Endocrinology 7 and 8 Flashcards
What are two important posterior pituitary hormones?
- ADH (antidiuretic hormone or vasopressin)
* Oxytocin
What is the major source of Antidiuretic hormone?
SON
What is the major source of Oxytocin?
PVN
What is the target of ADH?
- Kidney
* Blood Vessels
What is the target of Oxytocin?
- Uterus
* Mammary glnda
What cells do ADH act on in the kidneys?
Principle cells
Which receptor do ADH bind to?
The ADH receptor V2
What kind of receptor is the ADH V2 receptor?
A G-protein linked receptor
What does the binding of ADH to the receptor do?
Increases the amount of cAMP
What is the purpose of ADH?
To cause the insertion of water channels into the cell to allow water to be reabsorbed
Where on the cell are ADH receptors?
On the basal side
What does Vasopressin/ADH do?
It binds to the receptor on the basal membrane of cells lining the lumen and it is g-protein-linked and increases cAMP. This then increases pka which causes water channels (aquaporin two) to be inserted into the apical side to allow water to diffuse out and be reabsorbed
How does ADH affect Blood Volume and Pressure?
It decreases osmotic pressure on ECF by increasing volume of ECF and blood pressure
What causes increased release of ADH?
- An increase in osmotic pressure
* Decrease in BP and extracellular fluid
What receptors stimulate the brain to release ADH?
- Osmoreceptors in the hypothalamus detecting increased osmotic pressure of ECF
- Baroreceptors in the cardiovascular system detecting decreased volume of ECF and BP
What can happen if there is too much ADH?
There will be increased H2O retention and increased blood volume
What can happen if there is too little ADH?
- Central or neurogenic diabetes insipidus
* Nephrogenic diabetes insipidus
What is Central or Neurogenic Diabetes Insipidus?
Lack of ADH; large volume of dilute urine
What is Nephrogenic Diabetes Insipidus?
Abnormal ADH receptors in the kidney; a large volume of Dilute urine
What are the two major roles that oxytocin plays a part in?
- Parturition
* Lactation
What is the stimulus for the increased release of oxytocin?
The stretching of the cervix
What are the two main regions of the adrenal gland?
The outer cortex and the inner medulla
What are the three regions of the cortex from top to bottom?
- Zona Glomerulosa
- Zona Fasciculata
- Zona Reticularis
What kind of cells does medulla contain?
Chromaffin cells
What kind of hormones does the Glomerulosa produce?
Mineralcorticoids
What is an example of a mineralocorticoid?
Aldosterone
What hormone family does the Fasciculata produce?
Glucocorticoids
What is an example of a Glucocorticoids?
Cortisol
What hormone family does the Reticularis produce?
Androgens
What are examples of Androgens?
DHEA, Androsteredione
What is the main function of Mineralocorticoids?
To control salts/electrolyte levels
What is the main function of Glucocorticoids?
Control Carbohydrates
What is the starting material for steroid hormones?
Cholesterol
What is cholesterol converted to when making corticosteroids?
Pregnenolone
What is Pregnenolone converted to when making corticosteroids?
Progesterone
What are the major actions of Aldosterone on?
Electrolytes and water
What are the four effects of Aldosterone?
- Increased Na+ reabsorption by the kidney
- Increased H2O reabsorption by kidney
- Increased K+ secretion by kidney (K+ is lost)
- Increase H_ secretion by kidney (H+ is lost)
Can Aldosterone go into the cell?
Yes because it is a steroid hormone
How does Aldosterone cause its effects on Na+?
It causes the sodium channels on the apical membrane to be more active and allow sodium to diffuse back into the cell
How does Aldosterone cause its effects on K+?
It causes potassium channels on the apical membrane to be more active and cause K+ to move out of the cell
How does Aldosterone combine its effects on H+?
It increases the activity of a Na+-H+ exchanger on the apical membrane which transports Na+ into the cell and H+ out of the cell into the lumen
