Neuroendocrine Communication Quiz
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Questions and Answers

Which type of communication involves a hormone directly influencing the cell that released it?

  • Paracrine
  • Endocrine
  • Autocrine (correct)
  • Neurocrine

    • Which type of communication is exemplified by the release of digestive enzymes by the pancreas into the lumen of the digestive system?

  • Autocrine
  • Paracrine
  • Exocrine (correct)
  • Endocrine

    • Which of the following is NOT a characteristic of neuroendocrine communication?

  • Target cells are restricted to a specific location (correct)
  • Communication is relatively slow
  • Involves the release of neurohormones
  • Communication is indirect

    • Which of the following is a hypothalamic releasing factor?

    <p>Somatostatin (D)</p> Signup and view all the answers

    What is the primary function of hypothalamic releasing factors?

    <p>Stimulate the release of hormones from the anterior pituitary (C)</p> Signup and view all the answers

    How does somatostatin affect the pituitary gland?

    <p>Inhibits the release of thyroid-stimulating hormone (D)</p> Signup and view all the answers

    Which of the following is NOT a difference between neuronal and neuroendocrine communication?

    <p>Neuroendocrine communication uses neurotransmitters (C)</p> Signup and view all the answers

    Which of the following is an example of a neurohormone?

    <p>Oxytocin (D)</p> Signup and view all the answers

    Which part of the pituitary gland is associated with the storage and release of hormones produced in the hypothalamus?

    <p>Neurohypophysis (C)</p> Signup and view all the answers

    What role do neuroendocrine cells play in hormone secretion?

    <p>They integrate neural inputs and transduce them into endocrine outputs. (D)</p> Signup and view all the answers

    What type of hormones are produced in the hypothalamus and influence peripheral organs?

    <p>Neuroendocrine hormones (D)</p> Signup and view all the answers

    What is the main characteristic of the cleavage process involving prohormone convertases?

    <p>They cleave peptides into smaller fragments at dibasic sites. (D)</p> Signup and view all the answers

    What initiates the process of neuropeptide expression regulation?

    <p>Transcription factor activation (A)</p> Signup and view all the answers

    Which part of the brain houses neurons that are integral for neuroendocrine function?

    <p>Hypothalamus (B)</p> Signup and view all the answers

    Which embryonic layer is responsible for forming the central nervous system (CNS)?

    <p>Ectoderm (A)</p> Signup and view all the answers

    What role does the hypothalamus play in relation to the pituitary gland?

    <p>It regulates pituitary hormone secretion based on feedback signals. (D)</p> Signup and view all the answers

    What structure is formed during the gastrulation period that contributes to the CNS?

    <p>Neural tube (D)</p> Signup and view all the answers

    How is the hypothalamic region connected to the blood supply?

    <p>Via multiple blood vessels surrounding the CNS (C)</p> Signup and view all the answers

    What term describes a bundle of axonal nerve fibers with a common origin and target?

    <p>Tract (D)</p> Signup and view all the answers

    Which of the following neuropeptides is an example of a neurotransmitter as well as a neurohormone?

    <p>Somatostatin (D)</p> Signup and view all the answers

    Which area of the hypothalamus is most involved in regulating appetitive behavior?

    <p>Lateral hypothalamus (B)</p> Signup and view all the answers

    Which region of the hypothalamus is characterized by neuroendocrine nuclei and is very close to the 3rd ventricle?

    <p>Periventricular zone (D)</p> Signup and view all the answers

    What type of neurons are predominantly found in the supraoptic nucleus?

    <p>Magnocellular neurons (A)</p> Signup and view all the answers

    Which hormone is secreted by the anterior lobe of the pituitary gland and is responsible for stimulating the adrenal cortex?

    <p>Adrenocorticotropic Hormone (ACTH) (B)</p> Signup and view all the answers

    Which cell types in the anterior lobe of the pituitary are responsible for the production of Luteinizing Hormone (LH)?

    <p>Basophilic cells (A)</p> Signup and view all the answers

    Which nucleus is primarily associated with the biological clock of the body?

    <p>Suprachiasmatic nucleus (A)</p> Signup and view all the answers

    What is the primary function of Melanocyte Stimulating Hormone (MSH)?

    <p>Darkening of skin via melanin dispersion (D)</p> Signup and view all the answers

    What triggers the release of renin in the kidneys?

