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Microscopy of the hypothalamus, the hypothalamo-hypophyseal system

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1 Microscopy of the hypothalamus, the hypothalamo-hypophyseal system
Viktória Vereczki M.D., PhD. Department of Anatomy, Histology and Embryology Semmelweis University :00 a.m

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6 The structure of hypothalamus

7 Preoptic area lateral preoptic nucleus medial preoptic nucleus: tr. hypothalamo- hypophysealis LHRH Lateral zone: Cardiovascular functions, regulation of food and water intake lateralis hypothalamic nucleus tuberal nuclei medial forebrain bundle

8 Preoptic area

9 Medial zone 1. regio anterior ( supraoptic region)
supraoptic n.: supraopticohypophyseal tract (VAS, OXI) paraventricular n.: paraventriculohypophysealis tract (VAS, OXI) anterior n. suprachiasmatic n.: retinohypothalamic tract (VIP) 2. medial region ( tuberal region) ventromedial n. :satiety center dorsomedial n.: behavioral center arcuate n.: tr. hypothalamo-hypophysealis (relasing hormons) 3. posterior region (mamillary region) mamillary bodies dorsal hypothalamic nucleus

10 Medial Zone 1.

11 Medial zone 1. regio anterior ( supraoptic region)
supraoptic n.: supraopticohypophyseal tract (VAS, OXI) paraventricular n.:paraventriculohypophysealis tract(VAS, OXI) anterior n. suprachiasmatic n.: retinohypothalamic tract (VIP) 2. medial region ( tuberal region) ventromedial n. :satiety center dorsomedial n.: behavioral center arcuate n.: hypothalamo-hypophyseal tract (releasing hormons) 3. posterior region (mamillary region) mamillary bodies dorsal hypothalamic nucleus

12 Medial Zone 2. regio posterior regio anterior regio medialis

13 Afferent connections:
1. Fornix hippocampus-subicumum mamillary bodies 2. Medial forebrain bundle septum pellucidum zona lateralis hypothalami tegmentum mesencephali 3. Stria terminalis corpus amygdaloideum zona preoptica, medialis hypothalamus 4. Others: reticular formation (Ser, NA) nucleus of solitary tract parabrachial nucleus dorsomedial nucleus of thalamus retina prefrontal cortex

14 Afferent connetions of hypothalamus

15 Efferent connections:
Nervous and vascular links with the hypophysis: Hypothalamo-hypophyseal system A . Reciprocal paths to the limbic system B. Descending polysynaptic paths to lower autonomic and motor center

16 Efferent connections:
1. Fornix hippocampus-subicumum mamillary bodies 2. Medial forebrain bundle septum pellucidum zona lateralis hypothalami mesencephalic tementum 3. Stria terminalis corpus amygdaloideum zona preoptica, medialis hypothalamus 4. Mamillothalamic (Vicq d’Azyr) tract , part of the PAPEZ –ring mamillary bodies anterior thalamic nucleus 5. Hypothalamospinal tract paraventricular n n. dorsalis nervi vagi és dorsomedial n n. tr. solitarius 6. Dorsal longitudinal fascicle (Schütz-bundle) medial zone of hypothalamus substantia grisea centralis of mesencephalon 7. Mamillotegmental tract: mamillary bodies reticular formation of mesencephalic tementum

17 Efferent connetions of hypothalamus

18 Regulation of endocrine organs
Neurosecretion: secreration of neruon gets to the bloodstream NEUROENDOCRINOLOGY „The hypothalamus is the „head ganglion” of the autonomic nervous system (Sherrington1947) Portal circulation of hypophysys: hypothalamic factors reach directly the adenohypophysist Glandotrop hormons through systematic circulation reach endocrin glands Negative feedback: hormons of targeted organ inhibit the adenohypophysis Közp. idegr. Releasing hormon (pl. CRF) Adenohypophysis sejt (pl. corticotrop) Glandotrop hormon (pl. ACTH)

19 Hypothalamo-hypophyseal system

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21 Vessels of the hypophysis
Arteries (from ICA) SHA: Superior hypophyseal artery IHA: Inferior hypophyseal artery Portal vessels Carrying hormone releasing factors LPV: Long portal vessels SPV: short portal vessels Lateral hypophyseal vein Drains to cavernous sinus

