Neuro-endocrinology Flashcards
What is neuroendocrinology?
A branch of life sciences dealing with neurosecretion and the physiological interaction between the CNS and endocrine system
What are the basic components of the neuroendocrine system?
Parvocellular neurones and Magnocellular neurones in the hypothalamus act on the anterior and posterior pituitary in the pituitary gland, which act on target tissue, adrenal glands, thyroid gland and the gonads.
What is the function of the hypothalamus in neuroendocrinology?
To integrate autonomic responses and endocrine function with behaviour
Give 3 ways the hypothalamus controls homeostasis
Behaviour concerned with everyday homeostatic requirements of life Neuronal control through the autonomic nervous system Hormonal control through hormone release from the pituitary gland
What are the six homeostatic functions controlled by the hypothalamus and how is this achieved?
1) Blood pressure and electrolyte composition 2) Body temperature 3) Energy metabolism 4) Reproduction 5) Stress response 6) Growth 1) Control of drinking salt appetite and control of blood osmolarity and vasomotor tone 2) Metabolic thermoregulation and behaviours like seeing an appropriate environment 3) Feeding, digestion and metabolic rate 4) Hormonal control of mating, pregnancy, lactation 5) Adrenal stress hormones 6) Growth hormone
Which hypothalamic nuclei is responsible for: Stress Energy balance Osmoregulation Maternal Control Blood pressure
Paraventricular nucleus
Which hypothalamic nuclei is responsible for: Osmoregulation Maternal control
Supraoptic nucleus
Which hypothalamic nuclei is responsible for: Reproduction Growth Lactation
Arcuate nucleus
What is associated with a loss of Hypothalamic Orexin Neurones?
Narcolepsy
Where is the pituitary gland located?
In a bony cavity at the base of the brain called the Sella Turcica
How is the pituitary gland connected to the hypothalamus?
Via the pituitary stalk
Respectively, where do the anterior and posterior pituitary glands develop from?
A = Pharyngeal Epithelium P = Neuronal
Respectively, what cells do the anterior and posterior pituitary glands contain?
A = Glandular cells P = Axon terminals
Respectively, which neurons act on the anterior and posterior pituitary glands?
A = Parvocellular neurons P = Magnocellular neurons
Respectively, what is the neuroendocrinological action of the anterior and posterior pituitary gland?
A = Releasing/inhibiting factors via hypophysial portal system P = Hormones directly released from magnocellular axons
Which hormone is responsible for long bone growth?
Growth hormone
Which hormone is responsible for Thyroid stimulation and regulation? (T3 and T4 release)
Thyroid stimulating hormone
Which hormone is responsible for stimulation of the adrenal cortex? What is released on stimulation?
ACTH Corticosteroids
Which hormones are responsible for stimulation of the ovaries and testies? What is released on stimulation?
FSH and LH Oestrogen and progesterone are released by the ovaries Testosterone is released by the testis
What hormone is responsible for milk production in lactating women?
Prolactin
What does the hormone oxytocin do? Where is it released from?
Milk letdown in lactating women and uterine contractions in pregnant women Released from the posterior pituitary gland
What does the hormone ADH do? Where is it released from?
Kidney water retention Posterior pituitary gland
What is the feedback mechanism of prolactin?
Prolactin secretion causes the Parvocellular neurons in the anterior pituitary gland to reduce dopamine secretion, which in turn causes increased prolactin secretion and therfore more milk production Dopamine secretion and therefore milk production can also be regulated by a suckling stimulus
Describe the HPT axis (Hypothalamic-pituitary-thyroid axis) feedback loop What type of feedback loop is this?
Hypothalamus senses low levels of T3/T4 and responds by releasing TRH (thyrotropin-releasing hormone). TRH stimulates the anterior pituitary to produce TSH which in turn stimulates the thyroid to produce thyroid hormone until blood levels return to normal. This is a negative feedback look
Describe the HPA axis (Hypothalmic-pituitary- adrenal axis) feedback loop
HPA axis is responsible for the stress response. Hypothalamus releases CRH (corticotropin-releasing factor) which binds to receptors on the anterior pituitary gland causing CTH to be released. ACTH binds to receptors on the adrenal cortex and stimulates the release of cortisol. At a certain blood level of cortisol , the cortisol exerts negative feedback on to the release of CRH and ACTH
What are the 3 major neuroendocrine systems through whch the hypothalamus and anterior pituitary gland direct neuroendocrine function?
HPT axis HPA axis HPG axis
Describe the HPG axis (Hypothalmic-pituitary-gonadal axis) feedback loop
Describe the feedback loop in which vasopressin is released as a result of low blood pressure
Major restriction in blood volume is detected by baroreceptors
CN IX and CN X carry this information to the NTS in the brainstem
This either stimulates or inhibits the release of Vasporessin from the hypothalamus
Vasopressin acts of the V1 receptors on blood vessels, causing vasoconstriction and therefore an increase in blood pressure