    <p>Decrease in blood pressure (A)</p> Signup and view all the answers

    Which lobe of the pituitary gland is connected to the hypothalamus via the median eminence?

    <p>Anterior lobe (B)</p> Signup and view all the answers

    How does apelin affect vasopressin secretion?

    <p>It inhibits vasopressin secretion (C)</p> Signup and view all the answers

    What role does oxytocin play during childbirth?

    <p>It stimulates uterine contractions (A)</p> Signup and view all the answers

    What is the main role of Prolactin (PRL) in the pituitary gland?

    <p>Initiating milk production (C)</p> Signup and view all the answers

    Which hormone is NOT secreted by the anterior lobe of the pituitary gland?

    <p>Oxytocin (C)</p> Signup and view all the answers

    What effect does apelin have on the volume of urine secreted?

    <p>Increases the urinary volume (A)</p> Signup and view all the answers

    What physiological response occurs when there is water deprivation?

    <p>Increased secretion of AVP (C)</p> Signup and view all the answers

    Which hypothalamic zone is extensively connected throughout the brain and is involved in motivated behaviors?

    <p>Medial zone (B)</p> Signup and view all the answers

    Which neuropeptide is involved in the regulation of AVP neurons?

    <p>Apelin (B)</p> Signup and view all the answers

    Which hormone produced by the anterior lobe is primarily responsible for stimulating growth in tissues?

    <p>Growth Hormone (GH) (D)</p> Signup and view all the answers

    What morphological change occurs in oxytocin neurons during late pregnancy?

    <p>Reduction in glial cells (A)</p> Signup and view all the answers

    Which nucleus is a mix of magnocellular and parvocellular components in the hypothalamus?

    <p>Paraventricular nucleus (D)</p> Signup and view all the answers

    What is the primary structural function of the infundibulum in the context of the pituitary gland?

    <p>Connecting the hypothalamus and pituitary gland (B)</p> Signup and view all the answers

    What is the primary role of oxytocin during lactation?

    <p>Ejecting milk into the mammary ducts (B)</p> Signup and view all the answers

    Which neurotransmitter's receptors insertion is increased due to stimulation of magnocellular neurons?

    <p>ATP (A)</p> Signup and view all the answers

    Which component of the hypothalamic medio-lateral zones has not been clearly associated with a specific function due to its complexity?

    <p>Lateral zone (C)</p> Signup and view all the answers

    How are oxytocin and vasopressin related?

    <p>They are closely related hormones, but act independently (A)</p> Signup and view all the answers

    Which physiological effect does oxytocin NOT have?

    <p>Regulation of blood pressure (A)</p> Signup and view all the answers

    What is the primary function of the angiotensin system?

    <p>Regulation of blood pressure (C)</p> Signup and view all the answers

    What leads to the release of oxytocin during labor?

    <p>Physical stimulation, such as contractions (C)</p> Signup and view all the answers

    What occurs to the somatic cells of oxytocin neurons as pregnancy progresses?

    <p>Apposition increases among the cell bodies (D)</p> Signup and view all the answers

    What is the primary role of FSH during the follicular phase of the menstrual cycle?

    <p>To increase estradiol production (B)</p> Signup and view all the answers

    What signifies the transition from negative feedback to positive feedback in the menstrual cycle?

    <p>Surge of estradiol levels (B)</p> Signup and view all the answers

    What happens to the corpus luteum if pregnancy does not occur?

    <p>It degenerates within two weeks (C)</p> Signup and view all the answers

    What is the primary function of GnRH produced by GnRH neurons?

    <p>Stimulates the release of LH and FSH (D)</p> Signup and view all the answers

    How does a frame-shift mutation in the GnRH1 gene affect puberty?

    <p>Causes a complete absence of sexual development (B)</p> Signup and view all the answers

    What physiological effect does high progesterone have during the luteal phase?

    <p>Maintains the uterine lining for potential implantation (A)</p> Signup and view all the answers

    What regulates the episodic release of GnRH in males?

    <p>Sex steroid negative feedback (B)</p> Signup and view all the answers

    What dual role do the dendrons of GnRH neurons serve?

    <p>Function as both dendrites and axons (D)</p> Signup and view all the answers

    What occurs in the preoptic area of the brain concerning GnRH?

