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73 Cards in this Set
- Front
- Back
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WHat doubles in size in pregnancy?
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Pituitary gland
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What is the most richly perfused mammalian tissue?
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Pituitary gland
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Hypophysis
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Pituitary
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Ant. and Post. pituitary have
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Diff. embryol. origins
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Ant. pituitary known as
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Adenohypophysis
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Ant. pituitary derived from
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RATHKE's pouch-ectodermal outpouching of oropharynx
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Ant. pituitary contains cells that produce
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TROPHIC hormones
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Post. pituitary=
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Neurohypophysis
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post. pituitary comes from
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-Evagination of VENTRAL hypoth. & 3rd ventricle
-consists of axons/nerve endings of neurons whose cell bodies reside in hypoth. |
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Trophic hormones
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Feed other endocrine organs
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Rathke's pouch
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MIgrates backward to meet neurohypophysis.
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Ant. pituitary is
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Endocrine tissue
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Post. pituitary is
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Neuronla tissue
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Median eminece becomes
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Pituitary stalk
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Where is pituitary gland located?
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Found in SPHENOID bone in sella turcica(protuberance in sphenoid bone,near sphenoid sinus)
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Pituitary gland can be accessed thru
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Nose
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Pituitary gland is
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Small(1 cm)
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If you put 1 stick in your ear and 1 stick in your eye,where they meet is
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Pituitary gland
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Hypophyseal portal system found in
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Median eminence--> travels to ant. pituitary
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Portal system occurs when
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A capillary bed drains into another capillary bed via VEINS.
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What are the 2 types of neurons in the hypothalamus?
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-Short neurons:near 3rd ventricle,terminate in median eminence(releasing hormones)
-Long neurons from Supraoptic nucleus & Paraventricular nucleus(oxytocin + ADH) |
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oxytocin & ADH
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released directly in central circulation.
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How many hormones are released by ant. pituitary?
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6
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name them
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-TSH
-LH -FHS -GH -ACTH -Prolactin |
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How many cell types in ant. pituitary?
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6
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Name them and their hormones they secrete.
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-Somatotroph: GH
-Lactotroph: PRL -Thyrotroph: TSH -Corticotroph: ACTH -Gonadotroph: LH/FSH -Null cells : alpha-SU |
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In the hypothalamic-pituitary-adrenal axis,what is the hypoth. releasing hormone/pituitary trophic hormone/Glandular hormone?
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-Hypoth. releasing hormone:CRH
-Pit. trophic hormone: ACTH -Glandular hormone : cortisol |
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ACTH has
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SHORT feedback on CRH releae
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What regulates pituitary dev./gene expression ?
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Transcription factors-nuclear proteins which bind to promotor sequence of genes(TFs involved in early dev. of Ant. pituitary)
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Binding does what?
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Switches gene transcription on/off.
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A mutation of PIT-1 responsible for
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Pituitary hormone deficiency-deficient in GH,PRL,TSH.
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FGF-1
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promote growth of olfactory lobe + outgrowth of GnRH
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Kallmann syndrome
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-Cant smell
-no GnRH -no puberty -small testicles -no body hair -long bones(unicorn phenotype) |
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Pituitary and hypothalamic hormones are often initially synthesised as a
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Larger precursor molecule-prohormone.
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POMC
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prohormone metabolized to diff. hormones in diff. cells ,depending on the complement of processing enz. in cell in question.(regulate appetite/pigmentation)
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POMC mutations in humans lead to
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-Severe early onset obesity
-adrenal insufficiency -Red hair pigmentation |
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Hormone production is
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Pulsatile
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ACTH is higher in
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MORNING--> increased cortisol(reason why heart attacks occur more in MORNING)
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What is important for biological function of hormones?
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Glycosylation
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Name the glycoprotein hormones.
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-TSH
-FSH -LH -hCG(from placenta) |
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The 4 hormones above are diff. due to their
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Beta subunit(SAME alpha subunit)
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Mutations in one of the enz. that glycosylate these hormones can lead to
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Secondary hypothyroidism / hypogonadism.
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What is specifity spill over?
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-Excess of hCG can stimulate thyroid gland(gestational thyrotoxicosis)
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No TSH implies
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no functioning thyroid hormones--> CRETINISM
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When thyroid fails and hypothyroidism occurs,TSH levels increase with
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changes in glycosylation pattern--> lONGER t1/2 for TSH
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Gonadotrophins in females
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FSH and LH
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FSH
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-Stimulates growth of granulosa cells of ovarian follicle
-controls aromatase(estradiol production) in these cells. |
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LH
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-stimulates ovarian theca cells to produce androgens(converted to estrogens by granulosa cells)
-LH surge in mid menstrual cycle triggers ovulation. |
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In males,FSH
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-Stimulates seminiferous tubules to produce sperm in conjuction with intratesticular T
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LH in males
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Stimulates T production in testicular Leydig cells.
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ACTH
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-39 A.A
-Synthetized from POMC -Stimulates GCS from adrenal cortex |
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Clinically,if you want to measure cortisol level in Cushing's pt,you would measure it in
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Evening where it should be low.
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GH
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-Somatotropin
-191 A.A -secretion is typically pulsatile -secretion changes over lifecourse(high in growing kids) |
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GH stimulates
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-cell div.
-cell growth -protein synthesis -release of fatty acids(protein sparing) |
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GH inhibits
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Glc uptake
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Effects of GH mediated thru
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IGF-1
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IGFs
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-somatomedins
-structurally similar to proinsulin -exert some insulin-like effects -IGF-1 is most important somatomedin(SM-C) |
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IGF-1
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-made in liver
-bound to circulating binding proteins -levels fairly constant(unlike GH) --> better to check IGF in acromegaly cases. |
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GH control
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-Somatostatin -vely controls
-somatostatin stops body growth -somato. analogues used to treat GH overproducing tumours |
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PRL
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-Peptide hormone(198 AA)
-Stimulates lactation in postpartum period -Pituitary doubles in size during pregnancy -NOT glycosylated |
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High levels of oestrogen
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Inhibits lactation.
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PRL regulation is under
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-ve control
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Dopamine is
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PRL inhibiting factor
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Dopamine released via
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Stalk.
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Big tumour compressing pit. stalk may cause
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Mild increase in PRL levels.
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Role of hypothalamus
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-Body weight set point
-Core body temp -sleep wake cycle -memory and behaviour -thirst -ANS |
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PVN
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oxytocin
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SON
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ADH
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Thirst and ADH secretion stimulated by
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Increase in blood osmolality
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ADH retains water by
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Translocating aquaporin channels to renal tubular cell membranes.
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Oxytocin
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-Peptide hormone
-causes contraction of smooth muscle in uterus to promote labour -Also stimulates milk release from mammary glands |
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Pituitary is
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Body's thermostat
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It is important for
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-response to stress
-regulation of metabolic rate -reg. of growth/body composition -essential for normal gonadal function,childbirth,lactation. |
