Lecture 18: Endocrinology

Question 1

Describe the differences between the 2 pituitary components

Answer 1

Anterior pituitary (adenoohypophysis): true endocrine gland, releases ACTH, FSH, LH, TSH, prolactin, and GH

Posterior pituitary (neurohypophysis): neural tissue. composed of axon terminals from the hypothalamus, release neurohormones: ADH and oxytocin. has pars nervosa: where neurohormones are relased to the capillary

Question 2

Describe the 2 hormones released by the posterior pituitary

Answer 2

signals sent via supraoptic and paravertebral nuclei to cause release.

ADH: increase water uptake in distal convoluted tubule and collecting duct. Also causes vasoconstriction. osmoreceptors in supraoptic/paraventricular nuclei and baroreceptors in carotid sinus, aorta, left atrium trigger ADH release due to osmolarity and blood pressure.

Oxytocin: produced by cell bodies in the hypothalamus. creates uterine contractions, milk let-down/expulsion.

Question 3

Describe the 6 hormones released by the anterior pituitary

Answer 3

Corticotropes: Corticotropin-releasing hormone –> ACTH (adrenocorticotropic hormone) –> cortisol, acts at liver

thyrotrope: thyrotropin releasing hormone (TRH) –> thyroid stimulating hormone (TSH) –> T3 and thyroxine, acts at thyroid
gonadotrope: gonadotropin-releasing hormone –> FSH/LH –> estrogen/progesterone/testosterone, acts at ovaries and testes
somatotrope: growth hormone releasing hormone –> growth hormone–> IGF-1
lactotrope: dopamine –> prolactin

Question 4

How does feedback control regulate hormone levels?

Answer 4

can be either short or long loop feedback, tropic hormone feeds back to hypothalamus, long loop feedback goes to pituitary gland and hypothalamus

Question 5

Describe the different levels of endocrine dysfunction

Answer 5

Primary: problem with the endocrine gland

secondary: problem with the anterior pituitary
tertiary: problem with the hypothalamus

Question 6

Describe what happens in gigantism, acromegaly, and dwarfism

Answer 6

gigantism: too much GH as child
acromegaly: too much GH after puberty, results in bone formation, arthritis
dwarfism: too little GH before puberty, lack of bone/muscle formation (in adults)

Question 7

Describe the regulation of food intake

Answer 7

Hunger center = lateral hypothalamic nuclei
satiety center = ventromedial hypothalamic nuclei
food intake determined by blood glucose levels, also pancreatic polypeptides, inhibited by cholecystokinins

Question 8

Describe the growth hormone pathway

Answer 8

somatostatins inhibit PKA, growth hormone releasing hormone stimulates PKA to create more GH. GH eventually causes IGF-1 to negative feedback onto PKA
increase blood glucose, decrease fat stores, promote protein synthesis