    <p>High concentration of GnRH-producing neurons (B)</p> Signup and view all the answers

    In females, what triggers the surge release of GnRH?

    <p>Estrogen positive feedback (D)</p> Signup and view all the answers

    How does Kallman's syndrome affect olfactory function?

    <p>Leads to a complete loss of smell (B)</p> Signup and view all the answers

    What is a consequence of the lack of GnRH secretion?

    <p>Undeveloped ovaries and low estradiol levels (B)</p> Signup and view all the answers

    What characterizes the secretion dynamics of GnRH in the menstrual cycle?

    <p>It is released in episodic pulses (D)</p> Signup and view all the answers

    During which phase does the dominant follicle release the oocyte?

    <p>Ovulatory phase (D)</p> Signup and view all the answers

    What is the effect of hypertonic saline on OT release in the posterior pituitary during stimulation?

    <p>It increases OT release. (B)</p> Signup and view all the answers

    What role do noradrenergic neurons play during parturition in relation to OT release?

    <p>They stimulate OT neuron activity. (A)</p> Signup and view all the answers

    What is the primary function of Vasopressin (ADH) in the body?

    <p>Elevates blood pressure and promotes water reabsorption in the kidneys (A)</p> Signup and view all the answers

    How do OT neurons respond to elevated plasma osmolality?

    <p>They gradually increase firing activity. (D)</p> Signup and view all the answers

    What impact does oxytocin have on food intake and body weight regulation?

    <p>It reduces meal size and latency to eat. (D)</p> Signup and view all the answers

    Which structure in the hypothalamus produces hormones released directly into the bloodstream?

    <p>The magnocellular system (A)</p> Signup and view all the answers

    What characterizes the histology of the anterior pituitary gland?

    <p>Lack of neuronal cell bodies and structural hallmark of secreted proteins (D)</p> Signup and view all the answers

    What occurs with vasopressin release in relation to hypertonic stimulation?

    <p>Vasopressin release follows an immediate spike. (B)</p> Signup and view all the answers

    What triggers the release of corticotropin-releasing hormone (CRH) from the hypothalamus?

    <p>Stress stimuli or low cortisol levels (C)</p> Signup and view all the answers

    What influences the activation of OT neurons during lactation?

    <p>Pup stimulation of the female's ventrum. (B)</p> Signup and view all the answers

    Which statement best describes the relationship between OT and the HPA axis during stress?

    <p>OT inhibits the production of CRH in the PVN. (D)</p> Signup and view all the answers

    Where is the main location of gonadotropin production in the hypothalamus?

    <p>Preoptic area (POA) (B)</p> Signup and view all the answers

    What is the effect of removing parvocellular OT neurons observed in humans?

    <p>Development of obesity. (C)</p> Signup and view all the answers

    Which type of feedback mechanism involves the target organ sending signals back to the hypothalamus via hormones?

    <p>Long feedback (A)</p> Signup and view all the answers

    What is the role of pituicytes in the lobus nervosus?

    <p>Supporting and providing metabolic functions for neurosecretory axons (B)</p> Signup and view all the answers

    How do the roles of OT during pregnancy and lactation differ from its role in overall osmoregulation?

    <p>Dendritic priming is significant in pregnancy and lactation, but not in osmoregulation. (C)</p> Signup and view all the answers

    Which factor other than noradrenaline modulates OT neurons?

    <p>Steroid metabolites of progesterone. (B)</p> Signup and view all the answers

    How does adrenalectomy affect CRH production in the medial eminence?

    <p>It stimulates overproduction of CRH due to lack of feedback (A)</p> Signup and view all the answers

    What distinguishes the parvocellular system in the hypothalamus?

    <p>It initiates the release of hormones that act on the anterior pituitary (B)</p> Signup and view all the answers

    What happens to OT release after stress in animals with intact adrenal glands?

    <p>OT release shows a small temporary increase. (B)</p> Signup and view all the answers

    During hypertonic stimulation, what differentiates OT release from that of vasopressin?

    <p>OT increases followed by a decrease, while VP shows a steady rise. (D)</p> Signup and view all the answers

    What is a characteristic of the feedback control of hypothalamic hormone release?

    <p>Ultrashort feedback can occur within one nucleus (C)</p> Signup and view all the answers

    What effect does the antagonist have on vasopressin secretion in neurons?

