Week 8: Pituitary Flashcards
Identify the anatomy of pituitary
hangs down via pituitary stalk from hypothalamus
anterior portion resembles acinar endocrine tissue like the pancreas
posterior pituitary has neurons like the brain
Identify blood supply of the pituitary
The most vascular gland in the body g for g
Pituitary gland
Describe the feedback regulation of the anterior pituitary
Question
Pituitary gland
Endocrine rhythms
List of anterior pituitary hormones
6 listed
- ACTH
- Growth Hormone
- TSH
- LH
- FSH
- Prolactin
List of posterior pituitary hormones
2 listed
- Anti-diuretic hormone (Vasopressin)
- Oxytocin
Antidiuretic hormone structure and location
12 AA peptide released from neurosecretory elements in the posterior pituitary
Antidiuretic hormone AKA
ADH
or
vasopressin
ADH AKA
Antidiuretic hormone
or
Vasopressin
Stimulation of pituitary secretion of ADH
8 listed
- Plasma osmolality (hypothalamic osmo-receptors)
- Blood volume (Atrial & large vessel baroreceptors)
- Nausea
- Nicotine
- Morphine
- Angiotensin
- Hypoxia
- Hypercapnia
ADH MOA
Acts to stimulate free-water reabsorption in the distal renal tubules and collecting ducts through a cAMP-mediated mechanism thus inhibiting water diuresis
Vasopressin AKA
ADH
or
Anti-diuretic hormone
Source of ADH
produced by the Supra-optic nuclei of the hypothalamus
ADH functions
In the kidney
- decreases medullary flow
- increases water permeability in the distal tubules and collecting ducts (V2 receptors)
- Increases Na+, Cl-, K+ reabsorption
- Suppresses Renin secretion
In the Vasculature
- stimulates constriction of vascular smooth muscle (V1 receptors)
- increased blood pressure
- Increased SVR
Other actions
- Decreased hepatic gluconeogenesis
- Increased ACTH release (V3 receptors)
Describe the physiology of ADH secretion
What is polyuria?
Urine output > 3L/day in adults
What causes polyuria?
Not counting glucose-induced osmotic diuresis in uncontrolled DM there are 3 main causes
- Primary polydipsia
- Central Diabetes Insipidus
- Nephrogenic Diabetes Insipidus
What is Primary polydipsia?
- It is characterized by an increase in oral water intake
- This disorder is most often seen in middle-aged women and in patients with psychiatric illnesses including those taking a phenothiazine, which can lead to the sensation of a dry mouth
- Primary polydipsia can also be induced by hypothalamic lesions that directly affect the thirst center
Common drug that can cause Primary Polydipsia?
phenothiazine
What is Central DI?
- Associated with the deficient secretion of antidiuretic hormone (ADH)
- This condition is most often idiopathic or can be induced by trauma, pituitary surgery or hypoxic or ischemic encephalopathy
What is nephrogenic DI?
Characterized by normal ADH secretion but varying degrees of renal resistance to its water-retaining effect
Describe an approach to DI
First Aid approach to SIADH
Describe the relationship of plasma osmolality to ADH
Describe the relationship of urine osmolality to ADH levels
Describe hydration status and Plasma ADH and plasma osmolality
what is the most common type of polyuria?
DM
Lab findings on presentation of primary polydipsia
Water deprivation test results primary polydipsia
Desmospressin administration results in primary polydipsia
CDI AKA
Central diabetes insipidus
CDI Lab findings on presentation
Water deprivation tests in CDI
Desmopressin administration results in CDI
NDI AKA
Nephrogenic Diabetes Insipidus
Lab findings on presentation of NDI
Water deprivation test results of NDI
Desmopressin administration results of NDI
Clinical features of SIADH
Diagnostics of SIADH
SIADH AKA
Syndrome of inappropriate ADH Secretion
SIADH Characterized by
SIADH Etiologies
Treatment of SIADH
Oxytocin actions
- uterine contraction
- mammry gland enhancing milk ejection
- Men enhanced ejaculation
- Men and women enhanced orgasm
- inflammation
- enhanced wound healing
- feelings of generosity
- trust
- mothering instincts
- sexual arousal
- romantic attachment
- pair bonding
Oxytocin deficiencies
The anterior pituitary hormones and their stimuli
TSH stimulus
TRH from hypothalmus
TSH inhibition from the hypothalamus
Somatostatin
Prolactin inhibition from the hypothalamus
Dopamine
GH Stimulus from the hypothalamus
GNRH
TRH stimulates what in the posterior pituitary?
TSH secretion
&
Prolactin secretion
Prolactin Stimuli from the hypothalamus
TRH
LH Stimuli from the hypothalamus
GnRH
FSH Stimuli from the hypothalamus
GnRH
ACTH Stimuli from the hypothalamus
CRH
GnRH action on posterior pituitary
stimulates
LH
&
FSH
CRH action on posterior pituitary
Stimulates
ACTH
Dopamine actions on posterior pituitary
Inhibits
- Prolactin
GHRH actions on posterior pituitary
Stimulates
- GH