Unit 2 - Melatonin and EPO Flashcards
Which gland secretes melatonin?
the pineal gland
Where is the pineal gland located?
in the epithalamus
What is melatonin synthesized from?
tryptophan
What is the main physiologic function of melatonin?
it influences the reproductive cycle of seasonal breeders
What stimulus initiates the secretion of melatonin?
norepinephrine
How is the stimulus conveyed to the epiphysis?
in the absence of light, stimulus is sent from the brainstem to the superior cervical ganglion which send post sympathetic neurons to the pineal gland to release melatonin
What is the effect of melatonin on gonads in most sesonal breeders?
it inhibits gonadal activity
What is the effect of melatonin on gonads in goats and sheep?
it stimulates gonadal activity
Race horse breeders like to prepare mares for breeding by putting them under artificial light in winter. What is the physiological reason for this practice?
The reason is to trick the horse into thinking that it is a different season so that they can manipulate when they breed so their offspring are born at a certain time
What are some other important functions of melatonin?
Antagonizes MSH, exhibits circadian rhythmicity and entrains circadian clock in the suprachiasmatic nucleus
What is the chemical nature of erythropoietin?
glycoprotein
What releases erythropoietin?
endothelial cells of peritubular capillary cells in the kidney
What are the triggers of erythropoietin release?
decreased renal blood flow, cardiopulmonary disease, decrease hemoglobin concentration, hemorrhage, high altitude, hypotension
What are the functions of erythropoietin?
stimulates erythropoiesis in bone marrow and iron uptake in small intestine