    <p>It leads to increased vasopressin activity. (B)</p> Signup and view all the answers

    Which neuropeptides are synthesized by CRH neurons in the paraventricular nucleus (PVN)?

    <p>CRH, Vasopressin, Enkephalin, Cholecystokinin, and Neurotensin (B)</p> Signup and view all the answers

    What is the primary function of extrahypothalamic projections of parvocellular OT neurons?

    <p>To influence brainstem and hindbrain functions. (C)</p> Signup and view all the answers

    What is the primary effect of using colchicine in studying CRH neurons?

    <p>It causes strong accumulation of CRH neurons due to inhibited transport (B)</p> Signup and view all the answers

    What distinguishes the magnocellular system in terms of hormone release?

    <p>It releases hormones such as oxytocin and vasopressin directly into circulation (D)</p> Signup and view all the answers

    Which hormone is primarily associated with the role of stimulating uterine contractions?

    <p>Oxytocin (A)</p> Signup and view all the answers

    Where is oxytocin primarily located within the paraventricular nucleus?

    <p>Rostrally (A)</p> Signup and view all the answers

    Which hormone is directly involved in stimulating uterine contractions during childbirth?

    <p>Oxytocin (D)</p> Signup and view all the answers

    What is the primary action of vasopressin in the kidneys?

    <p>Increase retention of water (D)</p> Signup and view all the answers

    Which structure contains neurons that predominantly release both oxytocin and vasopressin?

    <p>Supraoptic nucleus (A)</p> Signup and view all the answers

    What role do neurophysins play in the secretion of oxytocin and vasopressin?

    <p>They are byproducts of hormone maturation (B)</p> Signup and view all the answers

    What kind of neurotransmission do oxytocin and vasopressin utilize in their receptors?

    <p>Activation of phospholipase C (A)</p> Signup and view all the answers

    Which part of the hypothalamus responds to visceral mechanical stimuli to regulate oxytocin and vasopressin release?

    <p>Nucleus of the solitary tract (D)</p> Signup and view all the answers

    What happens to vasopressin secretion in response to increased plasma osmolality?

    <p>It increases significantly (B)</p> Signup and view all the answers

    Which neuropeptide is likely involved in regulating vasopressin release in the neurohypophysis?

    <p>Enkephalin (A)</p> Signup and view all the answers

    Which elements are crucial for the structural formation of oxytocin and vasopressin?

    <p>An internal ring and 8 amino acids (A)</p> Signup and view all the answers

    Which hormone is classified as the 'antidiuretic hormone'?

    <p>Vasopressin (A)</p> Signup and view all the answers

    What is a characteristic feature of the anatomy of the paraventricular nucleus compared to the supraoptic nucleus?

    <p>It has multiple parvocellular sub-nuclei (C)</p> Signup and view all the answers

    What typically happens to vasopressin levels during hypotension?

    <p>They increase significantly (B)</p> Signup and view all the answers

    What role do inhibins play during the luteal phase with regard to FSH levels?

    <p>They decrease FSH production. (A)</p> Signup and view all the answers

    How does myostatin affect FSH production?

    <p>It reduces FSH levels by 50%. (B)</p> Signup and view all the answers

    What is the primary source of the growth hormone for follicles during the follicular phase?

    <p>FSH from gonadotropes. (C)</p> Signup and view all the answers

    What happens to non-dominant follicles at the end of the follicular phase?

    <p>They undergo atresia. (B)</p> Signup and view all the answers

    Which statement about follicle development is true?

    <p>Only the dominant follicle can be supported by LH. (B)</p> Signup and view all the answers

    What triggers the start of meiosis in an oocyte?

    <p>LH surge. (A)</p> Signup and view all the answers

    What is the main function of inhibin B during the follicular phase?

    <p>To provide negative feedback on FSH levels. (D)</p> Signup and view all the answers

    What effect does the presence of myostatin have on gonadotrope-produced activin B?

    <p>It diminishes activin B receptor binding. (B)</p> Signup and view all the answers

    How does the social context influence sugar consumption in subordinate male mice when oxytocin receptor blockade occurs?

    <p>It only increases consumption in non-social settings. (C)</p> Signup and view all the answers

    Why do all females start life with a complete set of oocytes?

    <p>They lose oocytes over time, making the initial set sufficient. (D)</p> Signup and view all the answers

    What role do parvocellular oxytocin neurons play in the context of pain perception?

