Beckett lecture: pituitary phgysiology Flashcards
Ventral hypothalamic neurons connect to what portal system?
Primary acpaillary plexus of the hypophyseal portal system
Neons from which nuclei supply the neurohypophysis?
Suproptic and Paraventricular
Which neutrons synthesis hormones for the post pituitary?
Mangocellular neurons
What is the name of the neuronal tract between the hypothalamus and the post pituitary
hypothalamic-hypophyseal tract
What 2 hormones are released by the posterior pituitary?
ADH and Oxytocin
What cells comprise the posterior pituitary?
Pituicytes (glial-like cells) and magnocllular neurons
Where does oxytocin originate?
Paraventricular and supraoptic nuclei
What are the functions of oxytocin?
Milk ejection and uterine smooth muscle contraction
What receptor does oxytocin act on?
GPCR
Where is ADH synthesised?
Mainly in the supraoptic nucleus
Name 3 functions of ADH
Reabsorption of water
Increase thirst
Vasoconstriction
What activates the cells for eh ant pit?
Rleasing/inhibitory hormones released from the hypothalamus
Outline the functions of FSH na LH
FSH: INCRASE Folliculogenesis and oestrogen/ sperm maturation
LH: increase ovulation, oestrogen and testosterone
What is the nature of GnRH secretion?
Pulsatile and suppressed by lactation, diet, exercise and stress
Which hormone suppresses GnRH
Corticotropin releasing hormone
What can cause hyperprolactinaemia?
Prolactinoma and Dopamine antagonists (schizophrenia)
What is the affect of prolactin on GnRH and therefore what ais the clinical presentation?
Prolactin inhibits GnRH causes an ovulation and amenoorhaoe in females and infertility in men/reducd libido
How can pituitary insufficiency arise?
Pituitary tumour/ destruction pit gland (i.e. inflammation), SAH, radiotheral
What are the secretions from the 2layers of the adrenal glands
medulla = catecholamines Cortex= steroids
Illustrate the correlation between site and secretion in the adrenal cortex
Zona reticularis: sex hormones
Zona fascicularis: glucocorticoids
Zone glomerulosa: aldosterone
What cells release adrenaline/noradrenaline?
Chromaffin cells
Effect of aacatecholamines?
Increase co, cerebral perfusion, pulmonary ventilation
What are the effects of cortisol on the immune system, liver uncle and adipose tissue?
Suppression immune, gluconeogenesis in liver, protein catabolism in muscle and lipolysis in the adipose tissue
What is the effect of cortisol on insulin?
Antagonist
What is the affect of cortisol on the heart?
Increases sensitivity to adrenaline and noradrenaline
How does cortisol affect the immune system?
Inhibits prostaglandin and leukotriene synthesis
What is the therapeutic utility of cortisol?
Allergies, autoimmune disease
How does cortisol levels vary?
In a diurnal variation
Two major effects of aldosterone?
Increase K excretion and incase na reabsorption
What are the manifestations of adrenocortical hyper secretion?
Cushing’s sndreom, hyperaldosteronism, andrenogenital syndrome
What can cause cushing’s syndrome?
Hypersection of CRH or acth (Pituitary causes = Cushing’s disease)
Adrenal cortex adenomas
Ectopic secretion
Glucocorticoi dose
Manifestations of cushing’s syndrome?
Adrenal diabetes
Fat redistribution
muscle and bone weakness (breakdown of protein)
What is conn’s syndrome
Small, aldosterone-secreting tumor of the zona glomerulosa
How does conn’s syndrome manifest?
Muscle paralysis, hypertension and low plasma rennin
What n cause adrenal androgen excess?
Tumours or congenital adrenal hyperplasia
