NEURO PHARMACOLOGY Flashcards
what is the three step pathway for the anterior pituitary gland
hypothalamus releases TRH which causes anterior pituitary to release TSH which releases thyroxine T4 from the thyroid gland
what are the symptoms of hypothyroidism
goitre
weight gain
cold intolerance
myxedema- puffy face due to deposition of sugar residues
what happens when it is a primary defect of the thyroid gland
the decrease in thyroxine will reduce its negative effect on the anterior pituitary increasing TSH
what happens if it is a secondary effect on the pituitary gland
TSH will fall and therefore thyroxine T4 falls as well
what are the two routes of drug therapy for hypothyroidism
Levothyroxine- converts T4 to T3 and so reduces the effect of T4 - oral medicine
Liothyronine-is a from of T3- intravenous injection
what are some side effects of thyroxine increase
weight loss diarrhoea vomitting angina heart failure
what happens in primary hyperthyroidism
thyroid stimulate a negative inhibitory feedback on the anterior pituitary to decrease TSH
what happens in secondary hyperthyroidism
TSH is elevated
how is the thyroid hormone synthesised
there is a sodium iodide co transporter which takes iodine into the lumen of the thyroid follicle. there is also thyroglobulin being synthesised in the cell and taken into the lumen. the thyroglobulin attaches to the MIT and DIT and T3 and T4 combine and this s does by the peroxidase enzyme. when TSH is released it causes the cutting of the thyroglobulin and the other parts which releases the T3 and T4
what is the treatment for hyperthyroidism
using competitive inhibitors of thyroperoxidase enzyme
how does the carbimazole drug work
it is a prodrug which inhibits thyroperoxidase and therefore the release of T3 and T4 bt takes 2-3 weeks to breakdown the plasma stores
how does the proythiouracil work
same as the carbimazole but also reduces the conversion of T4 to T3 which reduces the effect of the thyroid as there are more T3 receptors than T4.
what does block and replace mean
means the drug can completely stop th production of T3 and T4 causing hypothyroidism and then drugs are given to fix that
what are adverse effects of carbimazole and propylthyrouracil
neutropenia, rash and headache and joint pain
how are anterior pituitary adrenal hormones released
corticotrophin releasing hormone CRH releases ACTH from the anterior pituitary which is released to stimulate the release of cortisol from the adrenal cortex. cortisol can then inhibit ACTH in negative feedback.