    <p>They project to the spinal cord, influencing analgesia directly. (B)</p> Signup and view all the answers

    What causes the dominant follicle to continue to develop in the presence of reduced FSH?

    <p>It has gained sensitivity to LH. (B)</p> Signup and view all the answers

    Which scenario illustrates the influence of oxytocin on maternal behavior in female mammals?

    <p>Anti-OT antibodies prevent mothers from accepting their pups. (B)</p> Signup and view all the answers

    In which type of relationships is oxytocin particularly significant?

    <p>Social bonding and pair bonding in both genders. (B)</p> Signup and view all the answers

    At what stage do follicles become sensitive to FSH?

    <p>Antral stage. (D)</p> Signup and view all the answers

    What is a consequence of the absence of a father in offspring development?

    <p>Increased periods of unattended care. (B)</p> Signup and view all the answers

    How does circulating estradiol affect FSH levels during the follicular phase?

    <p>It suppresses FSH production. (C)</p> Signup and view all the answers

    What initiates the transition from the luteal phase to the follicular phase?

    <p>Decrease in progesterone levels. (D)</p> Signup and view all the answers

    How does oxytocin influence stress responses in females?

    <p>It decreases their stress response through male partners. (B)</p> Signup and view all the answers

    What changes occur to oxytocin receptor expression around parturition?

    <p>There is an increase in receptors in the brain. (C)</p> Signup and view all the answers

    How does oxytocin relate to reproductive processes in males?

    <p>It influences smooth muscle contractions. (D)</p> Signup and view all the answers

    What role does estradiol play in the regulation of kisspeptin neurons in the ARC nucleus?

    <p>It inhibits Kiss1 expression through Erα. (D)</p> Signup and view all the answers

    How is the LH surge triggered during the menstrual cycle?

    <p>Via a sharp increase in estradiol leading to positive feedback. (C)</p> Signup and view all the answers

    What is a significant difference between prairie voles and montane voles regarding oxytocin receptors?

    <p>Prairie voles have abundant OT receptors throughout their brains. (B)</p> Signup and view all the answers

    Why are animal models like voles valuable for studying social relationships?

    <p>They offer insights into human studies. (A)</p> Signup and view all the answers

    What happens to kisspeptin neuron activity during the first two stages of the menstrual cycle?

    <p>Kisspeptin activity remains stable. (A)</p> Signup and view all the answers

    What is the effect of progesterone on kisspeptin neurons after ovulation?

    <p>It stops the pulse generator activity. (A)</p> Signup and view all the answers

    What does oxytocin do in relation to autism spectrum disorders?

    <p>It enhances retention of social information. (B)</p> Signup and view all the answers

    What is one effect of oxytocin on cardiac synchronization during close relationships?

    <p>It promotes coordinated heart rate increases during interactions. (C)</p> Signup and view all the answers

    Why do KO estrogen receptor animals exhibit infertility?

    <p>They fail to ovulate due to no LH surges. (C)</p> Signup and view all the answers

    Which hormone is primarily responsible for stimulating the release of FSH and LH from the anterior pituitary?

    <p>Gonadotropin-releasing hormone (GnRH). (A)</p> Signup and view all the answers

    How does the action of estradiol on kisspeptin neurons differ between the ARC and AVPV?

    <p>It inhibits kisspeptin in ARC and stimulates it in AVPV. (D)</p> Signup and view all the answers

    What do high levels of estrogen stimulate in terms of GnRH secretion?

    <p>Enhanced kisspeptin synthesis and GnRH secretion. (D)</p> Signup and view all the answers

    What is true about estrogen in females during the ovulatory phase?

    <p>It stimulates GnRH production positively at ovulation. (D)</p> Signup and view all the answers

    What pattern of GnRH neuron activity is observed during the LH surge?

    <p>Significant increase in pulsatile GnRH secretion. (C)</p> Signup and view all the answers

    What role does the suprachiasmatic nucleus play in rodent hormone regulation?

    <p>It impacts the circadian rhythm affecting ovulation timing. (C)</p> Signup and view all the answers

    How does Erα influence kisspeptin expression in the AVPV?

    <p>By binding to DNA to stimulate expression. (B)</p> Signup and view all the answers

    What is the main output of KNDy neurons?

