24. Endocrine system I. Hypothalamus, the hypothalamic- hypophyseal system, epiphysis Flashcards
List 3 regions of Hypothalamic nuclei and areas
- Anterior region
- Middle region
- Posterior region
Hypothalamic nuclei and areas
-> Which 5 nuclei are included in anterior region?
- anterior nucl.
- preoptic med. and lat. nuclei
- paraventricular nucl.
- supraoptic nucl.
- suprachiasmatic nucl.
Hypothalamic nuclei and areas
-> Name 3 zones of middle region
- Periventricular zone
- Medial zone
- Lateral zone
Hypothalamic nuclei and areas
-> Which 5 nuclei are included in anterior region?
- anterior nucl.
- preoptic med. and lat. nuclei
- paraventricular nucl.
- supraoptic nucl.
- suprachiasmatic nucl.
Hypothalamic nuclei and areas
-> list 3 nuclei of medial zone in middle region?
- ventro- and dorsomedial nuclei
- infundibular (arcuate) nucl.
Hypothalamic nuclei and areas
-> List area and nuclei of lateral zone in middle region
- lateral hypothalamic area
- medial forebrain bundle
Hypothalamic nuclei and areas
-> List nuclei and areas in posterior region
- posterior hypothalamic nucl.
- corpus mamillare
Hypothalamic nuclei and areas
-> Which system do Hypothalamic nuclei and areas contribute to?
the hypothalamo-hypophyseal system
The hypothalamus is the center of homeostatic control and integration
-> List controlled functions
- fluid homeostasis, blood volume and pressure
- appetite and body weight
- sexual functions, reproduction
- circadian regulation
- body temperature
- stress response
- codes of set points
The hypothalamus orchestrates the responses to stimuli at three levels which are ____
- Neuroendocrine function
- Autonomic function
- Emotions and Drives
The hypothalamus orchestrates the responses to stimuli at three levels:
1. Neuroendocrine function
-> Explain
control of the pituitary gland. Hypothalamo-hypophyseal system.
The hypothalamus orchestrates the responses to stimuli at three levels:
2. Autonomic function
-> Explain
integrates autonomic functions via direct and indirect projections to preganglionic autonomic neurons located in the brain-stem and spinal cord.
The hypothalamus orchestrates the responses to stimuli at three levels:
3. Emotions and Drives function
-> Explain
it has numerous interconnections with the limbic system by which it generates behaviors involved in rage, aggression, escape, etc.
List Hypothalamic Inputs
List Hypothalamic outputs
Hypothalamic neuronal pathways
- Intrahypothalamic connections
- Extrahypothalamic connections: Mostly reciprocal connections!
- Bidirectional
- retinohypothalamic tract
Bidirectional hypothalamic neuronal pathways
- fornix
- stria terminalis
- medial forebrain bundle (MFB)
- dorsal longitudinal fascicle (FLD, Schütz)
Hypothalamic neuronal pathways
-> retinohypothalamic tract
mamillothalamic tract
mamillotegmental tract
hypothalamo-hypophyseal tract (HHT)
List Limbic afferents
List Hypothalamic efferents
mamillothalamic and mamillotegmental tracts
Hypothalamic efferents
-> 4 characteristics of mamillothalamic tract
- bundle of Vicq d’Azyr
- part of the Papez circuit
- from the mamillary body (medial n. )
to anterior thalamus - involved in memory functions
Hypothalamic efferents
-> 3 characteristics of mamillotegmental tract
- bundle of Gudden
- from the mamillary body (lateral n.)
to the midbrain tegmentum - relayed toward the brainstem
autonomic centers
Hypothalamic efferents
-> 3 characteristics of mamillotegmental tract
- bundle of Gudden
- from the mamillary body (lateral n.)
to the midbrain tegmentum - relayed toward the brainstem
autonomic centers
Suprachiasmatic nucleus: the biological clock
-> What is the pathway?
Retina
-> Retinohypothalamic tract
-> SCN
What is Melatonin?
the hormon pruduced by the pineal gland.
How does Epiphysis or pineal gland develop from?
Develops from neuroectoderm as an evagination in the roof of the diencephalon.
Histology of the pineal gland
The pituitary is connected with the hypothalamus via the ___
infundibulum
What is the blood supply of the hypothalamus?
Superior hypophyseal artery – internal carotid artery
Inferior hypophyseal artery - circulus arteriosus
Adeno- and neurohypophysis are the main parts of ___
the pituitary
What is the adenohypophysis?
anterior pituitary: produces its own hormones
What is the Neurohypohysis?
