Pituitary and Hypothalamus Flashcards
The preoptic area is derived from the:
Telencephalon
The medial preoptic nucleus produces:
Gonadotropin-releasing hormone (anterior pituitary will release LH and FSH)
The lateral hypothalamic nucleus is also referred to as _______
a “feeding center” (destruction causes weight loss, stimulation promotes feeding)
What are the 3 regions in the medial zone?
- Supraoptic region (internal to optic chiasm)
- Tuberal region (internal to tuber cinereum)
- Mammillary region (internal to mammillary bodies)
What are the 4 nuclei in the supraoptic region?
- Supraoptic
- Paraventricular
- Suprachiasmatic
- Anterior
Supraoptic and paraventricular nuclei contain _____ and _____ and transmit them to posterior pituitary via the supraopticohypophysial tract.
Oxytocin and ADH (vasopression)
The suprachiasmatic nucleus is believed to regulate what?
Circadian rhythms (receives input from retina, communicates with other nuclei)
The anterior nucleus is mostly involved in:
maintenance of body temperature
What 3 nuclei are in the tuberal region?
- Ventromedial
- Dorsomedial
- Arcuate
Bilateral lesion to the ventromedial nuclei leads to…
Continuous stimulation of hunger –> excessive eating (it’s a satiety center)
Lesion to lateral hypothalamus results in…
Inadequate production of feeding signal –> anorexia
Stimulation of dorsomedial nucleus of the thalamus leads to…
Unusually aggressive behavior, lasting during stimulation. Sham Rage.
The arcuate nucleus is the primary location for ________
neurons with releasing hormones. Transmitted to anterior pituitary via tuberoinfundibular tract and hypophysial portal system
What 4 nuclei are in the mammillary region?
- Medial mammillary
- Intermediate mammillary
- Lateral mammillary
- Posterior hypothalamic
Lesion of the mammillary body causes:
failure of retention of newly acquired memory, so that an immediate memory or a short-term memory is not processed into long-term memory (anterograde amnesia); hard to learn new tasks
What is Korsakoff Syndrome?
Caused by thiamine deficiency (associated with chronic alcoholism) –> progressive degeneration of mammillary bodies and related structures (hippocampus, MD thalamus)
What are some characteristics of Korsakoff Syndrome?
Difficulty understanding written material, conducting conversation due to forgetting what the just said, and confabulating memories to a synthesized memory that never occurred
The posterior hypothalamic nucleus is associated with _______
The PAG and has associated emotional, cardiovascular, and analgesic functions
The periventricular zone nuclei function similarly to the ______
Arcuate nuclei
What hormones cause a decrease in feeding? What is this stimulated by?
- TSH and ACTH
- leptin
Horner syndrome can ALSO be caused by:
Lesion to hypothalamomedullary fibers
What can cause diabetes insipidus?
Lesion to supraoptic, paraventricular nuclei, supraopticohypophysial tract, pituitary damage from tumor, shearing of pituitary stalk in head trauma
What is diabetes insipidus?
Deficiency of ADH, leading to polyuria, polydipsia, dilute urine (ethanol contributes to ADH deficiency)
Treatment: Synthetic vasopressin
ADH secreting tumor causes:
Hyponatremia
What is gigantism?
Excessive GH production before closure of growth plate –> bone overgrowth and large but weak muscles (excessive connective tissue)
What is acromegaly?
Overproduction of GH after closure of growth plate –> elongated face, malocclusion of jaw, sinus bulges, thickened lips, large hands/feet…excessive cortical thickening of bone, cardiomegaly, hypertension, diabetes mellitus
What is hyperthyroidism?
Overproduction of TSH –> increased T3/T4 in blood, causing nervousness, sweating, insomnia, tremor, weight loss, heat sensitivity, abnormal cardiovascular function, and cranial nerve signs (VI, then III and IV)
What is Cushing Disease?
Overproduction of ACTH (hyperadrenalism) –> Truncal obesity, violaceous striae (purple streaks), easy bruising, hypertension, facial hirsutism, moon-face, cervicodorsal fat pad
What causes insomnia?
Lesion to ventrolateral preoptic nucleus (VLPO) –> inability to inhibit tuberomammillary nucleus –> constant histamine production
What is narcolepsy?
Lesion to orexin neurons (lateral hypothalamic area) –> inability to stimulate tuberomammillary nucleus –> inadequate histamine release –> sudden, uncontrolled sleep
Adenomas in the pituitary can compress hypothalamic structures, leading to ______
functional deficits…
List some secreting pituitary tumors (most common one first):
Prolactin, GH, TSH, ACTH, LH, FSH
Non-secreting pituitary tumors/adenomas can cause:
Visual disturbances and headaches
Caudolateral hypothalamus lesion causes:
Inhibition of sympathetic activity and reduction in body temperature
Rostromedial hypothalamus lesion causes:
Inhibition of parasympathetic activity and increase in body temperature
What does a prolactin-secreting tumor cause?
- Galactorrhea (milk production)
- Amenorrhea (no menstruation)
How does the temperature regulation reflex work for rising temperature?
Blood reaches hypothalamus is warmer –> stimulate rostral hypothalamus –> heat dissipation mechanisms are activated (sweating, cutaneous vasodilation, ANS)
How does the temperature regulation reflex work for falling temperature?
Blood reaches hypothalamus is cooler –> stimulate caudal hypothalamus –> heat conversion mechanisms are activated (cutaneous vasoconstriction, ANS) and heat production (shivering, reticulospinal pathway)
What is the water balance reflex?
Osmolarity of blood sensed via neurons in anterior hypothalamus (near preoptic and PVN) –> ADH released from supraoptic nucleus and paraventricular nucleus
What is the rostral boundary of the hypothalamus?
Lamina terminalis (and anterior part of 3rd ventricle)
What is the superior boundary of the hypothalamus?
Hypothalamic sulcus
What is the lateral boundary of the hypothalamus?
Substantia innominata and posterior limb of internal capsule
What is the medial boundary of the hypothalamus?
Inferior part of 3rd ventricle
What is the caudal boundary of the hypothalamus?
Merges into midbrain tegmentum and PAG (externally, the mammillary body)
Where does the posterior pituitary (pars nervosa) come from?
Outpocketing of diencephalon
Where does the anterior pituitary (adenohypophysis) come from?
Rathke pouch (also, pars tuberalis and pars intermedia)