    <p>Kisspeptin (A)</p> Signup and view all the answers

    What triggers the negative feedback mechanism in the ARC nucleus?

    <p>A rise in estrogen levels. (C)</p> Signup and view all the answers

    Which statement describes the roles of kisspeptin in the regulation of GnRH in female rats?

    <p>Kisspeptin can both stimulate and inhibit GnRH neurons depending on location. (D)</p> Signup and view all the answers

    What mechanism is primarily responsible for the secretion of LH and FSH?

    <p>Pulsatile GNRH secretion (D)</p> Signup and view all the answers

    Which neurotransmitter is known to inhibit KNDy neurons?

    <p>Dynorphin (A)</p> Signup and view all the answers

    What changes occur to the kisspeptin expression when a female is ovariectomized (OVX) and then treated with E2?

    <p>Kisspeptin expression is upregulated. (A)</p> Signup and view all the answers

    What effect does kisspeptin have on GNRH neurons?

    <p>Stimulates their activity (C)</p> Signup and view all the answers

    What happens after blocking kisspeptin with an antagonist?

    <p>LH pulses stop (A)</p> Signup and view all the answers

    Which phase of the menstrual cycle is characterized by negative feedback due to high estradiol levels?

    <p>Follicular phase (A)</p> Signup and view all the answers

    Where do estrogen receptors (Er) predominantly exert a negative feedback effect?

    <p>In the arcuate nucleus (B)</p> Signup and view all the answers

    What is the consequence of knocking out the kisspeptin gene in an organism?

    <p>No LH secretion (A)</p> Signup and view all the answers

    What does the presence of estradiol do to kisspeptin mRNA expression in OVX females?

    <p>Decreases kisspeptin expression (A)</p> Signup and view all the answers

    What type of receptor is KISS1R (kisspeptin receptor)?

    <p>GPCR (G protein-coupled receptor) (C)</p> Signup and view all the answers

    What is the effect of estradiol on KNDy neuronal activity?

    <p>Decreases neuronal activity (A)</p> Signup and view all the answers

    What is the role of neurokin B in relation to KNDy neurons?

    <p>Stimulates the activity of KNDy neurons (A)</p> Signup and view all the answers

    What is one result of LH pulse frequency in OVX primates compared to those with their ovaries intact?

    <p>Higher pulse frequency (B)</p> Signup and view all the answers

    What regulates the activity of GNRH and consequently LH release in females?

    <p>Kisspeptin and neurokin B (B)</p> Signup and view all the answers

    How does the administration of a GNRH receptor antagonist affect LH and FSH levels in postmenopausal women?

    <p>It decreases LH and FSH levels by preventing GNRH from stimulating the pituitary. (C)</p> Signup and view all the answers

    In Kallman's syndrome, why does pulsatile GNRH administration result in a normal menstrual cycle?

    <p>It restores the sensitivity of the pituitary to GNRH, allowing for normal LH and FSH release. (A)</p> Signup and view all the answers

    What is the role of estrogen in regulating LH and FSH levels?

    <p>Estrogen provides negative feedback to the pituitary, leading to decreased LH and FSH production. (A)</p> Signup and view all the answers

    Which of the following statements accurately describes the structure of LH and FSH?

    <p>LH and FSH are dimeric glycoproteins sharing a common α subunit and unique β subunits. (A)</p> Signup and view all the answers

    How does the frequency of GNRH pulses influence the secretion of LH and FSH?

    <p>High frequency pulses favor LH secretion while low frequency pulses favor FSH secretion. (A)</p> Signup and view all the answers

    During the follicular phase of the menstrual cycle, FSH levels are higher than LH levels. Considering the effect of GNRH pulse frequency on LH and FSH secretion, what would you predict about the pulse frequency during this phase?

    <p>The pulse frequency is high to favor FSH secretion. (B)</p> Signup and view all the answers

    Which of the following hormones directly inhibits FSH secretion?

    <p>Inhibins A and B (A)</p> Signup and view all the answers

    How do activins influence FSH secretion?

    <p>Activins stimulate FSH secretion, acting as a positive feedback mechanism. (B)</p> Signup and view all the answers

    Which of the following is a factor that contributes to the secondary FSH surge during the estrus cycle in rodents?

    <p>Decreased inhibin levels (C)</p> Signup and view all the answers

    What is the effect of knocking out activin type II receptors in animal models?

