Hypothalamus I Flashcards
Name the hypothalamic nuclei and the region they reside in
¬ Preoptic – preoptic region ¬ Paraventricular – supraoptic region ¬ Supraoptic – supreoptic region ¬ Dorsomedial – tuberal region ¬ Ventromedial – tuberal region ¬ Posterior hypothalamic – mammillary region
What are the functional divisions of the hypothalamus ? What role do they play?
Lateral zone
Location: separted from the medial zone by the fornix
Function:
Integrate info from other hypothalamic nuclei engaged in emotions
Regulation of sleep wakefulness
Regulation of feeding
Middle zone - Magnocellular neurosecretory system
Location: nuclei interposed between the periventricular and lateral zones
Function:
Release of vasopressin and oxytocin from the posterior pituitary
Regulates the autonomic nervous system
Sets the biological rhythm via the suprachiasmatic nucleus
Periventricular Zone - Parvocellular neurosecretory
Location: small nuclei that border the third ventricle
Function: Regulating the release of endocrine hormones from the anterior pituitary gland
Blood supply of the hypothalamus
Posterior communicating artery, hypothalamic branch
Name the sensory organs that aren’t in the BBB
Area postrema
The subfornical organ (SFO)
Vascular organ of lamina terminalis
Name the secretory organs that aren’t in the BBB
Subcommissural organ (SCO) Posterior pituitary Pineal gland Median eminence Intermediate lobe of the pituitary gland
What circumventricular organs contain fenestrated capillaries?
All except subcommissural organ
What hypothalamic nuceli regulate the adenohypophysis?
dorsal medial, ventral medial and infundibular nuclei
Name the seven hormones which are released by the adenohypophysis. How are the regulated?
Human growth hormone Thyroid stimulating hormone Follicle stimulating hormone Luteinizing hormone Prolactin Adenocorticotropic hormone Melanocyte stimulating hormone
Regulated via inhibiting and releasing hormones of the hypothalamus which travel from the primary capillary bed to the secondary capillary plexus of hypopyseal portal system
What does the paraventricular, dorsomedial and ventromedial, medial eminence release?
Paraventricular nucleus: Thyrotropin RH
Dorsomedial and ventro medial hypothalamic nucleus and arcuate nucleus: Growth hormone RH
Median eminence: Luteinizing hormone RH
Describe how blood glucose levels are regulated via the adenohypophysis
Hypoglycaemia (low blood glucose)
Stimulates release of GHRH
Stimulates hGH by somatotrophs
hGH and IGFs breakdown liver glycogen into glucose which enters the blood rapidly and blood glucose level stabilises
If blood glucose continues to increase hyperglycaemia inhibits the release of GHRH
Hyperglycaemia (high blood glucose)
Stimulates the release of GHIH
Inhibits secretion of hGH by somatotrophs
A low level of hGH and IGFs decreases the rate of glycogen breakdown in the liver and glucose enters the blood more slowly and blood glucose returns to normal
If blood glucose continues to decrease, hypoglycaemia inhibits the release of GHIH
What hypothalamic nuclei regulate the neurohypopysis and what do they release?
Paraventricular: oxytocin
Supraoptic: vasopressin
What function division is the neuro and adenohypophysis?
neurohypophysis: magnocellular
adeno: parvocellular
Name the efferent projections of the hypothalamus
Mamillothalamic tract
mammilotegmental tract
