Endocrine Physiology Flashcards
Where is the preprohormones for protein and peptide hormones first synthesized?
Rough endoplasmic reticulum.
signal peptides are cleaved from preprohormone producing prohormone which is transported to the golgi aparatus.
What are amine hormones?
These are derivatives of tyrosine so mostly thyroid hormones, epinephrine, and norepinephrine.
Give an example of a hormone that functions through positive feedback.
Positive feedback is very rare.
LH reacting to estrogen release is an example.
As Estrogen is released before ovulation, it acts on the anterior pituitary to release LH. LH acts on the ovaries and increases estrogen release even more.
What do TSH, LH, and FSH all hav in common?
These all share the exact same alpha subunit however have different beta subunits.
It is important to understand that Beta subunit is the important portion.
What is the importance of POMC?
This is broke apart to form ACTH as well as melanocytre stimulating hormone.
Growth hormone is directly identical with what hormone?
Prolactin.
What effect does growth hormone have on glucose?
Decreases glucose uptake into cells.
What is octreotide?
A somatostatin analogue that treats excessive growth hormone release.
What is the difference between acromegally and gigantism?
Acromegally occurs in adults.
gigantism occurs in children.
How is prolactin controlled?
Thyroid releasing hormine from the hypothalamus increases Prolactin secretion.
Dopamine released from the hypothalamus decreases the secretion of prolactin.
Prolactin also negatively regulates itself by causing dopamine release.
What is bromocriptine?
A dopamine analogue that can be used to inhibit prolactin overgrowth.
What are the two hormones released from the posterior pituitary?
Oxytocin and ADH
Describe ADH’s effect on V1 cells vs V2 cells
Vi effects are contriction of vascular smooth muscle.
V2 effects are increased H2O permeability in the principal cells
What does oxytocin do?
Released from the periventricular nuclei of the posterior pituitary, it results in ejection of milk from the breast following suckling.
How does the dexamethasone suppresion test work?
Normally dexamethasone would stop ACTH secretion and subsequently cortisone release.
With ACTH-secreting tumors, low does dexamethasone does not inhibit cortisol secretion but high does does.
In people with adrenal cortical tumors, neither high or low dose dexamethasone inhibits cortisol secretion.
How do glucocorticoids (cortisol) exhibit antiinflammatory effects?
By inducing the synthesis if lipocortin which is an inhibitor of phospholipase A2.
Inhibits the release if IL-2 (recruits T cells)
Inhibit the release of histamine and serotonin from mast cells and platelets.
How does cortisol elevate blood pressure?
Up regulates alpha 1 receptors on arterioles increasing sensitivity to norepinephrine.
Why is there hyperpigmentation in adrenocortical deficiency?
Lack of cortisol leads to excessive ACTH release.
ACTH has a pigmentation effect.
How does glucose stimulate insulin release from beta cells?
Binds to Glut 2 receptors.
Glucose is formed into ATP closing the potassium channels leading to depolarization and calcium channels opening releasing insulin and C-peptide.
What effect does CCK and amino acids have on glucagon release?
Increase glucagon release.
How does magnesium interact with PTH?
Decreased magnesium can cause an increase in PTH.
Severe decreases in magnesium actually cause a deficiency in PTH.
Increased hyroxyproline excretion is a sign of …..
Increased bone reabsorption seen most commonly through PTH activity.
In children vitamin D deficiency causes…. In adults it causes?
In children it causes rickets
In adults it causes osteomalacia.