The Pituitary Gland Flashcards
What are the two distinct parts of the pituitary gland?
Anterior and posterior pituitary
Is the true endocrine tissue located in the anterior or posterior part of the pituitary?
Anterior
Posterior part is neuroendocrine tissue
What is the origin of the anterior pituitary?
Epithelial tissue origin
What is the origin of the posterior pituitary?
Neural tissue origin
In what part of the pituitary is the neural connection with the hypothalamus?
Posterior, also called the neurohypophysis, secretes neurohormones made in the hypothalamus
How is the anterior pituitary connected with the hypothalamus?
Via two connected capillary beds (portal system)
What is another name for the anterior pituitary?
The adenohypophysis
How does the hypothalamus control production of anterior pituitary hormones?
By releasing or inhibiting hormones that stimulate or inhibit hormone production from the anterior pituitary e.g. TRH (thyroid releasing hormone). These are TROPHIC hormones and control the release of other hormones
What are trophic hormones?
Hormones modulated by the hypothalamus which control the release of other hormones
How many hormones are released from the pituitary? What type of hormone are they? How many of these hormones are trophic?
6, all are peptide hormones, 5
What are the 6 anterior pituitary hormones? Which of these are trophic?
Thyroid stimulating hormone - TSH Adrenocorticotrophic hormone - ACTH Follicle stimulating hormone - FSH Luteinising hormone - LH Growth hormone - GH Prolactin
All but prolactin are trophic
What is the function of prolactin?
Stimulating milk production from the breast during lactation
What is the target and effect of TSH?
Thyroid gland, TH release
What is the target and effect of ACTH?
Adrenal cortex, cortisol release
What type of hormones bind to receptors on the anterior pituitary and stimulate/inhibit the release of AP hormones?
Hypothalamic releasing hormones
What type of hormone are hypothalamic hormones?
Neurohormones
What are the seven hypothalamic releasing hormones? What type of hormones are these?
Thyrotropin releasing hormone (TRH)
Corticotropin releasing hormone (CRH)
Growth hormone releasing hormone (GHRH)
Growth hormone inhibiting hormone (GHIH) aka somatostatin
Gonadotrophin releasing hormone (GnRH)
Prolactin releasing hormone (PRH)
Dopamine aka prolactin inhibiting hormone
All are peptides expect dopamine
What is the hypothalamo-hypophyseal portal system?
A network of tiny vessels which transfer hormones from hypothalamus to anterior pituitary
Where in the hypothalamo-hypophyseal portal system are hormones released from neurosecretory neurons?
The median eminence
What are the three integration centres involved in anterior pituitary feedback control?
Hypothalamus
Anterior pituitary
Target endocrine cell
What type of loop feedback does feedback from an endocrine target produce?
Long-loop feedback
What type of loop feedback does feedback from the anterior pituitary to the hypothalamus produce?
Short-loop feedback
What hormones does the posterior pituitary store and release? What type of hormone are these?
Vasopressin aka anti-diuretic hormones ADH
Oxytocin
Peptide neurohormones
What type of neurons synthesis the two peptide neurohormones stored and released in the posterior pituitary? Where are the cell bodies of these neurons?
Magnocellular neurons, specific areas of the hypothalamus
What is the main function of vasopressin?
Resulting water balance
What is the main function of oxytocin?
Milk ejection and uterine contraction
What is hyposecretion?
Too little hormone secreted
What is hypersecretion?
Too much hormone secreted
What is hyporesponsiveness?
Reduced response of the target cell
What is a primary endocrine disorder?
Those in which the defect is in the cell(s) that secrete the hormone
What is a secondary endocrine disorder?
Those in which there is too little or too much trophic hormone from the pituitary
What are tertiary endocrine disorders?
Ones which relate to hypothalamic defects
