Endocrine Systems Flashcards
What is the hypothalamus
Regulatory centre for many vital functions that receives nerve fibres from all areas of the brain
What are the different hypothalamic neuropeptides that regulate different endocrine cell types and produced by the anterior pituitary? (7 different ones)
- PRH (hypothalamic tropic hormone)
- PIH (dopamine)
- TRH
- CRH
- GHRH
- GHIH (Somatostatin)
- GnRH (Gonadotrophin)
What does the posterior pituitary secrete
Oxytocin and ADH (vasopressin)
What does PIH (dopamine) release and what does the product do
Produces TSH which stimulates thyroid gland to produce TH
What does TRH release and what does the product do
Produces ACTH which stimulates adrenal context to produce cortisol
What does GHRH and GHIH somatostatin release and what does that product do?
Release growth hormone that stimulates somatomedin from liver and cells throughout the body
What does GnRH release and what does the product do?
Release LH for gonads (androgen male) and FSH (oestrogen- female)
What does prolactin do?
Stimulates mammary gland development and production of milk
Also suppresses LH and FSH production
Maintains lactation
How is prolactin activated
Sleep sucking stimulus
Hypothalamus releases TRH (cortisol) and dopamine (somatostatin)- increased oestrogen levels
Explain the process of Hypothalamic Pituitary Testicular Axis
- Hypothalamus Releases GnRH
- Acts on anterior pituritary to release FHS and LH from gonadotrophin
- FSH stimulates sperm production
- LH produces testosterone- negative feedback loop on GnRH and LH secretion
Explain the process of Hypothalamic Pituritary (H-P) ovary axis?
- Hypothalamus Releases GnRH
- Acts on anterior pituritary to release FHS and LH from gonadotrophin
- FSH stimulates OVARIES- further development of ovarian follies and secretion of oestrogen, progesterone and inhibins
- LH stimulates ovulation and corpus luteum- secretion of progesterone, oestrogen’s and inhibin
Explain the process of the HPT axis?
- Hypothalamus Releases Thyroid Hormone
- TRH (thyroid releasing hormone) stimulates anterior pituitary
- Releases TSH (thyroid stimulating hormone)- negative feedback loop to hypothalamus is made
- Thyroid produced into T3 and T4 which has a negative feedback loop to the anterior pituitary and hypothalamus
What are the bodies direct response to growth hormone
Antagonistic effects to insulin
Reduce glucose transport into cells
Increase Lipolysis
Increased amino acid transport into tissue to maximise muscle growth, decrease plasma amino acid, urea
What does IGF (insulin growth factor) promote?
Linear growth of bones- stimulates cartilage growth plates
Growth/cell proliferation of soft tissues and viscera
What are the three disorders of GH secretion and explain them?
Hypopituritaryism- too little GH in childhood- dwarfism
GH secreting pituritary tumour-
excess GH leading to giantism in child
excess GH leading to acromegaly in adult (thickening of bones and soft tissue)
How do you treat disorders of GH secretion
Hypopituritaryism- replacement therapy with human growth hormone
Excess GH-
surgical removal of pituritary and/or somatostatin analogues
Use GH receptor antagonists
What are the three hormones excreted by the adrenal gland
Adrenaline
Cortisol
Aldosterone
Adrenaline use?
Secretion in response to stress and exercise to increase the heart rate
Cortisol use?
Essential for adapting to stress, mobilises glucose and has anti-inflammatory action
Aldosterone use?
Maintains balance of sodium and potassium use in blood
Describe the Hypothalamic Pituitary Axis?
- Hypothalamus: corticotropin releasing hormones (CRH)
- Anterior Pituitary: stimulates release of corticotropin
- Corticotropin stimulates release of cortisol by adrenal cortex
(steroid meds inhibit this axis)
What is Cushing Syndrome?
Cortisol over production
What are the symptoms of Cushing Syndrome
Central obesity Thickening of skin Bruising (capillary fragility) Hypertension (aldosterone production) Muscle/bone wasting
What is addison’s disease
lack of adrenal hormones- aka cortisol
How do you treat addison disease?
Administration of mineralocorticoids or hydrocortisone to replace cortisol
What is the role of vasopressin (ADH)?
Reduces the water excretion by the kidney and acts as a potent vasoconstrictor to increase the osmotic pressure of blood
What does ADH do to the renal nephron
Increased permeability of renal distal convoluted tubule and collect ducts to water
More water is reabsorbed from tubule
Reduced urine output
Restoration of blood osmolarity and volume
How do you treat hypo secretion of ADH?
Replacement with desmopressin given as nasal spray or injection (IV, SC, IM)
