
Liver, kidneys, skin
Characteristics of GLUT2
Low affinity (blood glucose should be higer than normal) and high capacity (a lot of glucose molecules can be taken up to produce adequate amount of insulin)
What is the middle layer of the adrenal cortex?
Fasciculate zone
What do acidophil cells in the anterior pituitary release?
GH and prolactin
Which type of glucose transporter is insulin dependent?
GLUT4
In which zone of the adrenal cortex are mineralocorticoids produced?
Glomerular zone (outer layer)
Why does the long-term release of glucocorticoids cause an increase in glycogen synthesis?
Glycogen is synthesized in preparation for acute stress and the increased need for glucose this requires.
Which hormones are transported from the hypothalamus to the anterior pituitary via the portal circulation?
GnRH, GHRH, TRH, CRH
What stimulates the production of calcitonin?
Hypercalcemia
Side effects of increased glucocorticoids
Hyperglycemia (steroid DM), muscle loss, central shift of adipose tissue, osteoporosis, high blood pressure, gastric ulcer, weak immune system
What stimulates PTH?
Hypocalcemia
Effect of adrenal cortex failure (no glucocorticoids/mineralocorticoids)
Hypoglycemia, low blood pressure, inadequate stress response, hyperpigmentation
Where is the gonadotrope releasing hormone (GnRH) released?
Hypothalamus
How does calcitonin act?
It acticated osteoblasts and calcium is absorbed into the bone
Effect of Conn-syndrome (hyperaldosteronism)
High BP, hypokalemia, high blood pH (metabolic alkalosis), low levels of free calcium
Target organs of aldosterone
Kidneys (collecting ducts), salivary glands, sweat glands, colon, and gallbladder
Effect of GnRH from hypothalamus on anterior pituitary gland
Stimulates release oof FSH and LH
Effect of insulin on lipoprotein lipase
Stimulation
Innervation of adrenal medulla
Sympathetic preganglionic fibers (Ach)