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23 tuberoinfundibular tract
Parvocellular tuberoinfundibular tract Tuberal nuclei: Arcuate nucleus (DA) Periventricular zone Paraventricular nucleus parvocellular part Supraopticus parvocellular part hypothalamic hormone Effect CRH POMC: ACTH+ β-LPH+ TRH TSH+ LHRH (GnRH) FSH+, LH+ GHRH GH+ DA PL- Somatostatin GH-, TH- Paraventricular nucleus Tuberal nuclei

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25 2. Magnocellular hypothalmo-neurohypophyseal system
N.paraventricularis N.supraopticus 2. Magnocellular hypothalmo-neurohypophyseal system Paraventricular nucleus magnocellular part Supraoptic nucleus magnocellular part hormones effect Antidiuretic or resorption of water vasopressin Oxytocin ejection of milk 2. uterine contraction Herring –bodies store them (neurophysisn 1 and 2) in the neurohypophysis

26 Eminentia mediana (Dr. Kántor O.) TRH= thyreotropin releasing hormon
EZ TRH TRH= thyreotropin releasing hormon IZ EZ AVP AVP= Arginin-Vasopressin (Dr. Kántor O.)

27 Neurohypophysis: Terminations of Supraotico-paraventriculohypo-physeal tract Herring –bodies store OXI and Vas (neurophysisn 1 and 2) in the neurohypophysis

28 Effects of oxytocin, vasopressin
♀: uterus: contraction during delivery breast: contraction of myoepithel cells → ejection of milk ♂: role in ejaculation? Vasopressin (antidiuretic hormon, ADH): kidney: distal convoluted tubules and collecting ducts Aquaporin-2 (water channel) → reauptake of water, concentration of urine. Destruction of the magnocellular hypothalamo-hypophysial tract: diabetes insipidus vessels: vasoconstrictor → elevates blood pressure ↑ ♂: role in sexual attachment

29 Functions of hypothalamus 1. thermoregulation 2. food intake 3
Functions of hypothalamus 1. thermoregulation 2. food intake 3. water metabolism 4. behavior: emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus

30 Functions of hypothalamus 1. thermoregulation 2. food intake 3
Functions of hypothalamus 1. thermoregulation 2. food intake 3. water metabolism 4. behavior: emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus

31 Functions of hypothalamus 1. thermoregulation 2. food intake 3
Functions of hypothalamus 1. thermoregulation 2. food intake 3. water metabolism 4. behavior: emotions, sexual behavior, 5.control of circadian rhytms (SCH, tr retinohypothalamicus

32 Functions of hypothalamus 1. thermoregulation 2. food intake 3
Functions of hypothalamus 1. thermoregulation 2. food intake 3. water metabolism 4. behavior: emotions, sexual behavior, anger reactions 5.control of circadian rhytms (SCH, tr retinohypothalamicus

33 Functions of hypothalamus 1. thermoregulation 2. food intake 3
Functions of hypothalamus 1. thermoregulation 2. food intake 3. water metabolism 4. behaviour: emotions, sexual behavior, anger,etc. 5. control of circadian rhytms (SCH, tr retinohypothalamicus ICC of Orexin in narcoleptic patient compared to control

34 5. control of circadian rhytms: retinohypothalamic tract
Medial zone Suprachiasmaticus nucleus (VIP) : retinohypothalamic tract of rat (Scale: 100 µm. OX= optic chiasm;SCH=suprachiasmatic nucleus)

35 Clinical disorders associated with hypothalamic lesions
-Obesity and wasting -bulimia or anorexia

36 In childood: pubertas precox, sexual retardation
-Sexual disorders : In childood: pubertas precox, sexual retardation After puberty: impotence or amenoohea 4,5 years old boy suffering in pubertas precox

37 -Hyperthermia and hypothermia
-Diabetes insipidus

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39 Literature Williams PL, Marwick R, Dyson M, Bannister LH. Gray’s Anatomy 37th ed. (Churchill Livingstone, 1989) Antony L. Mescher: Junqueira’s Basic Histology 12th ed.( Mc Gaw Hil, 2010) Netter’s concise Neuroanatomy Richard S. Snell: Clinical Neuroanatomy for medical students 3rd ed.(Little, Brown and Co. 1992)


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