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How does a endocrine hormone work?
Reaches systemic circulation and influences cells some distance away
What is the definition of a neuroendocrine hormone?
-secreted from neurons and travel through the blood stream
- influence cells some distance away
Explain the control of hormones through a negative feedback loop.
- Increased functioning of target cells results in a decreased rate of hormone from original secreting cell
What is an example of a positive feedback loop?
Dilation of the cervix in labor stimulates the posterior pituitary to secrete oxytocin which causes further dilation of cervix
How do steroid hormones act on cells?
- Enter the cell and bind to intracellular receptors to activate genes
- Activating gene causes transcription and translation of proteins
Which has a quicker effect as a hormone treating poison oak Epi or prednisone?
- Epi is fast
- Prednisone is a hormone which is slow acting
What is a problem with measuring hormones?
- If there is only a small quantity available it is hard to measure
Do lab test measure the biological activity of a hormone??
- No they only measure the amount of hormone
What are the two tissue types of the pituitary gland?
- Adenohypohysis (anterior)
- Neurophypophysis (posterior)
Where are the cell bodies which produce ADH and oxytocin located?
-Supra optic nuclei of hypothalamus
-Paraventricular nuclei of hypothalamus
How are neuropeptides from the posterior pituitary secreted?
- Directly from neuron into systemic circulation
What controls the release of the 6 hormones in the anterior pituitary?
- Releasing hormones from the hypothalamus
How is the anterior pituitary and hypothalamus connected?
-Hypothalamic-hypophysial portal blood vessels
What does ADH do?
- Regulates osmolarity of the body by altering renal excretion of water
- Acts on principle cells of distal renal tubules and collecting ducts to increase H20 re-absorption
What causes the release of ADH from the anterior pituitary?
- osmoreceptors in the hypothalamus are sensitive to blood osmolarity
- baroreceptors in the left atrium, aortic arch, carotid artery sense hypo/hyper volemia which signals the hypothalamus via the vagus nerve to decrease or increase secreation of ADH
What is SIADH?
- stands for syndrome of inappropriate ADH secretion
- a decrease in plasma osmolarity
- total body sodium is normal, too much total body free water
What stimulates the release of oxytocin?
- Suckling or nipple stimulation
- sight, sound, smell of infant
- Cervical dilation during labor and orgasm
How is oxytocin used clinically?
- Induce labor
- Reduce postpartum bleeding
- Psychiatric treatment
What are the 5 cell types that make the 6 anterior pituitary hormones?
What is the action of GH?
- Increase linear grown pre-closure of ephysial plate
- Increase protein synthesis
- Increase lean body mass
- Utilization of fats for energy source
- Increases insulin resistance (diabetogenic)
What stimulates the release of GH?
- Increased plasma levels of amino acids
What does Prolactin do?
- Inhibits GnRH which inhibits ovulation
- Breast development at puberty and pregnancy
What does too much prolactin cause?
- Infertility in males secondary to impaired spermatogenesis
What is galactorrhea?
- Too much prolactin causes destruction of dopamine source
- Hypothalamic-hypophysial portal tract interruption from pituitary tumor or trauma
What is a headache and galactorrhea a presenting symptom of?
Pituitary adenoma (30% of cases hyperprolactinemia)
What are the actions of TSH?
- Regulation of thyroid gland
- Regulates secretion of thyroid hormones, T3 & T4
What does the ACTH "family" include?
- MSH (melanocyte stimulating hormone)
- Alpha & beta lipotropin
What is the main action of ACTH?
Modulate cortisol secretion from the zona fasciculate of the adrenal cortex
What is the action of FSH?
- Stimulate development of follicles in ovary
- Stimulate spermatogenesis
What does LH do?
- Stimulates development of corpus luteum in ovaries
- Stimulates testosterone secretion of Leydig cells in testis
What effect does estrogen and progesterone have the hypothalamus?
Influence the release of FSH and LH
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