Neuroendocrine/Pituitary Flashcards
(47 cards)
What are the two main roles of the hypothalamus?
- Defense of homeostasis
- Integrates information for control of the endocrine system, the autonomic nervous system and neural systems concerned with motivation (i.e. limbic system)
What is homeostasis?
- Protecting cells in body from extremes
- Tendency for stability in the body established by system of control mechanisms
What is an example of homeostasis in the hypothalamus?
Receptor [to pressure, volume, pH] peripheral (baroreceptors) or central (temperature receptors in skin & CNS) –(afferent)–> hypothalamus —(efferent)—> Effects hormones, autonomic nervous system
What does the fornix do?
It projects information from the maxillary bodies down to the thalamus.
Where does the pituitary gland sit in relation to the brain?
At the base of the brain in indentation of sphenoid bone (sella turcica)
What are the parts of the pituitary gland?
- Anterior pituitary (adenohypophysis)
- Posterior pituitary (neurohypophysis) [infundibular stalk, posterior lobe]
- Median eminence (infundibulum)
What does the posterior pituitary secrete?
Vasopressin & Oxytocin
Where are Vasopressin or Oxytocin synthesized?
Magnocellular (very large) neurons in supraoptic (SON) and paraventricular nuclei (PVN) —> these neurons will secrete either vasopressin OR oxytocin
How are vasopressin or oxytocin stored and secreted?
- Stored in vesicles until released by neural activity (limbic system, motivation, emotions, solitary nucleus (bp, GI tract info))
- Transported via axons to nerve terminals in posterior pituitary
When the supraoptic nucleus and paraventricular nucleus is stimulated by limibic system or solitary nucleus. . .
. . .Magnocellular (large) hypothalamic neurons secrete peptides directly into systemic circulation
What three things does Vasopressin do?
In response to. . . .it does . . .
- Increased blood osmolality (inc. solute) –> Inc. water resorption by kidney
- Hypovolemia (dec. blood volume) –> Anti-diuretic (Inc. water resorption by kidney)
- Hypotension (dec. blood pressure) –> Inc. Vasoconstriction –> Inc. bp!
What does Oxytocin cause? (when released in blood)
In response to . . .it does. . .
- Suckling/Nursing –> Inc. Oxytocin –> “milk ejection reflex”/smooth muscle contraction in breast
- Uterine stimulation –> Inc. Oxytocin –> Uterine contraction (smoother muscle) –> delivery of newborn
What is another name for Vasopressin?
ADH (anti-dieretic hormone)
What does oxytocin cause when released in the brain?
Contributes to bonding between people!
-It is made in men and women but is more prevalent in women
The posterior pituitary secretes 2 hormones. What about the anterior pituitary?
It secretes “families” of hormones into systemic circulation
What are the somatomammotropins? What secretes them?
Growth hormone
Prolactin
-Secreted by Anterior Pituitary
[growth promoting, has to do with breast]
What stimulates growth hormone and what does this hormone effect?
- Exercise, stress, sleep (80% released during slow wave sleep)
- Growth (tissue) & Metabolism
What stimulates prolactin and what does this hormone effect?
- Sucking, stress
2. Development of mammary tissue –> lactation (milk production)
What are the three glycoproteins? What secretes them?
- Thyroid-stimulating hormone (TSH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Anterior Pituitary
What are the gonadotropins?
- Follicle-stimulatting hormone (FSH)
2. Luteinizing hormone (LH)
What stimulates TSH (thyroid stimulating hormone)? What does it do?
- Exposure to cold temperature causes. . .
2. Increase TSH –> Inc. cellular metabolism –> Inc. heat production
What regulates Follicle-stimulating hormone (FSH)? What does FSH cause?
Hypothalamic peptide
Men - Inc. spermatogenesis
Women - Development of ovarian follicle
What regulates Luteinizing hormone (LH)? What does LH cause?
Hypothalamic peptide
Men - Required for spermatogenesis, Stimulates testosterone (tropic effect - relating to cell growth?)
Women - Initiates ovulation (“trigger”), Stimulates progesterone
What are the two Opiomelanocortin peptides? What secretes them? What is their common precursor?
- Adrenocorticotropic hormone (ACTH)
- Beta-endorphin
- Anterior Pituitary
- Pro-opiomelanocortin (POMC) - you can cleave the end into ACTH and Beta-EP