    <p>It leads to increased LH secretion and a complete loss of FSH secretion. (A)</p> Signup and view all the answers

    What is the role of LH in the regulation of ovulation?

    <p>LH directly stimulates the release of the egg from the ovary. (C)</p> Signup and view all the answers

    How does FSH differ from LH in terms of its target cells and functions?

    <p>FSH targets granulosa cells surrounding oocytes in the ovaries, while LH targets theca/mural granulosa cells. (B)</p> Signup and view all the answers

    What is the main difference between the common α subunit of LH and FSH and their unique β subunits?

    <p>The α subunit is shared by other glycoprotein hormones, while the β subunit confers specific biological properties. (C)</p> Signup and view all the answers

    How is the differential regulation of LH and FSH secretion achieved, even though they are produced in the same cells and share the same α subunit?

    <p>Post-translational modifications of LH and FSH lead to different half-lives and target cell specificity. (B)</p> Signup and view all the answers

    What is the primary mechanism by which inhibins regulate FSH secretion?

    <p>Inhibins inhibit the synthesis and release of FSH from pituitary gonadotrope cells. (B)</p> Signup and view all the answers

    Study Notes

    Neuroendocrine Communication

    • Specialized form of chemical communication between animal cells
    • Modes:
      • Autocrine: Hormone/messenger directly affects releasing cell.
      • Paracrine: Hormone affects neighboring cells (e.g., gastrointestinal system).
      • Endocrine: Hormone released into blood, affects distant cells (e.g., thyroid gland).
      • Neurocrine: Neurotransmitter released at synapses.
      • Neuroendocrine: Neurohormones released by nerve cells into blood or portal circulation.

    What is a Hormone?

    • Chemical messenger produced by endocrine glands.
    • Released into general circulation or interstitial space.
    • Influences target cells via specific receptors.
    • Phylogenetically old type of intercellular communication.
    • Opposite of endocrine glands are exocrine glands (e.g., lacrimal, exocrine pancreas).

    Neuronal vs. Neuroendocrine Communication

    • Neuronal: Point-to-point connections, rapid communication, restricted target cells.
    • Neuroendocrine: Neuron releases neurohormone into bloodstream, reaches many target cells, indirect and relatively slow.

    Hormones

    • Hypothalamic hormones:
      • Hypothalamic releasing factors: Regulate anterior pituitary activity (e.g., stimulating or inhibiting the release of other hormones). Not stored in pituitary.
      • Neurohypophyseal hormones: Produced in hypothalamus, stored and released by posterior pituitary.

    Neuroendocrine Cells

    • Innervated by other neurons, receive neurotransmitter stimuli, and transduce neural information to endocrine outputs.
    • Located in specific brain regions (hypothalamus), vital for bodily functions.
    • Conserved across species.

    Biosynthesis of Peptide Hormones

    • Mostly small peptides (3-4 amino acid residues).
    • Can have diverse effects (neurotransmitters, neurohormones, paracrine factors).
    • Pituitary and peripheral hormones tend to be larger than hypothalamic peptides.
    • Diverse structures: amino acids, biogenic amines, peptides.
    • Regulation involves transcription factors, processing by endosomal compartments, and secretion.
    • Precursor proteins (e.g., POMC) can generate multiple hormones
    • Prohormone convertases (PC2, PC3) cleave precursors at diabasic sites (2 basic amino acids).
    • Cleavage process occurs in acidic environments (e.g., lysosomes) with order based on accessibility.

    Anatomy of Neuron

    • Soma/pericarion: Neuron body
    • Dendrites: Receive signals from other neurons
    • Axon: Transmits signals away from cell body, with a highly structured cytoskeleton for fast communication
    • CNS: High energy/oxygen consumption, requiring abundant blood supply.
    • Myelin: characteristic of long nerve cell projections.
    • Tracts/projections: Bundles of axons with common origin and target.

    Development of CNS

    • Neurolation forms neural tube from ectoderm.
    • Embryonic layers: endoderm (GI tract), mesoderm (muscles), ectoderm (skin).
    • Neural crest forms PNS and melanocytes.
    • Three brain vesicles (forebrain, midbrain, hindbrain) develop further.

