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Flashcards in Endocrine Systems Deck (28):

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)

1. PRH (hypothalamic tropic hormone)

2. PIH (dopamine)

3. TRH

4. CRH


6. GHIH (Somatostatin)

7. 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

1. Hypothalamus Releases GnRH

2. Acts on anterior pituritary to release FHS and LH from gonadotrophin

3. FSH stimulates sperm production

4. LH produces testosterone- negative feedback loop on GnRH and LH secretion


Explain the process of Hypothalamic Pituritary (H-P) ovary axis?

1. Hypothalamus Releases GnRH

2. Acts on anterior pituritary to release FHS and LH from gonadotrophin

3. FSH stimulates OVARIES- further development of ovarian follies and secretion of oestrogen, progesterone and inhibins

4. LH stimulates ovulation and corpus luteum- secretion of progesterone, oestrogen's and inhibin


Explain the process of the HPT axis?

1. Hypothalamus Releases Thyroid Hormone

2. TRH (thyroid releasing hormone) stimulates anterior pituitary

3. Releases TSH (thyroid stimulating hormone)- negative feedback loop to hypothalamus is made

4. 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 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?

1. Hypothalamus: corticotropin releasing hormones (CRH)

2. Anterior Pituitary: stimulates release of corticotropin

3. 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)