The Endocrine System: Hypothalamus and Pituitary Gland Flashcards
Hypothalamus and Pituitary
What is the generalized function of the hypothalamus and pituitary?
Relay stations that act in sequence
Hypothalamus
What is the anatomy of the Hypothalamus?
Essentially just two nuclei with processes that extend down into the posterior pituitary
Histology = brain/nervous tissue
Hypothalamus
What is the function of the Hypothalamus?
Releases peptide hormones that stimulate the pituitary
Hypothalamus
What triggers release of hormones from the Hypothalamus?
Sensory stimuli: Light, olfactory, autonomic, etc.
Other stimuli: Blood-bourne sterioids, hormones, blood glucose, blood pressure, stress, etc.
Hypothalamus
What happens to hormones released by the Hypothalamus?
- They accumulate in the axons fo the neurohypophysis
- Release in the median eminence that diffuse into the adenohypophysis
Hypothalamus
What hormones, from the Hypothalamus, accumulate in the axons in the neurohypophysis?
- Oxytocin
- Vasopressin
Hypothalamus
What hormones, from the Hypothalamus, diffuse into the adenohypophysis?
- Somatostatin
- Dopamine
- GHRH
- CRH
- GnRH
- TRH
Hypothalamus
Somatostatin
Inhibits GH and insulin secretion
Hypothalamus
Dopamine
Inhibits prolactin secretion by the pituitary
Directly impacts pituitary
Hypothalamus
Growth Hormone Releasing Hormone (GHRH)
Stimulates GH secretion by pituitary
Hypothalamus
Corticotropin-Releasing Hormone (CRH)
Stimulates ACTH secretion by the pituitary
Hypothalamus
Gonadotropin-Releasing Hormone (GnRH)
Stimulates LH/FSH secretion by the pituitary
Hypothalamus
Thyrotropin-Releasing Hormone (TRH)
Stimulates TSH secretion by the pituitary
The Pituitary Gland
What is the function of The Pituitary Gland?
- Receives signals from the CNS (specifically the hypothalamus)
- Sends signals to other endocrine glands and organs
The Pituitary Gland
What are the two parts of The Pituitary Gland?
- Neurohypophysis - posterior pituitary (nerve tissue) - Pars nervosa
- Adenohypophysis - anterior pituitary (glandular tissue - Pars distalis
The Pituitary Gland
What is the Pars intermedia?
Thin layer between the neurohypophysis and adenohypophysis containing colloid filled sacs (remnants of rathke’s pouch)
It also contains basophils and chromophobes from the adenohypophysis
The Pituitary Gland
The Neurohypophysis
Axons of nerves from hypothalamus
Pituicytes (supportive glial cells)
Neurosecretory bodies (herring bodies) containing hormones (Oxytocin and ADH (vasopressin)
The Pituitary Gland
What is the function of Antidiuretic Hormone?
aka ADH/Vasopressin
Increases water absorption in kidneys
Induces vasoconstriction
Increases Blood Volume/BP
The Pituitary Gland
What is the function of Oxytocin?
Stimulates smooth muscle contraction
Myoepithelial cells in lactating brest
The Pituitary Gland
Basophils produce…
endorphins
The Pituitary Gland
What three cell types are found in the adenohypophysis?
Acidophils
Basophils
Chromophobes
The Pituitary Gland
What type of hormones do acidophils produce?
Somatotropic
Mammotropic
The Pituitary Gland
What type of hormones do basophils produce?
Gonadotropic
Corticotropic
Thyrotropic
The Pituitary Gland
What are chromophobes?
They are thought to be stem cells or depleted cells
The Pituitary Gland
Describe Acidophils histologically
Trichrome: Highly magenta
H&E: Very eosinophilic
The Pituitary Gland
Describe basophils histologically
Blueish purple
The Pituitary Gland
Describe chromophobes histologically
Empty cytoplasm (resistant to dye)
Stem cells or Acidophils/basophils that have released all their contents
The Pituitary Gland
Do i need to know the major functions for the hormones on slide 32? She said just for reference?
The Pituitary Gland
What is the function of corticotropin - releasing hormone?
Stimulates release of proopiomelanocortin (POMC) by corticotropic basophils
Where is corticotropin-releasing hormone produced?
Hypothalamus
The Pituitary Gland
What happens once POMC is released by corticoptropic basophils?
POMC is cleaved to
* β - lipotropin (β-LPH) → β-LPH stimulates melanocytes to produce melanin → induces lipolysis and steriodogenesis
* ACTH