    Hypothalamus

    • Crucial structure for life, connecting major brain areas.
    • Transforms neural inputs into hormonal outputs, regulating pituitary gland, and other glands.
    • Hypothalamic nuclei with distinct distributions (preoptic area, medial zone, periventricular zone, lateral zone).
    • Contains important neuroendocrine nuclei and has vital circuits like MFB.

    Pituitary Gland

    • Endocrine gland located at the base of the brain.
    • Connected to hypothalamus via portal system.
    • Three lobes: anterior, intermediate, and posterior.

    Anterior Pituitary Hormones

    • Growth hormone (GH/somatotropin): Stimulates growth, protein synthesis, and metabolism.
    • Adrenocorticotropic hormone (ACTH): Stimulates cortisol release from adrenal cortex.
    • Thyroid-stimulating hormone (TSH/thyrotropin): Stimulates thyroid hormone release.
    • Follicle-stimulating hormone (FSH): Stimulates follicle growth and hormone production.
    • Luteinizing hormone (LH): Stimulates ovulation, hormone production.
    • Prolactin (PRL): Stimulates milk production.

    Intermediate Pituitary

    • Tiny in humans.
    • Produces melanocyte-stimulating hormone (MSH) and β-endorphin.

    Posterior Pituitary Hormones

    • Oxytocin (OT): Stimulates smooth muscle contractions.
    • Vasopressin (AVP/antidiuretic hormone): Promotes water retention and regulates blood pressure.
    • Neurophysins: Storage proteins for AVP & OT in Herring bodies.

    Hypothalamic Hormone Release Control Systems

    • Long feedback: Target organs or sensory input feedback to the hypothalamus.
    • Short feedback: Pituitary hormones feedback to hypothalamic neurons.
    • Ultrashort feedback: Autocrine/paracrine actions of hypothalamic hormones within a nucleus.

    Magnocellular System

    • OT and AVP primarily produced in PVN and SON, targeting posterior pituitary.
    • Unique structure: Secretion from neuronal dendrites as well as axon terminals.
    • Regulation: Visceral stimuli (cranial nerves IX & X), blood pressure sensors, brain stem nuclei (NTS), and limbic system inputs.
    • Role: Osmoregulation, uterine contraction, milk ejection, blood pressure regulation.
    • Water deprivation triggers OT & AVP secretion.

    Oxytocin and the Posterior Pituitary

    • Critical during parturition/birth, milk ejection, lactation, osmoregulation, social behaviors (bonding, stress responses).
    • Plasticity: Changes in neuron synapses and astrocytic processes, allowing for coordinated neuronal and hormonal activity..

    Positive and Negative Feedbacks

    • Negative feedback: Steroids inhibit GnRH secretion, kisspeptin activity and synthesis via estrogen receptor-alpha (ERα).
    • Positive feedback: High estrogen levels enhance kisspeptin secretion by different populations within the brain; this drives LH surge that triggers ovulation.

    Regulation of Gonadotropin Synthesis and Secretion

    • Glycoprotein hormones (LH, FSH) with unique beta subunits.
    • Frequency of GnRH pulses influences LH and FSH expression.
    • Inhibins (A, B) and activins regulate FSH.

    Female Reproductive System

    • HPG axis: Hypothalamic-pituitary-gonadal axis regulates reproduction through GnRH, FSH, and LH.
    • Menstrual cycle with follicular and luteal phases.
    • Estrogen and progesterone control ovarian function and uterine changes.
    • Gonadal hormones feed back to regulate the hypothalamus.
    • Positive vs negative estrogen feedback on kisspeptin release.
    • Estrogen receptors ERα and ERβ plays major roles.

    Kallman's Syndrome

    • Genetic disorder caused by failure of GnRH neurons to migrate.
    • Leads to hypogonadotropic hypogonadism (HH) and anosmia (lack of sense of smell).

    Conclusion

    • Neuroendocrine communication involves complex interactions between neural and hormonal systems.
    • Hypothalamus, pituitary, and gonads are key components in controlling reproductive and other essential body functions.
    • Numerous feedback mechanisms and precise timing of hormonal pulses are crucial for coordinated bodily functions.

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    Test your knowledge on neuroendocrine communication and its mechanisms. This quiz covers topics like hormone influence, pancreatic enzyme release, and the characteristics of neuroendocrine signaling. Challenge yourself with questions about hypothalamic releasing factors and their functions.

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