Neurohypohysis = posterior pituitary: does not produces hormones
Is the adenohypophysis a glandular or neuronal tissue?
a glandular tissue
What is the neurohypophysis?
the neurohypophysis is a neuronal tissue
What is the Hypophyseal cleft:?
The part between the pars intermedia and pars distalis
The adeno- and neurohypophysis have different embryological origin
-> Which one is the ectodermal one?
The adeno- and neurohypophysis are both ectodermal
The adeno- and neurohypophysis have different embryological origin
-> Embryological origin of Neurohypophysis
neuroectodermal
The adeno- and neurohypophysis have different embryological origin
-> Embryological origin of Adenohypophysis
ectodermal (hypophyseal placod)
Magnocellular neurons of the supraoptic and the paraventricular nucleus in the hypothalamus project to the neurohypophysis
-> Name the neurons that compose the hypothalamo-hypophysial tract?
Fibers of the magnocellular neurons
Magnocellular neurons of the supraoptic and the paraventricular nucleus in the hypothalamus project to the neurohypophysis
-> Magnocellular neurons express ___ (which types of hormones)
vasopressin (ADH) or oxytocin (different cells)
Magnocellular neurons of the supraoptic and the paraventricular nucleus in the hypothalamus project to the neurohypophysis
-> The role of Oxytocin
It stimulates uterus contraction, milk ejection, social bonding.
Magnocellular neurons of the supraoptic and the paraventricular nucleus in the hypothalamus project to the neurohypophysis
-> What is the role of vasopressin (ADH)?
ADH increases water absorption in the collecting ducts of the kidney nephron.
Oxytocin and vasopressin are transported via the axons connectedto carrier molecules called neurophysis
-> What are Herring bodies?
- large clusters of neurosecretory granules at the terminal portion of the axons
- oxytocin+neurophysin1 or ADH+neurophysin2 is stored in different terminals
- they can be seen at light microscopic level
Histology of the pars nervosa
-> Identify
- unmyelinited axons
- special glial cells - pituicytes, oval nucleus
- fenestrated capillaries
Parvocellular neurons project to the median eminence and release ____
hormones into the portal circulation
Parvocellular neurons of the hypothalamus regulate hormone production of the adenohypophysis
-> tuberoinfundibular neurosecretory system
Releasing and inhibiting hormones and their target in the anterior pituitary
-> List 6 hormones
GnRH: gonadotropin releasing hormone or luteinizing-hormone-releasing hormone (LHRH)
GHRH: growth hormone releasing hormone
SS: somatostatin
TRH: thyrotropin-releasing hormone
DA: dopamine
CRH: corticotropin-releasing hormone or factor (CRF)
Hypotalamic-pituitary-gonadal (HPG) axis
Hypotalamic-pituitary-thyroidal (HPT) axis
Hypotalamic-pituitary-adrenal (HPA) axis
Pituitary cell types in hematoxylin-eosin stained section
-> List acidophils and their roles
*Somatotrophes produce growth hormone (GH)
*Lactotrophes produce prolactin
Pituitary cell types in hematoxylin-eosin stained section
-> List basophils and their roles
- Thyrotrophes produce thyroid stimulating hormone (TSH)
- Gonadotrophes produce luteinizing hormone (LH) or follicle-stimulating hormone (FSH)
- Corticotrophes produce adrenocorticotrophic hormone (ACTH)
Pituitary cell types in hematoxylin-eosin stained section
-> Describe Chromophobes
- These are cells that have minimal or no hormonal content.
- Many of the chromophobes may be acidophils or basophils that have degranulated and thereby are depleted of hormone.
- Some chromophobes may also represent stem cells that have not yet differentiated into hormone-producing cells.
Hormone producing cells of the anterior pituitary can be identified by immunohistochemistry
-> What is the distribution of Gonadotropes (LH and FSH coexpressing cells)?
Gonadotropes (LH and FSH coexpressing cells):
* comprise 10–15% of anterior pituitary cells and are scattered throughout the anterior pituitary.
What type of cells are in pars distalis?
Acidophil, basophil and chromophobe cells
What type of cells are in pars tuberalis?
Basophil cells
Identify
Identify
The pars intermedia is very small in adults and may contain ___
colloid-filled cysts
Identify
The pars intermedia is very small in adults and may contain cysts
-> Cysts filled with ___
colloid
The pars intermedia is very small in adults and may contain colloid-filled cysts which is lined with ____
cuboidal cells
The pars intermedia is very small in adults and may contain colloid-filled cysts are remainders of ____
The Rathke’s pouch
